Immunogenicity and protective efficacy of cold-adapted X-31 live attenuated pre-pandemic H5N1 influenza vaccines

Yo Han Jang, Eun Ju Jung, Young Ho Byun, Kwang Hee Lee, Eun Young Lee, Yoon Jae Lee, Baik Lin Seong

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10 Citations (Scopus)


Despite global efforts to control influenza viruses, they have taken a heavy toll on human public health worldwide. Among particular threats is highly pathogenic avian H5N1 influenza virus (HPAI) due to not only its high mortality in humans but also possible human-to-human transmission either through reassortment with other human influenza viruses such as 2009 pandemic H1N1 influenza virus, or by genetic mutations. With the aim of developing effective vaccines against the H5N1 viruses, we generated two live attenuated H5N1 vaccine candidates against A/Indonesia/05/2005 (clade 2.1) and A/chicken/Korea/ES/2003 (clade 2.5) strains, in the genetic background of the cold-adapted donor strain of X-31. In mice, a single dose of immunization with each of the two vaccines was highly immunogenic inducing high titers of serum viral-neutralizing and hemagglutinin-inhibiting antibodies against the homologous H5N1 strain. Furthermore, significant levels of cross-clade antibody responses were induced by the vaccines, suggesting a broad-spectrum cross-reactivity against the heterologous H5N1 strains. The immunizations provided solid protections against heterologous lethal challenges with H5N2 virus, significantly reducing the morbidity and challenge virus replications in the respiratory tracts. The robustness of the antibody responses against both the homologous and heterologous strains, together with efficient protection against the lethal H5N2 challenge, strongly support the protection against wild type H5N1 infections. These results could serve as an experimental basis for the development of safe and effective H5N1 pre-pandemic vaccines while further addressing the biosecurity concerns associated with H5N1 HPAI.

Original languageEnglish
Pages (from-to)3339-3346
Number of pages8
Issue number33
Publication statusPublished - 2013 Jul 18

Bibliographical note

Funding Information:
This work was supported by the R&D Programs of Korean governments : MKE [grant number: 10031969], MEST [grant number: 2010-0001932 ], MHW [grant number: A085105 ], and Korea CDC [grant number: 2009-E00522-00 ]. This work was also supported from Yonsei University Research Fund 2012.

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Immunology and Microbiology(all)
  • veterinary(all)
  • Public Health, Environmental and Occupational Health
  • Infectious Diseases


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