Singh Gagandeep, Kafle Sujan, Assato Patricia, Goraya Mankanwal, Morozov Igor, Richt Juergen A
Department of Diagnostic Medicine/Pathobiology (DMP), College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506, USA.
Department of Plant Pathology and Environmental Microbiology, The Pennsylvania State University, University Park, PA 16802, USA.
Viruses. 2025 Jun 3;17(6):811. doi: 10.3390/v17060811.
The 2024 outbreak of highly pathogenic avian influenza virus (HPAIV) H5N1 in U.S. dairy cattle presented an unprecedented scenario where the virus infected bovine mammary glands and was detected in milk, raising serious concerns for public health and the dairy industry. Unlike previously described subclinical influenza A virus (IAV) infections in cattle, H5N1 infection induced severe clinical symptoms, including respiratory distress, mastitis, and abnormal milk production. To understand the host immune responses and changes, particularly in the mammary gland, we performed single-cell RNA sequencing analysis on bovine milk somatic cells (bMSCs) in vitro exposed to an H5N1 isolate from an infected dairy farm. We identified ten distinct cell clusters and observed a shift toward type-2 immune responses, characterized by T cells expressing and , and three different subtypes of epithelial cells based on the expression of genes associated with milk production. Our study revealed temporal dynamics in cytokine expression, with a rapid decline in luminal epithelial cells and an increase in macrophages and dendritic cells, suggesting a role in increased antigen presentation. While viral RNA was detected in bulk-exposed bMSC samples via qRT-PCR, no viral reads were observed in the scRNA-seq data, indicating that the immune responses captured may be due to exposure to viral components rather than productive infection. This research fills a critical gap in understanding the immune responses of bovine mammary glands to H5N1 exposure and highlights the need for further investigation into therapeutic strategies for managing such outbreaks.
2024年美国奶牛中高致病性禽流感病毒（HPAIV）H5N1的爆发呈现出一种前所未有的情况，即该病毒感染了牛乳腺并在牛奶中被检测到，这引发了对公共卫生和乳制品行业的严重担忧。与先前描述的牛亚临床甲型流感病毒（IAV）感染不同，H5N1感染引发了严重的临床症状，包括呼吸窘迫、乳腺炎和异常产奶。为了解宿主的免疫反应和变化，特别是在乳腺中的情况，我们对来自受感染奶牛场的H5N1分离株体外暴露后的牛乳腺体细胞（bMSC）进行了单细胞RNA测序分析。我们鉴定出十个不同的细胞簇，并观察到向2型免疫反应的转变，其特征是表达 和 的T细胞，以及基于与产奶相关基因表达的三种不同亚型的上皮细胞。我们的研究揭示了细胞因子表达的时间动态，管腔上皮细胞迅速减少，巨噬细胞和树突状细胞增加，表明在增加抗原呈递中发挥作用。虽然通过qRT-PCR在大量暴露的bMSC样本中检测到病毒RNA，但在scRNA-seq数据中未观察到病毒读数，这表明所捕获的免疫反应可能是由于暴露于病毒成分而非有生产性的感染。这项研究填补了理解牛乳腺对H5N1暴露的免疫反应方面的关键空白，并强调需要进一步研究管理此类疫情的治疗策略。
