Isolation and characterization of lymphocyte associated foamy virus from a red uakari monkey (Cacajao rubicundus)

Simian Foamy Viruses in Central and South America: A New World of Discovery

Foamy viruses (FVs) are the only exogenous retrovirus to date known to infect neotropical primates (NPs). In the last decade, an increasing number of strains have been completely or partially sequenced, and molecular evolution analyses have identified an ancient co-speciation with their hosts. In this review, the improvement of diagnostic techniques that allowed the determination of a more accurate prevalence of simian FVs (SFVs) in captive and free-living NPs is discussed. Determination of DNA viral load in American primates indicates that oral tissues are the viral replicative site and that buccal swab collection can be an alternative to diagnose SFV infection in NPs. Finally, the transmission potential of NP SFVs to primate workers in zoos and primate centers of the Americas is examined.

An expanded search for simian foamy viruses (SFV) in Brazilian New World primates identifies novel SFV lineages and host age-related infections

Background

While simian foamy viruses have co-evolved with their primate hosts for millennia, most scientific studies have focused on understanding infection in Old World primates with little knowledge available on the epidemiology and natural history of SFV infection in New World primates (NWPs). To better understand the geographic and species distribution and evolutionary history of SFV in NWPs we extend our previous studies in Brazil by screening 15 genera consisting of 29 NWP species (140 monkeys total), including five genera (Brachyteles, Cacajao, Callimico, Mico, and Pithecia) not previously analyzed. Monkey blood specimens were tested using a combination of both serology and PCR to more accurately estimate prevalence and investigate transmission patterns. Sequences were phylogenetically analyzed to infer SFV and host evolutionary histories.

Results

The overall serologic and molecular prevalences were 42.8 and 33.6 %, respectively, with a combined assay prevalence of 55.8 %. Discordant serology and PCR results were observed for 28.5 % of the samples, indicating that both methods are currently necessary for estimating NWP SFV prevalence. SFV prevalence in sexually mature NWPs with a positive result in any of the WB or PCR assays was 51/107 (47.7 %) compared to 20/33 (61 %) for immature animals. Epidemiological analyses revealed an increase in SFV prevalence with age in captive Cebus monkeys. Phylogenetic analysis identified novel SFVs in Cacajao,Leontopithecus, and Chiropotes species that had 6–37 % nucleotide divergence to other NWP SFV. Comparison of host and SFV phylogenies showed an overall cospeciation evolutionary history with rare ancient and contemporaneous host-switching for Saimiri and Leontopithecus and Cebus xanthosternos, respectively.

Conclusions

We identified novel SFV in four neotropical monkey genera in Brazil and demonstrate that SFV prevalence increases with age in Cebus monkeys. Importantly, our test results suggest that both molecular and serological screening are currently required to accurately determine infection with NWP SFV. Our study significantly expands knowledge of the epidemiology and natural history of NWP SFVs. The tools and information provided in our study will facilitate further investigation of SFV in NWPs and the potential for zoonotic infection with these viruses.

Frequent foamy virus infection in free-living chimpanzees of the Taï National Park (Côte d'Ivoire)

Foamy viruses are frequently found in non-human primates and apes in captivity. However, data on simian foamy virus (SFV) infection in apes from the wild are limited. Necropsy specimens were collected from 14 West African chimpanzees (Pan troglodytes verus) from three communities in the Taï National Park, Côte d'Ivoire. PCR analysis revealed SFV-related int- and env-specific sequences in 12/14 chimpanzees. Two young chimpanzees were not infected. Plasma from 'PCR-positive' chimpanzees reacted against Pr71/74(gag) in Western blot analysis. Phylogenetic analysis demonstrated clustering of all analysed sequences with SFVcpz previously identified from the other P. troglodytes verus, although interestingly the sequences were diverse and no grouping according to a particular animal community was observed. The body compartments of two infected animals were examined and found to contain SFV sequences. Frequent SFV infections in chimpanzees from this area significantly increase the potential risk of zoonotic transmission to rural populations through direct contact, hunting and consumption of bush meat.

Productive persistent infection of hematopoietic cells by human foamy virus

Human foamy virus can establish persistent infections in human hematopoietic cell lines, such as H92.1.7 (erythroblastoid cells), Jurkat (CD4+ T cells), and U937 (myeloid-monocytic cells). The infection is characterized by constant production of infectious viruses (for > 2 1/2 years) with no cytopathic effects on the host cells. Electron microscopy of the infected cells showed a viral morphology similar to that observed for particles produced after acute infection. We have detected, in addition to the full-length form of bel1, a previously described deletion in the bel1 gene of the proviral DNA in these cells. RNA containing this 301-bp deletion, which mapped to the splice donor and acceptor sites of the intron of the bet gene, was also found in encapsidated virion RNA. However, the presence of this defective provirus harboring the deletion in bel1 does not prevent productive persistence in these chronically infected cells, since the virus titer does not decrease during cultivation.

Generation of macaque B lymphoblastoid cell lines with simian Epstein-Barr-like viruses: transformation procedure, characterization of the cell lines and occurrence of simian foamy virus

Two simian Epstein-Barr-like viruses, a rhesus Epstein-Barr virus and Herpesvirus papio, were used to transform B cells from rhesus or cynomolgus macaques. The resulting cell lines exhibited predominantly a B lymphocyte phenotype and expressed Epstein-Barr virus antigens. The majority of B lymphoblastoid cell lines from macaques, which were seropositive for simian foamy virus, developed giant cells in culture. The cytopathic agent was identified as a foamy virus and was transmissible to human embryonal fibroblasts. Treatment of cell cultures with AZT abolished giant cell formation.

Effects of human recombinant alpha and gamma and of highly purified natural beta interferons on simian Spumavirinae prototype (simian foamy virus 1) multiplication in human cells

The present study demonstrates the inhibitory effect of human recombinant interferons (r-Hu-IFN) alpha and gamma, and that of highly purified natural human interferon beta on the replication of simian foamy virus type 1 (SFV1) in human AV3-cell cultures. All IFN led to strong inhibition of the SFV1 cytopathic effect. Electron microscopy showed a 70 to 95% decrease in viral particles. Significant inhibition of virus-associated reverse transcriptase activity was found in supernatant fluids of infected IFN-treated cultures. Metabolic labelling of the virus confirmed the inhibition of extracellular release of SFV1. PAGE analysis of immunoprecipitates indicated a reduction in viral-specific protein bands. Altogether, these results indicate that the mechanism of inhibition of Spumavirinae infection by interferon differs from that described for the other Retroviridae, and particularly for types B, C and D viruses. Our data is of therapeutic interest since Spumavirinae have been linked to pathological processes such as de Quervain thyroiditis.

Characterization of a foamy virus isolated from Cercopithecus aethiops lymphoblastoid cells

A virus derived from cells of a lymphoblastoid line originating from the lymph node of a healthy African green monkey was characterized as a typical member of the foamy virus subgroup of retroviridae by its morphological, physicochemical, biological and biochemical properties (reverse transcriptase activity). Besides the usual host range of foamy viruses, the isolated strain revealed a remarkable T-lymphotropism, distinguishing it from the prototypes of foamy viruses previously isolated from African green monkeys. Two foamy virus infections are demonstrated in human contacts of the African green monkey colony, with the animal harbouring the isolate.