IC50* for selected rhesus monkeys with high-titer nAb activity.

*IC50, 50% inhibitory concentration given as reciprocal serum dilution for 50% neutralization.1determined in TZM-bl assays.2determined in human PBMC-based assays.3phage display selection performed; n.d. not determined.ZM135M, ZM233M.PB6, and ZM109F are primary HIV clade C isolates from Zambia. No neutralization was seen against five HIV clade C isolates from South Africa and four others from Zambia (not shown). SHIV-2873Nip is a Tier 1 (i.e. neutralization-sensitive) R5 virus that encodes env of a recently transmitted, R5 HIV clade C isolated from a Zambian infant [71]. SHIVSF162P3 is a Tier 2 virus (i.e. more difficult to neutralize and representative of most primary HIV isolates), HIVSF162.LS is a Tier 1 virus.