H. Toro et I. Fernandez, AVIAN INFECTIOUS-BRONCHITIS - SPECIFIC LACRIMAL IGA LEVEL AND RESISTANCE AGAINST CHALLENGE, Journal of veterinary medicine. Series B, 41(7-8), 1994, pp. 467-472
Since circulating antibody titres against infectious bronchitis virus
(IBV) often correlate poorly with protection against re-infection, the
lachrymal specific IgA level of IBV vaccinated chickens was evaluated
as an indicator of resistance against challenge. For this purpose, th
e postvaccination (pv) IBV specific lachrymal IgA response was monitor
ed in 30 chickens at 3-day intervals until a rise of this specific iso
type was detected. On day 19 pv, all birds (vaccinated group and non-v
accinated controls) were challenged with the moderately attenuated H-5
2 IBV strain via the ocular route. Protection was assessed by viral re
isolation attempts in SPF embryonated chicken eggs (ECE) from tracheal
swabs 4 days after challenge. Virus was detected in all control birds
by the second passage in ECE. IBV was reisolated from 27% (eight bird
s) of all H-120-primed birds after five passages in ECE. These results
demonstrate that lachrymal-fluid-specific IgA levels in chickens are
associated with resistance against IBV reinfection and are therefore a
suitable source of antibodies that could be used for flock profiling.