Simian immunodeficiency virus selectively infects proliferating CD4+ T cells in neonatal rhesus macaques

Abstract

Abstract Infants infected with HIV have a more severe course of disease and persistently higher viral loads than HIV-infected adults. However, the underlying pathogenesis of this exacerbation remains obscure. Here we compared the rate of CD4+ and CD8+ T-cell proliferation in intestinal and systemic lymphoid tissues of neonatal and adult rhesus macaques, and of normal and age-matched simian immunodeficiency virus (SIV)–infected neonates. The results demonstrate infant primates have much greater rates of CD4+ T-cell proliferation than adult macaques, and that these proliferating, recently “activated” CD4+ T cells are infected in intestinal and other lymphoid tissues of neonates, resulting in selective depletion of proliferating CD4+ T cells in acute infection. This depletion is accompanied by a marked increase in CD8+ T-cell activation and production, particularly in the intestinal tract. The data indicate intestinal CD4+ T cells of infant primates have a markedly accelerated rate of proliferation and maturation resulting in more rapid and sustained production of optimal target cells (activated memory CD4+ T cells), which may explain the sustained “peak” viremia characteristic of pediatric HIV infection. Eventual failure of CD4+ T-cell turnover in intestinal tissues may indicate a poorer prognosis for HIV-infected infants.