Epitopic mutations within seven p24 and gp120 epitopes, corresponding to a total of 13 CTL escape and secondary mutations appearing over the first three years of infection, were introduced into the PIC1362 HIV-1 sequence alone or in combination to produce 6 NL4-3/p24 and 13 NL4-3/gp120 mutant chimeric viruses for fitness analyses (see below). This evidence concerns the gene ITIH4 and infection.