CXCR5 and HIV infectious disease: Virus-specific CXCR5+ CD8+ T cells have been identified in the blood and lymph nodes of patients with chronic HIV infection, and HIV-specific TFC cells have been shown to exist in the follicular zone of lymph nodes (Sen et al., 2016; Velu et al., 2018; Xiao et al., 2018; Fenwick et al., 2019).