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OJVR
Online Journal of Veterinary Research©
Volume 13
(2):37-47, 2009
Infectious bronchitis live vaccine increases H9N2 avian influenza virus
replication in broiler chickens.
Tavakkoli H1, Asasi K1, Mohammadi A2
Department of 1 Avian
Medicine and 2Pathobiology, School of Veterinary Medicine, Shiraz
University, Iran
ABSTRACT
Tavakkoli H, Asasi K, Mohammadi A, Infectious bronchitis live vaccine enhances H9N2 avian
influenza virus replication in broiler chickens, Online J Vet Res, 13 (2):37-47, 2009. H9N2 avian influenza virus (AIV)
has a low pathogenic index yet it causes high mortality, probably due to
co-infections. Infectious Bronchitis Live Vaccine (IBLV) is used extensively in
chicken farms throughout Asia. In this study, a real time PCR assay was
performed to study the effect of IBLV on H9N2 avian influenza virus replication in broiler
tissue. Three groups of 25 one day old
commercial broiler chicks were used. All birds, except the control group, were
challenged with A/Chicken/Iran/SH-110/99(H9N2) virus. One group was further vaccinated
with H120 strain of IBLV. Infected chicks exhibited facial edema,
conjunctivitis, depression, lacrimation, ruffled
feathers, coughing, sneezing, swelling of infra
orbital sinuses and gasping but symptoms were most severe in chicks given IBLV.
Tissue samples from
trachea, kidney, lung, and feces were collected at 3, 7, 11 and
15 days post-inoculation (PI) for molecular detection and quantitation
of the H9N2 AIV. The H9N2 AIV titer from chicks given IBLV was generally higher
than other groups on all days PI and persisted longer in lung and kidney
tissues, and feces. These findings suggest that IBLV not only exacerbates the
severity of H9N2 AIV clinical sings in infected birds but also increases
replication and shedding of this virus.
Key words: H9N2 avian
influenza virus, Infectious bronchitis virus, co-infection, real time PCR
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