Identification of V2 apex broadly neutralizing antibodies. (a) Rhesus macaques from which V2 apex lineages have been isolated in this study are grouped by their respective infecting SHIV strain. Animals previously described by Roark et al. (2021) for polyclonal V2 apex mutational mapping are denoted with #. (b) Neutralization of two sets of heterologous wild-type and V2 apex epitope mutant viruses by rhesus macaque plasma or purified polyclonal IgG (RM41328) for SHIV-infected rhesus macaques reported in this study. Plasma neutralization assays were repeated twice. (c) Representative FACS gating schemes for the two different single-cell sorting strategies. Top: Identification of 5695-b lineage members by collecting double-positive cells stained with a heterologous Env SOSIP probe conjugated with two different fluorophores. Bottom: Identification of 42056-a lineage members by collecting single-positive cells staining with heterologous wild-type and C-strand mutant Env SOSIP probe pairs.