Serological profiles of commercial broiler breeders and their progeny. 1. Infectious bronchitis virus.

Serum samples were collected from broiler breeders and their 1-day-old, 2-week-old, and 5-week-old progeny from different regions of the United States. Individual samples were tested by hemagglutination-inhibition (HI) against six infectious bronchitis virus (IBV) strains: Massachusetts 41 (Mass), H52, Connecticut 46 (Conn), Arkansas 99, SE17, and JMK. The use of multiple strains to test broiler flocks resulted in the detection of seroconversions to Conn and JMK vaccination that were not detected with the IBV Mass HI test. Further, HI titers were detected to IBV strains not used for flock vaccination. In some cases, those titers could be due to cross reactions to antigens common to each of the virus strains. In two breeder flocks, the highest HI titers were to heterologous strains.