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

Abstract

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^ 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.

Single-step multiplex reverse transcription-polymerase chain reaction for the detection and differentiation of QX-like infectious bronchitis virus from the Thai variant and vaccine strains H120, Ma5, and 4/91

“…Currently, QX-like IBV is the predominant genotype of IBV in Thailand [2]. The spread of QX-like IBV is controlled through the use of live attenuated vaccines, which is difficult because different serotypes of vaccines do not provide adequate protection [17,18]. Therefore, rapid detection of the virus within an infected chicken flock is important for controlling QX-like IBV outbreaks.…”

Evaluation of the antigen relatedness and efficacy of a single vaccination with different infectious bronchitis virus strains against a challenge with Malaysian variant and QX-like IBV strains

“…On the other hand, some IBV strains can provide cross-protection against other serotypes [ 10 ]. In many studies, these IBV strains are identified as protectotype strains [ 11 25 26 27 ].…”

“…In studies of chickens vaccinated with the Mass vaccine strain, the most commonly used IB vaccine could not provide adequate protection against the field IBV Belgian B1648 strain [ 9 ], Holland D1466, South Africa 890/80, Brazil 50/96 [ 10 ], Iranian QX-like [ 11 ], and Thai QX-like [ 12 ]. In another study, chickens vaccinated with the variant IB 4/91 vaccine showed poor protection against local IBV Holland D1466, South Africa 890/80, and Honduras 22/97 strains [ 10 ].…”

Efficacy of commercial polyvalent avian infectious bronchitis vaccines against Chinese QX-like and TW-like strain via different vaccination strategies

“…In this study, 93% clinical protection effects against the QX-like strain was generated by administration of the polyvalent vaccine C at 1 D of age and the polyvalent vaccine B at 10 D of age, whereas the boost of vaccination was changed in group 3, and only 80% protection rate was provided ( Table 2 ). At present, no study has demonstrated the mechanism about the change of protection effect that was based on changing the boost of vaccination ( Karimi et al., 2018 ).…”

“…Some studies had showed that a single vaccine with different serotype affords less protection against QX-like and TW-like IBV strains ( Gao et al., 2016 ; Karimi et al., 2018 ). Despite the development of homologous vaccines was often impractical, immunization with multiple serotype vaccines had been proven to be beneficial and broadened the protective spectrum (i.e., “protectotype concept”) ( Cook et al., 1999 ; Zhao et al., 2015 ).…”