Here we describe a SHIV which: 1) encodes env of a recently transmitted, pediatric HIV clade C strain from Zambia; 2) is highly replication competent as shown by long-term follow up of an initial cohort of macaques used to adapt the infectious molecular clone of this SHIV-C, SHIV-1157i; 3) uses R5 as coreceptor for viral entry [8]; and 4) is pathogenic with gradual disease progression to AIDS. The gene discussed is ERVW-1; the disease is AIDS.