chick syncytial virus chick syncytial virus the chick syncytial virus is a virus in the genus gammaretrovirus. chick syncytial virus virus classification (unranked): virus realm: riboviria kingdom: pararnavirae phylum: artverviricota class: revtraviricetes order: ortervirales family: retroviridae genus: gammaretrovirus species: chick syncytial virus