title: Genetic bases of the temperature-sensitive phenotype of a master donor virus used in live attenuated influenza vaccines: A/Leningrad/134/17/57 (H2N2).
abstract: Trivalent live attenuated influenza vaccines whose type A components are based on cold-adapted A/Leningrad/134/17/57 (H2N2) (caLen17) master donor virus (MDV) have been successfully used in Russia for decades to control influenza. The vaccine virus comprises hemagglutinin and neuraminidase genes from the circulating viruses and the remaining six genes from the MDV. The latter confer temperature-sensitive (ts) and attenuated (att) phenotypes. The ts phenotype of the vaccine virus is a critical biological determinant of attenuation of virulence. We developed a plasmid-based reverse genetics system for MDV caLen17 to study the genetic basis of its ts phenotype. Mutations in the polymerase proteins PB1 and PB2 played a crucial role in the ts phenotype of MDV caLen17. In addition, we show that caLen17-specific ts mutations could impart the ts phenotype to the divergent PR8 virus, suggesting the feasibility of transferring the ts phenotype to new viruses of interest for vaccine development.
authors.affiliation: Influenza Division, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA 30333, USA.
authors.forename: Irina
authors.initials: I
authors.lastname: Isakova-Sivak
authors.forename: Li-Mei
authors.initials: LM
authors.lastname: Chen
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Matsuoka
authors.forename: J Theo M
authors.initials: JT
authors.lastname: Voeten
authors.forename: Irina
authors.initials: I
authors.lastname: Kiseleva
authors.forename: Jacco G M
authors.initials: JG
authors.lastname: Heldens
authors.forename: Han van
authors.initials: Hv
authors.lastname: den Bosch
authors.forename: Alexander
authors.initials: A
authors.lastname: Klimov
authors.forename: Larisa
authors.initials: L
authors.lastname: Rudenko
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Cox
authors.forename: Ruben O
authors.initials: RO
authors.lastname: Donis
mesh_terms: D005822:Genetic Vectors; D005838:Genotype; D006801:Humans; D053121:Influenza A Virus, H2N2 Subtype / Q000235:genetics* / Q000254:growth & development*; D007252:Influenza Vaccines / Q000235:genetics*; D020125:Mutation, Missense; D010641:Phenotype; D010957:Plasmids; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics / Q000378:metabolism; D012426:Russia; D013696:Temperature; D014613:Vaccines, Attenuated / Q000235:genetics; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D007252:Influenza Vaccines; C057027:PB2 protein, Influenzavirus A; D014613:Vaccines, Attenuated; D014764:Viral Proteins; C077346:influenza virus polymerase basic protein 1; D012324:RNA-Dependent RNA Polymerase