Dynamics of CCR5 expression by CD4(+) T cells in lymphoid tissues during simian immunodeficiency virus infection.

Early viral replication and profound CD4(+) T-cell depletion occur preferentially in intestinal tissues of macaques infected with simian immunodeficiency virus (SIV). Here we show that a much higher percentage of CD4(+) T cells in the intestine express CCR5 compared with those found in the peripheral blood, spleen, or lymph nodes. In addition, the selectivity and extent of the CD4(+) T-cell loss in SIV infection may depend upon these cells coexpressing CCR5 and having a "memory" phenotype (CD45RA(-)).

Identifying the target cell in primary simian immunodeficiency virus (SIV) infection: highly activated memory CD4(+) T cells are rapidly eliminated in early SIV infection in vivo.

It has recently been shown that rapid and profound CD4(+) T-cell depletion occurs almost exclusively within the intestinal tract of simian immunodeficiency virus (SIV)-infected macaques within days of infection. Here we demonstrate (by three- and four-color flow cytometry) that this depletion is specific to a definable subset of CD4(+) T cells, namely, those having both a highly and/or acutely activated (CD69(+) CD38(+) HLA-DR(+)) and memory (CD45RA(-) Leu8(-)) phenotype. Moreover, we demonstrate that this subset of helper T cells is found primarily within the intestinal lamina propria.

Ultrastructural morphology of Enterocytozoon bieneusi in biliary epithelium of rhesus macaques (Macaca mulatta).

Enterocytozoon bieneusi is the most common microsporidian parasite found in humans with acquired immunodeficiency syndrome. A nearly identical organism was recently recognized in rhesus macaques (Macaca mulatta). Ultrastructural examination of this microsporidian parasite in biliary epithelium of rhesus macaques reveals characteristics unique to E.

Localization of persistent Enterocytozoon bieneusi infection in normal rhesus macaques (Macaca mulatta) to the hepatobiliary tree.

Enterocytozoon bieneusi is the most common microsporidian parasite recognized in human patients with AIDS. Recently, we identified a virtually identical organism causing a spontaneous infection associated with hepatobiliary and intestinal disease in simian immunodeficiency virus (SIV)-infected macaques. To examine the natural history of the infection, we examined captive rhesus macaques for E.

Gastrointestinal tract as a major site of CD4+ T cell depletion and viral replication in SIV infection.

Human and simian immunodeficiency virus (HIV and SIV) replicate optimally in activated memory CD4(+) T cells, a cell type that is abundant in the intestine. SIV infection of rhesus monkeys resulted in profound and selective depletion of CD4+ T cells in the intestine within days of infection, before any such changes in peripheral lymphoid tissues. The loss of CD4+ T cells in the intestine occurred coincident with productive infection of large numbers of mononuclear cells at this site.