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OJVR
Online Journal of
Veterinary Research©
Volume 13 (2):37-46, 2009. Extensively
redacted 2017.
Infectious bronchitis live vaccine enhances 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, Onl J Vet Res, 13 (2):37-47, 2009. H9N2
avian influenza virus (AIV) has low pathogenicity yet 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 controls, 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 which were most severe in chicks given IBLV on day
7 PI. 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 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 increase replication and
shedding of this virus.
Key words: H9N2
avian influenza virus, Infectious bronchitis virus, co-infection, real time PCR.
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