Recombination was screened using a GARD (51) and all analyses were subsequently performed in separate for each nonrecombinant fragment (Table S2)

Recombination was screened using a GARD (51) and all analyses were subsequently performed in separate for each nonrecombinant fragment (Table S2). after 412 y of suppressive cART. Our detailed analysis of these eight patients indicates that persistent HIV-1 in peripheral blood and GALT is found primarily in memory CD4+T cells [CD45RO+/CD27(+/)]. The HIV-1 infection frequency of CD4+T cells from peripheral blood and GALT was higher in patients who initiated treatment during Gemcabene calcium chronic compared with acute/early infection, indicating that early initiation of therapy results in lower HIV-1 reservoir size in blood and gut. Phylogenetic analysis revealed an HIV-1 genetic change between RNA sequences isolated before initiation of cART and intracellular HIV-1 sequences from the T-cell subsets after 412 y of suppressive cART in four of the eight patients. However, evolutionary rate analyses estimated no greater than three nucleotide substitutions per gene region analyzed during all of the 412 y of suppressive therapy. We also identified a clearly replication-incompetent viral sequence in multiple memory T cells in one patient, strongly supporting asynchronous cell replication of a cell containing integrated HIV-1 DNA as the source. This study indicates that persistence of a remarkably stable population of infected memory cells will be the primary barrier to a cure, and, with little evidence of viral replication, this population could be maintained by homeostatic cell proliferation or other processes. Combinational, antiretroviral therapy (cART) effectively suppresses but does not eradicate HIV-1 infection (1). Persistent low-level HIV-1 can still be detected in plasma (27) and cellular Gemcabene calcium reservoirs (810) even after several years of suppressive cART, Gemcabene calcium and cessation of current treatments invariably results in resumption of viral replication. Resting-memory CD4+T cells are a well-defined reservoir of HIV-1, and the reservoir is established when an activated CD4+T cell becomes infected by HIV-1 but transitions to a resting state (9) or perhaps when resting cells are infected directly (1113). Central and transitional memory T cells have recently been identified as major contributors to the HIV-1 reservoir in the memory T-cell population (14). Nave T cells have also been demonstrated to contain HIV-1 DNA in patients on suppressive therapy, although at a lower infection frequency than the memory T-cell population (15). In addition, many other cell types, including monocyte/macrophages, have been proposed to play a role in HIV-1 persistence (reviewed in ref.16). These long-lived HIV-1infected cells have been detected in peripheral blood. Several studies, however, suggest that the reservoir is largely established and maintained in lymphoid tissues, and that the infected cells circulating in blood may not be representative of the population of infected cells in tissue. For example, the majority of lymphocytes are sequestered in the gastrointestinal tract, and gut-associated lymphoid tissue (GALT) has been shown to be a major viral reservoir in patients on suppressive antiretroviral therapy (1722). In addition to the persistence of long-lived, latently infected cells, low-level viral replication has been Gemcabene calcium proposed as a mechanism that maintains HIV-1 during cART. If complete viral replication cycles persist, despite suppressive antiretroviral therapy, this would lead to de novo cellular infection and a constant replenishment of the viral reservoir. Investigations into whether HIV-1 replication continues during suppressive therapy have been carried out with peripheral blood and GALT samples but have led to potentially contradictory results. Some studies have found an absence of genetic evolution in viral reservoirs (2329) and no reduction of plasma RNA during intensification of cART Cav3.1 (30,31), suggesting that cART is effective in preventing viral replication in these anatomical sites. In contrast, increased numbers of 2-long terminal repeat circles in peripheral blood mononuclear cells and decreased amounts of unspliced HIV-1 RNA in CD4+T cells isolated from the terminal ileum have been reported during raltegravir.