Shi Lei, Lang Yuekun, Roy Sawrab, Shen Zhenyu, Gupta Dipali, Dai Chao, Khalid Muhammad Afnan, Mitchell William J, Zhang Shuping, Webby Richard, Richt Juergen, Ma Wenjun
Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA.
Department of Molecular Microbiology & Immunology, School of Medicine, University of Missouri, Columbia, Missouri, USA.
mBio. 2025 Jul 9;16(7):e0395724. doi: 10.1128/mbio.03957-24. Epub 2025 Jun 12.
Unprecedented outbreaks caused by the H5N1 highly pathogenic avian influenza virus (HPAIV) among dairy cows in the United States have raised significant concerns. Whether other subtypes of influenza A viruses (IAVs) can infect and transmit in cattle remains largely unknown. Herein, we infected cattle respiratory and mammary gland cells with different IAVs and two groups of Holstein calves intranasally or orally with a swine H3N2 virus to determine their susceptibility. Naive calves were co-housed with infected animals to investigate virus transmission. Results showed that tested swine and avian IAVs could infect cattle primary nasal turbinate and tracheal epithelial cells, as well as immortalized mammary gland epithelial cells and fibroblasts. No obvious clinical signs, including fever, were observed in infected and contact calves, but macroscopic lung lesions were found in necropsied animals in both groups on day 5 post-infection. Viral shedding was detected in three out of four nasally infected calves but not in orally infected or the two groups of contact animals. Interestingly, viral RNA and antigen could not be detected in all tissues from individual necropsied animals from either infection group, but viral RNA and sequences were detected in serum samples of two nasally infected calves on day 7 post-infection, not on other days and in other animals. Additionally, only the nasally infected animals seroconverted. Our results indicate that in addition to H5N1 HPAIV, swine H3N2 virus can infect cattle but does not transmit efficiently among them, suggesting that other subtypes of IAVs could infect and replicate in cattle.IMPORTANCEHighly pathogenic avian influenza H5N1 virus outbreaks in U.S. dairy herds have raised questions about whether other subtypes of influenza A viruses (IAVs) can infect and transmit in cattle. In this study, we investigated the susceptibility and infection of different IAVs in bovine primary and immortalized cells and Holstein calves. Results showed that avian H5N1 and H9N2, and swine H3N2 IAVs could infect beef cattle primary nasal turbinate and tracheal epithelial cells, as well as immortalized mammary gland epithelial cells and fibroblasts. Moreover, the swine H3N2 could infect the calves through intranasal infection, but not through oral infection, despite no obvious clinical signs and efficient transmission being observed. Our results demonstrate that other subtypes of IAVs can infect cattle and might pose threats to public and animal health.
H5N1高致病性禽流感病毒（HPAIV）在美国奶牛群中引发的前所未有的疫情引起了人们的高度关注。甲型流感病毒（IAV）的其他亚型是否能在牛群中感染和传播，目前仍 largely unknown。在此，我们用不同的IAV感染牛呼吸道和乳腺细胞，并给两组荷斯坦犊牛经鼻或经口接种猪H3N2病毒，以确定它们的易感性。将未接触过病毒的犊牛与感染动物共同饲养，以研究病毒传播情况。结果表明，所测试的猪和禽流感病毒能感染牛的原代鼻甲和气管上皮细胞，以及永生化乳腺上皮细胞和成纤维细胞。在感染和接触的犊牛中未观察到明显的临床症状，包括发热，但在感染后第5天对两组动物进行尸检时发现肺部有宏观病变。在4头经鼻感染的犊牛中有3头检测到病毒 shedding，但经口感染的犊牛或两组接触动物中未检测到。有趣的是，在任一感染组的个体尸检动物的所有组织中均未检测到病毒RNA和抗原，但在感染后第7天，在2头经鼻感染的犊牛的血清样本中检测到病毒RNA和序列，其他时间和其他动物中未检测到。此外，只有经鼻感染的动物出现了血清转化。我们的结果表明，除H5N1 HPAIV外，猪H3N2病毒也能感染牛，但在牛群中传播效率不高，这表明IAV的其他亚型可能在牛群中感染和复制。
重要性
美国奶牛群中高致病性H5N1禽流感病毒疫情引发了关于甲型流感病毒（IAV）其他亚型是否能在牛群中感染和传播的疑问。在本研究中，我们调查了不同IAV在牛原代和永生化细胞以及荷斯坦犊牛中的易感性和感染情况。结果表明，禽流感H5N1和H9N2以及猪H3N2 IAV能感染肉牛的原代鼻甲和气管上皮细胞，以及永生化乳腺上皮细胞和成纤维细胞。此外，猪H3N2能通过经鼻感染犊牛，但不能通过经口感染，尽管未观察到明显的临床症状和有效传播。我们的结果表明，IAV的其他亚型能感染牛，可能对公众和动物健康构成威胁。
