John C. Sauter

Latent viral infections rely on a precise coordination of the immune response to control sporadic viral reactivation. CD8+ T cells play a crucial role in controlling viral latency by generating diverse memory responses in an epitope-specific manner. Among these distinct responses, conventional and inflationary memory responses have been described during herpesvirus infections. Using a newly generated TCR transgenic mouse strain, we investigated the transcriptomic and epigenetic remodeling of distinct epitope-specific CD8+ T cells during CMV infection across tissues at both population and single-cell levels. Our findings reveal that whereas the transcriptomic and epigenetic landscapes of conventional and inflationary memory responses diverge in the spleen and liver, these molecular programs converge in the salivary gland, a site of CMV persistence. Thus, we provide evidence that the dynamics of memory CD8+ T cell responses are distinct between tissues.

Natural killer (NK) cells are innate lymphocytes that exhibit adaptive traits particularly evident during cytomegalovirus (CMV) infection. Following mouse CMV (MCMV) infection, NK cells upregulate the transcription factors IRF4 and IRF8, which are indispensable for their survival and proliferation upon viral infection. However, it is unclear whether these factors are expressed within the same individual cell and whether deficiency in one could be compensated by the other. In this study, we observed that a subset of NK cells co-express high levels of IRF4 and IRF8 in an NFκB-dependent manner. These IRF4HighIRF8High NK cells are specifically enriched for activated but immature cells with high proliferative potential during MCMV infection. Functionally, NK cells lacking both IRF4 and IRF8 develop normally, but experience a more severe expansion defect during virus exposure compared to NK cells deficient in a single factor. Thus, our study reveals a cooperative interplay between IRF4- and IRF8-dependent transcriptional networks in regulating NK-cell antiviral responses.