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Host age dependency of regression of Rous sarcomas of chickens.

Summary Tumors were induced in Regional Poultry Research Laboratory line 6 chickens inoculated in the wing web with Rous sarcoma virus the Bryan high-titer strain of pseudotype, at 1, 14, and 28 days of age. Tumor regression failed to occur in chicks inoculated at 1 and 14 days of age, but an incidence of regression of 50% was observed in chicks inoculated at 28 days of age. Chick survival time postinoculation and the incidence of visceral metastases were directly related to chick age at inoculation. The age-dependent changes in the incidence of regression and metastases probably were associated with developing immunological maturity of the host.