Humans and animals harbor infections caused by DNA (herpes and pox) and retroviruses. Retrovirus initial integration into dsDNA, might target the cell genome or co-infecting viral genomes, leading to possibly altered biology and evolution.
Chickens are advantaged for virus diversity studies, as being natural hosts enabling experimental infection reproduction.
First example for the creation of viral diversity through molecular recombinations are the avian oncogenic viruses, both herpes and retroviruses, as well as the in vivo creation of virus recombinants between two different retroviruses. We analysed naturally-acquired mixed infection, experimentally infected chickens and embryonated eggs and demonstrated the events of molecular recombination between MDV and retroviruses in vivo.
Second example are the fowlpox virus (FPV), which contains various inserts of the reticuloendotheliosis virus (REV).
Third example are the Circoviruses, whose origin is from plants to vertebrates; A plant nanovirus recombined with a vertebrate calicivirus, followed by a reverse transcription step facilitated by retroviruses or retrotransposons. Circoviruses are circular single-stranded DNA viruses with host specificity for bacteria, animals, humans and plants. The chicken infectious anemia virus (CAV) causes both symptomatic or asymptomatic signs and immunosuppression. Similar circoviruses infect many animals, including humans, is mostly under-estimated.
Finally, the mechanism of diversity creation of viruses, as exemplified by the three examples of avian viruses, might contribute to the variety of life on earth.
