TZM-BL neutralization assay was conducted using H9-derived SIVmac251 and (a) purified IgA from pooled fecal matter from SIV-infected macaques using jacalin, α-Mon IgA, Peptide M, and SSL7 columns, respectively, with the total IgA used on the X-axis. (b) Purified IgA from fecal matter from vaccinated macaque P879 using α-Mon IgA, Peptide M, and SSL7 columns with the total IgA used on the X-axis. (c)&(d) same as (a)&(b) respectively, only with amount of SIVmac251 Env-specific IgA used on the X-axis.