Avian infectious bronchitis: specific lachrymal IgA level and resistance against challenge.
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, the post-vaccination (pv) IBV specific lachrymal IgA response was monitored in 30 chickens at 3-day intervals until a rise of this specific isotype was detected. On day 19 pv, all birds (vaccinated group and non-vaccinated controls) were challenged with the moderately attenuated H-52 IBV strain via the ocular route. Protection was assessed by viral reisolation 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 birds) 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.
Toro
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Department of Animal Pathology, College of Veterinary Sciences, University of Chile, Santiago.
Fernandez
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D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis / Q000097:blood; D002645:Chickens; D018352:Coronavirus Infections / Q000276:immunology / Q000662:veterinary*; D007071:Immunoglobulin A, Secretory / Q000032:analysis*; D007074:Immunoglobulin G / Q000097:blood; D001351:Infectious bronchitis virus / Q000276:immunology*; D011201:Poultry Diseases / Q000276:immunology*; D013047:Specific Pathogen-Free Organisms; D013666:Tears / Q000276:immunology*
D000914:Antibodies, Viral; D007071:Immunoglobulin A, Secretory; D007074:Immunoglobulin G