Inactivation of the human immunodeficiency virus by hypericin: evidence for photochemical alterations of p24 and a block in uncoating.

Following attachment and entry of human immunodeficiency virus (HIV) into a host cell, the HIV genomic RNA is reverse transcribed to cDNA. This step may be inhibited by hypericin, a compound that induces alterations of the retroviral capsid. Incubation of HIV with hypericin rendered the virus noninfectious. The replication of HIV was blocked early; HIV cDNA could not be detected in cells challenged with hypericin-treated HIV. Hypericin did not inhibit the binding of recombinant gp120 to CD4+ cells, nor did hypericin inhibit syncytium formation. However, reverse transcriptase activity could not be released from hypericin-treated virions. Western blot analysis revealed altered mobility of the HIV major capsid protein (p24) following hypericin treatment. Hypericin-treated recombinant HIV p24 exhibited similar altered mobility. The inactivation of HIV infectivity and the alterations in p24 mobility required hypericin incubations in the presence of visible light. Collectively, these data suggest that photochem...