title: Cold adaptation improves the growth of seasonal influenza B vaccine viruses.
abstract: Gene reassortment has proved useful in improving yields of influenza A antigens of egg-based inactivated vaccines, but similar approaches have been difficult with influenza B antigens. Current regulations for influenza vaccine seed viruses limit the number of egg passages and as a result resultant yields from influenza B vaccine seed viruses are frequently inconsistent. Therefore, reliable approaches to enhance yields of influenza B vaccine seed viruses are required for efficient vaccine manufacture. In the present study three stable cold-adapted (ca) mutants, caF, caM and caB derived from seasonal epidemic strains, B/Florida/4/2006, B/Malaysia/2506/2004 and B/Brisbane/60/2008 were prepared, which produced high hemagglutinin antigen yields and also increased viral yields of reassortants possessing the desired 6:2 gene constellation. The results demonstrate that consistent improvements in yields of influenza B viruses can be obtained by cold adaptation following extended passage. Taken together, the three ca viruses were shown to have potential as donor viruses for the preparation of high-yielding influenza B vaccine viruses by reassortment.
authors.affiliation: Centre for Biomedical Research, Burnet Institute, 85 Commercial Road, Melbourne 3004, VIC, Australia; School of Applied Sciences, RMIT University, Plenty Road, Bundoora 3083, VIC, Australia. Electronic address: hyunsuh@burnet.edu.au.
authors.forename: Hyunsuh
authors.initials: H
authors.lastname: Kim
authors.affiliation: Influenza Research and Development, bioCSL Limited, 63 Poplar Road, Parkville 3052, VIC, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Schoofs
authors.affiliation: Centre for Biomedical Research, Burnet Institute, 85 Commercial Road, Melbourne 3004, VIC, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Anderson
authors.affiliation: Centre for Biomedical Research, Burnet Institute, 85 Commercial Road, Melbourne 3004, VIC, Australia; School of Applied Sciences, RMIT University, Plenty Road, Bundoora 3083, VIC, Australia.
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Tannock
authors.affiliation: Influenza Research and Development, bioCSL Limited, 63 Poplar Road, Parkville 3052, VIC, Australia.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Rockman
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002645:Chickens; D003080:Cold Temperature; D004285:Dogs; D006385:Hemagglutination Inhibition Tests; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000302:isolation & purification; D009981:Influenza B virus / Q000235:genetics / Q000254:growth & development*; D007252:Influenza Vaccines; D061985:Madin Darby Canine Kidney Cells; D010063:Ovum / Q000821:virology; D016865:Reassortant Viruses / Q000235:genetics / Q000254:growth & development; D012692:Serial Passage; D014776:Virus Cultivation
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines
keywords: Cold adaptation; Growth; Inactivated vaccine; Influenza B virus