Cocirculation of Two env Molecular Variants, of Possible Recombinant Origin, in Gorilla and Chimpanzee Simian Foamy Virus Strains from Central Africa

Abstract

Simian foamy virus (SFV) is a ubiquitous retrovirus in nonhuman primates (NHPs) that can be transmitted to humans, mostly through severe bites. In the past few years, our laboratory has identified more than 50 hunters from central Africa infected with zoonotic SFVs. Analysis of the complete sequences of five SFVs obtained from these individuals revealed that env was the most variable gene. Furthermore, recombinant SFV strains, some of which involve sequences in the env gene, were recently identified. Here, we investigated the variability of the env genes of zoonotic SFV strains and searched for possible recombinants. We sequenced the complete env gene or its surface glycoprotein region (SU) from DNA amplified from the blood of (i) a series of 40 individuals from Cameroon or Gabon infected with a gorilla or chimpanzee foamy virus (FV) strain and (ii) 1 gorilla and 3 infected chimpanzees living in the same areas as these hunters. Phylogenetic analyses revealed the existence of two env variants among both the gorilla and chimpanzee FV strains that were present in zoonotic and NHP strains. These variants differ greatly (>30% variability) in a 753-bp-long region located in the receptor-binding domain of SU, whereas the rest of the gene is very conserved. Although the organizations of the Env protein sequences are similar, the potential glycosylation patterns differ between variants. Analysis of recombination suggests that the variants emerged through recombination between different strains, although all parental strains could not be identified. IMPORTANCESFV infection in humans is a great example of a zoonotic retroviral infection that has not spread among human populations, in contrast to human immunodeficiency viruses (HIVs) and human T-lymphotropic viruses (HTLVs). Recombination was a major mechanism leading to the emergence of HIV. Here, we show that two SFV molecular envelope gene variants circulate among ape populations in Central Africa and that both can be transmitted to humans. These variants differ greatly in the SU region that corresponds to the part of the Env protein in contact with the environment. These variants may have emerged through recombination between SFV strains infecting different NHP species.

An Immunodominant and Conserved B-Cell Epitope in the Envelope of Simian Foamy Virus Recognized by Humans Infected with Zoonotic Strains from Apes

“…8A and B). Two gorilla SFV genotypes that differ mostly in the central region of the env gene infect humans and NHPs (20), and we recently described coinfection by strains from the two genotypes (15). Binding magnitude to peptide N 96 -V 110 did not differ between individuals found to be infected with one or two SFV genotypes (Fig.…”

“…A single SFV-infected individual exclusively recognized peptide N 96 -V 110 -cae_agm22, whereas 31 recognized peptide N 96 -V 110 . All SFV sequences from Central African hunters and NHPs had a W at position 108 (9,20), including the two individuals whose plasma samples reacted with peptide cae_agm22. We cannot exclude the presence of gorilla SFV quasispecies carrying a W108R change in body compartments other than blood or their circulation prior to sampling.…”

Genome Analysis and Replication Studies of the African Green Monkey Simian Foamy Virus Serotype 3 Strain FV2014

“…The large number of studies demonstrating broad distribution of SFVs in Old World and New World NHPs and species-specific prevalence of SFV strains have been based on sequence analysis of genomic regions [8,[24][25][26][27][28][29][30][31][32][33][34]. Whole-genome analysis of some isolates has shown that genetically-diverse SFV strains circulating in different NHP species have contributed to the generation of recombinant viruses involving the SU region in env [11,12,35]. It is noted that sequence variation in SU was initially characterized in feline foamy viruses [36].…”

Eleventh International Foamy Virus Conference—Meeting Report

“…These variants differed greatly (>30% variability at the nucleotide level) in a 753-bp-long region located in the receptor-binding domain of SU, whereas the remainder of the env gene was largely conserved. Analysis of recombination, by different methods, suggests that the variants emerged through recombination events between different strains, although not all parental strains could yet be identified [13]. Preliminary data provided evidence for dual infection with strains from different genotypes in gorillas, chimpanzees and humans.…”