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Simian foamy viruses (SFV) are complex retroviruses that are ubiquitous in nonhuman primates (NHP) and are zoonotically transmitted to humans, presumably through NHP saliva, by licking, biting, and other behaviors. We have studied SFV in free-ranging rhesus macaques in Bangladesh. It has been previously shown that SFV in immunocompetent animals replicates to detectable levels only in superficial epithelial cells of the oral mucosa, although latent proviruses are found in most, if not all, tissues. In this study, we compare DNA sequences from latent SFV proviruses found in blood cells of 30 Bangladesh rhesus macaques to RNA sequences of transcriptionally active SFV from buccal swabs obtained from the same animals. Viral strains, defined by differences in SFV gag sequences, from buccal mucosal specimens overlapped with those from blood samples in 90% of animals. Thus, latent proviruses in peripheral blood mononuclear cells (PBMC) are, to a great extent, representative of viruses likely to be transmitted to other hosts. The level of SFV RNA in buccal swabs varied greatly between macaques, with increasing amounts of viral RNA in older animals. Evidence of APOBEC3-induced mutations was found in gag sequences derived from the blood and oral mucosa.

Simian foamy viruses (SVF) are ubiquitous in nonhuman primates (NHP). SFV can be zoonotically transmitted to humans who either work with or live commensally with NHP. We analyzed the blood of 45 Bangladeshi performing monkey owners (an ethnic group called the Bedey) for SFV infection. Surprisingly, a PCR assay failed to detect SFV infection in any of these participants. This is in contrast to our previously reported infection rate of about 5% among Bangladeshi villagers.

Simian Foamy Virus (SFV) can be transmitted from non-human primates (NHP) to humans. However, there are no documented cases of human to human transmission, and significant differences exist between infection in NHP and human hosts. The mechanism for these between-host differences is not completely understood. In this paper we develop a new Bayesian approach to the detection of APOBEC3-mediated hypermutation, and use it to compare SFV sequences from human and NHP hosts living in close proximity in Bangladesh. We find that human APOBEC3G can induce genetic changes that may prevent SFV replication in infected humans in vivo., Author Summary Simian Foamy Virus (SFV) is a very common retrovirus in monkeys. When an infected monkey bites a human it can transmit the virus to the human; however, there are no documented cases of human to human transmission. There also appear to be significant differences between infection in monkey and human hosts. The reason for these differences in the two hosts is not completely understood. In this paper we show that a family of host defense enzymes called APOBEC3 may prevent replication of SFV in humans. They do this by changing the genome of the virus so that it cannot replicate. Although this same process also happens in monkeys, it appears to happen less than in humans, and the changes that the monkey APOBEC3 enzymes make are less likely to prevent the virus from replicating. We are able to make these inferences by seeing characteristic types of mutations in a collection of virus DNA sequences sampled in Bangladesh. We develop new statistical methodology to do this analysis.

Foamy viruses (FV) are complex retroviruses that naturally infect all nonhuman primates (NHP) studied to date. Zoonotic transmission of Old World NHP simian foamy viruses (SFV) has been documented, leading to nonpathogenic persistent infections. To date, there have been no reports concerning zoonotic transmission of New World monkey (NWM) SFV to humans and resulting infection. In this study, we developed a Western blot assay to detect antibodies to NWM SFV, a nested PCR assay to detect NWM SFV DNA, and a β-galactosidase-containing indicator cell line to assay replication of NWM SFV. Using these tools, we analyzed the plasma and blood of 116 primatologists, of whom 69 had reported exposures to NWM. While 8 of the primatologists tested were seropositive for SFV from a NWM, the spider monkey, none had detectable levels of viral DNA in their blood. We found that SFV isolated from three different species of NWM replicated in some, but not all, human cell lines. From our data, we conclude that while humans exposed to NWM SFV produce antibodies, there is no evidence for long-term viral persistence.