HUMAN FOAMY VIRUS-REPLICATION - A PATHWAY DISTINCT FROM THAT OF RETROVIRUSES AND HEPADNAVIRUSES

Human foamy virus (HFV) is the prototype of the Spumavirus genus of Re troviridae. In all other retroviruses, the pol gene products, includin g reverse transcriptase, are synthesized as Gag-Pol fusion proteins an d are cleaved to functional enzymes during viral budding or release, I n contrast, the Pol protein of HFV is translated from a spliced messen ger RNA and lacks Gag domains, Infectious HFV particles contain double -stranded DNA similar in size to full-length provirus, suggesting that reverse transcription has taken place in viral particles before new r ounds of infection, reminiscent of hepadnaviruses. These data suggest that foamy viruses possess a replication pathway containing features o f both retroviruses and hepadnaviruses but distinct from both.