• Decrease font size
  • Return font size to normal
  • Increase font size
U.S. Department of Health and Human Services

Scientific Publications by FDA Staff

  • Print
  • Share
  • E-mail

Search Publications



Starting Date

Ending Date

Order by

Entry Details

Virol J 2011 May 21;8:251

Intramuscular immunization of mice with live influenza virus is more immunogenic and offers greater protection than immunization with inactivated virus.

Harris K, Ream R, Gao J, Eichelberger MC


BACKGROUND: Influenza virus continues to cause significant hospitalization rates in infants and young children. A 2-dose regime of trivalent inactivated vaccine is required to generate protective levels of hemagglutination inhibiting (HAI) antibodies. A vaccine preparation with enhanced immunogenicity is therefore desirable. METHODS: Mice were inoculated intramuscularly (IM) with live and inactivated preparations of A/Wisconsin/67/2005 (H3N2). Serum cytokine levels, hemagglutinin (HA)-specific antibody responses and nucleoprotein (NP)-specific CD8+ T cell responses were compared between vaccinated groups, as well as to responses measured after intranasal infection. The protective efficacy of each vaccine type was compared by measuring virus titers in the lungs and weight loss of mice challenged intranasally with a heterosubtypic virus, A/PR/8/34 (H1N1). RESULTS: Intramuscular administration of live virus resulted in greater amounts of IFN-¿, IL-12 and IFN-¿, HA-specific antibodies, and virus-specific CD8+ T cells, than IM immunization with inactivated virus. These increases corresponded with the live virus vaccinated group having significantly less weight loss and less virus in the lungs on day 7 following challenge with a sublethal dose of a heterosubtypic virus. CONCLUSIONS: Inflammatory cytokines, antibody titers to HA and CD8+ T cell responses were greater to live than inactivated virus delivered IM. These increased responses correlated with greater protection against heterosubtypic virus challenge, suggesting that intramuscular immunization with live influenza virus may be a practical means to increase vaccine immunogenicity and to broaden protection in pediatric populations.

Category: Journal Article
PubMed ID: #21600020 DOI: 10.1186/1743-422X-8-251
PubMed Central ID: #PMC3123286
Includes FDA Authors from Scientific Area(s): Biologics
Entry Created: 2011-10-03 Entry Last Modified: 2012-08-29