Characterisation of osteopetrosis induced by virus strain Pts 56 in guinea fowl.

Avian osteopetrosis virus strain Pts 56 inoculated i.v. into 1 to 2-day-old guinea fowls induced bone growths (in up to 100% of birds). Their gross appearance and localisation differed markedly from osteopetrotic lesions in chickens and turkeys. Osteoblast proliferation in the periosteum as well as cell transformation into the chondral tissue were observed histologically. Periosteal bone formation, cartilage formation and endochondral ossification were observed to be taking place simultaneously or consecutively during tumour development. As a result the bone growths in guinea fowls were very marked, occurring often as cauliflower-like formations near the epiphyses. The data obtained supported the view that the transmission of virus strain Pts 56 in an unnatural and highly susceptible host offered an opportunity not only for investigations on the oncogenic spectrum of avian osteopetrosis viruses but also for the use of guinea fowl as an animal model for the study of human bone growths.