Mechanisms of immune evasion of monkeypox virus.

The mpox (disease caused by the monkeypox virus) epidemic in 2022 provides a good opportunity to study the immune response to mpox. Vaccinia virus-infected monocytes could be recognized by monkeypox virus-specific CD4+ and CD8+ T cells, which produce inflammatory cytokines including IFNγ and TNFα. However, these cells are mostly unable to react to monkeypox virus-infected cells. The monkeypox virus also has no effect on the expression of MHC classes. Cells infected with monkeypox virus can prevent T cells from being activated via their T cell receptors. Insensitivity is an MHC-independent strategy for controlling antiviral T cells activation and inflammatory cytokines production. It is likely a critical aspect of virus spread in the infected host. The ability of monkeypox virus to spread efficiently as cell-associated viremia may be explained by the evasion strategies employed by the virus to subvert immunological surveillance by virus-specific T cells.