Impact of ECTV C15 expression on the development of CD4+ effector T cells

Orthopoxviruses, such as variola and Mpox, encode a myriad of immunomodulatory proteins to promote pathogenesis. One notable family is the B22 family of proteins, which are highly conserved surface glycoproteins that potently inhibit T cell activation in vitro and ex vivo. However, there has been limited work investigating the impact of B22 proteins on both CD4+ and CD8+ T cell responses in vivo. Therefore, we used ectromelia (ECTV) as a natural host-pathogen model to investigate the impact of its B22 protein, C15, on T cell responses in vivo. To broadly investigate the impact of C15 on CD4+ effector (CD62L-CD44+) T cell development, we performed bulk RNA-seq on splenic CD4+ effector T cells 7 days post-infection with either WT ECTV or ECTV∆C15.