Nitric oxide as an endogenous mutagen for Sendai virus without antiviral activity.
Nitric oxide (NO) may affect the genomes of various pathogens, and this mutagenesis is of particular interest for viral pathogenesis and evolution. Here, we investigated the effect of NO on viral replication and mutation. Exogenous or endogenous NO had no apparent antiviral effect on influenza A virus and Sendai virus. The mutagenic potential of NO was analyzed with Sendai virus fused to a green fluorescent protein (GFP) gene (GFP-SeV). GFP-SeV was cultured in SW480 cells transfected with a vector expressing inducible NO synthase (iNOS). The mutation frequency of GFP-SeV was examined by measuring loss of GFP fluorescence of the viral plaques. GFP-SeV mutation frequency in iNOS-SW480 cells was much higher than that in parent SW480 cells and was reduced to the level of mutation frequency in the parent cells by treatment with an NO synthase (NOS) inhibitor. Immunocytochemistry showed generation of more 8-nitroguanosine in iNOS-SW480 cells than in SW480 cells without iNOS transfection. Authentic 8-nitroguanosine added exogenously to GFP-SeV-infected CV-1 cells increased the viral mutation frequency. Profiles of the GFP gene mutations induced by 8-nitroguanosine appeared to resemble those of mutations occurring in mouse lungs in vivo. A base substitution that was characteristic of both mutants (those induced by 8-nitroguanosine and those occurring in vivo) was a C-to-U transition. NO-dependent oxidative stress in iNOS-SW480 cells was also evident. Together, the results indicate unambiguously that NO has mutagenic potential for RNA viruses such as Sendai virus without affecting viral replication, possibly via 8-nitroguanosine formation and cellular oxidative stress.
Department of Microbiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860-8556, Japan.
Jun
J
Yoshitake
Takaaki
T
Akaike
Teruo
T
Akuta
Fumio
F
Tamura
Tsutomu
T
Ogura
Hiroyasu
H
Esumi
Hiroshi
H
Maeda
D000818:Animals; D002460:Cell Line; D049452:Green Fluorescent Proteins; D006151:Guanosine / Q000031:analogs & derivatives / Q000378:metabolism; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009153:Mutagens / Q000494:pharmacology*; D009154:Mutation / Q000187:drug effects; D009569:Nitric Oxide / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009574:Nitro Compounds / Q000378:metabolism; D018384:Oxidative Stress; D029082:Sendai virus / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D014779:Virus Replication
C481144:8-nitroguanosine; D008164:Luminescent Proteins; D009153:Mutagens; D009574:Nitro Compounds; D006151:Guanosine; D049452:Green Fluorescent Proteins; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse