Human Foamy Virus Replication: A Pathway Distinct from That of Retroviruses and Hepadnaviruses

Abstract

Human foamy virus (HFV) is the prototype of the Spumavirus genus of Retroviridae. In all other retroviruses, the pol gene products, including reverse transcriptase, are synthesized as Gag-Pol fusion proteins and are cleaved to functional enzymes during viral budding or release. In contrast, the Pol protein of HFV is translated from a spliced messenger 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 rounds of infection, reminiscent of hepadnaviruses. These data suggest that foamy viruses possess a replication pathway containing features of both retroviruses and hepadnaviruses but distinct from both.

Spliced human endogenous retroviral HERV-H env transcripts in T-cell leukaemia cell lines and normal leukocytes: alternative splicing pattern of HERV-H transcripts.

“…Another possible explanation of this splice pattern could be the existence of distinct, incompletely spliced, gag and pol transcripts retaining either of the two ' introns ', which contain most of gag and pol regions, respectively. The human foamy virus pol gene has been shown to be expressed as a Pro-Pol polyprotein (Lo$ chelt & Flu$ gel, 1996) transcribed from a spliced pol transcript (Yu et al, 1996).…”

Do lipid rafts mediate virus assembly and pseudotyping?

“…Cryo-electron micrographs ( Fig. 1) of a preparation of feline foamy virus (FFV) grown in Crandel feline kidney (CrFK) cells show that it contains two morphologically distinct viruses: FFV (Fischer et al, 1998;Wilk et al, 2000Wilk et al, , 2001bWinkler et al, 1997;Yu et al, 1996;Zemba et al, 1998) and feline leukaemia virus (FLV) (Bolognesi, 1974;Essex et al, 1973;Gallo & Wong-Staal, 1982). These are seen as individual particles in Fig.…”

Pattern of seroreactivity against feline foamy virus proteins in domestic cats from Germany

“…Foamy viruses (FVs), also known as spumaretroviruses, are a distinct subfamily within the Retroviridae with distinguishing features in their replication pathway and a complex genomic organisation ( [Yu et al, 1996], [Neumann-Haefelin et al, 1993], [Linial, 1999], [Bastone et al, 2003] and [Rethwilm, 2003]). FV infections are persistent and infected animals show a sustained antibody response against Gag and Bet that is used for serological identification of infected hosts via ELISA and/or immunoblotting ( , [Hahn et al, 1994], [Heneine et al, 2003], [Khan and Kumar, 2006], [Saib, 2003] and [Williams and Khan, 2010]).…”