Maxine L. Linial

Our laboratory is interested in the replication and biology of foamy viruses. These complex retroviruses comprise their own subfamily. Foamy viruses (FV) are prevalent in most primate species, and in some accidentally infected humans, as well as in cats, horses, and cows. These viruses are cytopathic to fibroblasts in culture, but do not have deleterious effects on the growth of some other cell types. Many FV have been molecularly cloned, and have been developed as vectors. In particular, their broad host range and lack of pathogenicity are attractive features for human gene therapy. Our lab works on the molecular biology of viral replication, as well as the biology of viral replication in macaques, and the epidemiology of zoonotic infections.

Foamy viruses occupy a unique niche quite distinct from all other groups of retroviruses. Although their genomes are similar to other complex retroviruses, such as HIV, they have many unique features. Aspects of their replication are more similar to that of the hepadnaviruses such as HBV than to other retroviruses. For example, the mechanism of expression of their reverse transcriptase from a specific, spliced mRNA has not been seen in any other reverse transcriptase encoding virus. In addition, unlike either HIV or HBV, FV requires the Env proteins, but not the Pol proteins, to bud from cells. We have also found that the functional genome of FV is DNA rather than RNA, clearly setting it apart from other retroviruses. We are focusing on understanding the steps in FV assembly and also the unique properties of the viral reverse transcriptase.

We have been studying how FV can establish life long persistent infections without ensuing pathology. Using naturally infected rhesus macaques, we have found that viral replication is confined to tissues of the oral mucosa. Recently, we have shown that superficial epithelial cells, destined to be sloughed into saliva, are the in vivo target cells for FV replication. This limited niche can explain the lack of viral pathology, and the efficient transmission through saliva.

In collaboration with investigators at the University of Washington Primate Center, we have initiated investigations of FV transmission from macaques to humans in areas of Asia where such contacts are abundant. We have found that about 3% of humans with high levels of contacts with monkeys are infected with FV. Future studies will address the issues of human to human viral transmission.

Academic Experience:
Editorial Board of "Virology"
Editorial Board of "Journal of Virology"