Journal articles: 'VLRE'

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Das, Sabyasachi, Masayuki Hirano, Jonathan Rast, and Max D. Cooper. "Hypothetical evolutionary models of the variable lymphocyte receptor genes in jawless vertebrates." Journal of Immunology 204, no. 1_Supplement (May 1, 2020): 92.35. http://dx.doi.org/10.4049/jimmunol.204.supp.92.35.

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Abstract Both humoral and cellular arms of an adaptive immune system are common to jawed and jawless vertebrates. However, whereas antigen recognition in the jawed vertebrates is mediated by immunoglobulin domain-based B cell receptors and T cell receptors, antigen recognition in jawless vertebrates is mediated by leucine-rich repeat (LRR) sequences in variable lymphocyte receptors (VLRs). Three types of VLR genes (VLRA, VLRB and VLRC) have been characterized in the extant jawless vertebrates, lampreys and hagfishes. VLRA- and VLRC-producing cells are T cell-like, while VLRB-producing cells are B cell-like. The VLRs are assembled by copying neighboring LRR sequences into the incomplete germline genes. In searching for the evolutionary origin of the VLRs we identified hypothetical VLR-like progenitors in amphioxus and tunicates (VLRPs). Molecular cladistics markers and phylogenetic analysis suggest the VLRPs are structurally more similar than other ancestral candidates to assembled VLRs. Based on our further analysis we propose alternative models for the origin of VLRs: (A) Among the VLRs, VLRB is most similar to the ancestral state and two subsequent duplication events gave rise to VLRC and VLRA-like genes; each of the three ancestral VLR genes in a common jawless vertebrate ancestor was then modified by cut and paste transposition of the internal DNA region encoding multiple LRR modules. (B) A cut and paste transposition event in an ancestral VLRB-like gene was followed by sequential duplication events which gave rise to VLRC and VLRA. In both models, subsequent duplications and fragmentations have generated a large array of genomic donor cassettes. Thus, after the emergence of the three VLR loci, each has undergone independent evolution.

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Li, Jianxu, Peng Guo, Masayuki Hirano, Brantley Herrin, and Max Cooper. "Cellular and molecular characterization of hagfish VLR-based adaptive immune system (VET2P.1043)." Journal of Immunology 192, no. 1_Supplement (May 1, 2014): 207.15. http://dx.doi.org/10.4049/jimmunol.192.supp.207.15.

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Abstract Jawless vertebrates have an alternative adaptive immune system in which variable lymphocyte receptors (VLR) are somatically diversified through recombinatorial assembly of leucine-rich repeat cassettes during lymphocyte development. Three VLR loci (VLRA, VLRB, and VLRC) have been defined in lampreys and each is expressed by a distinct lymphocyte population. Lamprey VLRA and VLRC are expressed by T-like lineages of lymphocytes, whereas VLRB is expressed by a B-like lineage of lymphocytes, much like αβ T, γδ T and B cells in jawed vertebrates. Recently we have revised the nomenclature for the hagfish VLRs by defining a third VLR gene. Here, monoclonal and polyclonal antibodies were generated against invariant residues of hagfish VLRA, VLRB and VLRC and these were used to identify VLR-bearing lymphocytes and their products. We found that hagfish VLRA, VLRB and VLRC are expressed by three separate lymphocyte populations. Size-exclusion chromatography and western blot analysis indicated that multivalent VLRB proteins are released into the circulation, which suggests that hagfish VLRB+ cells are B-cell like. In contrast, neither VLRA nor VLRC was detectable in the plasma, supporting the hypothesis that these two lymphocyte populations are T-cell like. The demonstration of three lymphocyte populations in both lampreys and hagfish suggests that this tripartite lymphocytic differentiation program already existed in a common ancestor of the two cyclostome lineages around 480 Mya.

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Guo, Peng, Lanier Gartland, Jianxu Li, Masayuki Hirano, Matthew Alder, Brantley Herrin, Jeffrey Sides, Masanori Kasahara, and Max Cooper. "Characterization of adaptive immune receptors in hagfish (170.13)." Journal of Immunology 186, no. 1_Supplement (April 1, 2011): 170.13. http://dx.doi.org/10.4049/jimmunol.186.supp.170.13.

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Abstract Instead of the immunoglobulin based antigen receptors of jawed vertebrates, jawless fish use variable lymphocyte receptors (VLRs) comprised of leucine-rich-repeat (LRR) segments for antigen recognition. Two VLR genes, VLRA and VLRB, have been identified in both lampreys and hagfish. A third VLR, so called VLRC was recently discovered in lampreys. An extensive VLR repertoire is generated through the insertion of diverse LRR sequences into an incomplete germline VLR gene by a gene conversion mechanism. Earlier studies of sea lampreys have shown that VLRB lymphocytes resemble B cells of jawed vertebrates, whereas VLRA lymphocytes are similar to T cells. For the present studies, monoclonal and polyclonal antibodies against the invariant stalk regions of hagfish VLRA and VLRB were produced to identify the VLR-bearing lymphocytes and their products. Flow cytometric analysis indicated that VLRA and VLRB are expressed by separate lymphocyte populations, with VLRA lymphocytes being the dominant population. Western blot and gel-filtration analyses indicated that hagfish VLRB antibodies are released into the circulation as multimeric proteins that are formed by non-covalent linkage of four or five disulfide-bonded VLRB dimers. Conversely, soluble VLRA is not detected in hagfish plasma. These findings indicate that distinctive T-like and B-like lineages are a common feature of the adaptive immune system in both lampreys and hagfish, in keeping with their monophyletic relationship.

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Hirano, Masayuki, Yoichi Sutoh, Sabyasachi Das, and Max Cooper. "Evolution of the AID/APOBEC family of cytidine deaminases in lampreys." Journal of Immunology 202, no. 1_Supplement (May 1, 2019): 73.1. http://dx.doi.org/10.4049/jimmunol.202.supp.73.1.

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Abstract Jawless vertebrates, lampreys and hagfish, have antigen receptors termed variable lymphocyte receptors (VLRs), which are composed of leucine-rich repeat (LRR) segments. Three types of VLR genes, VLRA, VLRB and VLRC, are somatically assembled in lymphocytes by a gene conversion-like process. In this process, flanking LRR gene cassettes are randomly and sequentially incorporated in a piece-wise fashion into an incomplete germline VLR gene to generate mature VLR genes. Activation-induced cytidine deaminase (AID), a member of AID/APOBEC family of cytidine deaminases (CDAs), is a well-known contributor to antigen receptor diversification in jawed vertebrates. We have only limited information about the molecular basis for the assembly and diversification of VLR genes in jawless vertebrates. Two AID/APOBEC-type CDAs, CDA1 and CDA2, have been reported in lampreys. We have previously shown that CDA1 is expressed in VLRA+ and VLRC+ lymphocytes, whereas the CDA2 is expressed in VLRB+ lymphocytes. VLRA and VLRC gene assembly coincide with expression of CDA1 in the gill tip region displaying thymus-equivalent features. Although CDA1 has been shown to induce C to U mutations in bacterial and yeast DNA, mutational activity of CDA2 has not been reported. To find molecules for VLRB gene assembly, we have searched the lamprey genomic database and our transcriptome data from lamprey lymphocytes, and have identified four splice variants of CDA2. Gene expression analysis indicated that all CDA2 splice variants are expressed only in VLRB+ cells. We also found that some of the CDA2 splice variants have AID-like mutational activity in the in vitro system. These results suggest the function and regulation of CDA2 splice variants in VLRB+ cells.

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Das, Sabyasachi, Jianxu Li, Masayuki Hirano, Jonathan Rast, and Max D. Cooper. "Evolutionary modification of the VLR-based adaptive immune system in jawless vertebrates: Functional implications." Journal of Immunology 200, no. 1_Supplement (May 1, 2018): 59.2. http://dx.doi.org/10.4049/jimmunol.200.supp.59.2.

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Abstract The three types of variable lymphocyte receptor genes, VLRA, VLRB and VLRC, in the extant jawless vertebrates, encode antigen receptors, the remarkably diverse repertoire of which is generated by insertion of neighboring leucine rich repeat (LRR) sequences into the incomplete germline genes. In both lampreys and hagfish, the B-cell like VLRB+ cells differentiate into VLRB-secreting plasma cells, whereas the αβ and γδ T cell-like VLRA+ and VLRC+ cells express their VLR products solely as cell surface proteins. However, in comparative studies of lampreys and hagfish, we find that remarkable functional differences have evolved in these lymphocyte lineages. In contrast with their striking predominance in lampreys, the VLRB+ cells constitute a minor lymphocyte population in hagfish, and the VLRC+ cells are predominate. Notably the germline VLRB gene in hagfish contains a short non-coding intervening sequence, whereas the VLRB genes in sea lampreys and Japanese lampreys have very long intervening sequences which contain multiple transposable elements that may influence VLRB expression. In keeping with the relative low numbers of hagfish VLRB+ cells, antibody responses to a model immunogen, sheep erythrocytes, are much less robust in hagfish than in lampreys. Thus, even though the fundamental genetic program for differentiation of two prototypic T-like lymphocyte lineages and one B-like lineage is conserved in both jawless and jawed vertebrates, the genetic programs used for fine tuning of the VLR-based immunity have undergone notable independent evolutionary changes in lampreys and hagfish over the past ~480 million years.

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Morimoto, Ryo, Connor P. O’Meara, Stephen J. Holland, Inês Trancoso, Ahmed Souissi, Michael Schorpp, Danièle Vassaux, et al. "Cytidine deaminase 2 is required for VLRB antibody gene assembly in lampreys." Science Immunology 5, no. 45 (March 13, 2020): eaba0925. http://dx.doi.org/10.1126/sciimmunol.aba0925.

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The antibodies of jawless vertebrates consist of leucine-rich repeat arrays encoded by somatically assembled VLRB genes. It is unknown how the incomplete germline VLRB loci are converted into functional antibody genes during B lymphocyte development in lampreys. In Lampetra planeri larvae lacking the cytidine deaminase CDA2 gene, VLRB assembly fails, whereas the T lineage–associated VLRA and VLRC antigen receptor gene assemblies occur normally. Thus, CDA2 acts in a B cell lineage–specific fashion to support the somatic diversification of VLRB antibody genes. CDA2 is closely related to activation-induced cytidine deaminase (AID), which is essential for the elaboration of immunoglobulin gene repertoires in jawed vertebrates. Our results thus identify a convergent mechanism of antigen receptor gene assembly and diversification that independently evolved in the two sister branches of vertebrates.

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Li, Jianxu, Brantley Herrin, Peng Guo, and Max Cooper. "Analysis of the assembly mechanism for multimeric lamprey VLRB antibodies (43.19)." Journal of Immunology 184, no. 1_Supplement (April 1, 2010): 43.19. http://dx.doi.org/10.4049/jimmunol.184.supp.43.19.

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Abstract Instead of the immunoglobulin-type antigen receptors in jawed vertebrates, the surviving jawless vertebrates use variable lymphocyte receptors (VLRs) that are constructed with variable leucine-rich repeat (LRR) sequences to recognize antigens. Two VLR genes in lamprey and hagfish are somatically assembled during lymphopoiesis using a gene conversion-like mechanism in which highly diverse LRR flanking sequences are copied in serial fashion to construct mature VLRs. Lamprey have been shown to secrete polymeric VLRB antibodies that consist of 8-12 identical disulfide-linked subunits. The overall structure of VLRB antibodies resembles that of IgM antibodies in that both are composed of 4-6 dimers. Previous studies have shown that eight cysteines in the C-terminal hydrophobic region are involved in assembly of the multivalent VLRB antibodies through formation of disulfide bonds. We have characterized a panel of VLRB Cys to Ser mutants using site-directed mutagenesis to determine which cysteines are used for disulfide bond formation and VLRB polymerization. Two or more disulfide bonds were found to be essential for VLRB dimerization and polymerization. Our data further suggest that the carboxy-terminal cysteines 5, 6, 7, and 8 form the cornerstone for VLRB dimerization and polymerization, whereas cysteines 1, 2, 3, and 4 contribute to the stability of the polymer structure.

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Hassan, Khan M. A., John D. Hansen, Brantley R. Herrin, and Chris T. Amemiya. "Generation of Lamprey Monoclonal Antibodies (Lampribodies) Using the Phage Display System." Biomolecules 9, no. 12 (December 12, 2019): 868. http://dx.doi.org/10.3390/biom9120868.

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The variable lymphocyte receptors (VLRs) consist of leucine rich repeats (LRRs) and comprise the humoral antibodies produced by lampreys and hagfishes. The diversity of the molecules is generated by stepwise genomic rearrangements of LRR cassettes dispersed throughout the VLRB locus. Previously, target-specific monovalent VLRB antibodies were isolated from sea lamprey larvae after immunization with model antigens. Further, the cloned VLR cDNAs from activated lamprey leukocytes were transfected into human cell lines or yeast to select best binders. Here, we expand on the overall utility of the VLRB technology by introducing it into a filamentous phage display system. We first tested the efficacy of isolating phage into which known VLRB molecules were cloned after a series of dilutions. These experiments showed that targeted VLRB clones could easily be recovered even after extensive dilutions (1 to 109). We further utilized the system to isolate target-specific “lampribodies” from phage display libraries from immunized animals and observed an amplification of binders with relative high affinities by competitive binding. The lampribodies can be individually purified and ostensibly utilized for applications for which conventional monoclonal antibodies are employed.

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Yu, Cuiling, Götz Ehrhardt, and Max Cooper. "A lamprey monoclonal VLR antibody against human CD5 (65.34)." Journal of Immunology 186, no. 1_Supplement (April 1, 2011): 65.34. http://dx.doi.org/10.4049/jimmunol.186.supp.65.34.

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Abstract The recently identified VLRB antibodies of the agnathan sea lamprey use highly variable leucine-rich repeats (LRRs) that assume a solenoid shape to bind antigens. Solved structures of monoclonal VLRB antibodies complexed to the H-trisaccharide or HEL show that antigens bind to variable residues in the beta-sheets located on the concave surface of specific VLRB antibodies. In this study we screened clones of a lamprey VLR cDNA expression library prepared from animals immunized with human CD4+ T cells to identify a monoclonal VLRB antibody (T32) that bound to human T lymphocytes, but not mouse T cells. Modulation of the expression levels of the TCR/CD3 complex by mouse antibodies did not affect VLR T32 binding. Staining of T cells, tonsilar B cells and malignant B-CLL cells with VLRB T32 and a mouse anti-CD5 mAb (clone UCHT2) demonstrated a diagonal co-staining pattern for each population of the test cells. Transfection of the CD5-negative OCI-Ly3 cell line with a human CD5 cDNA construct resulted in VLR T32 binding of transfected but not of untransfected cells. Staining of CD5+ cells by VLR T32 was not blocked by pre-incubation with the mouse UCHT2 anti-CD5 mAb, which suggests that they recognizes different CD5 epitopes. We conclude that lamprey monoclonal VLR antibodies offer useful alternatives to conventional antibodies for biomedical purposes.

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Moot, Robert, Sunil Raikar, Lauren C. Fleischer, David McCarty, Melissa Querrey, Christopher B. Doering, and H. Trent Spencer. "Expanding the Ligand Binding Repertoire of Chimeric Antigen Receptors Using Lamprey Variable Lymphocyte Receptors." Blood 126, no. 23 (December 3, 2015): 3244. http://dx.doi.org/10.1182/blood.v126.23.3244.3244.

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Abstract Although chimeric antigen receptors (CARs) are yielding promising clinical results, the technology remains limited by the availability of conjugate cancer cell target antigens. As a means to increase both the identification of cancer cell target antigens and simultaneously generate unique single chain binding domain structures we utilized the immune system of jawless vertebrates. Sea lamprey possess an adaptive immune system primarily characterized by variable lymphocyte receptors (VLRs) as membrane bound and soluble immune effectors analogous but not homologous to immunoglobulins (Ig). VLRs have a fundamentally different structure and geometry than Ig-based antibodies while still demonstrating high degrees of specificity and avidity. Additionally, VLRs exist naturally as single chain structures with their variable region consisting of multiple assembled repeating sequences termed leucine rich repeats. These repeats can be directly inserted onto a CAR scaffold by genetic engineering. To test this platform technology, a yeast display method previously described (Tasumi et al., PNAS 2009; Xu et al., Humana press 2011) was used as a means of assaying and selecting appropriate VLRs. VLRs meeting the set criteria are sequenced and cloned into a lentiviral vector (LV) CAR transgene cassette plasmid. We constructed a CAR containing a well characterized VLR specific for the B cell receptor of a murine B cell leukemia (BCL) cell line. The CAR design incorporates the anti-BCL-VLR, Myc tag, CD28 transmembrane domain, and the intracellular CD3ζ signaling domain. SIN VLR-CAR LV was produced at high titer (~1x108) and used to transduce Jurkat cells. Transduced Jurkat cells showed successful CAR protein expression confirmed via Western Blot as well as persistent surface CAR expression for over 2 months with cell viability remaining over 85%. To determine whether the VLR was capable of signaling through the CAR, transduced Jurkat cells were incubated with the BCL cell line expressing the target B cell receptor. Using this assay, we demonstrated potent T cell activation via the VLR-CAR. CAR expressing T-cells demonstrated activation in ~80% of the cells. Furthermore, NK-92 cells expressing the VLR-CAR demonstrated an ability to recognize and kill BCL cells at target to effector ratios as low as 1:1, with 30% target cell killing. Little to no killing was observed with a control B cell line. Additionally, we created a CAR using a published VLR sequence targeting the human surface antigen CD5 (Yu et al., J. Immunol Methods, 2012). CD5 is primarily a T-cell marker, thus an anti-CD5-VLRCAR could be potentially used to target T-cell malignancies. Jurkat cells were transduced with high titer SIN VLR-CAR LV at various MOIs. Since Jurkat cells express CD5 on their surface, we tested the different transduced groups for self-activation at several time points. The corresponding transduced copy number was determined using quantitative PCR. The degree of activation directly correlated with the LV copy number, with highest activation being seen when the MOI approach 50, with >60% highly activated cells. No activation was observed in the GFP control groups. Additionally, we engineered three different CAR constructs consisting of two CD5 VLRs connected by either a helical linker with a 180° rotation, a helical linker with a 360° rotation, or a non-rigid linker allowing for flexibility among the two VLRs. Transduced Jurkat cells expressing the double CD5-VLR CARs indicated, via flow cytometry, that linking two VLRs does not provide any benefit in terms of activation compared to the single CD5-VLR-CAR. Current testing includes the use of NK-92 cells expressing the anti-CD5-VLR-CAR against T cell leukemia cell lines. Collectively, these results show that VLRs can be used to increase the repertoire of CAR binding motifs. Furthermore, these data suggest that VLRs provide both a unique and effective method for activating CAR-T cells and can expand the number and variety of antigens that may be targeted. Disclosures Doering: Expression Therapeutics: Equity Ownership; Bayer Healthcare: Consultancy, Honoraria, Research Funding.

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Collins, Bernard C., Hiro Nakahara, Sharmistha Acharya, Max D. Cooper, Brantley R. Herrin, and Ian A. Wilson. "Crystal structure of an anti-idiotype variable lymphocyte receptor." Acta Crystallographica Section F Structural Biology Communications 73, no. 12 (November 14, 2017): 682–87. http://dx.doi.org/10.1107/s2053230x1701620x.

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Variable lymphocyte receptors (VLRs), the leucine-rich repeat (LRR)-based antigen receptors of jawless fish, have great utility in a wide variety of biochemical and biological applications, similar to classical Ig-based antibodies. VLR-based reagents may be particularly useful when traditional antibodies are not available. An anti-idiotype lamprey VLR, VLR39, has previously been identified that recognizes the heavy-chain CDR3 of the B-cell receptor (BCR) of a leukemic clone from a patient with chronic lymphocytic leukemia (CLL). VLR39 was used successfully to track the re-emergence of this clone in the patient following chemotherapy. Here, the crystal structure of VLR39 is presented at 1.5 Å resolution and compared with those of other protein-specific VLRs. VLR39 adopts a curved solenoid fold and exhibits substantial structural similarity to other protein-binding VLRs. VLR39 has a short LRRCT loop that protrudes outwards away from the concave face and is similar to those of its protein-specific VLR counterparts. Analysis of the VLR39–BCR interaction by size-exclusion chromatography and biolayer interferometry using the scFv version of the BCR confirms that VLR39 recognizes the BCR Fv region. Such VLR-based reagents may be useful for identifying and monitoring leukemia in CLL patients and in other clinical diagnostic assays.

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Tasumi, S., C. A. Velikovsky, G. Xu, S. A. Gai, K. D. Wittrup, M. F. Flajnik, R. A. Mariuzza, and Z. Pancer. "High-affinity lamprey VLRA and VLRB monoclonal antibodies." Proceedings of the National Academy of Sciences 106, no. 31 (July 22, 2009): 12891–96. http://dx.doi.org/10.1073/pnas.0904443106.

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Boehm, Thomas, Masayuki Hirano, Stephen J. Holland, Sabyasachi Das, Michael Schorpp, and Max D. Cooper. "Evolution of Alternative Adaptive Immune Systems in Vertebrates." Annual Review of Immunology 36, no. 1 (April 26, 2018): 19–42. http://dx.doi.org/10.1146/annurev-immunol-042617-053028.

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Adaptive immunity in jawless fishes is based on antigen recognition by three types of variable lymphocyte receptors (VLRs) composed of variable leucine-rich repeats, which are differentially expressed by two T-like lymphocyte lineages and one B-like lymphocyte lineage. The T-like cells express either VLRAs or VLRCs of yet undefined antigen specificity, whereas the VLRB antibodies secreted by B-like cells bind proteinaceous and carbohydrate antigens. The incomplete VLR germline genes are assembled into functional units by a gene conversion–like mechanism that employs flanking variable leucine-rich repeat sequences as templates in association with lineage-specific expression of cytidine deaminases. B-like cells develop in the hematopoietic typhlosole and kidneys, whereas T-like cells develop in the thymoid, a thymus-equivalent region at the gill fold tips. Thus, the dichotomy between T-like and B-like cells and the presence of dedicated lymphopoietic tissues emerge as ancestral vertebrate features, whereas the somatic diversification of structurally distinct antigen receptor genes evolved independently in jawless and jawed vertebrates.

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Umlauf, Benjamin J., Paul A. Clark, Jason M. Lajoie, Julia V. Georgieva, Samantha Bremner, Brantley R. Herrin, John S. Kuo, and Eric V. Shusta. "Identification of variable lymphocyte receptors that can target therapeutics to pathologically exposed brain extracellular matrix." Science Advances 5, no. 5 (May 2019): eaau4245. http://dx.doi.org/10.1126/sciadv.aau4245.

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Diseases that lead to blood-brain barrier (BBB) disruption will pathologically expose normally inaccessible brain extracellular matrix (ECM) to circulating blood components. Therefore, we hypothesized that brain ECM-targeting moieties could specifically target the disrupted BBB and potentially deliver therapies. Variable lymphocyte receptors (VLRs) that preferentially associate with brain ECM were identified from an immune VLR library via yeast surface display biopanning coupled with a moderate throughput ECM screen. Brain ECM binding of VLR clones to murine and human brain tissue sections was confirmed. After systemic administration, P1C10, the lead brain ECM-targeting VLR candidate, specifically accumulated in brains with mannitol-disrupted BBB and at disrupted BBB regions in two different intracranial glioblastoma models. We also demonstrate P1C10’s ability to deliver doxorubicin-loaded liposomes, leading to significantly improved survival in glioblastoma-bearing mice. Thus, VLRs can be used to selectively target pathologically exposed brain ECM and deliver drug payloads.

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Englezos, Peter, Nicolas Kalogerakis, and P. Raj Bishnoi. "Simultaneous regression of binary VLE and VLLE data." Fluid Phase Equilibria 61, no. 1-2 (January 1990): 1–15. http://dx.doi.org/10.1016/0378-3812(90)90001-4.

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Li, Qingwei, Fenfang Wu, Liyong Chen, and Xu Qiao. "The cytolytic effects of lamprey variable lymphocyte receptors (172.7)." Journal of Immunology 188, no. 1_Supplement (May 1, 2012): 172.7. http://dx.doi.org/10.4049/jimmunol.188.supp.172.7.

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Abstract Lamprey uses variable lymphocyte receptors (VLR), a leucine-rich-repeat (LRR)-based receptors, for antigen recognition instead of the immunoglobulin (Ig)-based receptors used in vertebrates. We report herein the cytolytic effects of antigen stimulated sera in Japanese lamprey (Lampetra japonica) for bacteria and tumor cells. We demonstrated that the antigen-specific VLRB antibodies mediates cytotoxicity, and the humoral immunity based cell lysis involved deposition of VLRB on the surface of target cells with formation of pore-like structures that disrupt cell wall integrity. Our finding provides evidence of role of VLRB in lamprey humoral immunity, and offers new insight into the evolution of adaptive immunity.

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Laursen, Torben, Peter Rasmussen, and Simon Ivar Andersen. "VLE and VLLE Measurements of Dimethyl Ether Containing Systems." Journal of Chemical & Engineering Data 47, no. 2 (March 2002): 198–202. http://dx.doi.org/10.1021/je010154+.

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Holland, Stephen J., Lesley M. Berghuis, Justin J. King, Lakshminarayan M. Iyer, Katarzyna Sikora, Heather Fifield, Sarah Peter, et al. "Expansions, diversification, and interindividual copy number variations of AID/APOBEC family cytidine deaminase genes in lampreys." Proceedings of the National Academy of Sciences 115, no. 14 (March 19, 2018): E3211—E3220. http://dx.doi.org/10.1073/pnas.1720871115.

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Cytidine deaminases of the AID/APOBEC family catalyze C-to-U nucleotide transitions in mRNA or DNA. Members of the APOBEC3 branch are involved in antiviral defense, whereas AID contributes to diversification of antibody repertoires in jawed vertebrates via somatic hypermutation, gene conversion, and class switch recombination. In the extant jawless vertebrate, the lamprey, two members of the AID/APOBEC family are implicated in the generation of somatic diversity of the variable lymphocyte receptors (VLRs). Expression studies linked CDA1 and CDA2 genes to the assembly of VLRA/C genes in T-like cells and the VLRB genes in B-like cells, respectively. Here, we identify and characterize several CDA1-like genes in the larvae of different lamprey species and demonstrate that these encode active cytidine deaminases. Structural comparisons of the CDA1 variants highlighted substantial differences in surface charge; this observation is supported by our finding that the enzymes require different conditions and substrates for optimal activity in vitro. Strikingly, we also found that the number of CDA-like genes present in individuals of the same species is variable. Nevertheless, irrespective of the number of different CDA1-like genes present, all lamprey larvae have at least one functional CDA1-related gene encoding an enzyme with predicted structural and chemical features generally comparable to jawed vertebrate AID. Our findings suggest that, similar to APOBEC3 branch expansion in jawed vertebrates, the AID/APOBEC family has undergone substantial diversification in lamprey, possibly indicative of multiple distinct biological roles.

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Yu, Xiaoli, Fenfang Wu, Liyong Chen, Xin Liu, Huaying Wang, Peng Su, Yinglun Han, et al. "Lamprey variable lymphocyte receptors mediate complement-dependent cytotoxicity (172.20)." Journal of Immunology 188, no. 1_Supplement (May 1, 2012): 172.20. http://dx.doi.org/10.4049/jimmunol.188.supp.172.20.

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Abstract An alternative adaptive immune system is present in the most basal vertebrates, lampreys and hagfish, the only surviving jawless vertebrates. These eel-like fish use leucine-rich-repeat (LRR)-based receptors, called variable lymphocyte receptors (VLRs), for antigen recognition instead of the immunoglobulin (Ig)-based receptors used in jawed vertebrates. We showed that in Japanese lamprey (Lampetra japonica), antigen-specific VLRB antibodies interact with C1q-like and C3 proteins to mediate complement-dependent cytotoxicity for bacteria and tumor cells. The immune based lysis involved deposition of VLRB and C1q-like protein complex on the surface of target cells, activation of C3, and ultimate disruption of cell wall integrity. The demonstration of functional interaction between VLRB and complement components in lamprey provides evidence for the emergence of cooperative innate and adaptive immune responses at a pivotal point in vertebrate evolution, before or in parallel with the evolution of Ig-based antibodies and the classical complement activation pathway.

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J Umlauf, Benjamin, Paul A Clark, Jason M Lajoie, Julia V Georgieva, Samantha Bremner, Brantley R Herrin, Eric V Shusta, and John S Kuo. "SCIDOT-05. DEVELOPING VARIABLE LYMPHOCYTE RECEPTORS THAT TARGET PATHOLOGICALLY EXPOSED NEURAL ECM TO TREAT GLIOBLASTOMA." Neuro-Oncology 21, Supplement_6 (November 2019): vi273. http://dx.doi.org/10.1093/neuonc/noz175.1146.

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Abstract INTRODUCTION The median survival of gliobastoma (GBM) patients remains less than two years despite aggressive treatments. Current targeted GBM therapies demonstrate initial therapeutic benefit; however, patients relapse due to therapeutic resistance and failure to eliminate GBM cells at the invasive margin. Therefore, we propose a two-prong approach: first, target pathologic disruption of the blood brain barrier (BBB) via exposure of neural ECM rather than disease markers to overcome therapy-resistant GBM; and second, designing therapeutic payloads that extracellularly spread throughout the tumor volume. METHODS Variable Lymphocyte Receptors (VLRs, a lamprey-derived antigen recognition system) were identified with high specificity for neural ECM. Candidate VLRs underwent further refinement using ex vivo tissue staining. Utilizing pathologic disruption of BBB as an approach for targeting GBM was confirmed in vivo with intracranial murine glioblastoma models. Finally, an immunogenic peptide was attached via a cleavable linker to the neural ECM binding VLRs for conditional release extracellularly to spread throughout the tumor. RESULTS The lead neural ECM-binding VLR candidate, named P1C10, demonstrates diffuse binding to parenchymal neural ECM, without detectable binding to other tissues. P1C10 demonstrates nanomolar affinity for neural ECM, and preferentially accumulates in intracranial GL261 and U87 murine GBM models. Finally, P1C10-targeted doxorubicin-loaded liposomes significant increased survival of mice with intracranial GBM. In additional studies, treating murine GBM models with a P1C10 VLR linked to an immunogenic peptide reduced GBM proliferation and increased infiltration of cytotoxic T cells. CONCLUSIONS We present proof-of-concept demonstration for targeting intracranial GBM via neural ECM exposed at pathological BBB disrupted sites. Additionally, P1C10 neural ECM-targeting VLR delivers chemotherapy-loaded nanoparticles and immunogenic peptides designed to spread extracellularly throughout the tumor. Thus, this novel strategy links a physiological ECM targeting scheme with extracellular-released therapeutics to treat primary GBM, and has potential for delivering therapies to other CNS diseases with pathological BBB.

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Sadhukhan, Samir K., Chayanika Bose, Debashis Saha, and Asis Chattopadhyay. "Analytical Study of a Dual Pointer Based Strategy for Location Update Using Node B Sojourn Time in UMTS Networks." International Journal of Business Data Communications and Networking 14, no. 2 (July 2018): 44–70. http://dx.doi.org/10.4018/ijbdcn.2018070104.

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This article describes how Universal Mobile Telecommunications System (UMTS) is a 3G cellular network standard that uses location update (LU) and location search (LS) for mobility management. LU requires update in two location registers (LRs) - home LR (HLR) and visiting LR (VLR) - where one HLR controls multiple VLRs. HLR updates (HLRUs) are costlier, and hence should be less frequent. To achieve it, VLRs maintain a forward pointer chain among themselves, instead of updating HLR. But a lengthy chain increases LS cost considerably. So, we propose to restrict the chain length to unity by introducing an additional backward pointer, and using the concept of root-VLR similar to the home agent concept of mobile IP. We derive a closed form solution to approximate the average HLRUs per call, and substantiate it by simulation in cases of both random and diurnal mobilities. Results reveal substantial reduction in HLRUs per call, even when call-to-mobility ratio is high. UMTS operators will find the analysis worth considering, while managing their 3G networks.

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Chan, Justin T. H., Yanling Liu, Srijit Khan, Jonathan R. St-Germain, Chunxia Zou, Leslie Y. T. Leung, Judi Yang, et al. "A tyrosine sulfation–dependent HLA-I modification identifies memory B cells and plasma cells." Science Advances 4, no. 11 (November 2018): eaar7653. http://dx.doi.org/10.1126/sciadv.aar7653.

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Memory B cells and plasma cells are antigen-experienced cells tasked with the maintenance of humoral protection. Despite these prominent functions, definitive cell surface markers have not been identified for these cells. We report here the isolation and characterization of the monoclonal variable lymphocyte receptor B (VLRB) N8 antibody from the evolutionarily distant sea lamprey that specifically recognizes memory B cells and plasma cells in humans. Unexpectedly, we determined that VLRB N8 recognizes the human leukocyte antigen–I (HLA-I) antigen in a tyrosine sulfation–dependent manner. Furthermore, we observed increased binding of VLRB N8 to memory B cells in individuals with autoimmune disorders multiple sclerosis and systemic lupus erythematosus. Our study indicates that lamprey VLR antibodies uniquely recognize a memory B cell– and plasma cell–specific posttranslational modification of HLA-I, the expression of which is up-regulated during B cell activation.

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Laursen, Torben, and Simon Ivar Andersen. "VLE and VLLE Measurements of Dimethyl Ether Containing Systems. 2." Journal of Chemical & Engineering Data 48, no. 5 (September 2003): 1085–87. http://dx.doi.org/10.1021/je025599s.

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Yu, Cuiling, Brantley Herrin, David Jaye, Max Cooper, and Götz Ehrhardt. "A lamprey monoclonal VLR antibody recognizes a novel plasma cell antigen (P3020)." Journal of Immunology 190, no. 1_Supplement (May 1, 2013): 114.11. http://dx.doi.org/10.4049/jimmunol.190.supp.114.11.

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Abstract Variable lymphocyte receptor B (VLRB) antibodies of the jawless sea lamprey are composed of leucine-rich repeat (LRR) units instead of the Ig-based units of conventional mammalian antibodies. Structural analyses of three monoclonal VLRB antibodies paired with their cognate antigens indicate that antigens bind to variable residues in the beta-sheets located on the inner concave surface of the solenoid VLRB protein and to a flexible loop structure protruding from the C-terminal LRR. We recently demonstrated that VLRB antibodies can be used in standard laboratory techniques such as flow immunocytometry, western blotting, immunoprecipitation and mass spectrometry-based protein identification. In an effort to identify novel biomarkers on human plasma cells, we screened a VLRB library generated from lamprey larvae immunized with human bone marrow of multiple myeloma patient and isolated a monoclonal VLRB antibody (MM3) that selectively recognized plasma cells from myeloma patients, normal individuals and two non-human primates, Rhesus macaque and Sooty mangabey monkeys. Surprisingly, screening of a diverse panel of human cell lines indicated expression of the MM3 antigen by two of nine B cell lines, but not by plasmacytoma cell lines. Trypsin and periodate sensitivity of the MM3 epitope suggested the glycoprotein nature of the cell membrane antigen. We conclude that the recombinant VLR MM3 antibody recognizes a novel plasma cell marker.

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Das, S., J. Li, S. J. Holland, L. M. Iyer, M. Hirano, M. Schorpp, L. Aravind, M. D. Cooper, and T. Boehm. "Genomic donor cassette sharing during VLRA and VLRC assembly in jawless vertebrates." Proceedings of the National Academy of Sciences 111, no. 41 (September 16, 2014): 14828–33. http://dx.doi.org/10.1073/pnas.1415580111.

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Rim, J. M., and D. J. Han. "Process development for nitrogen removal of swine waste." Water Science and Technology 42, no. 3-4 (August 1, 2000): 239–46. http://dx.doi.org/10.2166/wst.2000.0386.

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This research aims to effectively remove nutrients in swine waste by a combined process of upflow anaerobic sludge blanket (UASB) and biofilm process. For effective removal of nutrients, both anaerobic and anoxic reactors were constructed consecutively within a single anaerobic/denitrification (SAD) reactor to which aerobic reactor for nitrification was connected. The total reactor was operated within range of 0.4 to 3.1 kg COD/m3/d of organics volumetric loading rate (VLR) and the removal rates of TCOD were 80 to 95%. Ammonia nitrogen was removed over 90% in VLR of less than 0.1 kg N/m3/d but removal rate was reduced to 70% in VLR of over 0.6 kg N/m3/d. However, complete denitrification was observed in all VLRs, which might be due to the maintenance of optimal temperature, sufficient inner carbon source, and use of NOx as an electron acceptor by anaerobic and anoxic microorganisms.

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Wyczesany, Andrzej. "Simulation of N-Propanol Dehydration Process Via Heterogeneous Azeotropic Distillation Using the NRTL Equation." Chemical and Process Engineering 38, no. 1 (March 1, 2017): 163–75. http://dx.doi.org/10.1515/cpe-2017-0013.

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Abstract Numerical values of the NRTL equation parameters for calculation of the vapour - liquid - liquid equilibria (VLLE) at atmospheric pressures have been presented for 5 ternary mixtures. These values were fitted to the experimental VLLE and vapour - liquid equilibrium (VLE) data to describe simultaneously, as accurately as possible, the VLE and the liquid - liquid equilibria (LLE). The coefficients of this model called further NRTL-VLL were used for simulations of n-propanol dehydration via heterogeneous azeotropic distillation. The calculations performed by a ChemCAD simulator were done for 4 mixtures using hydrocarbons, ether and ester as an entrainer. In majority simulations the top streams of the azeotropic column had composition and temperature similar to the corresponding experimental values of ternary azeotropes. The agreement between the concentrations of both liquid phases formed in a decanter and the experimental values of the LLE was good for all four simulations. The energy requirements were the most advantageous for the simulation with di-npropyl ether (DNPE) and isooctane. Simulations were performed also for one mixture using the NRTL equation coefficients taken from the ChemCAD database. In that case the compositions of the liquid organic phases leaving the decanter differed significantly from the experimental LLE data.

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Li, Jun, Qinghua Ma, Huaixiu Liu, Xiaoping Song, Yue Pang, Peng Su, Feng Sun, et al. "Complement component C1q plays a critical role in VLRA/VLRC-mediated immune response." Developmental & Comparative Immunology 111 (October 2020): 103750. http://dx.doi.org/10.1016/j.dci.2020.103750.

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Hang, Kaiyu, Walter G. Bircher, Andrew S. Morgan, and Aaron M. Dollar. "Manipulation for self-Identification, and self-Identification for better manipulation." Science Robotics 6, no. 54 (May 19, 2021): eabe1321. http://dx.doi.org/10.1126/scirobotics.abe1321.

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The process of modeling a series of hand-object parameters is crucial for precise and controllable robotic in-hand manipulation because it enables the mapping from the hand’s actuation input to the object’s motion to be obtained. Without assuming that most of these model parameters are known a priori or can be easily estimated by sensors, we focus on equipping robots with the ability to actively self-identify necessary model parameters using minimal sensing. Here, we derive algorithms, on the basis of the concept of virtual linkage-based representations (VLRs), to self-identify the underlying mechanics of hand-object systems via exploratory manipulation actions and probabilistic reasoning and, in turn, show that the self-identified VLR can enable the control of precise in-hand manipulation. To validate our framework, we instantiated the proposed system on a Yale Model O hand without joint encoders or tactile sensors. The passive adaptability of the underactuated hand greatly facilitates the self-identification process, because they naturally secure stable hand-object interactions during random exploration. Relying solely on an in-hand camera, our system can effectively self-identify the VLRs, even when some fingers are replaced with novel designs. In addition, we show in-hand manipulation applications of handwriting, marble maze playing, and cup stacking to demonstrate the effectiveness of the VLR in precise in-hand manipulation control.

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Mashinyan, Alexander A., Nina V. Kochergina, Olga V. Biryukova, and Dzhamil Dzh Babayev. "Virtual laboratory work in physics at a technical university." Perspectives of Science and Education 58, no. 4 (September 1, 2022): 209–24. http://dx.doi.org/10.32744/pse.2022.4.13.

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Introduction. In the post-pandemic period, when all universities are switching to full–time education, the problem of the meaning and place of virtual laboratory work (hereinafter referred to as VLR) in physics at a technical university has arisen in a new way. The following questions have become relevant: about the frequency of the use of different types of VLR in universities in Russia and abroad; about the effectiveness of their use for the formation of practical and intellectual experimental skills; about methods and means of training that allow to increase the effectiveness of the formation of experimental skills when performing VLR in physics. Materials and methods. Our research is based on the methodology of conducting a physical experiment and the requirements of digital learning. The methods of analysis of modern sources on the problem of the use of VLR in physics, questioning of teachers and testing of students on the problem of the formation of experimental skills when conducting VLR in physics in technical universities were used. The questionnaire was attended by physics teachers of MGUPP and the National Research University "MPEI". Testing was conducted among students of 1-2 courses of the named universities. Results. The most common types of VLR are VLR animations and VLR videos and the frequency of their use in technical universities. It was found that the frequency of using VRL animations is 24%, and VRL videos – 53%. It is proved that VLR animations with an interactive component make it possible to effectively form the practical and intellectual skills of students in laboratory classes. To strengthen the independence of students when performing VLR, methods of using interactive tests and using Excel calculation tables are proposed. In the Moodle environment, tests for 15 VLRs have been developed, an example of a test for VLR "Light Interference" is given. 10 Excel calculation tables have been created to monitor the results of laboratory work by students. Such tables for the VLR "Ohm's Law" and "Determination of the Poisson ratio by the Reichardt method" are given in the article. Conclusion. The prospects for further research include the creation of electronic lecture notes and their inclusion together with interactive tests and calculation tables in a demonstration and information complex on general physics.

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Fernández, L., J. Ortega, and J. Wisniak. "New computational tool to evaluate experimental VLE and VLLE data of multicomponent systems." Computers & Chemical Engineering 106 (November 2017): 437–63. http://dx.doi.org/10.1016/j.compchemeng.2017.07.003.

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Umlauf, Benjamin, Paul Clark, Jason Lajoie, Julia Georgieva, Samantha Bremner, Brantley Herrin, Eric Shusta, and John Kuo. "EXTH-67. IDENTIFICATION AND DEVELOPMENT OF NEURAL ECM-BINDING LAMPREY ANTIBODIES (VARIABLE LYMPHOCYTE RECEPTORS) THAT TARGET GLIOBLASTOMA." Neuro-Oncology 21, Supplement_6 (November 2019): vi96. http://dx.doi.org/10.1093/neuonc/noz175.397.

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Abstract INTRODUCTION The median survival of glioblastoma (GBM) patients remains less than two years even with state-of-the-art treatment. Current targeted GBM therapies demonstrate initial therapeutic benefit; however, patients relapse due to therapeutic selection of treatment resistant GBM cellular populations. Therefore, we propose targeting pathologic disruption of the blood brain barrier (BBB) via exposure of neural ECM, rather than disease markers, to overcome therapy-resistant GBM. METHODS We identify Variable Lymphocyte Receptors (VLRs, the antigen recognition system used by lamprey) that demonstrate high specificity for neural ECM. Candidate VLRs underwent further refinement using in vitro binding assays and ex vivo tissue staining. Utilizing pathologic disruption of BBB as an approach for targeting GBM was confirmed in vivo using intracranial murine glioblastoma models. RESULTS The lead neural ECM-binding VLR candidate, named P1C10, demonstrates diffuse binding to parenchymal neural ECM, without detectable binding to other tissues. P1C10 demonstrates nanomolar affinity for in vitro derived neural ECM, and preferentially accumulates at intracranial GL261 and U87 lesions in murine GBM models. Finally, administration of P1C10-targeted doxorubicin-loaded liposomes significantly extends the survival of mice bearing intracranial U87 GBM. CONCLUSIONS We identified VLRs that bind neural ECM, and demonstrate their utility for delivering compounds and nanoparticles to sites of GBM induced blood brain barrier disruption. This novel strategy allows for targeting therapeutics via the underlying physiology of GBM rather than relying on cellular disease markers that are often lost in patients that relapse after targeting therapies.

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Baburao, Barath, and Donald P. Visco. "VLE/VLLE/LLE Predictions for Hydrogen Fluoride Mixtures Using an Improved Thermodynamic Equation of State." Industrial & Engineering Chemistry Research 41, no. 19 (September 2002): 4863–72. http://dx.doi.org/10.1021/ie020341g.

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Gomis, V., A. Font, M. D. Saquete, and J. García-Cano. "LLE, VLE and VLLE data for the water–n-butanol–n-hexane system at atmospheric pressure." Fluid Phase Equilibria 316 (February 2012): 135–40. http://dx.doi.org/10.1016/j.fluid.2011.11.025.

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Fernández, Luís J., Juan Ortega, and Jaime Wisniak. "A rigorous method to evaluate the consistency of experimental data in phase equilibria. Application to VLE and VLLE." AIChE Journal 63, no. 11 (August 9, 2017): 5125–48. http://dx.doi.org/10.1002/aic.15876.

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Saquete, María Dolores, Alicia Font, Jorge García-Cano, and Inmaculada Blasco. "Study of the LLE, VLE, and VLLE of the Ternary System Water + 1-Butanol + Isoamyl Alcohol at 101.3 kPa." Journal of Chemical & Engineering Data 63, no. 10 (September 11, 2018): 3733–43. http://dx.doi.org/10.1021/acs.jced.8b00308.

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McDowell, John V., Shian-Ying Sung, Linden T. Hu, and Richard T. Marconi. "Evidence That the Variable Regions of the Central Domain of VlsE Are Antigenic during Infection with Lyme Disease Spirochetes." Infection and Immunity 70, no. 8 (August 2002): 4196–203. http://dx.doi.org/10.1128/iai.70.8.4196-4203.2002.

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ABSTRACT It has been postulated that the vls system of the Lyme disease spirochetes contributes to immune evasion through antigenic variation. While it is clear that vlsE undergoes sequence change within its variable regions at a high frequency during the early stages of infection, a definitive role in immune evasion has not been demonstrated. In this report we assessed the murine and human humoral immune response to recombinant (r)-VlsE variants that originally arose during infection in mice. Immunoblot analyses of r-VlsE variants were conducted by using serum samples collected from mice infected with Borrelia burgdorferi clones that carried different vlsE variants. All of the r-VlsE variants were recognized by infection sera regardless of the identity of the infecting clone or isolate. In addition, all variants were immunoreactive with a panel of human Lyme disease patient serum samples. It is evident from these analyses that the infection-induced VlsE variants share common epitopes that reside within conserved segments of these proteins. However, preabsorption experiments revealed that the variable regions of the central domain of VlsE, which undergo rapid mutation during infection, also influence the antigenic properties of the protein. A subset of the antibodies elicited against vlsE variants that differ in the sequences of their variable regions were found to be variant specific. Hence, in spite of a robust antibody response to conserved segments of VlsE, infection-induced sequence changes within the variable regions alter the antigenicity of VlsE. These results provide the first direct evidence of antigenic variation in the VlsE protein.

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Lawrenz, Matthew B., R. Mark Wooten, and Steven J. Norris. "Effects of vlsE Complementation on the Infectivity of Borrelia burgdorferi Lacking the Linear Plasmid lp28-1." Infection and Immunity 72, no. 11 (November 2004): 6577–85. http://dx.doi.org/10.1128/iai.72.11.6577-6585.2004.

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ABSTRACT The loss of linear plasmid lp28-1, which contains the vls antigenic variation locus, is associated with reduced infectivity of Borrelia burgdorferi in immunocompetent mice. The recombinant shuttle vector pBBE22, which includes the virulence determinant BBE22 from lp25 and restores infectivity to readily transformable B. burgdorferi lacking lp25 and lp56, was used to determine the effect of trans expression of vlsE on virulence. Spirochetes lacking lp28-1 were complemented with the plasmid pBBE22:vlsE, containing both BBE22 and vlsE. VlsE protein produced by this construct was expressed and surface accessible in in vitro-cultured B. burgdorferi, as determined by surface proteolysis and immunoblot analysis. Clones lacking lp25 but containing lp28-1 and either pBBE22 or pBBE22:vlsE were reisolated consistently from immunocompetent mice 8 weeks after infection. In contrast, a clone lacking both lp25 and lp28-1 and complemented with pBBE22:vlsE was isolated from only a single tissue of one of six C3H/HeN mice 8 weeks postinfection. These results indicate that either an intact vls antigenic variation locus or another determinant on lp28-1 is required to restore complete infectivity. In addition, an isogenic clone that retained lp28-1 was complemented with the vlsE shuttle plasmid and was examined for vlsE sequence variation and infectivity. Sequence variation was not observed for the shuttle plasmid, indicating that the cis arrangement of vlsE and the vls silent cassettes in lp28-1 facilitate vlsE gene conversion. Lack of vlsE sequence variation on the shuttle plasmid thus did not result in clearance of the trans-complemented strain in immunocompetent mice under the conditions tested.

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Ohnishi, Jun, Brad Schneider, William B. Messer, Joseph Piesman, and Aravinda M. de Silva. "Genetic Variation at the vlsE Locus of Borrelia burgdorferi within Ticks and Mice over the Course of a Single Transmission Cycle." Journal of Bacteriology 185, no. 15 (August 1, 2003): 4432–41. http://dx.doi.org/10.1128/jb.185.15.4432-4441.2003.

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ABSTRACT The Lyme disease spirochete, Borrelia burgdorferi, causes a persistent infection in the vertebrate host even though infected animals mount an active immune response against the spirochete. One strategy used by the spirochete to evade vertebrate host immunity is to vary the structure and expression of outer membrane antigens. The vlsE locus represents the best-studied example of antigenic variation in B. burgdorferi. During vertebrate host infection, recombination between the active vlsE locus and silent, partial vlsE copies leads to gene conversion events and the generation of novel alleles at the expression site. In the present study, we followed a population of B. burgdorferi organisms moving through vertebrate host and tick stages to complete one transmission cycle. The major goal of the study was to determine if the vlsE locus was subject to different selective pressure and/or recombination frequency at different stages of the spirochete's life cycle. We report here that the vlsE genetic diversity generated within the rodent host was maintained through the larval and nymphal tick stages. Therefore, naturally infected ticks are likely to transmit spirochete populations with multiple vlsE alleles into naive vertebrate hosts. Although vlsE genetic diversity in mice was maintained through tick stages, the dominant vlsE alleles were different between tick stages as well as between individual ticks. We propose that population-level bottlenecks experienced by spirochetes, especially during the larval-to-nymphal molt, are responsible for individual infected ticks harboring different dominant vlsE alleles. Although vlsE genetic diversity is maintained through tick stages, the VlsE protein is unlikely to be of functional importance in the vector, because the protein was expressed by very few (<1%) bacteria in the vector.

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Cai, Jialin, Shensheng Zhen, Dengpan Gao, and Xianbao Cui. "Phase Equilibrium (VLE, LLE, and VLLE) Data of the Ternary System: Ionic Liquid [OMIM][PF6] + Butan-1-ol + Butyl Acetate." Journal of Chemical & Engineering Data 59, no. 7 (June 27, 2014): 2171–76. http://dx.doi.org/10.1021/je5000296.

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Benmekki, El-Houari, and G. Ali Mansoori. "The role of mixing rules and three-body forces in the phase behavior of mixtures: simultaneous VLE and VLLE calculations." Fluid Phase Equilibria 41, no. 1-2 (January 1988): 43–57. http://dx.doi.org/10.1016/0378-3812(88)80035-9.

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Bykowski, Tomasz, Kelly Babb, Kate von Lackum, Sean P. Riley, Steven J. Norris, and Brian Stevenson. "Transcriptional Regulation of the Borrelia burgdorferi Antigenically Variable VlsE Surface Protein." Journal of Bacteriology 188, no. 13 (July 1, 2006): 4879–89. http://dx.doi.org/10.1128/jb.00229-06.

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ABSTRACT The Lyme disease agent Borrelia burgdorferi can persistently infect humans and other animals despite host active immune responses. This is facilitated, in part, by the vls locus, a complex system consisting of the vlsE expression site and an adjacent set of 11 to 15 silent vls cassettes. Segments of nonexpressed cassettes recombine with the vlsE region during infection of mammalian hosts, resulting in combinatorial antigenic variation of the VlsE outer surface protein. We now demonstrate that synthesis of VlsE is regulated during the natural mammal-tick infectious cycle, being activated in mammals but repressed during tick colonization. Examination of cultured B. burgdorferi cells indicated that the spirochete controls vlsE transcription levels in response to environmental cues. Analysis of PvlsE::gfp fusions in B. burgdorferi indicated that VlsE production is controlled at the level of transcriptional initiation, and regions of 5′ DNA involved in the regulation were identified. Electrophoretic mobility shift assays detected qualitative and quantitative changes in patterns of protein-DNA complexes formed between the vlsE promoter and cytoplasmic proteins, suggesting the involvement of DNA-binding proteins in the regulation of vlsE, with at least one protein acting as a transcriptional activator.

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Lawrenz, M. B., J. M. Hardham, R. T. Owens, J. Nowakowski, A. C. Steere, G. P. Wormser, and S. J. Norris. "Human Antibody Responses to VlsE Antigenic Variation Protein of Borrelia burgdorferi." Journal of Clinical Microbiology 37, no. 12 (1999): 3997–4004. http://dx.doi.org/10.1128/jcm.37.12.3997-4004.1999.

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VlsE is a 35-kDa surface-exposed lipoprotein of Borrelia burgdorferi that was shown previously to undergo antigenic variation through segmental recombination of silent vlscassettes with vlsE during experimental mouse infections. Previous data had indicated that sera from North American Lyme disease patients and experimentally infected animals contained antibodies reactive with VlsE. In this study, sera from patients with Lyme disease, syphilis, and autoimmune conditions as well as from healthy controls were examined for reactivity with VlsE by Western blotting and enzyme-linked immunosorbent assay (ELISA). Strong Western blot reactivity to a recombinant VlsE cassette region protein was obtained consistently with Lyme disease sera. Although sera from Lyme disease patients also reacted with a band corresponding to VlsE in B. burgdorferi B31-5A3, interpretation was complicated by low levels of VlsE expression in in vitro-cultured B. burgdorferi and by the presence of comigrating bands. An ELISA using recombinant VlsE was compared with an ELISA using sonically disrupted B. burgdorferi as the antigen. For a total of 93 Lyme disease patient sera examined, the VlsE ELISA yielded sensitivities of 63% for culture-confirmed erythema migrans cases and 92% for later stages, as compared to 61 and 98%, respectively, for the “whole-cell” ELISA. The specificities of the two assays with healthy blood donor sera were comparable, but the VlsE ELISA was 90% specific with sera from syphilis patients, compared to 20% specificity for the whole-cell ELISA with this group. Neither assay showed reactivity with a panel of sera from 20 non-Lyme disease arthritis patients or 20 systemic lupus erythematosus patients. Our results indicate that VlsE may be useful in the immunodiagnosis of Lyme disease and may offer greater specificity than ELISAs using whole B. burgdorferi as the antigen.

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Embers, Monica E., Mary B. Jacobs, Barbara J. B. Johnson, and Mario T. Philipp. "Dominant Epitopes of the C6 Diagnostic Peptide of Borrelia burgdorferi Are Largely Inaccessible to Antibody on the Parent VlsE Molecule." Clinical and Vaccine Immunology 14, no. 8 (June 13, 2007): 931–36. http://dx.doi.org/10.1128/cvi.00075-07.

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ABSTRACTLyme borreliosis (LB) is a disease for which antibody-based detection assays are often required for diagnosis. The variable surface molecule VlsE and IR6, one of its invariable regions, are commonly targeted by the antibody response in infected individuals. A series of enzyme-linked immunosorbent assays was performed to comparatively examine the antibody responses of North American LB patients (n= 37) to VlsE and invariable segments of this molecule. Both immunoglobulin M (IgM) and IgG responses to full-length VlsE and to peptides reproducing invariable regions 2, 4, and 6, as well as the invariable domains at the amino and carboxyl termini of VlsE, were assessed. The proportions and specificities of reactivity to the invariable segments were tested by using cognate peptides as competitors for VlsE binding by patient serum antibodies. IR6 epitopes (by the C6 peptide) were found to dominate the response to invariable segments. IR6 (C6)-specific antibodies were detected in 78% of the serum specimens, whereas <40% of patients generated antibodies that bound the N- or C-terminal domain and <12% of patients responded to either IR2 or IR4. Interestingly, 15 of 37 patients generated IgG antibodies that reacted with C6 but not with VlsE. Conversely, IgM responses were frequent for VlsE but not for invariable segments. A representative number of the serum specimens (n= 8) that contained IgG antibodies reacting with both C6 and VlsE was assessed in competition experiments, using C6 as a competitor. Only half of these specimens contained IgG antibodies whose binding to VlsE could be inhibited >50% by competition with the added C6 peptide. The median percent inhibition was 45.5%. These findings indicate that IR6 epitopes are largely concealed from the VlsE molecular surface and that full-length VlsE-based diagnosis likely detects antibodies to conformational and/or variable region epitopes.

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Sima, Sergiu, Adrian Victor Crişciu, and Catinca Secuianu. "Phase Behavior of Carbon Dioxide + Isobutanol and Carbon Dioxide + tert-Butanol Binary Systems." Energies 15, no. 7 (April 3, 2022): 2625. http://dx.doi.org/10.3390/en15072625.

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In recent years, the dramatic increase of greenhouse gases concentration in atmosphere, especially of carbon dioxide, determined many researchers to investigate new mitigation options. Thermodynamic studies play an important role in the development of new technologies for reducing the carbon levels. In this context, our group investigated the phase behavior (vapor–liquid equilibrium (VLE), vapor–liquid–liquid equilibrium (VLLE), liquid–liquid equilibrium (LLE), upper critical endpoints (UCEPs), critical curves) of binary and ternary systems containing organic substances with different functional groups to determine their ability to dissolve carbon dioxide. This study presents our results for the phase behavior of carbon dioxide + n-butanol structural isomers binary systems at high-pressures. Liquid–vapor critical curves are measured for carbon dioxide + isobutanol and carbon dioxide + tert-butanol binary systems at pressures up to 147.3 bar, as only few scattered critical points are available in the literature. New isothermal vapor–liquid equilibrium data are also reported at 363.15 and 373.15 K. New VLE data at higher temperature are necessary, as only another group reported some data for the carbon dioxide + isobutanol system, but with high errors. Phase behavior experiments were performed in a high-pressure two opposite sapphire windows cell with variable volume, using a static-analytical method with phases sampling by rapid online sample injectors (ROLSI) coupled to a gas chromatograph (GC) for phases analysis. The measurement results of this study are compared with the literature data when available. The new and all available literature data for the carbon dioxide + isobutanol and carbon dioxide + tert-butanol binary systems are successfully modeled with three cubic equations of state, namely, General Equation of State (GEOS), Soave–Redlich–Kwong (SRK), and Peng–Robinson (PR), coupled with classical van der Waals mixing rules (two-parameter conventional mixing rules, 2PCMR), using a predictive method.

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Zhang, Jing-Ren, and Steven J. Norris. "Genetic Variation of the Borrelia burgdorferi Gene vlsE Involves Cassette-Specific, Segmental Gene Conversion." Infection and Immunity 66, no. 8 (August 1, 1998): 3698–704. http://dx.doi.org/10.1128/iai.66.8.3698-3704.1998.

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ABSTRACT The Lyme disease spirochete Borrelia burgdorferipossesses 15 silent vls cassettes and a vlsexpression site (vlsE) encoding a surface-exposed lipoprotein. Segments of the silent vls cassettes have been shown to recombine with the vlsE cassette region in the mammalian host, resulting in combinatorial antigenic variation. Despite promiscuous recombination within the vlsE cassette region, the 5′ and 3′ coding sequences of vlsE that flank the cassette region are not subject to sequence variation during these recombination events. The segments of the silent vlscassettes recombine in the vlsE cassette region through a unidirectional process such that the sequence and organization of the silent vls loci are not affected. As a result of recombination, the previously expressed segments are replaced by incoming segments and apparently degraded. These results provide evidence for a gene conversion mechanism in VlsE antigenic variation.

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Bassett, Mark J. "The Dark Corona Character in Seedcoats of Common Bean Cosegregates with the Pink Flower Allele vlae." Journal of the American Society for Horticultural Science 120, no. 3 (May 1995): 520–22. http://dx.doi.org/10.21273/jashs.120.3.520.

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Crosses were made with two common bean (Phaseolus vulgaris L.) parents that have pink flowers (vlae/-) and mineral-brown seedcoats with dark corona, viz., vlae BC3 5-593 (derived from Lamprecht V0491) and F3 vlae dark corona (derived from Lamprecht M0048). The third parent v BC2 5-593 had white flowers (v/v) and mineral-brown seedcoats without dark corona (derived from Lamprecht M0056). The F2 progenies of the crosses v BC2 5-593 × vlae BC3 5-593 and F3vlae dark corona × v BC2 5-593 segregated for only two phenotypic classes: either pink flowers and seeds with dark corona or white flowers and seeds without dark corona. Thus, it was demonstrated that the dark corona character (Cor) is either tightly linked to vlae (<4 map units) or is a pleiotropic effect of vlae. Pleiotropy is more probable, but tight linkage cannot be ruled out. A linkage of 15 map units between Cor and R (currently, R is known to be tightly linked with C) reported by Lamprecht was not found by subsequent authors, and the linkage map of common bean should be revised accordingly, i.e., no linkage exists between V (Cor) and C.

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Sung, Shian-Ying, John V. McDowell, and Richard T. Marconi. "Evidence for the Contribution of Point Mutations tovlsE Variation and for Apparent Constraints on the Net Accumulation of Sequence Changes in vlsE during Infection with Lyme Disease Spirochetes." Journal of Bacteriology 183, no. 20 (October 15, 2001): 5855–61. http://dx.doi.org/10.1128/jb.183.20.5855-5861.2001.

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ABSTRACT In the Lyme disease spirochetes, both the ospE andvlsE gene families have been demonstrated to undergo sequence variation during infection. To further investigate the mechanisms associated with the generation of vls variation, single-nucleotide polymorphism and subsequent DNA sequence analyses were performed on the vlsE gene and its paralog, BBJ51, a related gene with a frameshift mutation. These analyses focused on a series of postinfection clonal populations obtained from mice infected with Borrelia burgdorferi B31MIpc or its clonal derivative, B31MIc53. vlsE, but not BBJ51, was found to undergo sequence changes during infection. Consistent with that reported previously (J.-R. Zhang et al., Cell 89:275–285, 1997) many of the sequence changes appear to have arisen through gene conversion events and to be localized to the variable regions of vlsE. However, analysis of the vlsE nucleotide sequences revealed that some sequence changes were the result of point mutations, as these changes did not have potential contributing sources in thevls cassettes. To determine if sequence changes accumulate in vlsE over long-term infection, thevlsE genes of clonal populations recovered after 7 months of infection in mice were analyzed. While new sequence changes developed, a significant number of these changes resulted in the restoration of the vlsE sequence of the original infecting clone. In addition, we noted that some positions within the variable regions (VR) are stable even though the cassettes possess residues that could contribute to sequence variation through gene conversion. These analyses suggest that the total number of amino acid sequence changes that can be maintained by VlsE levels off during infection. In summary, in this report we demonstrate that the development of point mutations serves as a second mechanism by which vlsE sequence variation can be generated and that the capacity for vlsEvariation, while still significant, is less than previously postulated.

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Ahmed, Saifuddin, Nicolas Ferrando, Jean-Charles de Hemptinne, Jean-Pierre Simonin, Olivier Bernard, and Olivier Baudouin. "A New PC-SAFT Model for Pure Water, Water–Hydrocarbons, and Water–Oxygenates Systems and Subsequent Modeling of VLE, VLLE, and LLE." Journal of Chemical & Engineering Data 61, no. 12 (November 10, 2016): 4178–90. http://dx.doi.org/10.1021/acs.jced.6b00565.

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Khan, Srijit, Yanling Liu, Laura M. Ernst, Leslie Y. T. Leung, Patrick Budylowski, Shilan Dong, Paolo Campisi, et al. "Detection of Human CD38 Using Variable Lymphocyte Receptor (VLR) Tetramers." Cells 9, no. 4 (April 12, 2020): 950. http://dx.doi.org/10.3390/cells9040950.

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CD38 is a multifunctional cell surface receptor expressed on multiple cell lineages of hematopoietic origin with high levels of expression on human plasma cells. Previously, we isolated the monoclonal variable lymphocyte receptor B (VLRB) MM3 antibody from the evolutionarily distant sea lamprey, which recognized the CD38 ectoenzyme exclusively on human plasma cells in a manner that correlated with CD38 enzymatic activity. The plasma cell-specific binding of VLRB MM3 contrasts with the broad pattern of expression of CD38-determined conventional antibodies specific for this antigen. In an effort to facilitate the application of this unique reagent in combination with conventional antibody panels, we explored a strategy to generate VLRB MM3 tetramers. The resulting reagent maintained the threshold-based recognition of CD38. Increased sensitivity achieved with VLRB MM3 tetramers also showed preferential recognition of germinal center centroblasts over centrocytes. VLRB MM3 tetramers thus provided a unique and versatile single-step staining reagent for the detection of human CD38 that is readily incorporated into multi-color flow cytometry panels.

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Journal articles on the topic 'VLRE'

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