ABSTRACT
Vaccines based on recombinant viruses represent a promising strategy for the development of a prophylactic vaccine against HIV-1. However, despite a proven capacity to stimulate potent HIV-1-specific immune responses, viral systems have limited utility in homologous prime-boost regimens due to the generation of anti-vector immune responses. It is therefore important to develop a diverse set of vaccine candidates that can be combined in different heterologous prime-boost regimens and/or to identify a vaccine candidate that is less sensitive to anti-vector mediated immunity. In this report, we describe the design and pre-clinical immunogenicity of a Semliki Forest virus-based vaccine, VREP-C, encoding Indian origin HIV-1 clade C antigens. We show that a single immunization with VREP-C stimulates HIV-1-specific IFNgamma ELISPOT responses, which were efficiently boosted by a second and a third homologous VREP-C immunization resulting in highly potent cytotoxic T cell responses. These results suggest that VREP-C may be a valuable component of a future prophylactic vaccine against HIV-1.
Subject(s)
AIDS Vaccines/immunology , HIV Infections/immunology , HIV-1/immunology , Semliki forest virus/genetics , Semliki forest virus/immunology , T-Lymphocytes, Cytotoxic/immunology , Vaccines, Synthetic/immunology , AIDS Vaccines/administration & dosage , Animals , Antibodies, Viral/blood , Cytokines/analysis , Enzyme-Linked Immunosorbent Assay , HIV Antibodies/blood , HIV Antigens/genetics , HIV Antigens/immunology , HIV Infections/prevention & control , Immunization, Secondary , Immunoglobulin G/blood , Interferon-gamma/analysis , Mice , Mice, Inbred BALB C , Models, Animal , Neutralization Tests , Vaccines, Synthetic/administration & dosageABSTRACT
OBJECTIVES: To determine the role of the hepatitis C virus 3' untranslated region in viral mRNA translation in transfected cells and in cell extracts. STUDY DESIGN/METHODS: Noninfectious hepatitis C virus mini-genome RNAs with various deletions in the viral 3' untranslated region were transfected into cells or translated in vitro, and the translation efficiency was determined. RESULTS: We have found that the presence of the hepatitis C virus 3' untranslated region modestly increases mRNA translation. The positive effect correlated with the binding of a 45-kDa cytoplasmic factor to the hepatitis C virus 3' untranslated region. Furthermore, the U-rich sequence in the hepatitis C virus 3' untranslated region inhibits translation of capped and polyadenylated mRNAs as a result of the hybridization. CONCLUSIONS: The modest effect of the hepatitis C virus 3' untranslated region on translation suggests that it does not play a major role in mRNA translation. The inhibitory effect of the hepatitis C virus 3' untranslated region on translation of polyadenylated mRNAs supports the notion that translation of hepatitis C virus mRNAs occurs independently of a polyA tail.
Subject(s)
3' Untranslated Regions/genetics , Gene Expression Regulation, Viral , Hepacivirus/genetics , Protein Biosynthesis , RNA, Messenger/metabolism , 3' Untranslated Regions/metabolism , HeLa Cells , Humans , Poly A/metabolism , RNA Caps/metabolism , RNA, Viral/metabolism , Ribosomes/metabolism , TransfectionABSTRACT
We have analysed hepatitis C virus (HCV) RNAs in an in vitro RNA degradation assay. We found that the 3' end of positive polarity HCV RNA is sensitive to cytosolic RNases whereas the 3' end of negative polarity HCV RNA is relatively stable. Interaction of the HCV 3' untranslated region with the cellular La protein prevented premature degradation of the HCV RNA. One may speculate that HCV RNAs interact with La protein in infected cells to prevent premature degradation of the viral RNAs.
