AI Summary
This article discusses the role of nucleocapsid protein (N) or nucleoprotein (NP) in RNA viruses and its potential for immunosuppression. N proteins coat the viral genome, protecting it from immune sensors and inducing strong antibody and T cell responses. N proteins are often highly expressed and can be found on the infected cell surface, where they can modulate host immunity by sequestering chemokines. The article suggests that surface N could be a target for anti-viral intervention.
Nucleocapsid protein (N), or nucleoprotein (NP) coats the genome of most RNA viruses, protecting and shielding RNA from cytosolic RNAases and innate immune sensors, and plays a key role in virion biogenesis and viral RNA transcription. Often one of the most highly expressed viral gene products, N induces strong antibody (Ab) and T cell responses. N from different viruses is present on the infected cell surface in copy numbers ranging from tens of thousands to millions per cell, and it can be released to bind to uninfected cells. Surface N is targeted by Abs, which can contribute to viral clearance via Fc-mediated cellular cytotoxicity. Surface N can modulate host immunity by sequestering chemokines (CHKs), extending prior findings that surface N interferes with innate and adaptive immunity. In this review, we consider aspects of surface N cell biology and immunology and describe its potential as a target for anti-viral intervention.
The host immune response drives the evolution of viral immunoevasion mechanisms. Large DNA viruses such as herpesviruses and poxviruses encode the best-known and most obvious immunomodulatory proteins. These include interferon (IFN) antagonists, homologs of host cytokines, CHKs and their receptors, and inhibitors of antigen presentation1,<a