Platelets function as an acute viral reservoir during HIV-1 infection by harboring virus and T-cell complex formation

Platelets were recently found to harbor infectious HIV virions in infected individuals who are on antiretroviral treatment with poor CD41 T-cell recovery. In this study, we screened platelets from recently infected individuals, before and after antiretroviral therapy, for the presence of virus and examined platelet activation, as well as CD41 T-cell recovery. This was followed by in vitro studies assessing platelet-CD41 T-cell complex formation as a contributing factor to viral transmission. HIV1 platelets were detected in 10 of 10 acutely infected individuals with no prior history of antiretroviral therapy. The percentage of HIV1 platelets dropped significantly after 3 months of antiretroviral therapy in all of the study participants. These individuals also demonstrated significant recovery of CD41 T cells. Interestingly, the percentage of HIV1 platelets correlated positively with viral load but not with CD41 T-cell count. Furthermore, we found that platelet activation with soluble CD40L or thrombin receptor activator peptide 6 (TRAP6) increased platelet-virus interactions in vitro. TRAP6-mediated interactions were reduced by platelet antagonists, aspirin, and R406. We demonstrated that platelets transmit the virus to CD41 T cells, and this transinfection was abolished by inhibiting platelet-T-cell complex formation via exposure to an anti-CD62P antibody. Additionally, treatment with TRAP6 significantly increased the transinfection, which was also inhibited by aspirin and R206. These results reveal that platelets have the potential to promote HIV viral spread during the acute stage of infection, by harboring infectious virus transmitting infection to susceptible CD41 T cells through complex formation.