Pathobiology of the highly pathogenic avian influenza viruses H7N1 and H5N8 in different chicken breeds and role of Mx 2
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Pathobiology of the highly pathogenic avian influenza viruses H7N1 and H5N8 in different chicken breeds and role of Mx 2032 G/A polymorphism in infection outcome Raúl Sánchez‑González1,2* , Antonio Ramis1,2, Miquel Nofrarías1, Nabil Wali1, Rosa Valle1, Mónica Pérez1, Albert Perlas1,2 and Natàlia Majó1,2
Abstract Chickens are highly susceptible to highly pathogenic avian influenza viruses (HPAIVs). However, the severity of infec‑ tion varies depending of the viral strain and the genetic background of the host. In this study, we evaluated the pathogenesis of two HPAIVs (H7N1 and H5N8) and assessed the susceptibility to the infection of local and com‑ mercial chicken breeds from Spain. Eight chicken breeds were intranasally inoculated with 1 05 ELD50 of A/Chicken/ Italy/5093/1999 (H7N1) or A/Goose/Spain/IA17CR02699/2017 (H5N8 clade 2.3.4.4. B) and monitored during 10 days. Chickens were highly susceptible to both HPAIVs, but H7N1 was considerably more virulent than H5N8 as demon‑ strated by the highest mortality rates and shortest mean death times (MDT). Both HPAIVs produced severe necrosis and intense viral replication in the central nervous system, heart and pancreas; however, the lesions and replication in other tissues were virus-dependent. High levels of viral RNA were detected by the oral route with both viruses. In contrast, a low number of H5N8-inoculated chickens shed by the cloacal route, demonstrating a different pattern of viral shedding dependent of the HPAIV. We found a high variation in the susceptibility to HPAIVs between the different chicken breeds. The birds carrying the genotype AA and AG at position 2032 in chicken Mx gene presented a slightly higher, but not significant, percentage of survival and a statistically significant longer MDT than GG individuals. Our study demonstrated that the severity of HPAI infection is largely dependent of the viral isolate and host factors, under‑ lining the complexity of HPAI infections. Keywords: highly pathogenic avian influenza, Gs/GD lineage, classical strain, chickens, breed, pathogenicity Highlights • H7N1 HPAIV is more virulent to chickens than H5N8 HPAIV. • The lower cloacal excretion of H5N8 suggests a lower adaptation to chickens.
*Correspondence: raul.sanchezgo@e‑campus.uab.cat 1 IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA‑UAB), Campus de la Universitat Autònoma de Barcelona (UAB), Bellaterra, España Full list of author information is available at the end of the article
• Huge differences in susceptibility to HPAIVs exist between chicken breeds.
Introduction Chickens are highly susceptible to highly pathogenic avian influenza viruses (HPAIVs); however, the severity of infection varies depending on the viral strain. The inoculation of most HPAIVs in chickens causes evident clinical signs (e.g. apathy, nervous signs) and gross lesions (e.g. cutaneous edema, cyanosis of the comb and
© The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use,
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