CD4⁺ Tfh cells are preferentially SIV-infected in LNs. CD4⁺ T cells from LNs of SIV-infected RMs were sorted into 3 populations: naive (circles), central memory (squares), and Tfh cells (inverted triangles). Quantitative real-time PCR was used to determine the SIV infection frequency of each subset. P values represent Mann-Whitney U t test results. Horizontal bar represents median.