Small intestine CD4⁺ T cells are profoundly depleted during acute simian-human immunodeficiency virus infection, regardless of viral pathogenicity

To analyze the relationship between acute virus-induced injury and the subsequent disease phenotype, we compared the virus replication and CD4 ⁺ T-cell profiles for monkeys infected with isogenic highly pathogenic (KS661) and moderately pathogenic (#64) simian-human immunodeficiency viruses (SHIVs). Intrarectal infusion of SHIV-KS661 resulted in rapid, systemic, and massive virus replication, while SHIV-#64 replicated more slowly and reached lower titers. Whereas KS661 systemically depleted CD4⁺ T cells, #64 caused significant CD4⁺ T-cell depletion only in the small intestine. We conclude that SHIV, regardless of pathogenicity, can cause injury to the small intestine and leads to CD4⁺ T-cell depletion in infected animals during acute infection.