HIV-1 spreads from lymphocytes to normal human keratinocytes suitable for autologous and allogenic transplantation.
Normal human keratinocytes can reconstitute in vitro cohesive sheets of epithelium suitable for grafting onto patients. Despite the widespread use of autografts and allografts, no data are yet available on productive infection by human immunodeficiency virus (HIV-1) of human keratinocytes. To address this point, we challenged keratinocytes at the second passage of culture with HTLV-IIIB virus by cell-free and cell-mediated inoculum. Viral entry was not achieved by cell-free inoculum, thus demonstrating that cultured keratinocytes do not provide the membrane requirements for viral binding and/or internalization. By contrast, the cell-mediated inoculum overcame specific receptor constraints, leading to viral integration and productive infection. The p24gag viral protein was transiently released in the culture supernatant, although at low level. The viral progeny produced by infected keratinocytes was rescued and amplified by co-culture experiments performed with the HIV-1 high sensitive CEM-SS human T-cell line. Viral integration, p24gag production, and secondary transmission to lymphoid cells was further confirmed with keratinocytes infected at the fourth passage of culture. Taken together, our results demonstrate that cultured keratinocytes can be infected by HTLV-IIIB virus, which can be maintained in semi-latent form for several passages after inoculum and rescued to full replication by a proper target. The in vitro demonstration of lympho-epithelial HIV-1 spreadings warns against the use of inappropriately screened biopsies for the preparation of skin grafts.