Ubiquitously expressed transcript isoform 2 (UXT-V2) restricts HSV-2 replication by targeting glycoprotein B for degradation through ubiquitin-proteasome pathway

Herpes simplex virus 2 (HSV-2) is a major pathogen causing neonatal herpes and increasing the risk of human immunodeficiency virus 1 (HIV-1) infection. However, the mechanisms underlying host restriction of HSV-2 infection are still not fully understood. The ubiquitously expressed transcript isoform 2 (UXT-V2), an α-type prefoldin protein, functions as a versatile transcription factor associated with numerous human tumors, but its role in viral infection remains unclear. In this study, we found that ectopic expression of UXT-V2 significantly inhibited HSV-2 replication, while knockout of endogenously expressed UXT-V2 promoted HSV-2 proliferation. Further analysis revealed that UXT-V2 restricts HSV-2 replication independent of its role in regulating NF-κB. In the context of HSV-2 infection or in viral glycoprotein B (gB)-transfected cells, UXT-V2 facilitates K48-linked ubiquitination of gB, leading to its degradation via the proteasome pathway, thereby inhibiting viral replication. Furthermore, we identified that UXT-V2 interacts with gB, recruiting the E3 ligase TRIM21 to facilitate K48-linked ubiquitination of gB. HSV-2, in turn, reduces the abundance of UXT-V2 proteins both in vitro and in mice, highlighting the complexity of HSV-2-host interactions. Collectively, our findings, for the first time, demonstrate an anti-HSV-2 role of UXT-V2, unveiling a novel host immune defense mechanism involved in regulating glycoprotein homeostasis.