Our finding of a large number of recombination breakpoints distributed across the gp120 envelope protein in abnormal tissues with high levels of replication-competent macrophages is consistent with in vitro studies, which showed that while a single round of viral replication in T-lymphocytes in culture generated an average of nine recombination events, the infection of macrophages led to approximately 30 crossover events per cycle [11]. This evidence concerns the gene ITIH4 and infection.