title: Reverse mutation of the virulence-associated S2 gene does not cause an attenuated equine infectious anemia virus strain to revert to pathogenicity.
abstract: The contribution of S2 accessory gene of equine infectious anemia virus (EIAV) to the virulence of pathogenic strains was investigated in the present study by reverse mutation of all four consensus S2 mutation sites in an attenuated EIAV proviral strain, FDDV3-8, to the corresponding sequences of a highly pathogenic strain DV117. The S2 reverse-mutated recombinant strain FDDVS2r1-2-3-4 replicated with similar kinetics to FDDV3-8 in cultivated target cells. In contrast to the results of other studies of EIAV with dysfunctional S2, reverse mutation of S2 only transiently and moderately increased the plasma viral load of inoculated horses, and induction of transient immunosuppression did not boost viral pathogenicity. In addition, inoculation of FDDVS2r1-2-3-4 induced partial protection to a challenge pathogenic virus. These results suggest that the attenuated EIAV vaccine strain with multiple mutations in multiple genes will not easily revert to a virulent phenotype.
authors.affiliation: State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Gao
authors.forename: Cheng-Gang
authors.initials: CG
authors.lastname: Jiang
authors.forename: Xue-Feng
authors.initials: XF
authors.lastname: Wang
authors.forename: Yue-Zhi
authors.initials: YZ
authors.lastname: Lin
authors.forename: Jian
authors.initials: J
authors.lastname: Ma
authors.forename: Xiu-E
authors.initials: XE
authors.lastname: Han
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Zhao
authors.forename: Rong-Xian
authors.initials: RX
authors.lastname: Shen
authors.forename: Wen-Hua
authors.initials: WH
authors.lastname: Xiang
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Zhou
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004859:Equine Infectious Anemia / Q000473:pathology* / Q000821:virology; D006736:Horses / Q000821:virology; D004860:Infectious Anemia Virus, Equine / Q000235:genetics / Q000472:pathogenicity*; D008969:Molecular Sequence Data; D009154:Mutation; D014613:Vaccines, Attenuated / Q000235:genetics* / Q000276:immunology; D019562:Viral Load; D014764:Viral Proteins / Q000235:genetics*; D014765:Viral Vaccines / Q000235:genetics* / Q000276:immunology; D014774:Virulence / Q000235:genetics; D014779:Virus Replication
chemical_list: C402643:S2 protein, Equine infectious anemia virus; D014613:Vaccines, Attenuated; D014764:Viral Proteins; D014765:Viral Vaccines
keywords: EIAV; Pathogenicity; Reverse mutation; S2