Maloney Sara M, Shaw Teressa M, Nennig Kylie M, Larsen Malorie S, Shah Aadit, Kumar Ashish, Marcotrigiano Joseph, Grove Joe, Snijder Eric J, Kirchdoerfer Robert N, Bailey Adam L
Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA.
University of Wisconsin-Madison Cellular and Molecular Pathology Graduate Program, Madison, Wisconsin, USA.
mBio. 2025 Jul 9;16(7):e0062325. doi: 10.1128/mbio.00623-25. Epub 2025 May 27.
Arteriviruses are a family of single-stranded, positive-sense RNA (+ssRNA) viruses that infect diverse animal hosts. Many arteriviruses are macrophage-tropic, consistent with their utilization of the macrophage-specific molecule CD163 as a receptor. However, the horse arterivirus (equine arteritis virus, EAV), which infects additional cell types beyond macrophages, does not utilize CD163 in its entry mechanism. Here, we use a genome-wide CRISPR knockout screen to identify alternative receptors that could explain this discrepancy in arterivirus receptor utilization and tropism, identifying the plasma membrane tetraspanin CD81 as a required host factor for EAV infection. Genetic knockout of CD81 or pre-incubation with soluble CD81 protected cells from infection with EAV, but had no impact on susceptibility to other arteriviruses. Bypassing the entry step of the viral life cycle by transfecting the EAV genome into CD81-knockout cells produced infectious EAV, implicating CD81 in the EAV entry process. Screening of CD81 orthologs from natural arterivirus hosts identified the brushtail possum CD81 as unsupportive of EAV entry, indicating that CD81 incompatibility can serve as a barrier to cross-species infection. Horse/possum CD81 chimeras were then used to map the structural domains of CD81 engaged by EAV, identifying alpha helix "D" on the large extracellular loop of CD81 as critical for EAV entry. This study identifies the first example of receptor switching in the family and, given the broad tissue distribution of CD81 expression, suggests that the adoption of CD81 enabled an expansion of EAV tropism.IMPORTANCEArteriviruses are a family of diverse positive-sense RNA viruses that can infect a wide range of animal hosts, but many details regarding how arteriviruses gain entry into cells remain unclear. Most arteriviruses are thought to utilize the macrophage-specific molecule CD163 as a receptor; however, the horse arterivirus (equine arteritis virus, EAV) infects additional cell types beyond macrophages and does not utilize CD163. In this study, we identified the host factor CD81 as a significant player in EAV entry. Beyond the implications that this discovery holds for equine health, this study adds to the increasingly complex picture of arterivirus entry and demonstrates that these viruses are capable of adopting new host molecules as receptors, with consequences for the types of cells these viruses infect, the disease they cause, and their mode(s) of transmission.
动脉炎病毒是一类单链正义RNA（+ssRNA）病毒，可感染多种动物宿主。许多动脉炎病毒具有巨噬细胞嗜性，这与其利用巨噬细胞特异性分子CD163作为受体一致。然而，马动脉炎病毒（马动脉炎病毒，EAV）除了感染巨噬细胞外还能感染其他细胞类型，其进入机制并不利用CD163。在此，我们使用全基因组CRISPR敲除筛选来鉴定可解释动脉炎病毒受体利用和嗜性差异的替代受体，确定质膜四跨膜蛋白CD81是EAV感染所需的宿主因子。CD81基因敲除或与可溶性CD81预孵育可保护细胞免受EAV感染，但对其他动脉炎病毒的易感性没有影响。通过将EAV基因组转染到CD81基因敲除细胞中绕过病毒生命周期的进入步骤可产生有感染性的EAV，这表明CD81参与了EAV的进入过程。从天然动脉炎病毒宿主中筛选CD81直系同源物发现，帚尾袋貂的CD81不支持EAV进入，这表明CD81不兼容性可作为跨物种感染的障碍。然后使用马/袋貂CD81嵌合体来定位EAV结合的CD81结构域，确定CD81大细胞外环上的α螺旋“D”对EAV进入至关重要。本研究确定了该病毒家族中受体转换的首个实例，鉴于CD81表达的广泛组织分布，表明采用CD81使EAV嗜性得以扩展。
动脉炎病毒是一类多样的正义RNA病毒，可感染多种动物宿主，但关于动脉炎病毒如何进入细胞的许多细节仍不清楚。大多数动脉炎病毒被认为利用巨噬细胞特异性分子CD163作为受体；然而，马动脉炎病毒（马动脉炎病毒，EAV）除了感染巨噬细胞外还能感染其他细胞类型，且不利用CD163。在本研究中，我们确定宿主因子CD81是EAV进入过程中的重要参与者。除了这一发现对马健康的影响外，本研究还增加了动脉炎病毒进入过程这一日益复杂的图景，并证明这些病毒能够采用新的宿主分子作为受体，这对它们感染的细胞类型、引起的疾病及其传播方式都会产生影响。
