Although CD8+ T cells play an important role in the containment of adult HIV-1 replication their role in infant HIV-1 infection is not as well understood. of HIV-specific CD8+ T cells expressed HLA-DR (mean 80% range 68-85%) and CD95 (mean 88% range 79-96%) suggesting sustained activation and vulnerability to apoptosis. Despite comparable expansion of HIV-specific CD8+ T cells of a similar phenotype to adults during early infection infant T cells failed to contain HIV-1 replication and remained persistently FGFR3 activated and vulnerable to apoptosis during chronic illness. Introduction The natural history of human being immunodeficiency computer virus type-1 (HIV-1) illness in babies differs markedly from adults. In adults plasma viral weight peaks during acute illness and is consequently reduced to a >1 log lower level set-point over the next 6-8 weeks . This viral weight set-point may be managed for years sometimes at levels below detection. In contrast babies experience very high plasma viral lots (often more than 1 million copies/ml) and lack the characteristic decrease to set-point observed in adults     . Infant CD4+ T cells are rapidly depleted during the 1st year of existence and there is much morbidity due to opportunistic illness. In the absence of antiretroviral therapy (ART) 2 mortality rates as high as 52% have been reported in African cohorts    . Adult studies of HIV-1 illness and SIV models have shown the importance of HIV-specific CD8+ T cells in limiting viral replication    . The quick HIV-1 disease progression experienced by babies may be a consequence of suboptimal T cell reactions during early existence. Studies carried out in perinatally infected infants report less frequent detection of CD8+ T cell reactions and responses of a smaller magnitude than are typically observed in HIV-infected adults  . You will find conflicting findings concerning the association between CD8+ T cell reactions and HIV-1 viral weight or disease progression in babies and children; with some studies showing a positive bad or absence of correlation     . The detection of escape mutations suggests some infant CD8+ T cells exert adequate selection pressure to drive viral development  . In 85 vertically infected infants examined longitudinally during the 1st year of existence we observed an increase in the magnitude of HIV-specific IFN-γ reactions over time . We also found infants who acquired HIV-1 after one month of age were able to generate IFN-γ reactions more rapidly than babies with or peripartum illness . Collectively these data suggest that the capacity of the infant cellular immune system to generate HIV-specific IFN-γ reactions increases rapidly in the 1st months of existence. Understanding the specific mechanisms by which infant T cells fail to consist of HIV-1 is important to the design of vaccines appropriate for use in babies. In addition problems in infant immune responses that clarify poor viral control may contribute more broadly to our understanding of HIV-1 immune pathogenesis. With this study we longitudinally describe the rate of recurrence and phenotype of HIV-specific CD8+ T cells during main and chronic HIV-1 illness in a group of Kenyan infants. Results Characteristics of selected participants The results of IFN-γ-ELISPOT assays performed in the previously characterized cohort study  were Bosentan used to select babies with high-level reactions for more detailed phenotypic studies using class I HLA tetramers. A total of 85 children Bosentan became Bosentan infected during the course of the study 72 acquired HIV-1 before the 1st month of existence and 61 of these experienced ELISPOT data. Of these 61 babies with early HIV-1 acquisition 26 (43%) experienced ELISPOT responses greater than 400 HIVSFU/million PBMC. Of these 7 infants experienced responses directed at HIV-1 epitopes for which we were able to create tetramers and experienced adequate cells cryopreserved for circulation cytometry studies. Table 1 shows the virologic and immunologic characteristics for the selected babies. The median peak response to these peptides was 993 HIVSFU/106 PBMC (Table 1 range 450-2040). HIV-1 RNA viral lots Bosentan were high the imply maximum was 6.7 log10 (SD ±0.65) and the mean set-point was 6.2 log10 copies/ml (SD ±0.53). The level of.