Comparison of whole gene and whole virus scrambled antigen approaches for DNA prime and fowlpox virus boost HIV type 1 vaccine regimens in macaques

Screening and confirmatory testing of MHC class I alleles in pig-tailed macaques

Pig-tailed macaques (Macaca nemestrina) are a commonly studied primate model of human AIDS. The Mane-A1*084:01 MHC class I allele (previously named Mane-A*10) is important for the control of SIV infection by CD8+ T cells in this model. Validated methods to detect this allele in large numbers of macaques are lacking. We studied this MHC allele using sequence-specific PCRs in 217 pig-tailed macaques and identified 75 (35%) positive animals. We then performed massively parallel pyrosequencing with a universal 568-bp MHC class I cDNA-PCR amplicon for 50 of these 75 macaques. All 50 animals expressed Mane-A1*084:01 or closely related variants of the Mane-A1*084 lineage. Mane-A1*084 transcripts accounted for an average of 20.9% of all class I sequences identified per animal. SIV infection of a subset of these macaques resulted in the induction of SIV-specific CD8+ T cell responses detected by Mane-A1*084:01 tetramers. An average of 19 distinct class I transcripts were identified per animal by pyrosequencing. This analysis revealed 89 new Mane class I sequences as well as 32 previously described sequences that were extended with the longer amplicons employed in the current study. In addition, multiple Mane class I haplotypes that had been inferred previously based on shared transcript profiles between unrelated animals were confirmed for a subset of animals where pedigree information was available. We conclude that sequence-specific PCR is useful to screen pig-tailed macaques for Mane-A1*084:01, although pyrosequencing permits a much broader identification of the repertoire of MHC class I sequences and haplotypes expressed by individual animals.

Construction and characterization of a recombinant fowlpox virus containing HIV-1 multi-epitope-p24 chimeric gene in mice

The epidemic of HIV/AIDS is sweeping across the world. It is of great importance to figure out new ways to curb this disease. Epitope-based vaccine is one of these solutions. In this study, a chimeric gene was obtained by combination of a designed HIV-1 multi-epitope gene (MEG) and HIV-1 p24 gene. A recombinant plasmid pUTA2-MEGp24 was then constructed by inserting MEGp24 gene into the downstream of the promoter (ATI-P7.5x20) of fowlpox virus (FPV) transfer vector pUTA2. The recombinant plasmid and wild-type FPV 282E4 strain were then co-transfected into CEF cells and homologous recombination occurred. A recombinant virus expressing HIV-1 protein MEGp24 was screened by genome PCR and Western blot assay. Large scale preparation and purification of the recombinant fowlpox virus (rFPV) were then carried out. BALB/c mice were immunized intramuscularly with the rFPV for three times on day 0, 14 and 42. Mice were executed and sampled one week after the third inoculation. Anti-HIV-1 antibody in serum and Th1 cytokines in the supernatant of cultured spleen cells were assayed by ELISA. The count of T lymphocyte subsets and the CTL activity of spleen lymphocytes were analyzed by flow cytometry and lactate dehydrogenase (LDH) release assay, respectively. The results showed that HIV-1 specific antibody in serum and increased T lymphocyte subsets (CD4(+) T, CD8(+) T) were detected in the immunization group. CTL target-killing activity and higher secretion of Th1 cytokines (IFN-gamma and IL-2) of spleen lymphocytes stimulated by H-2(d)-restricted CTL peptide were observed in immunized mice. We concluded that the rFPV may induce HIV-1 specific immunity especially cellular immunity in mice.

MHC class I allele frequencies in pigtail macaques of diverse origin

Pigtail macaques (Macaca nemestrina) are an increasingly common primate model for the study of human AIDS. Major Histocompatibility complex (MHC) class I-restricted CD8(+) T cell responses are a critical part of the adaptive immune response to HIV-1 in humans and simian immunodeficiency virus (SIV) in macaques; however, MHC class I alleles have not yet been comprehensively characterized in pigtail macaques. The frequencies of ten previously defined alleles (four Mane-A and six Mane-B) were investigated in detail in 109 pigtail macaques using reference strand-mediated conformational analysis (RSCA). The macaques were derived from three separate breeding colonies in the USA, Indonesia and Australia, and allele frequencies were analysed within and between these groups. Mane-A*10, an allele that restricts the immunodominant SIV Gag epitope KP9, was the most common allele, present in 32.1% of the animals overall, with similar frequencies across the three cohorts. Additionally, RSCA identified a new allele (Mane-A*17) common to three Indonesian pigtail macaques responding to the same Gag CD8(+) T cell epitope. This broad characterization of common MHC class I alleles in more than 100 pigtail macaques further develops this animal model for the study of virus-specific CD8(+) T cell responses.