title: Generation of a live rabies vaccine strain attenuated by multiple mutations and evaluation of its safety and efficacy.
abstract: An amino acid substitution at position 333 in rabies virus G protein is known to determine the pathogenicity: strains with Arg or Lys at that position kill adult mice after intracerebral inoculation, whereas strains with other amino acids cause non-lethal infection. Based on those findings, attenuated rabies virus strains have been established and used for oral vaccines mainly for wild animals. However, considering the possibility of back-mutation to the virulent phenotype, a strain that is attenuated by multiple mutations not only in the G protein but also in other viral proteins would be more appropriate as a safe live vaccine. We previously demonstrated that the fixed rabies virus Ni-CE strain, which causes only transient body weight loss in adult mice after intracerebral inoculation, is mainly attenuated by mutations in the N, P and M proteins, while this strain has virulent-type Arg at position 333 in the G protein. In this study, to obtain a live vaccine strain that is attenuated by multiple mutations, we generated Ni-CE mutant, Ni-CE(G333Glu) strain, which has an Arg-to-Glu mutation at position 333 in the G protein, and examined its pathogenicity and immunogenicity. We found that, in contrast to Ni-CE strain, Ni-CE(G333Glu) strain did not cause transient body weight loss in adult mice after intracerebral inoculation. The attenuated phenotype of Ni-CE(G333Glu) strain did not change even after 10 serial intracerebral passages in suckling mice. We also demonstrated that inoculation of Ni-CE(G333Glu) strain induced virus-neutralizing antibody in immunized mice and protected the mice from lethal challenge. These results indicate that Ni-CE(G333Glu) strain is a promising candidate for development of a live rabies vaccine with a high safety level.
authors.affiliation: The United Graduate School of Veterinary Sciences, Gifu University, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Naoto
authors.initials: N
authors.lastname: Ito
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Masatani
authors.forename: Masako
authors.initials: M
authors.lastname: Abe
authors.forename: Satoko
authors.initials: S
authors.lastname: Yamaoka
authors.forename: Yuki
authors.initials: Y
authors.lastname: Ito
authors.forename: Kota
authors.initials: K
authors.lastname: Okadera
authors.forename: Makoto
authors.initials: M
authors.lastname: Sugiyama
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D001835:Body Weight; D005260:Female; D042822:Genomic Instability; D007267:Injections / Q000009:adverse effects; D051379:Mice; D020125:Mutation, Missense; D011819:Rabies Vaccines / Q000008:administration & dosage / Q000009:adverse effects* / Q000235:genetics / Q000276:immunology*; D011820:Rabies virus / Q000235:genetics / Q000472:pathogenicity; D012692:Serial Passage; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects / Q000235:genetics / Q000276:immunology
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D011819:Rabies Vaccines; D014613:Vaccines, Attenuated