However, recently, it has been shown that V3 Abs (i) can neutralize tier 2 and 3 viruses if Ab and virus are coincubated for 4 to 24 h (23), (ii) play an in vivo role in constraining the native Env trimer to a neutralization-resistant phenotype (29), (iii) correlate with reduced infection of infants born to HIV-infected mothers (30), (iv) correlate with a reduced rate of infection in human vaccinees (31, –, 33), and (v) exert immune pressure, reflected in the sequence of the viruses transmitted to vaccinees in the RV144 human vaccine trial (17, 18). The gene discussed is ERVW-1; the disease is infection.