A Vaccine Encoding Conserved Promiscuous HIV CD4 Epitopes Induces Broad T Cell Responses in Mice Transgenic to Multiple Common HLA Class II Molecules

Current HIV vaccine approaches are focused on immunogens encoding whole HIV antigenic proteins that mainly elicit cytotoxic CD8+ responses. Mounting evidence points toward a critical role for CD4+ T cells in the control of immunodeficiency virus replication, probably due to cognate help. Vaccine-induced CD4+ T cell responses might, therefore, have a protective effect in HIV replication. In addition, successful vaccines may have to elicit responses to multiple epitopes in a high proportion of vaccinees, to match the highly variable circulating strains of HIV. Using rational vaccine design, we developed a DNA vaccine encoding 18 algorithm-selected conserved, “promiscuous” (multiple HLA-DR-binding) B-subtype HIV CD4 epitopes - previously found to be frequently recognized by HIV-infected patients. We assessed the ability of the vaccine to induce broad T cell responses in the context of multiple HLA class II molecules using different strains of HLA class II- transgenic mice (-DR2, -DR4, -DQ6 and -DQ8). Mice displayed CD4+ and CD8+ T cell responses of significant breadth and magnitude, and 16 out of the 18 encoded epitopes were recognized. By virtue of inducing broad responses against conserved CD4+ T cell epitopes that can be recognized in the context of widely diverse, common HLA class II alleles, this vaccine concept may cope both with HIV genetic variability and increased population coverage. The vaccine may thus be a source of cognate help for HIV-specific CD8+ T cells elicited by conventional immunogens, in a wide proportion of vaccinees

Streptococcus pyogenes strains in Sao Paulo, Brazil: molecular characterization as a basis for StreptInCor coverage capacity analysis

Abstract\ud \ud Background\ud Several human diseases are caused by Streptococcus pyogenes, ranging from common infections to autoimmunity. Characterization of the most prevalent strains worldwide is a useful tool for evaluating the coverage capacity of vaccines under development. In this study, a collection of S. pyogenes strains from Sao Paulo, Brazil, was analyzed to describe the diversity of strains and assess the vaccine coverage capacity of StreptInCor.\ud \ud \ud Methods\ud Molecular epidemiology of S. pyogenes strains was performed by emm-genotyping the 229 isolates from different clinical sites, and PCR was used for superantigen profile analysis. The emm-pattern and tissue tropism for these M types were also predicted and compared based on the emm-cluster classification.\ud \ud \ud Results\ud The strains were fit into 12 different emm-clusters, revealing a diverse phylogenetic origin and, consequently, different mechanisms of infection and escape of the host immune system. Forty-eight emm-types were distinguished in 229 samples, and the 10 most frequently observed types accounted for 69 % of all isolates, indicating a diverse profile of circulating strains comparable to other countries under development. A similar proportion of E and A-C emm-patterns were observed, whereas pattern D was less frequent, indicating that the strains of this collection primarily had a tissue tropism for the throat. In silico analysis of the coverage capacity of StreptInCor, an M protein-conserved regionally based vaccine candidate developed by our group, had a range of 94.5 % to 59.7 %, with a mean of 71.0 % identity between the vaccine antigen and the predicted amino acid sequence of the emm-types included here.\ud \ud \ud Conclusions\ud This is the first report of S. pyogenes strain characterization in Sao Paulo, one of the largest cities in the world; thus, the strain panel described here is a representative sample for vaccine coverage capacity analysis. Our results enabled evaluation of StreptInCor candidate vaccine coverage capacity against diverse M-types, indicating that the vaccine candidate likely would induce protection against the diverse strains worldwide.“Conselho Nacional de Desenvolvimento Científico e Tecnológico” [CNPq 557814/2009-0]“Fundação de Amparo à Pesquisa do Estado de Sao Paulo” [FAPESP 2007/59262-3

A DNA Vaccine Encoding Multiple HIV CD4 Epitopes Elicits Vigorous Polyfunctional, Long-Lived CD4+ and CD8+ T Cell Responses

T-cell based vaccines against HIV have the goal of limiting both transmission and disease progression by inducing broad and functionally relevant T cell responses. Moreover, polyfunctional and long-lived specific memory T cells have been associated to vaccine-induced protection. CD4+ T cells are important for the generation and maintenance of functional CD8+ cytotoxic T cells. We have recently developed a DNA vaccine encoding 18 conserved multiple HLA-DR-binding HIV-1 CD4 epitopes (HIVBr18), capable of eliciting broad CD4+ T cell responses in multiple HLA class II transgenic mice. Here, we evaluated the breadth and functional profile of HIVBr18-induced immune responses in BALB/c mice. Immunized mice displayed high-magnitude, broad CD4+/CD8+ T cell responses, and 8/18 vaccine-encoded peptides were recognized. In addition, HIVBr18 immunization was able to induce polyfunctional CD4+ and CD8+ T cells that proliferate and produce any two cytokines (IFNγ/TNFα, IFNγ/IL-2 or TNFα/IL-2) simultaneously in response to HIV-1 peptides. For CD4+ T cells exclusively, we also detected cells that proliferate and produce all three tested cytokines simultaneously (IFNγ/TNFα/IL-2). The vaccine also generated long-lived central and effector memory CD4+ T cells, a desirable feature for T-cell based vaccines. By virtue of inducing broad, polyfunctional and long-lived T cell responses against conserved CD4+ T cell epitopes, combined administration of this vaccine concept may provide sustained help for CD8+ T cells and antibody responses- elicited by other HIV immunogens

NK1.1 cells are required to control T cell hyperactivity during Trypanosoma cruzi infection.

Submitted by Ana Maria Fiscina Sampaio ([email protected]) on 2015-06-18T12:17:42Z No. of bitstreams: 1 Cardillo F NK! 1 are required....pdf: 1290378 bytes, checksum: 13c8e37095d5f8e755e95fbabbf02a6b (MD5)Approved for entry into archive by Ana Maria Fiscina Sampaio ([email protected]) on 2015-06-18T13:03:27Z (GMT) No. of bitstreams: 1 Cardillo F NK! 1 are required....pdf: 1290378 bytes, checksum: 13c8e37095d5f8e755e95fbabbf02a6b (MD5)Made available in DSpace on 2015-06-18T13:03:27Z (GMT). No. of bitstreams: 1 Cardillo F NK! 1 are required....pdf: 1290378 bytes, checksum: 13c8e37095d5f8e755e95fbabbf02a6b (MD5) Previous issue date: 2004University of São Paulo. Institute for Biomedical Sciences IV. Department of Immunology. São Paulo, SP, Brasil / University of São Paulo. Department of Clinical Analysis. São Paulo, SP, Brasil / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Laboratório de Doença Experimental de Chagas, Imunologia Celular e Auto-imunidade. Salvador, BA, BrasilUniversity of São Paulo. Department of Clinical Analysis. São Paulo, SP, BrasilUniversity of São Paulo. Institute for Biomedical Sciences IV. Department of Immunology. São Paulo, SP, BrasilUniversity of São Paulo. Institute for Biomedical Sciences IV. Department of Immunology. São Paulo, SP, Brasil / University of São Paulo. Department of Clinical Analysis. São Paulo, SP, Brasil / Fundação Oswaldo Cruz. Centro de Pesquisas Gonçalo Moniz. Laboratório de Doença Experimental de Chagas, Imunologia Celular e Auto-imunidade. Salvador, BA, BrasilBACKGROUND: This study evaluated the regulatory function of NK1.1+ cells during Trypanosoma cruzi infection. MATERIAL/METHODS: Both thymectomized (Tx C57Bl/6) and euthymic C57Bl/6 mice (C57Bl/6) were infected intraperitoneally with the Tulahuen strain. NK1.1+ cells were depleted in vivo by anti-NK1.1 mAb. Spleen cells were analyzed by flow cytometry for the expression of CD44 and CD69 on T cells. Supernatants from splenocytes were used to measure nitrite concentration (quantified by Griess reagent). Interleukin 2 and IFN-gamma levels were determined by ELISA. The protocols used herein were approved by the Institutional Committee for Ethics. Student's t or Kruskal-Wallis tests were applied, as indicated. RESULTS: The number of T cells expressing CD69 increased progressively during T. cruzi infection in NK1.1 cell-depleted C57Bl/6 mice. In spite of an increased early T cell activation during infection, the percentage of CD4+ CD44high T cells did not augment in NK1.1 cell-depleted C57Bl/6 mice compared with untreated C57Bl/6 controls. Serum levels of IFN-gamma in anti-NK1.1-treated mice were higher than in non-depleted animals. Con-A-stimulated spleen cell supernatants from NK1.1 cell-depleted animals contained increased levels of IL-2 and nitric oxide (NO) during early infection. CONCLUSIONS: After the first week of infection, NO overproduction and high levels of IFN-gamma in anti-NK1.1-tre-ated C57Bl/6 mice appeared to be related to susceptibility and hyperactivation of peripheral T cells. Finally, this study suggests a novel regulatory function of NK1.1+ cells during T. cruzi infection. Without NK1.1 cells, T lymphocytes are hyperactivated but do not differentiate to effector/memory T cells in infected C57Bl/6 mice

Long-term administration of IgG2a anti-NK1.1 monoclonal antibody ameliorates lupus-like disease in NZB/W mice in spite of an early worsening induced by an IgG2a-dependent BAFF/BLyS production

The role of natural killer (NK) T cells in the development of lupus-like disease in mice is still controversial. We treated NZB/W mice with anti-NK1.1 monoclonal antibodies (mAbs) and our results revealed that administration of either an irrelevant immunoglobulin G2a (IgG2a) mAb or an IgG2a anti-NK1.1 mAb increased the production of anti-dsDNA antibodies in young NZB/W mice. However, the continuous administration of an anti-NK1.1 mAb protected aged NZB/W mice from glomerular injury, leading to prolonged survival and stabilization of the proteinuria. Conversely, the administration of the control IgG2a mAb led to an aggravation of the lupus-like disease. Augmented titres of anti-dsDNA in NZB/W mice, upon IgG2a administration, correlated with the production of BAFF/BLyS by dendritic, B and T cells. Treatment with an anti-NK1.1 mAb reduced the levels of interleukin-16, produced by T cells, in spleen cell culture supernatants from aged NZB/W. Adoptive transfer of NK T cells from aged to young NZB/W accelerated the production of anti-dsDNA in recipient NZB/W mice, suggesting that NK T cells from aged NZB/W are endowed with a B-cell helper activity. In vitro studies, using purified NK T cells from aged NZB/W, showed that these cells provided helper B-cell activity for the production of anti-dsDNA. We concluded that NK T cells are involved in the progression of lupus-like disease in mature NZB/W mice and that immunoglobulin of the IgG2a isotype has an enhancing effect on antibody synthesis due to the induction of BAFF/BLyS, and therefore have a deleterious effect in the NZB/W mouse physiology