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Hepatitis C virus (HCV) is a worldwide problem which does not have an effective vaccine and more than 170 million people worldwide are chronically infected by HCV. T cell responses are associated with spontaneous clearance of HCV infection. We report here the development of recombinant Lambda bacteriophage nanoparticles encoding HCV Core antigen. The aim of this study was to investigate the antigen-specific immune responses triggered in mice by different prime-boost combinations of DNA and Lambda phage nanoparticles encoding the HCV Core. The homologous prime/boost with recombinant Lambda nanoparticles induced higher levels of cellular and humoral immune response than the DNA vaccines. However, a heterologous prime/boost of HCV Core protein, using DNA vaccine priming followed by Lambda boost, induced highest level of lymphocyte proliferation, CD8 lymphocytes with cytotoxic function, and shifting the immune response toward a T helper (Th1) pattern and in overall improved immunity. Our study provides a new, safe, and effective vaccine for the prime-boost regimen which augments robust immunity and highlights novel promising strategies in HCV vaccine development. [ABSTRACT FROM AUTHOR]

Abstract: Correlation of hepatitis C virus (HCV) spontaneous resolution with Th1 and CD8+CTL responses during natural infection implies the potentiality of poly-CTL-epitopic HCV vaccines. We recently reported in silico design and construction of DNA vaccines (pcPOL-plasmids) harboring HCV CTL epitopes. Herein, we provide data of mice immunization by pcPOL, (encoding; core132–142 [C], E2405–414 [E4], E2614–622 [E6] and NS31406–1415 [N] CD8+CTL epitopes as CE4E6N polytope) and its HBsAg-fused counterpart (pcHPOL), compared to the adjuvant-formulated (Montanide+CpG) CE4E6N synthetic-peptide immunization. All vaccinated groups developed different levels of cellular responses, however, only the pcHPOL-immunized mice elicited strong CTLs and IFN-γ-secreting cells that were further augmented towards a Th1 response and partial tumor protection by DNA-prime/peptide-boosting regimen. Priming with HBsAg alone could not afford its augmenting effect indicating the importance of priming by polytope itself. Hence, fusion of immunocarriers like HBsAg conjoined with DNA-prime/peptide-boost immunization regimen seems a strategy to enhance the epitope-specific immune responses towards poly-CTL-epitopic vaccines. [Copyright &y& Elsevier]

Abstract: HIV-1 specific cellular immune responses play a significant part in controlling HIV-1 viral replication and are an important component of an HIV-1 vaccine induced immune response. We reported earlier that recombinant DNA vaccine delivered intramuscularly, and recombinant Listeria monocytogenes, delivered orally induced CD8+ and CD4+ T cell immune responses in rhesus macaques and that this vaccine protocol showed partial protection against an SIV239 challenge. In this paper, we have analyzed the SIV antigen-specific immune responses at the time of challenge and during the subsequent infection course. We find that the immune status of the animals, as measured by the frequency of antigen-specific IFN-gamma secreting peripheral blood mononuclear cells, at the time of challenge correlates more strongly with viral loads at set point than peak viral loads. The correlation between the immune response and viral load was strongest early, as viral set-point was just being established and disintegrates overtime. This study demonstrates the cellular immune response to SIV at the time of challenge of a nonhuman primate is able to impact on viral set-point following SIV239 challenge. Further, this study demonstrates that as virus replicates the T cell immune response to SIV antigens induced by the vaccine is modulated by antigen encountered by immune cells during viral replication. [Copyright &y& Elsevier]

Abstract: DNA vaccines and recombinant Listeria monocytogenes that express and secrete SIV Gag and Env antigens were combined in a nonhuman primate prime-boost immunogenicity study followed by a challenge with SIV239. We report that recombinant DNA vaccine delivered intramuscularly, and recombinant L. monocytogenes delivered orally each individually have the ability to induce CD8+ and CD4+ T cell immune responses in a nonhuman primate. Four rhesus monkeys were immunized at weeks 0, 4, 8, and 12 with the pCSIVgag and pCSIVenv DNA plasmids and boosted with SIV expressing L. monocytogenes vaccines at weeks 16, 20, and 28. Four rhesus monkeys received only the L. monocytogenes vaccines at weeks 16, 20, and 28. A final group of monkeys served as a control group. Blood samples were taken before vaccination and 2 weeks post each injection and analyzed by ELISPOT for CD4+ and CD8+ T cell responses. Moderate vaccine induced SIV-specific cellular immune responses were observed following immunization with either DNA or L. monocytogenes vectors. However, the SIV antigen-specific immune responses were significantly increased when Rhesus macaques were primed with SIV DNA vaccines and boosted with the SIV expressing L. monocytogenes vectors. In addition, the combined vaccine was able to impact SIV239 viral replication following an intrarectal challenge. This study demonstrates for the first time that oral L. monocytogenes can induce a cellular immune response in a nonhuman primate and is able to enhance the efficacy of a DNA vaccine as well as provide modest protection against SIV239 challenge. [Copyright &y& Elsevier]