Baquero-Perez Belinda, Kuchipudi Suresh V, Ho Jemima, Sebastian Sujith, Puranik Anita, Howard Wendy, Brookes Sharon M, Brown Ian H, Chang Kin-Chow
School of Veterinary Medicine and Science, University of Nottingham, Loughborough, Leicestershire, United Kingdom.
Virology Department, Animal and Plant Health Agency, Weybridge, Addlestone, Surrey, United Kingdom.
J Virol. 2015 Mar;89(5):2494-506. doi: 10.1128/JVI.03421-14. Epub 2014 Dec 24.
Skeletal muscle, at 30 to 40% of body mass, is the most abundant soft tissue in the body. Besides its primary function in movement and posture, skeletal muscle is a significant innate immune organ with the capacity to produce cytokines and chemokines and respond to proinflammatory cytokines. Little is known about the role of skeletal muscle during systemic influenza A virus infection in any host and particularly avian species. Here we used primary chicken and duck multinucleated myotubes to examine their susceptibility and innate immune response to influenza virus infections. Both chicken and duck myotubes expressed avian and human sialic acid receptors and were readily susceptible to low-pathogenicity (H2N3 A/mallard duck/England/7277/06) and high-pathogenicity (H5N1 A/turkey/England/50-92/91 and H5N1 A/turkey/Turkey/1/05) avian and human H1N1 (A/USSR/77) influenza viruses. Both avian host species produced comparable levels of progeny H5N1 A/turkey/Turkey/1/05 virus. Notably, the rapid accumulation of viral nucleoprotein and matrix (M) gene RNA in chicken and duck myotubes was accompanied by extensive cytopathic damage with marked myotube apoptosis (widespread microscopic blebs, caspase 3/7 activation, and annexin V binding at the plasma membrane). Infected chicken myotubes produced significantly higher levels of proinflammatory cytokines than did the corresponding duck cells. Additionally, in chicken myotubes infected with H5N1 viruses, the induction of interferon beta (IFN-β) and IFN-inducible genes, including the melanoma differentiation-associated protein 5 (MDA-5) gene, was relatively weak compared to infection with the corresponding H2N3 virus. Our findings highlight that avian skeletal muscle fibers are capable of productive influenza virus replication and are a potential tissue source of infection.
Infection with high-pathogenicity H5N1 viruses in ducks is often asymptomatic, and skeletal muscle from such birds could be a source of infection of humans and animals. Little is known about the ability of influenza A viruses to replicate in avian skeletal muscle fibers. We show here that cultured chicken and duck myotubes were highly susceptible to infection with both low- and high-pathogenicity avian influenza viruses. Infected myotubes of both avian species displayed rapid virus accumulation, apoptosis, and extensive cellular damage. Our results indicate that avian skeletal muscle fibers of chicken and duck could be significant contributors to progeny production of highly pathogenic H5N1 viruses.
骨骼肌占体重的30%至40%，是人体中最丰富的软组织。除了在运动和姿势方面的主要功能外，骨骼肌还是一个重要的先天性免疫器官，具有产生细胞因子和趋化因子以及对促炎细胞因子作出反应的能力。在任何宿主，尤其是禽类中，关于骨骼肌在甲型流感病毒全身感染过程中的作用知之甚少。在这里，我们使用原代鸡和鸭多核肌管来研究它们对流感病毒感染的易感性和先天性免疫反应。鸡和鸭的肌管都表达禽类和人类唾液酸受体，并且很容易感染低致病性（H2N3 A/野鸭/英格兰/7277/06）和高致病性（H5N1 A/火鸡/英格兰/50 - 92/91和H5N1 A/火鸡/土耳其/1/05）的禽类和人类H1N1（A/苏联/77）流感病毒。两种禽类宿主产生的子代H5N1 A/火鸡/土耳其/1/05病毒水平相当。值得注意的是，鸡和鸭肌管中病毒核蛋白和基质（M）基因RNA的快速积累伴随着广泛的细胞病变损伤以及明显的肌管凋亡（广泛的微观泡状突起、半胱天冬酶3/7激活以及质膜上的膜联蛋白V结合）。感染的鸡肌管产生的促炎细胞因子水平明显高于相应的鸭细胞。此外，在感染H5N1病毒的鸡肌管中，与感染相应的H2N3病毒相比，干扰素β（IFN-β）和IFN诱导基因，包括黑色素瘤分化相关蛋白5（MDA-5）基因的诱导相对较弱。我们的研究结果突出表明，禽类骨骼肌纤维能够进行有 productive 的流感病毒复制，并且是一个潜在的感染组织来源。
鸭子感染高致病性H5N1病毒通常无症状，此类禽类的骨骼肌可能是人类和动物的感染源。关于甲型流感病毒在禽类骨骼肌纤维中复制的能力知之甚少。我们在此表明，培养的鸡和鸭肌管对低致病性和高致病性禽流感病毒感染高度敏感。两种禽类感染的肌管都显示出病毒快速积累、凋亡和广泛的细胞损伤。我们的结果表明，鸡和鸭的禽类骨骼肌纤维可能是高致病性H5N1病毒子代产生的重要贡献者。
