Marek's Disease I. Propagation of the Connecticut A (Conn-A) Isolate in Chicks

Abstract

The Connecticut A (Conn-A) Marek''s disease (MD) agent isolated from 14-week-old SLX pullets with clinical signs of MD was transferred 20 times in specific-pathogen-free (SPF) day-old White Leghorn chicks. Clinical signs developed in 15-25% of the birds 28-84 days postinoculation. Histopathologic lesions characteristic for MD were observed in 80% of the birds examined. On initial passage, 17% of inoculated birds had clinical signs and 67% had histologic lesions. The agent had no RIF [resistance-inducing factor] or COFAL [complement fixation avian leukosis] activity, and did not produce RSV [Rous sarcoma virus] antibodies.