There are currently no non-human primate models with fully defined major histocompatibility complex (MHC) class II genetics. We recently showed that 6 common MHC haplotypes account for essentially all MHC diversity in cynomolgus macaques (Macaca fascicularis) from the island of Mauritius. Here we employ cDNA cloning and sequencing to comprehensively characterize full length MHC class II alleles expressed at the Mafa-DPA, -DPB, -DQA, -DQB, -DRA, and -DRB loci on the 6 common haplotypes. We describe 34 full-length MHC class II alleles, 12 of which are completely novel. Polymorphism was evident at all six loci, including DPA which is considered monomorphic in rhesus macaques. Similar to other old world monkeys, Mauritian cynomolgus macaques (MCM) share MHC class II allelic lineages with humans at the DQ and DR loci, but not at the DP loci. Additionally, we identified extensive sharing of MHC class II alleles between MCM and other non-human primates. The characterization of these full length expressed MHC class II alleles will enable researchers to generate MHC class II transferent cell lines and tetramers that can be used to explore CD4+ T-lymphocyte responses in MCM.

The importance of a broad CD8-T lymphocyte (CD8-TL) immune response to HIV is unknown. Ex vivo measurements of immunological activity directed at a limited number of defined epitopes provide an incomplete portrait of the actual immune response. Here we examined viral loads in SIVinfected MHC homozygous and heterozygous Mauritian cynomolgus macaques (MCM). Chronic viremia in MHC homozygous macaques was 80-fold greater than in MHC heterozygous macaques. Virus from MHC homozygous macaques accumulated 11 to 14 variants consistent with escape from CD8-TL responses after one year of SIV infection. The pattern of mutations detected in MHC heterozygous macaques suggests that their epitope-specific CD8-TL responses are a composite of NIH Public Access

f Specific major histocompatibility complex (MHC) class I alleles are associated with an increased frequency of spontaneous control of human and simian immunodeficiency viruses (HIV and SIV). The mechanism of control is thought to involve MHC class I-restricted CD8 ؉ T cells, but it is not clear whether particular CD8 ؉ T cell responses or a broad repertoire of epitope-specific CD8 ؉ T cell populations (termed T cell breadth) are principally responsible for mediating immunologic control. To test the hypothesis that heterozygous macaques control SIV replication as a function of superior T cell breadth, we infected MHC-homozygous and MHC-heterozygous cynomolgus macaques with the pathogenic virus SIVmac239. As measured by a gamma interferon enzyme-linked immunosorbent spot assay (IFN-␥ ELISPOT) using blood, T cell breadth did not differ significantly between homozygotes and heterozygotes. Surprisingly, macaques that controlled SIV replication, regardless of their MHC zygosity, shared durable T cell responses against similar regions of Nef. While the limited genetic variability in these animals prevents us from making generalizations about the importance of Nef-specific T cell responses in controlling HIV, these results suggest that the T cell-mediated control of virus replication that we observed is more likely the consequence of targeting specificity rather than T cell breadth.

Cynomolgus macaques (Macaca fascicularis) are quickly becoming a useful model for infectious disease and transplantation research. Even though cynomolgus macaques from different geographic regions are used for these studies, there has been limited characterization of full-length Major Histocompatibility Complex (MHC) Class I immunogenetics of distinct geographic populations. Here, we identified 48 MHC class I cDNA nucleotide sequences in eleven Indonesian cynomolgus macaques, including 41 novel Mafa-A and Mafa-B sequences. We found seven MHC class I sequences in Indonesian macaques that were identical to MHC class I sequences identified in Malaysian or Mauritian macaques. Sharing of nucleotide sequences between these geographically distinct populations is also consistent with the hypothesis that Indonesia was a source of the Mauritian macaque population. In addition, we found that the Indonesian cDNA sequence Mafa-B*7601 is identical throughout its peptide binding domain to Mamu-B*03, an allele that has been associated with control of SIV viremia in Indian rhesus macaques. Overall, a better understanding of the MHC class I alleles present in Indonesian cynomolgus macaques improves their value as a model for disease research and it better defines the biogeography of cynomolgus macaques throughout Southeast Asia.

Simian immunodeficiency virus (SIV)-infected macaques are the preferred animal model for human immunodeficiency virus (HIV) vaccines that elicit CD8؉ T cell responses. Unlike humans, whose CD8 ؉ T cell responses are restricted by a maximum of six HLA class I alleles, macaques express up to 20 distinct major histocompatibility complex class I (MHC-I) sequences. Interestingly, only a subset of macaque MHC-I sequences are transcriptionally abundant in peripheral blood lymphocytes. We hypothesized that highly transcribed MHC-I sequences are principally responsible for restricting SIV-specific CD8 ؉ T cell responses. To examine this hypothesis, we measured SIV-specific CD8؉ T cell responses in MHC-I homozygous Mauritian cynomolgus macaques. Each of eight CD8 ؉ T cell responses defined by full-proteome gamma interferon (IFN-␥) enzyme-linked immunospot (ELISPOT) assay were restricted by four of the five transcripts that are transcriptionally abundant (>1% of total MHC-I transcripts in peripheral blood lymphocytes). The five transcriptionally rare transcripts shared by these animals did not restrict any detectable CD8؉ T cell responses. Further, seven CD8 ؉ T cell responses were defined by identifying peptide binding motifs of the three most frequent MHC-I transcripts on the M3 haplotype. Combined, these results suggest that transcriptionally abundant MHC-I transcripts are principally responsible for restricting SIV-specific CD8 ؉ T cell responses. Thus, only a subset of the thousands of known MHC-I alleles in macaques should be prioritized for CD8 ؉ T cell epitope characterization.

CD8 ؉ T cell responses rapidly select viral variants during acute human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV) infection. We used pyrosequencing to examine variation within three SIV-derived epitopes (Gag 386-394 GW9, Nef 103-111 RM9, and Rev 59-68 SP10) targeted by immunodominant CD8 ؉ T cell responses in acutely infected Mauritian cynomolgus macaques. In animals recognizing all three epitopes, variation within Rev 59-68 SP10 was associated with delayed accumulation of variants in Gag 386-394 GW9 but had no effect on variation within Nef 103-111 RM9. This demonstrates that the entire T cell repertoire, rather than a single T cell population, influences the timing of immune escape, thereby providing the first example of conditional CD8 ؉ T cell escape in HIV/SIV infection.

Rapid evolution and high intrahost sequence diversity are hallmarks of human and simian immunodeficiency virus (HIV/SIV) infection. Minor viral variants have important implications for drug resistance, receptor tropism, and immune evasion. Here, we used ultradeep pyrosequencing to sequence complete HIV/SIV genomes, detecting variants present at a frequency as low as 1%. This approach provides a more complete characterization of the viral population than is possible with conventional methods, revealing low-level drug resistance and detecting previously hidden changes in the viral population. While this work applies pyrosequencing to immunodeficiency viruses, this approach could be applied to virtually any viral pathogen.

e Hepatitis C virus (HCV) is the leading cause of liver disease worldwide. In this study, we analyzed four treatment-naïve patients infected with subtype 1a and performed Roche/454 pyrosequencing across the coding region. We report the presence of low-level drug resistance mutations that would most likely have been missed using conventional sequencing methods. The approach described here is broadly applicable to studies of viral diversity and could help to improve the efficacy of direct-acting antiviral agents (DAA) in the treatment of HCV-infected patients.