title: Foot-and-mouth disease virus low-fidelity polymerase mutants are attenuated.
abstract: Previous studies have shown that RNA viruses can be attenuated by either increased or decreased viral polymerase replication fidelity. Although foot-and-mouth disease virus (FMDV) high-fidelity RNA-dependent RNA polymerase (RdRp) variants with an attenuated phenotype have been isolated using mutagens, no FMDV mutant with a low-fidelity polymerase has been documented to date. Here, we describe the generation of several FMDV RdRp mutants using site-directed mutagenesis via a reverse genetic system. Mutation frequency assays confirmed that five rescued FMDV RdRp mutant populations had lower replication fidelity than the wild-type virus population, which allowed us to assess the effects of the change in replication fidelity on the virus phenotype. These low-fidelity FMDV RdRp mutants showed increased sensitivity to ribavirin or 5-fluorouracil (5-FU) treatment without a loss of growth capacity in cell cultures. In addition, decreased fitness and attenuated virulence were observed for the RdRp mutants with lower fidelity. Importantly, based on a quantitative analysis for fidelity and virulence, we concluded that lower replication fidelity is associated with a more attenuated virus phenotype. These results further contribute to our understanding of the replication fidelity of polymerases of RNA viruses and its relationship to virulence attenuation.
authors.affiliation: Division of Livestock Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 427 Maduan Street, Harbin, 150001, P. R. China.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Xie
authors.forename: Haiwei
authors.initials: H
authors.lastname: Wang
authors.forename: Jianxiong
authors.initials: J
authors.lastname: Zeng
authors.forename: Chen
authors.initials: C
authors.lastname: Li
authors.forename: Guohui
authors.initials: G
authors.lastname: Zhou
authors.forename: Decheng
authors.initials: D
authors.lastname: Yang
authors.forename: Li
authors.initials: L
authors.lastname: Yu
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology; D001483:Base Sequence; D002460:Cell Line; D006224:Cricetinae; D024882:Drug Resistance, Viral / Q000235:genetics; D005472:Fluorouracil / Q000494:pharmacology; D005536:Foot-and-Mouth Disease / Q000821:virology; D029544:Foot-and-Mouth Disease Virus / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics* / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D009154:Mutation; D059645:Mutation Rate; D012367:RNA, Viral / Q000096:biosynthesis / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D012254:Ribavirin / Q000494:pharmacology; D017423:Sequence Analysis, RNA; D014779:Virus Replication / Q000235:genetics*
chemical_list: D000998:Antiviral Agents; D012367:RNA, Viral; D012254:Ribavirin; D012324:RNA-Dependent RNA Polymerase; D005472:Fluorouracil