Persistent Infection with SIVmac Chimeric Virus Having <i>tat, rev, vpu, env</i> and <i>nef</i> of HIV Type 1 in Macaque Monkeys

A chimeric human and simian immunodeficiency virus carrying the tat, rev, vpu, env, and nef genes of human immunodeficiency virus type 1 was generated. The chimeric virus, NM-3n, grew competently in peripheral blood mononuclear cells from cynomolgus monkeys like the parental SIVmac. Two cynomolgus monkeys and one rhesus monkey inoculated with NM-3n raised antibodies to SIVmac Gag and HIV-1 Env. The antibodies raised in the cynomolgus monkeys persisted for at least 1.7 years. The antibodies contained virus neutralizing activity not only to the original chimeric virus but also to the parental HIV-1. Infectious viruses were isolated from one of the cynomolgus monkeys 37 and 63 weeks after inoculation and from the rhesus monkey continuously from 6 weeks after infection onward. The recovered virus maintained its chimeric structure but included several clones with mutations in the env V3 region. When the recovered virus was inoculated to another rhesus monkey, no difference in the frequency of virus recovery was seen from the originally infected monkeys. These carrier monkeys have so far shown no sign of the disease.