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Role of free radicals in viral pathogenesis and mutation
Author(s) -
Akaike Takaaki
Publication year - 2001
Publication title -
reviews in medical virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.06
H-Index - 90
eISSN - 1099-1654
pISSN - 1052-9276
DOI - 10.1002/rmv.303
Subject(s) - peroxynitrite , reactive nitrogen species , pathogenesis , biology , immune system , viral pathogenesis , reactive oxygen species , virus , nitric oxide , radical , superoxide , immunology , viral replication , microbiology and biotechnology , biochemistry , endocrinology , enzyme
Oxygen radicals and nitric oxide (NO) are generated in excess in a diverse array of microbial infections. Emerging concepts in free radical biology are now shedding light on the pathogenesis of various diseases. Free‐radical induced pathogenicity in virus infections is of great importance, because evidence suggests that NO and oxygen radicals such as superoxide are key molecules in the pathogenesis of various infectious diseases. Although oxygen radicals and NO have an antimicrobial effect on bacteria and protozoa, they have opposing effects in virus infections such as influenza virus pneumonia and several other neurotropic virus infections. A high output of NO from inducible NO synthase, occurring in a variety of virus infections, produces highly reactive nitrogen oxide species, such as peroxynitrite, via interaction with oxygen radicals and reactive oxygen intermediates. The production of these various reactive species confers the diverse biological functions of NO. The reactive nitrogen species cause oxidative tissue injury and mutagenesis through oxidation and nitration of various biomolecules. The unique biological properties of free radicals are further illustrated by recent evidence showing accelerated viral mutation by NO‐induced oxidative stress. NO appears to affect a host's immune response, with immunopathological consequences. For example, NO is reported to suppress type 1 helper T cell‐dependent immune responses during infections, leading to type 2 helper T cell‐biased immunological host responses. NO‐induced immunosuppression may thus contribute to the pathogenesis of virus infections and help expansion of quasispecies population of viral pathogens. This review describes the pathophysiological roles of free radicals in the pathogenesis of viral disease and in viral mutation as related to both nonspecific inflammatory responses and immunological host reactions modulated by NO. Copyright © 2001 John Wiley & Sons, Ltd.