105,250 research outputs found
Localization of T helper cell epitopes in the vesicular stomatitis virus: the nucleoprotein is responsible for serotype cross-reactive T help.
No full textThe glycoprotein (G) of vesicular stomatitis virus (VSV) is known to contain the biologically relevant sites for virus-neutralizing antibodies as well as T helper (Th) cell epitopes. The capacity of other VSV proteins to elicit potent Th cell responses has not yet been investigated. Additionally, a short-lived cross-reactivity between the two serologically distinct VSV serotypes Indiana (IND) and New Jersey (NJ) on the T helper cell level has been reported. Here we address the question of whether the VSV nucleoprotein (N) or matrix protein (M) can elicit T help to VSV-G-specific B cells and which of the VSV proteins contains the elements responsible for the IND/NJ cross-reactivity. The N, G, and M of the VSV Indiana serotype produced in a recombinant baculovirus system were assayed for the ability to activate VSV-specific Th cells to induce immunoglobulin class switch of neutralizing antibody responses in vivo in C57BL/6 (H-2b) mice. All three VSV-IND proteins helped in the production of neutralizing IgG antibodies to the homologous VSV-Indiana serotype but only VSV-IND N was able to trigger an IgG response to the heterologous VSV-New Jersey serotype. This data suggest that Th epitope(s) in the VSV-IND N are responsible for the observed cross-reactivity of T helper cells
Cloning of an unidentified T-cell receptor alpha chain gene from a vesicular stomatitis virus-specific helper T-cell clone
No full textA vesicular stomatitis virus glycoprotein-specific, class II restricted, CD4(+) T-cell clone was obtained and the unidentified T-cell receptor alpha chain cloned in order to establish a T-cell receptor (TCR) alpha chain transgenic mouse line. Polymerase chain reaction (PCR) strategies have been developed to clone TCR chain genes starting from T-cell cDNA. There remain difficulties, however, in cloning the functional TCR alpha chain due to the complexity of the protocols applied if the variable (V) alpha region rearranged is not known. The strategy described here allows the identification and cloning of alpha chains that are not recognized by any of the anti-V alpha monoclonal antibodies available: three 5' consensus V alpha primers designed from all known V alpha gene sequences and a primer specific for the constant (C) alpha region were used and the PCR product sequenced. The: T-cell clone displayed two alpha gene rearrangements, only one of which giving rise to a functional protein. The alpha chain used by the T-cell clone contained a Vol 3.1 and a J alpha region which has been described only at the genomic level, but never in a functional TCR. The complete alpha chain gene was cloned by enriching the alpha chain-encoding cDNA by ligation-anchored PCR and using an alpha specific primer pair. The use of the present method, even if the sequence of the 5' untranslated (UT) region of the alpha chain is not known, is also discussed
Correlation of tolerogenicity of a viral antigen with its immunogenicity. (vol 158, pg 5106, 1997)
No full textInduction of B cell tolerance or activation was analyzed with vesicular stomatitis virus (VSV) glycoprotein (G) expressed as a neo-self Ag, A membrane form of VSV-C expressed in all tissues, including the bone marrow, induced unresponsiveness at both the Th and B cell level, whereas a soluble form of VSV-C expressed peripherally in liver and kidney did not tolerize B cells and only reversibly anergized Th cells, Interestingly, a similar correlation was found for activation of mature lymphocytes. When mature normal spleen cells were transferred into the two transgenic mouse lines, the membrane form of VSV-G was strongly immunogenic for both Th and B cells, and high VSV-G-specific IgG Ab titers were induced in these transgenic mice, In contrast, spleen cells transferred into mice expressing the soluble form of VSV-C were not activated, and no VSV-C specific Abs were induced, These results indicate that highly immunogenic Ags are strongly tolerogenic for both immature B and T cells
CHARACTERIZATION OF T-HELPER EPITOPES OF THE GLYCOPROTEIN OF VESICULAR STOMATITIS-VIRUS
No full textThe T-helper (Th) cell epitopes in the glycoprotein (GP) of vesicular stomatitis virus serotype Indiana (VSV-IND) were analyzed with a complete panel of overlapping synthetic peptides. Three Th-cell epitopes in C57B/6 (H-2(b)) mice and two epitopes in BALB/c (H-2(d)) mice were defined by their ability to stimulate in vitro proliferation of virus-primed, CD8(+) T-cell-depleted spleen cells in a class II-restricted manner. A series of CD4(+), I-A(b)-restricted T-cell hybridomas from VSV-primed C57B/6 mice were characterized by their production of interleukin-2 and interleukin-3 upon stimulation with VSV-IND or purified VSV GP in vitro. Of nine hybridomas derived from three independent fusions five were specific for amino acids (aa) 415 to 433 (p8) of VSV-IND GP, three recognized aa 52 to 71 (p41), and one reacted against aa 316 to 335 (p17). Fluorocytometric analysis of Th hybridomas or VSV-stimulated T-cell lines with monoclonal antibodies specific for the T-cell receptor V beta chain did not reveal obvious correlations between the T-cell receptor V beta gene segment used and the epitope recognized. All three peptides recognized by 11-2(b) mice and both epitopes recognized by H-2(d) mice which were characterized in primed T-cell populations were capable of activating specific Th cells in vivo as measured by the induction of antibody class switch from immunoglobulin M (IgM) to IgG. Thus, the epitopes are relevant for VSV GP-specific Th response in vivo and are able to provide functional help for the production of anti-VSV-specific neutralizing IgG antibodies
Regulation of RAG‐1 and CD69 expression in the thymus during positive and negative selection
No full textSuccessful interaction of the T cell receptor (TCR) with major histocompatibility complex (MHC) molecules during thymic selection down-regulates the expression of the recombination activating genes (RAG)-1 and -2 in cortical thymocytes and thereby prevents further endogenous TCR alpha-chain gene rearrangements (Borgulya, P., Kishi, H., Uematsu, Y. and von Boehmer, H., Cell. 1992. 69: 529-537; Brändle, D., Müller, C., Rülicke, T., Hengartner, H. and Pircher, H., Proc. Natl. Acad. Sci. USA 1992. 89: 9529-9533). To address the question whether down-regulation of RAG-1 activity represents an irreversible process we have blocked TCR-MHC interactions of thymocytes with thymic stromal cells. Firstly, transgenic (Tg) mice expressing a virus-specific MHC class I (H-2Db)-restricted TCR were injected with anti-Db or anti-CD8 monoclonal antibodies and RAG-1 expression was examined by in situ hybridization on thymus sections. The results show that cortical thymocytes up-regulated RAG-1 expression within 24 h after antibody administration. Secondly, immature thymocytes from TCR Tg mice were released from the thymic microenvironment and cultured in vitro for 14 h in single-cell suspension. The amount of RAG-1 mRNA was increased sixfold in cultured cells when compared to freshly isolated thymocytes. In addition, we show that immature thymocytes from TCR transgenic mice bearing non-selective MHC molecules (H-2d) down-regulated RAG-1 expression after antigen-induced TCR engagement. Cytofluorometric analysis further revealed that surface expression of CD69 on immature thymocytes inversely correlated with RAG-1 expression during positive and negative selection processes
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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