Figure 5. Neutralization and ADCC on the day of intravenous challenge with SIV_mac251_NE.

Macaques were challenged with an intravenous dose of SIV_mac251_NE on week 46 after inoculation with SIV_mac239Δnef or SIV_mac239Δnef/E543-3env. Sera collected the day of challenge were evaluated for neutralization of SIV_mac251_NE (A) and ADCC against SIV_mac251_NE-infected cells (B). Solid black symbols indicate animals that became infected by SIV_mac251_NE. Dashed lines indicate 50% activity. Target cells infected with SHIV_SF162P3 served as a negative control for ADCC assays (gray). Differences in 50% ADCC titers were not significant (C). However, AUC values for ADCC were higher among the immunized animals that remained uninfected versus the immunized animals that became infected (2-tailed Mann-Whitney U test, P = 0.0091) (D). None of these macaques had the MHC class I alleles Mamu-A*01, -B*08 or -B*17 associated with reduced viral replication [67]–[69].