Currently, more than 36 million people are infected with HIV. Although the introduction of highly active anti-retroviral therapy (HAART) (1, 2) has led to substantial advances in the clinical management of HIV infected individuals, HAART cannot completely eliminate the virus (3). This is because CD4 T helper cells, harboring the virus, remain dormant reservoirs. These reservoirs are difficult to measure and are present even in HAART-treated HIV infected individuals with undetectable levels of HIV in the blood. A growing body of studies has revealed follicular helper (Tfh) CD4 T cells, a highly differentiated CD4 T cell population localized in immunologically sanctuary sites (follicle/germinal center) (4), as a major reservoir of HIV (5). The present Frontiers in Immunology eBook compiles 16 timely review articles focusing on the dynamics of major follicular immune cell types in HIV/SIV infection and their potential role for disease pathogenesis and the viral persistence in the lymph node.Vaccari M et al (6) provide an overview of follicular T cell populations in the SIV NHP model. The phenotype and function of NHP Tfh cells as well as their role in viral reservoir formation and the impact of HIV/SIV infection on Tfh dynamics is discussed. Besides their role as immune suppressors, the possible role of Tfr cells in the development of high avidity antigen-specific antibodies is discussed. The recent literature for follicular CD8 T cell dynamics and in vivo manipulation to study their role is reviewed. The authors, convincingly reveal the importance of NHP studies to understand the follicular dynamics in HIV/SIV pathogenesis and explore in vivo manipulations targeting these cell populations. Investigation of follicular CD4 T cell heterogeneity is an important parameter for the understanding of generation of neutralizing antibodies as well as the formation of viral reservoir. Velu V et al (7) discuss several follicular CD4 T cell subsets including CXCR3+ Th1-like follicular helper CD4 T cells. High levels of IFNg and IP-10 observed in HIV/SIV could represent a mechanism for the differentiation of Tfh towards a Tfh1 phenotype. Given the differential levels of CCR5 expression by Tfh subsets, future studies should take under consideration this heterogeneity when the virus reservoir is under investigation. Tfh1 cells were found in vaccinated non-human primates the authors suggest that local inflammatory signals could represent critical regulators of Tfh1 cell dynamics. The authors show the need for further mechanistic studies aiming to understand the dynamics of follicular CD4 and CD8 T cells. Tracking the movement of cells between different anatomical compartments in human subjects is highly challenging. Analysis of phenotypically alike cells could represent a starting point for the investigation of cell subsets from compartments with possible dynamic interchange. Banga R et al (8) provide data showing that circulating CXCR3+CXCR5- CD4 T cells is the major blood compartment containing replication competent virus in cART, aviremic individuals. Among the parameters analyzed, the frequency of PD-1+ cells was significantly correlated with the enrichment of replication competent virus in the circulating CXCR3+ CD4 T cell compartment. The data suggest a connection between the presence of infected lymph node and circulating CXCR3+ CD4 T cells. The potential role of CD8 T cells in viral control has been shown by several HIV/SIV studies. Xiao M et al (9) review recent data on CD8 T cells expressing the receptor CXCR5 (fCD8 T cells) and have the ability to migrate into follicular areas. A comparison between fCD8 dynamics in chronic LCMV and HIV infection revealed key …