Efficacy of H120 and Ma5 avian infectious bronchitis vaccines in early challenge against QX strain.

Infectious bronchitis (IB) is a highly infectious avian pathogen, which affects the respiratory tract, gut, reproductive system, and kidney of chicks of all ages. Many different serotypes of IB virus (IBV) are recognized which cause different clinical manifestations. According to the antigenic differences, different serotypes of the virus do not cross-protect. Massachusetts serotype induces the best cross-protection against other serotypes. Recently, the IBV QX strain has been detected in Iran. QX strain causes permanent damage to the oviduct if it occurs in the early life cycle and is a significant factor in layer and breeder chicken flocks. In this study, we compare the H120 and Ma5 vaccines' protection against early challenge with the QX strain in commercial chicks. one-day-old commercial chicks were divided into six groups. Groups 1 and 2 were unvaccinated groups. Groups 3 and 5 were vaccinated with the H120 vaccine (eye drop) and groups 4 and 6 were vaccinated with Ma5 (eye drop) on the 6th day (5 days after vaccination). Groups 2, 3 and 4 challenged (oculonasal) with QX strain (10^4 EID50). Ciliostasis test, histopathology, and quantitative real-time RT-PCR were done at 11 days-old of age. Results showed that neither H120 nor Ma5 could induce proper cross-protection against QX early challenge, but the viral load and adverse pathological records in vaccinated chicks were less than that in the non-vaccinated groups. It can be concluded that vaccination on the first day of the life of a chick offers not full protection against the IBV QX strain but reduced the viral load and pathological damages in vaccinated chickens. Applying other forms of vaccination and using different genotypes on one-day-old chicks are suggested.

Correction to: Efficacy of H120 and Ma5 avian infectious bronchitis vaccines in early challenge against QX strain.

[This corrects the article DOI: 10.1007/s13337-017-0414-4.].

Co-circulation of three clusters of 793/B-like avian infectious bronchitis virus genotypes in Iranian chicken flocks.

Avian infectious bronchitis (IB) is an acute and highly contagious viral disease causing severe economic losses in the poultry industry. The 793/B IB virus is an important infectious bronchitis virus (IBV) genotype currently circulating in several countries, including Iran. One hundred confirmed IBV samples (between 2014 and 2015; from 15 provinces in Iran) were selected for genotyping based on S1 sequencing. After phylogenetic analysis, it was found that 30% of the IBV isolates belonged to the 793/B genotype. Results showed that the Iranian 793/B-like IBV isolates could be divided in to three clusters: 4/91-like (50%), 1/96-like (40%), and IB88-like (10%). The sequence similarity between Iranian 793/B-like IBV isolates is 87.69%-100%. The highest identity is between the 4/91 and IB88 clusters (96.38%), and the lowest similarity is between the 1/96 and IB88 clusters (87.62%). This study provides a comprehensive analysis of 793/B-type IBV in Iran and characterization of IBV molecular epidemiology in the country.