UCLA

HIV-1 transmission is typically associated with the genetic bottleneck in which a single viral isolate, known as the transmitted/founder (T/F) virus, establishes successful infection in a new host. Current understanding of T/F virus properties is mostly limited to studies of envelope and very little is known about other post-entry viral properties. Here, T/F viruses from 3 successive generations of mother-to-child transmission (MTCT) were characterized. Nef mediated downregulation of human leukocyte antigen (HLA) class I and CD4, and Gag-Pol associated replication capacity appeared normal. Our results revealed no significant differences in these functions. The entry efficiency of T/F viruses and the maternal source were also similar however, the Envs of two maternal subsets varied in CD4 and CCR5 requirements for viral entry. Further understanding of whether there are unique functional characteristics of T/F viruses may perhaps provide an opportunity to design a vaccine or other intervention to prevent HIV-1 transmission.