Co-administration of certain DNA vaccine combinations expressing different H5N1 influenza virus antigens can be beneficial or detrimental to immune protection

Ami Patel, Michael Gray, Yan Li, Darwyn Kobasa, Xiaojian Yao, Gary P. Kobinger

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Achieving broad-spectrum immunity against emerging zoonotic viruses such as avian influenza H5N1 and other possible pandemic viruses will require generation of cross-protective immune responses. Strong antibody responses generated against the H5HA protein are protective, however, antigenic variation between diverging isolates can interfere with virus neutralization. The current study investigates co-administration of an H5 HA DNA vaccine with other variable and conserved influenza antigens (NA, NP, and M2). All antigens were derived from the A/Hanoi/30408/2005 (H5N1) virus and the contribution towards overall protection and immune activation was assessed against lethal homologous and heterologous challenges. An (HA. +. NA) combination afforded the best protection against homologous challenge and (HA. +. NP) was comparable to HA alone against heterologous A/Hong Kong/483/1997 challenge. Interestingly, combining all four H5 antigens at a single site did not improve protection against matched challenge and unexpectedly reduced survival by 30% against a heterologous challenge. Survival was also significantly decreased against heterologous challenge following combination of (HA. +. NP) with an unrelated antigen. Although there were no significant changes in antibody titres, significantly lower T-cell responses were detected against all antigens except HA in each combination. Co-administration of the vaccines at different injection sites restored T-cell responses but did not improve overall protection. Similar observations were also recorded following combination of HA and NP antigens using two different adenovirus-based backbones. Overall, the data suggest that co-administering certain H5N1 antigens offer better or comparable protection to HA alone, however, combining extra antigens may be unnecessary and lead to unfavourable immune responses.

Original languageEnglish (US)
Pages (from-to)626-636
Number of pages11
Issue number3
StatePublished - Jan 11 2012
Externally publishedYes


  • Antibody response
  • Antigen combination
  • Antigen competition
  • Cell-mediated response
  • DNA vaccine
  • H5N1 influenza
  • Multivalent vaccine

ASJC Scopus subject areas

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


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