Graduate Student University of Hawaii at Manoa Honolulu, Hawaii, United States
Disclosure(s):
Matthew Putnam, DVM: No financial relationships to disclose
Introduction/Rationale: The global outbreak of Mpox virus (MPXV) clade IIb, comprising ~106,000 cases predominantly in men, has raised serious concerns regarding sexual transmission. Pox viruses evade immune detection by blocking pathogen sensing and inhibiting antiviral responses. We here characterized MPXV infection in human testicular cells to gain insights into the landscape of cell-type-specific testicular response to infection.
Methods: Human primary Sertoli (SC) and Leydig (LC) cells were infected with MPXV clade IIb (MOI 0.005). Infection was confirmed by quantitative PCR and plaque assays. RNA-seq analysis was conducted using RNA samples from infected SC and LC at days 1, 3, and 5 post-infection (dpi). Differentially expressed genes (DEGs) were identified based on strict cutoffs (log2 fold-change >|1.5|; adj. p-value < 0.05) and analyzed for enrichment in virus-response and steroidogenesis pathways using Ingenuity Pathway Analysis.
Results: Productive infection was confirmed in both SC and LC with peak virus titers at 5 dpi without significant cell death. Although viral replication was evident by 1 dpi, the number of DEGs remained low (86 in LC and 51 in SC), while they were above 3000 at 5 dpi in both cell types. Notably, canonical viral sensing, cell death, and inflammatory pathways showed no significant activation in either cell type at any time point. Sirtuin family genes (SIRTs) were upregulated at 3 and 5 dpi, correlating with downregulation of antiviral response genes, including DNA virus-sensing gene IFI16.
Conclusion: This is the first evidence that MPXV can infect key human testicular types and suppress key antiviral pathways similar to vaccinia virus. In addition to functioning as post-virus sensing immune brakes, SIRTs are also crucial for spermatogenesis. Our data suggest that SIRT upregulation favors viral replication by promoting cell survival via autophagy and apoptosis inhibition, while simultaneously dampening innate immunity through suppression of NF-κB and interferon signaling.
