Human Immunodeficiency Virus Type 1 (HIV-1) and Herpes Simplex Virus Type 2 (HSV-2) Can Coinfect and Simultaneously Replicate in the Same Human CD4 + Cell: Effect of Coinfection on Infectious HSV-2 and HIV-1 Replication

Experiments were designed to determine whether HIV-1 and herpes simplex virus type 2 (HSV-2) coinfection leads to simultaneous replication of both viruses in the same human CD4⁺ cell (MT-4 cell line) and the possible effects of coinfection on infectious virus production. Results from transmission electron microscopy analysis revealed replication of typical HSV-2 nucleocapsids in the nucleus and budding of HIV-1 particles through the plasma membrane and through intracytoplasmic vacuoles containing enveloped HSV-2 particles in the same coinfected cell. Coinfection of HIV-1 persistently infected H9IIIB or promonocytic U1 cells with HSV-2 did not alter total production of infectious HSV-2 or the percentage of HSV-2 infectious centers compared with control H9 and U937 cells infected with HSV-2 alone. However, in coinfected promonocytic U1 cells HSV-2 induced infectious HIV-1 production measured by syncytial plaque assay. In summary, both HIV-1 and HSV-2 can coinfect and simultaneously replicate in the same human CD4⁺ cell. Interactions between HIV-1 and HSV-2 appear to be unidirectional, resulting in accelerated replication of HIV-1 as reported by Albrecht et al. (J Virol 1989;63:1861-1868), but not HSV-2 as shown by us.