ENPEP and infection: Antibodies against SIV gp140 and HIV-1 gp160, raised in SIV-infected macaques and gp160-immunized rabbits, totally inhibited these interactions (Figure 3e–h and Figure 4e–h), whereas pre-immune sera (NI) obtained from the same animal before infection or immunization had no effect on these interactions (Figure 3e–h and Figure 4E–H).