Screening for simian foamy virus infection by using a combined antigen Western blot assay: evidence for a wide distribution among Old World primates and identification of four new divergent viruses

Abstract

Simian foamy viruses (SFVs) belong to a genetically and antigenically diverse class of retroviruses that naturally infect a wide range of nonhuman primates (NHPs) and can also be transmitted to humans occupationally exposed to NHPs. Current serologic detection of SFV infection requires separate Western blot (WB) testing by using two different SFV antigens [SFV(AGM) (African green monkey) and SFV(CPZ) (chimpanzee)]. However, this method is labor intensive and validation is limited to only small numbers of NHPs. To facilitate serologic SFV testing, we developed a WB assay that combines antigens from both SFV(AGM) and SFV(CPZ). The combined-antigen WB (CA-WB) assay was validated with 145 serum samples from 129 NHPs (32 African and Asian species) and 16 humans, all with known SFV infection status determined by PCR. Concordant CA-WB results were obtained for all 145 PCR-positive or -negative primate and human specimens, giving the assay a 100% sensitivity and specificity. In addition, no reactivity was observed in sera from persons positive for human immunodeficiency virus or human T cell lymphotropic virus (HIV/HTLV) (n = 25) or HIV/HTLV-negative U.S. blood donors (n = 100). Using the CA-WB assay, we screened 360 sera from 43 Old World primate species and found an SFV prevalence of about 68% in both African and Asian primates. We also isolated SFV from the blood of four seropositive primates (Allenopithecus nigroviridis, Trachypithecus françoisi, Hylobates pileatus, and H. leucogenys) not previously known to be infected with SFV. Phylogenetic analysis of integrase sequences from these isolates confirmed that all four SFVs represent new, distinct, and highly divergent lineages. These results demonstrate the ability of the CA-WB assay to detect infection in a large number of NHP species, including previously uncharacterized infections with divergent SFVs.

Frequent Simian Foamy Virus Infection in Persons Occupationally Exposed to Nonhuman Primates

“…Most primate species investigated thus far, including prosimians, New World monkeys, and Old World monkeys and apes, harbor SFV (15,21). In captivity, more than 70% of adult NHPs are infected with SFV (15,21), possibly reflecting the ease of transmissibility of this virus among NHPs in close contact.…”

“…Most primate species investigated thus far, including prosimians, New World monkeys, and Old World monkeys and apes, harbor SFV (15,21). In captivity, more than 70% of adult NHPs are infected with SFV (15,21), possibly reflecting the ease of transmissibility of this virus among NHPs in close contact. Phylogenetic analysis indicates species-specific viral lineages, suggesting a longstanding coexistence and coevolution between SFVs and their NHP host species (5,13,15,29).…”

“…In captivity, more than 70% of adult NHPs are infected with SFV (15,21), possibly reflecting the ease of transmissibility of this virus among NHPs in close contact. Phylogenetic analysis indicates species-specific viral lineages, suggesting a longstanding coexistence and coevolution between SFVs and their NHP host species (5,13,15,29). However, evidence supporting the existence of a human-specific foamy virus (FV) is not available.…”

Retroviruses in Wild-Born Semi-Captive East African Sanctuary Chimpanzees (Pan troglodytes schweinfurthii)~!2010-01-28~!2010-03-24~!2010-04-20~!

“…Phylogenetic tree analysis was performed with the NJ method using the 23 SFV sequences generated in this study and published relevant SFV sequences from all chimpanzee subspecies, as well as from gorilla, bonobo, orangutan, African and Asian monkeys and one sequence of an SFVinfected human [4,6,[8][9][10].…”

“…Amplification of SFV proviral genomic region (425 bp; 6086 -6492 on SFV reference sequence NC_001364) was performed using generic primers targeting the viral integrase (int) region as previously described [6]. Standard PCR conditions were used for both rounds of amplification with the exception of the annealing temperatures of 60°C for 45 cycles for the first round and 55°C for 45 cycles for the second round, respectively.…”