Memory CD4 + T-Lymphocyte Loss and Dysfunction during Primary Simian Immunodeficiency Virus Infection

Abstract

ABSTRACT It has long been appreciated that CD4 + T lymphocytes are dysfunctional in human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV)-infected individuals, and it has recently been shown that HIV/SIV infections are associated with a dramatic early destruction of memory CD4 + T lymphocytes. However, the relative contributions of CD4 + T-lymphocyte dysfunction and loss to immune dysregulation during primary HIV/SIV infection have not been fully elucidated. In the current study, we evaluated CD4 + T lymphocytes and their functional repertoire during primary SIVmac251 infection in rhesus monkeys. We show that the extent of loss of memory CD4 + T lymphocytes and staphylococcal enterotoxin B-stimulated cytokine production by total CD4 + T lymphocytes during primary SIVmac251 infection is tightly linked in a cohort of six rhesus monkeys to set point plasma viral RNA levels, with greater loss and dysfunction being associated with higher steady-state viral replication. Moreover, in exploring the mechanism underlying this phenomenon, we demonstrate that the loss of functional CD4 + T lymphocytes during primary SIVmac251 infection is associated with both a selective depletion of memory CD4 + T cells and a loss of the functional capacity of the memory CD4 + T lymphocytes that escape viral destruction.