Human foamy virus

Human foamy virus (HFV) is a VI spumavirus virus also known as spumaretrovirus. It is a member of the Retroviridae family and for this reason has two positive sense RNA genomes. This means that this virus is a true diploid. The virus was first identified in 1971 from lymphoblastoid cells within a Kenya patient with nasopharyngeal carcinoma (above the soft palate of pharynx of the nasal passage). The isolation and sequencing of a chimpanzee foamy virus isolate made clear, that human foamy virus is a variant of that widespread simian foamy virus, hence, not no authentic infectious agent present in human populations.

Genome
The viral genome of this retrovirus is complex, as it contains not only the gag, pol and env genes, but also genes that encode proteins that are not incorporated into the viral particle. These are termed bel-1 (tas) and bet. The function for bet is still unclear; however, it is known that the tas gene is a transactivator that plays a role in viral replication.

The way in which the virus replicates also differs from that of most retroviruses, as it may leave the cells via exocytosis using vesicles from the endoplasmic reticulum where some reverse transcription of the virus has taken place. Also, when reverse transcription happens late in viral replication, some particles produced contain DNA instead of RNA.

Symptoms
Humans are an accidental host for the virus (most people only become infected when exposed to it within the laboratory or from a monkey bite), so there are no known symptoms of this disease. To date, no human-to-human transmission has been documented.