title: Improvement of the H5N1 influenza virus vaccine strain to decrease the pathogenicity in chicken embryos.
abstract: The avian influenza vaccine strain A/duck/Hokkaido/Vac-1/2004 (H5N1) (Vac-1) was found to be pathogenic in chicken embryos (CEs). In order to decrease the pathogenicity of Vac-1 in CEs, a series of reassortant viruses was generated between Vac-1 and A/Puerto Rico/8/1934 (H1N1) (PR8), and their pathogenicity and growth potential were compared in CEs. The results indicated that either the PB1 or PA protein was responsible for the pathogenicity of Vac-1 in CEs. The HA titers of the allantoic fluids of CEs inoculated with the recombinant H5N1 viruses, of which pathogenicity was lower than that of the recombinant Vac-1 prepared by reverse genetics in CEs, were equivalent to those of CEs inoculated with the recombinant Vac-1. One of the reassortant viruses, rg-PR8-PA/Vac-1 (H5N1), in which the PA gene was replaced with the corresponding gene of PR8, yielded allantoic fluids with the same HA titer as that of Vac-1, indicating that this reassortant should be a good candidate as an improved vaccine strain.
authors.affiliation: Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Kita-ku, Sapporo, Hokkaido, Japan.
authors.forename: Norikazu
authors.initials: N
authors.lastname: Isoda
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sakoda
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Okamatsu
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Tsuda
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kida
mesh_terms: D000482:Allantois / Q000821:virology; D000818:Animals; D002642:Chick Embryo; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D053124:Influenza A Virus, H5N1 Subtype / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D007252:Influenza Vaccines / Q000009:adverse effects*; D016865:Reassortant Viruses / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D019562:Viral Load
chemical_list: D007252:Influenza Vaccines