VP3 protein of Senecavirus A promotes viral IRES-driven translation and attenuates innate immunity by specifically relocalizing hnRNPA2B1.

ABSTRACT

Viruses deploy sophisticated strategies to hijack the host's translation machinery to favor viral protein synthesis and counteract innate cellular defenses. However, little is known about the mechanisms by which Senecavirus A (SVA) controls the host's translation. Using a series of sophisticated molecular cell manipulation techniques, heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) was identified as an essential host factor involved in translation control in SVA-infected cells. It was also determined that the SVA structural protein, VP3, binds to and relocalizes hnRNPA2B1, which interferes with the host's protein synthesis machinery to establish a cellular environment that facilitates viral propagation via a two-pronged strategy first, hnRNPA2B1 serves as a potent internal ribosome entry site (IRES) trans-acting factor, which is selectively co-opted to promote viral IRES-driven translation by supporting the assembly of translation initiation complexes. Second, a strong repression of host cell translation occurs in the context of the VP3-hnRNPA2B1 interaction, resulting in attenuation of the interferons response. This is the first study to demonstrate the interaction between SVA VP3 and hnRNPA2B1, and to characterize their key roles in manipulating translation. This novel dual mechanism, which regulates selective mRNA translation and immune evasion of virus-infected cells, highlights the VP3-hnRNPA2B1 complex as a potential target for the development of modified antiviral or oncolytic reagents. IMPORTANCE Viral reproduction is contingent on viral protein synthesis, which relies entirely on the host's translation machinery. As such, viruses often need to control the cellular translational apparatus to favor viral protein production and avoid host innate defenses. Senecavirus A (SVA) is an important virus, both as an emerging pathogen in the pork industry and as a potential oncolytic virus for neuroendocrine cancers. Here, heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1) was identified as a critical regulator of the translational landscape during SVA infection. This study supports a model whereby the VP3 protein of SVA efficiently subverts the host's protein synthesis machinery through its ability to bind to and relocalize hnRNPA2B1, not only selectively promoting viral internal ribosome entry site-driven translation but also resulting in global translation shutdown and immune evasion. Together, these data provide new insights into how the complex interactions between translation machinery, SVA, and innate immunity contribute to the pathogenicity of the SVA.