Non-Simian Foamy Viruses: Molecular Virology, Tropism and Prevalence and Zoonotic/Interspecies Transmission

Abstract

Within the field of retrovirus, our knowledge of foamy viruses (FV) is still limited. Their unique replication strategy and mechanism of viral persistency needs further research to gain understanding of the virus-host interactions, especially in the light of the recent findings suggesting their ancient origin and long co-evolution with their nonhuman hosts. Unquestionably, the most studied member is the primate/prototype foamy virus (PFV) which was originally isolated from a human (designated as human foamy virus, HFV), but later identified as chimpanzee origin; phylogenetic analysis clearly places it among other Old World primates. Additionally, the study of non-simian animal FVs can contribute to a deeper understanding of FV-host interactions and development of other animal models. The review aims at highlighting areas of special interest regarding the structure, biology, virus-host interactions and interspecies transmission potential of primate as well as non-primate foamy viruses for gaining new insights into FV biology.

Identification of Novel, Highly Expressed Retroviral MicroRNAs in Cells Infected by Bovine Foamy Virus

“…Spumaviruses, more commonly referred to as foamy viruses, are an ancient group of generally nonpathogenic retroviruses that infect many mammalian species, with the notable exception of humans (13,32). However, while no human foamy virus has been identified, there have been several reports documenting the zoonotic infection of individuals who came into contact with primates by a range of primate foamy virus (PFV) species (33,34).…”

“…Among species that are susceptible to foamy viruses, infection is often common, and BFV has been detected in a considerable fraction of domesticated cattle in several different countries (18,19). However, as is also the case for PFVs in either their natural hosts or zoonotically infected humans, there is little evidence that BFV exerts a significant deleterious effect in infected cows (13,18).…”

“…In this article, we present data demonstrating that bovine foamy virus (BFV), a member of the spumavirus subfamily of retroviruses (13), expresses three viral miRNAs at high levels in infected cells both in culture and in vivo. Interestingly, the BFV miRNAs, like the previously reported BLV miRNAs, are transcribed by Pol III and contain stems that are predicted to be too short for recognition by Drosha in the context of the BFV genomic RNA.…”

Foamy-like endogenous retroviruses are extensive and abundant in teleosts

“…2), is the p3 cleavage site: a viral Pro cleavage site motif VX|XV (Kehl et al 2013) very near the C-terminus. In PpERV-1, this motif is VG|RV, -34 aa from the C-terminus.…”

Eleventh International Foamy Virus Conference—Meeting Report

“…Neutralizing antibodies against cell-free FV are detected in most animal and human hosts. Antigenic classes match with host species and env genotypes (see session 2 summary, section 2.2) [32]; and (5) last, but not least, antibodies can prevent FV transmission between hosts, as shown in experimental transfusion experiments [33]. Several key steps of virus-induced immune responses remained to be studied for FVs, including the activation of cytosolic nucleic acid sensors, inflammasome and natural killer (NK) cells by FVs, FV-virus specific T lymphocytes, and antiviral activities of antibodies other than neutralization of cell-free virus.…”