Comparative Pathogenicity of Malaysian QX-like and Variant Infectious Bronchitis Virus Strains in Chickens at Different Age of Exposure to the Viruses

Khanh, Nguyen Phuc; Tan, Sheau Wei; Yeap, Swee Keong; Lee, H.J.; Choi, Kang Seuk; Hair-Bejo, M.; Bích, Trần Ngọc; Omar, Abdul Rahman

doi:10.1016/j.jcpa.2018.04.006

Cited by 16 publications

(11 citation statements)

References 43 publications

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“…It is also noteworthy that Mass IBV isolate originating in SK was not detectable at 12 dpi in cloacal swabs. Since the major source of IBV genome in cloaca is due to IBV replication in gastrointestinal tract [63], it is possible that 15SK-02 IBV infection in gastrointestinal tract may have been cleared by 12 dpi. Overall, these two Mass IBV variants have similar pathogenicity with only slight differences which also agree with the minor genetic differences of these 2 Mass type IBV isolates.…”

Section: Discussionmentioning

confidence: 99%

Comparative features of infections of two Massachusetts (Mass) infectious bronchitis virus (IBV) variants isolated from Western Canadian layer flocks

et al. 2018

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BackgroundInfectious bronchitis virus (IBV) is one of the leading causes of mortality and morbidity in chickens. There are numerous serotypes and variants, which do not confer cross protection resulting in failure of currently used IBV vaccines. Although variant IBV isolates with major genetic differences have been subjected to comparative studies, it is unknown whether minor genetic differences in IBV variants within a serotype are different in terms of pathogenesis and eliciting host responses. Two Massachusetts (Mass) variant IBV isolates recovered from commercial layer flocks in the Western Canadian provinces of Alberta (AB) and Saskatchewan (SK) were compared genetically and evaluated for their pathogenicity, tissue distribution and ability to recruit and replicate in macrophages.ResultsAlthough whole genome sequencing of these two Mass IBV isolates showed low similarity with the M41 vaccinal strain, they had an identical nucleotide sequence at open reading frames (ORFs) 3a, 3b, envelop (E), matrix (M), 5a and 5b. The rest of the ORFs of these 2 IBV isolates showed 99.9% nucleotide similarity. However, upon experimental infection, we found that the IBV isolate originating from AB was different to the one that originated in SK due to higher tracheal lesion scores and lower lung viral replication and lower genome loads in cecal tonsils. Nevertheless, both IBV isolates elicited host responses characterized by significant macrophage recruitment to the respiratory tract and there was evidence that both IBV isolates replicated within tracheal and lung macrophages.ConclusionsOverall, this study shows that Mass variant IBV isolates, although possessing minor genetic variations, can lead to significant differences in pathogenicity in young chickens. Further studies are required to investigate the pathogenicity of these two Mass variant IBV isolates in laying hens.Electronic supplementary materialThe online version of this article (10.1186/s12917-018-1720-9) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Comparative features of infections of two Massachusetts (Mass) infectious bronchitis virus (IBV) variants isolated from Western Canadian layer flocks

et al. 2018

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“…Among the numerous genotypes, QX-like IBVs have emerged and gradually evolved into the predominant circulating genotype worldwide since the 1990s [18,[23][24][25][26]. Analyses of genetic evolution, antigenicity and pathogenicity reveal many major differences among QX-like IBVs and other serotypes [17,[27][28][29]. Several QX-like IBV vaccines have also been developed to combat infections induced by the virus [30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Pathogenic characteristics of a QX-like infectious bronchitis virus strain SD in chickens exposed at different ages and protective efficacy of combining live homologous and heterologous vaccination

Shao

Zhao

et al. 2020

Vet Res

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Continued reports of infections with infectious bronchitis virus (IBV) variants have occurred since its first isolation in the 1930s. Currently, QX-like IBVs are the predominant circulating genotype around the world. Here, the pathogenicity of QX-like IBV strain SD was characterized in chickens at different ages of exposure to the virus, and the protection efficacy of available vaccine combinations against IBV was evaluated. The results revealed that QX-like IBV strain SD was severely pathogenic in chickens, causing respiratory, urinary and reproductive infections, irrespective of age, based on clinical observations, viral distribution in tissues and a ciliostasis study. Severe respiratory signs, tracheal cilia injury, nephritis and abnormal development of the oviduct and ovarian follicles were evident throughout the experiment. A challenge experiment demonstrated that the homologous QX vaccine showed superior protection efficacy compared with other available vaccines, confirming the importance of IBV vaccine seed homology against the circulating IBV strains. Our findings aid an understanding of the pathogenicity of QX-like IBVs that may help to further control the infection.

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“…KM91 was detected and persisted in the trachea and kidneys for the first 3 weeks and in the cecal tonsils throughout the whole period of observation (4 weeks). Pathogenic field isolates of QX-like and variant IBVs also persisted for a long time in the trachea, proventriculus, kidneys and cecal tonsils of infected chickens [ 24 ]. Therefore, embryo and cold adaptation apparently decreased pathogenicity and changed the tissue tropism of K2 and BP-caKII in embryonated eggs and chickens.…”

Section: Discussionmentioning

confidence: 99%

Pathobiological and Genomic Characterization of a Cold-Adapted Infectious Bronchitis Virus (BP-caKII)

Hong

Lee

et al. 2018

Viruses

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We established a cold-adapted infectious bronchitis virus (BP-caKII) by passaging a field virus through specific pathogen-free embryonated eggs 20 times at 32 °C. We characterized its growth kinetics and pathogenicity in embryonated eggs, and its tropism and persistence in different tissues from chickens; then, we evaluated pathogenicity by using a new premature reproductive tract pathogenicity model. Furthermore, we determined the complete genomic sequence of BP-caKII to understand the genetic changes related to cold adaptation. According to our results, BP-caKII clustered with the KII genotype viruses K2 and KM91, and showed less pathogenicity than K2, a live attenuated vaccine strain. BP-caKII showed delayed viremia, resulting in its delayed dissemination to the kidneys and cecal tonsils compared to K2 and KM91, the latter of which is a pathogenic field strain. A comparative genomics study revealed similar nucleotide sequences between BP-caKII, K2 and KM91 but clearly showed different mutations among them. BP-caKII shared several mutations with K2 (nsp13, 14, 15 and 16) following embryo adaptation but acquired multiple additional mutations in nonstructural proteins (nsp3, 4 and 12), spike proteins and nucleocapsid proteins following cold adaptation. Thus, the establishment of BP-caKII and the identified mutations in this study may provide insight into the genetic background of embryo and cold adaptations, and the attenuation of coronaviruses.

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Comparative Pathogenicity of Malaysian QX-like and Variant Infectious Bronchitis Virus Strains in Chickens at Different Age of Exposure to the Viruses

Cited by 16 publications

References 43 publications

Comparative features of infections of two Massachusetts (Mass) infectious bronchitis virus (IBV) variants isolated from Western Canadian layer flocks

Comparative features of infections of two Massachusetts (Mass) infectious bronchitis virus (IBV) variants isolated from Western Canadian layer flocks

Pathogenic characteristics of a QX-like infectious bronchitis virus strain SD in chickens exposed at different ages and protective efficacy of combining live homologous and heterologous vaccination

Pathobiological and Genomic Characterization of a Cold-Adapted Infectious Bronchitis Virus (BP-caKII)

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