Genetic Stability of Foamy Viruses: Long-Term Study in an African Green Monkey Population

Abstract

The genetic variability of the envelope surface domain (SU) of simian foamy virus (FV) of African green monkeys was studied. To assess the interindividual diversity of FV, isolates were obtained from 19 animals living together in a monkey house. The monkeys had been imported from Kenya prior to being placed in long-term housing in the research institute. In addition, a simian FV isolate and proviral DNA were obtained from an animal caretaker infected in this setting. DNA of the complete SU (1779 to 1793 bp) was analyzed by PCR and sequencing. The sequences revealed four clusters with high homologies (>95%). Between the clusters, divergencies ranged from 3 to 25%. Obviously, the clusters reflect four different strains or subtypes of simian FV type 3 that were prevalent in the colony. In contrast to lentiviruses, hypervariable regions could not be detected in the FV SU. Furthermore, to analyze the intraindividual diversity of FV, we investigated the virus population within an individual monkey at a given time point and its evolution over 13 years. For this purpose, 22 proviral SU clones generated by PCR from one oral swab and seven isolates obtained from the same animal between 1982 and 1995 were examined. These sequences revealed exceptionally high homology rates (99.5 to 100%), and only a minimal genetic drift was recognized within the series of isolates. In conclusion, the low in vivo divergency of FV SU suggests that genetic variability is not important for the maintenance of FV persistence.

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

“…Second, we observed that amino acid changes in apes and OWM SFV sequences are located at positions found to have a minor impact on recognition by plasma samples. Third, we observed a major exception, i.e., the W 108 R change in some Chlorocebus SFV strains (22). Systematic testing of plasma samples revealed rare recognition of peptide cae_agm22 by samples from two gorilla SFV-infected individuals, leading to modification of the putative binding motif to 96 NKDIQVLGPVID/VW/RNV 110 .…”

Origin, evolution and innate immune control of simian foamy viruses in humans

“…SFV genomes display a high evolutionary conservation among all the species infected and SFV genetic variability within one infected animal is very low over time (<1% variation over 13 years) [28]. This genetic stability might be explained by the long co-evolution with their host [29 ] and their subsequent efficient adaptation.…”

HTLV-3/4 and simian foamy retroviruses in humans: Discovery, epidemiology, cross-species transmission and molecular virology

“…The prevalence of FVs in naturally infected animals is generally high, but can vary widely according to species and environmental conditions. Several epidemiological studies indicated that, among captive NHP populations (Blewett et al, 2000;Calattini et al, 2004;Hussain et al, 2003;Schweizer et al, 1999Schweizer et al, , 1995, but also in free-range colonies (Calattini et al, 2006c;Mouinga-Ondeme et al, 2010) and in the wild (Jones-Engel et al, 2005;Leendertz et al, 2010;Liu et al, 2008), SFV seroprevalence can reach up to 75-100% in adults, but is generally much lower in infants and juveniles (Liu et al, 2008). SFV virions are present at a high concentration in the saliva of infected NHPs (from 10 4 to 10 9 FV RNA copies/10 4 cells equivalent).…”