SAMHD1 Polymorphisms were Significantly Correlated with HIV/SIV Virus Load in PBMC from Chinese Rhesus Macaques and Cynomolgus Macaques.

Background: Sterile alpha motif and histidine aspartate domain containing deoxynucleoside triphosphate triphosphohydrolase 1 (SAMHD1) is one of the novel restriction factors that potently supresses HIV-1 infection in myeloid cells at an early stage in the viral replication cycle. SAMHD1 activity is blocked by the action of viral accessory protein x (Vpx), which targets and recruits SAMHD1 for proteasomal degradation, in the SIVsm/HIV-2 lineage.

Methods: The impact of SAMHD1 polymorphisms on viral replication in Chinese-origin rhesus macaques (CR) and cynomolgus macaques of Vietnamese origin (CM) have not been reported until now. Therefore, we aimed to explore the polymorphisms, as well as the impact of polymorphisms, on HIV- 2 and SIV infections among CR and CM.

Results: We found two variants, T168C and T320C, located in the SAM domain of CR SAMHD1, which were significantly correlated with the HIV-2ROD/SIVmac239 virus load, suggesting that T168C and T320C probably affected HIV-2ROD and anti-SIVmac239 replication in CR, respectively. Conversely, T320C possibly affected CM SAMHD1-mediated HIV-2ROD restriction. However, none of the variants were correlated with CM SAMHD1-mediated SIVmac239 restriction.

Conclusion: Based on these results, we concluded that SAMHD1 polymorphisms did not affect SIVmac239 replication in CM, but perhaps altered HIV-2ROD infection; however, different sites of the SAM domain of SAMHD1 were responsible for restricting the replication of different viruses in CR.