Hatchability and mortality following infection of chick embryos with subgroup a Rous sarcoma virus

An investigation, using Rhode Island Red, New Hampshire, Columbian and Australorp, was conducted to study the correlation between chorioallantoic membrane (CAM)-infection phenotype to challenge with Bryan strain of Rous sarcoma virus (BS-RSV) of subgroup A and subsequent mortality, following hatching. A total of 806 CAMs and 438 chicks over nine hatch-replicates in three experiments provided evidence that infection via an inoculation of the CAM induced rapid and high mortality, about 72%, averaged over the four breeds, from a fibrosarcomatous liver tumour (LT) in CAM-susceptible chicks. In contrast, only 14% of chicks inoculated via the yolk sac died from liver tumours. Infection via the CAM reduced hatchability by about 28% (P<0.01) as compared to the hatchability of embryos infected via the yolk sac. About 21% of chicks which developed no pocks on the CAM after RSV inoculation developed liver tumours and died.