ELECTRON-MICROSCOPIC STUDY OF HUMAN-HERPESVIRUS 6-INFECTED HUMAN T-CELL LINES SUPERINFECTED WITH HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1

Human herpesvirus 6 I(HHV-6) has been proposed as one of the co-factor s responsible for the development of acquired immunodeficiency syndrom e (AIDS) in human immunodeficiency virus (HIV) carriers. We analyzed t he interaction between HHV-6 and HIV-1 in superinfected cells. Cell-fr ee HIV-I could superinfect human T cell lines, MT-4 and Molt-4, which had been previously infected with HHV-6. Both HIV-I and HHV-6 replicat ed in the same cells. We observed two types of morphologically disting uished cells as early as 4 days after superinfection. One type (D) was degenerate cells with intracellular and extracellular HHV-6 and with less HIV-I virions. The other type (I) was relatively intact cells wit h both HIV-I and HHV-6 virions. Replication of HIV-1 was more active i n the type I as compared with type D cells. The level of HIV-1 reverse transcriptase (RT) activity in the culture supernatants of cells supe rinfected on day 0 declined after day 7, while that in the supernatant s of cell cultures infected with HIV-1 alone remained high between day s 12 and 40. These results suggest that the superinfection of the HHV- 6-infected cells with HIV-I may induce a degenerative process in these cells.