Combination of H120 and 1/96 avian infectious bronchitis virus vaccine strains protect chickens against challenge with IS/1494/06 (variant 2)-like infectious bronchitis virus

Abstract

Avian infectious bronchitis (IB) is a worldwide chicken disease, caused by avian infectious bronchitis virus (IBV) which infects all commercial poultry lines. The present study was done to evaluate protection caused by two different serotype vaccines (Massachusetts and 793/B) in order to evaluate protection against challenge with IS/1494/06-like virus (variant 2-like virus), which is prevalent in the Middle East. SPF chickens were divided into four groups (n = 20). First and second group as negative control group and non-vaccinated-challenged group received no vaccine. Groups 3 and 4 received H120-H120 and H120-1/96 IBV vaccine strains at the 1st and 14th day, respectively. Twenty one days after last vaccination, non-vaccinated-challenged group and vaccinated group were challenged using variant 2-like IBV. Serum samples were collected before challenge to measure humoral immune response of chickens. Five days after challenge, the tissue samples from the trachea, lungs and kidneys were taken to evaluate cilliary activity, viral load (quantitative real-time RT-PCR), and histopathological evaluation. Clinical sign scores were also recorded after challenge. Overall, the results showed a protective efficacy of the used vaccination program. Best cross protection (69.2%) was obtained in the H120-1/96 vaccinated group. Virus replication of the challenged virus in H120-1/96 group compared with H120-H120 group showed a significant reduction of viral load in trachea (1.5×103 compared to 503) and kidneys. Clinical sign scores of the challenged groups showed significant effect of the vaccination program to reduce clinical signs. The trachea pathological scores and histopathological findings in the lungs and kidneys also confirmed better protective efficacy of vaccinated groups. In conclusion, using combination of heterologous IBV vaccine serotypes (Massachusetts and 793/B) would be a better strategy to control variant 2-like viruses, but more evaluation is needed using other circulating isolates to find the best combination of vaccines.

Molecular identification of infectious bronchitis virus isolated from respiratory diseases in some Iranian broiler flocks

“…Varinat 2 viruses are still among the main strains of Jordan, Egypt, Turkey,and other countries of the Middle East [9]. Because variant 2 vaccine is not used in Iran and the current vaccines do not confer complete protection against this virus, the possibility of a wider spread of this variant is high [26].…”

Including 793/B type avian infectious bronchitis vaccine in 1-day-old chicken increased the protection against QX genotype

“…The essential issue in IBV infection is to protect trachea from virus lesions. The inconvenient situation in the house including high ammonia, dust, CO 2 , and another microorganism in the air would make the condition worse (Habibi et al 2017). In the present study, the vaccinated groups 3 and 4 showed a slight lesion in the trachea in comparison to the no-vaccinated-challenged group.…”

Microarray analysis of infectious bronchitis virus infection of chicken primary dendritic cells

“…The threat of IBV infection is global, as this respiratory virus can cause acute and contagious respiratory infections in poultry, resulting in serious economic losses [3, 4]. The strategy of reducing IBV infection through vaccination has been recognised as a viable option to control IBV and has been somewhat successful [5, 6]. The continuing prevalence of IBV might be attributable to divergent IBV subtypes.…”