Circulating strains of variant infectious bursal disease virus may pose a challenge for antibiotic-free chicken farming in Canada

Differential gene expression in chicken primary B cells infected ex vivo with attenuated and very virulent strains of infectious bursal disease virus (IBDV)

“…Even in the absence of overt clinical signs, immunosuppression caused by IBDV infection can be an underlying cause of increased susceptibility to secondary infections, some of which can be zoonotic. For example, pre-exposure of chickens to IBDV exacerbated the pathology, persistence or shedding of Salmonella enteritidis, Campylobacter jejuni and Escherichia coli [29][30][31], and a recent case-control study in Pakistan identified a history of IBDV infection in flocks as a significant risk factor associated with avian influenza virus (AIV) infection in chickens [32]. Moreover, experimental inoculation with IBDV prolonged the shedding of a subsequent AIV challenge [33], and it was possible to adapt a mallard H5N2 AIV to chickens by serial passage in birds that had previously been inoculated with IBDV, but not in birds that lacked IBDV exposure [34].…”

Differential gene expression in chicken primary B cells infected ex vivo with attenuated and very virulent strains of infectious bursal disease virus (IBDV)

“…Even in the absence of overt clinical signs, immunosuppression caused by IBDV infection can be an underlying cause of increased susceptibility to secondary infections, some of which can be zoonotic. For example, pre-exposure of chickens to IBDV exacerbated the pathology, persistence, or shedding of Salmonella enteritidis, Campylobacter jejuni and Escherichia coli (29–31), and a recent case-control study in Pakistan identified a history of IBDV infection in flocks as a significant risk factor associated with avian influenza virus (AIV) infection in chickens (32). Moreover, experimental inoculation with IBDV prolonged the shedding of a subsequent AIV challenge (33), and it was possible to adapt a mallard H5N2 AIV to chickens by serial passage in birds that had previously been inoculated with IBDV, but not in birds that lacked IBDV exposure (34).…”

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“…The broiler eggs were obtained from a local hatchery (Prairie Pride Chick Sales Ltd., Saskatchewan, Canada), where broiler-breeders undergo routine IBDV (classic strains) hyper-immunization [6]. Based on the latter reference, the broiler breeder parent flocks of those broiler chicks had been vaccinated against IBDV at 14 days of Abstract Kurukulasuriya, et al (2017) are reporting the efficacy of two IBD vaccines against an early (6 days post-hatch) challenge with a variant Canadian IBDV strain in broilers.…”

“…In particular, it would have been interesting to know if the breeders were correctly vaccinated against the chicken infectious anemia virus (CAV), since it is known that early CAV infection in broilers is inducing immunosuppression and interference on HVTvectored vaccine take. The immune status of the breeder flock relative to other viruses such as fowl adenoviruses (FAdV) and avian adeno-associated virus (AAAV) which are frequently found in Canada was not mentioned as well [6].…”

“…Indeed, a recent epidemiological study demonstrated that the majority of circulating strains in Canada have high sequence identity to NC171 [4]. This strain was shown to induce early (6 days post-hatch) infection and immunosuppression in broiler chickens with high levels of maternally-derived antibodies (MDAs) [6]. The batch of this challenge strain was a bursal homogenate from infected SPF chickens that was titrated in embryonated eggs.…”