Adenovirus E3 protein modulates leukocyte functions

Abstract

To resist viral infections, leukocytes perform effector functions, such as direct killing of infected cells (elicited by natural killer cells and T lymphocytes) and production of virus-neutralizing antibodies (elicited by B lymphocytes). These effector functions require differentiation of the leukocyte and are preceded by activation of the B- and T-cell receptors and by production of cytokines from multiple cell types. Activation of these effector functions requires a complex signaling network that involves kinases and phosphatases that transfer phosphate groups between each other in the leukocyte cytoplasm. Many viruses have developed systems to resist the effector functions of leukocytes, but (to the best of my knowledge) until now there have been no reports of viral proteins that target these signaling networks. In PNAS, Windheim et al. (1) report a unique resistance system developed by human adenovirus type 19 (HAdV-19). This virus encodes a protein (sec49K) that is secreted from infected cells and targets one of the key regulatory molecules of leukocytes, receptor protein tyrosine phosphatase (RPTP) CD45 (1).