J Vet Sci.  2017 Aug;18(S1):299-306. 10.4142/jvs.2017.18.S1.299.

Optimized clade H5N1 recombinant-vaccine strains against highly pathogenic avian influenza

  • 1Laboratory of Avian Diseases, Seoul National University, Seoul 88026, Korea.
  • 2Laboratory of Poultry Production Medicine, Seoul National University, Seoul 88026, Korea. kwonhj01@snu.ac.kr
  • 3College of Veterinary Medicine and BK21 PLUS for Veterinary Science, Seoul National University, Seoul 88026, Korea.
  • 4Center for Infectious Diseases, Korean National Institute of Health, Osong 28159, Korea.
  • 5Laboratory of Foreign Animal Disease, Animal and Plant Quarantine Agency, Gimcheon 39660, Korea.
  • 6Laboratory of Avian Diseases, Animal and Plant Quarantine Agency, Gimcheon 39660, Korea.
  • 7Laboratory of Avian Diseases, College of Veterinary Medicine, Konkuk University, Seoul 05029, Korea.


A/Puerto Rico/8/34 (PR8)-derived recombinant viruses have been used for seasonal flu vaccines; however, they are insufficient for vaccines against some human-fatal H5N1 highly pathogenic avian influenza (HPAI) viruses (HPAIV) due to low productivity. Additionally, the polymerase basic 2 (PB2) protein, an important mammalian-pathogenicity determinant, of PR8 possesses several mammalian-pathogenic mutations. We previously reported two avian PB2 genes (01310 and 0028) related to efficient replication in embryonated chicken eggs (ECEs) and nonpathogenicity in BALB/c mice. In this study, we generated PR8-derived H5N1 recombinant viruses harboring hemagglutinin (attenuated) and neuraminidase genes of a clade H5N1 HPAIV (K10-483), as well as the 01310 or 0028 PB2 genes, and investigated their replication and immunogenicity. Compared with a control virus harboring six internal PR8 genes (rK10-483), the recombinant viruses possessing the 01310 and 0028 PB2 genes showed significantly higher replication efficiency in ECEs and higher antibody titers in chickens. In contrast to rK10-483, none of the viruses replicated in BALB/c mice, and all showed low titers in Madin-Darby canine kidney cells. Additionally, the recombinant viruses did not induce a neutralization antibody but elicited decreased protective immune responses against K10-483 in mice. Thus, the highly replicative and mammalian nonpathogenic recombinant H5N1 strains might be promising vaccine candidates against HPAI in poultry.


influenza A virus H5N1 subtype; polymerase basic 2 gene; reverse genetics; vaccines; virulence
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