Abstract
Foamy viruses (FVs), also known as spumaretroviruses, are complex retroviruses that are seemingly nonpathogenic in natural hosts. In natural hosts, which include felines, bovines, and nonhuman primates (NHPs), a large percentage of adults are infected with FVs. For this reason, the effect of FVs on infections with other viruses (co-infections) cannot be easily studied in natural populations. Most of what is known about interactions between FVs and other viruses is based on studies of NHPs in artificial settings such as research facilities. In these settings, there is some indication that FVs can exacerbate infections with lentiviruses such as simian immunodeficiency virus (SIV). Nonhuman primate (NHP) simian FVs (SFVs) have been shown to infect people without any apparent pathogenicity. Humans zoonotically infected with simian foamy virus (SFV) are often co-infected with other viruses. Thus, it is important to know whether SFV co-infections affect human disease.
Highlights
Foamy viruses (FVs) comprise the Spumaretrovirinae subfamily of the family Retroviridae and are designated spumaretroviruses [1]
There is a report of one worker who is seropositive for both simian FVs (SFVs) and simian retrovirus type D (SRV D) [56]
Fifty-six percent of the hunters bitten by nonhuman primates (NHPs) and infected with human T-cell lymphotropic virus-1 (HTLV-1) were infected with SFV, suggesting that these two viruses may have been co-transmitted via the bites [54]
Summary
Foamy viruses (FVs) comprise the Spumaretrovirinae subfamily of the family Retroviridae and are designated spumaretroviruses [1]. The coelacanth is an ancient marine four-lobed fish believed to be the organism that first became terrestrial and is the ancestor of all terrestrial organisms This indicates that FVs have existed for an estimated 400 million years [3], making Spumaretrovirinae the oldest known extant vertebrate virus subfamily. In research settings, there is some evidence that FVs can exacerbate the pathogenesis of other viruses This phenomenon cannot be well studied in natural infections, as finding FV uninfected adult animals is difficult. While humans have contacts with felines and bovines, there is no evidence for actual infection of humans with FVs from these species (reviewed in [14]). 2–5% of individuals in North America who report contact with NHPs are FV-infected, as determined by SFV polymerase chain reaction (PCR) (reviewed in [14]). If this cellular niche for SFV replication is altered as described below for experimental simian immunodeficiency virus (SIV) infections, there may be potential for pathogenic effects
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