Prior infection of pigs with a recent human H3N2 influenza virus confers minimal cross-protection against a European swine H3N2 virus
Article first published online: 28 MAR 2013
© 2013 John Wiley & Sons Ltd
Influenza and Other Respiratory Viruses
Volume 7, Issue 6, pages 1260–1268, November 2013
How to Cite
2013). Prior infection of pigs with a recent human H3N2 influenza virus confers minimal cross-protection against a European swine H3N2 virus. Influenza and Other Respiratory Viruses 7(6), 1260–1268.et al. (
- Issue published online: 5 NOV 2013
- Article first published online: 28 MAR 2013
- Manuscript Accepted: 21 FEB 2013
- Belgian Federal Public Service Health
- Food Chain Safety, and Environment. Grant Number: RT 09/6227
- European Commission. Grant Number: FP7-GA 258084
- H3N2 swine influenza virus;
- human H3N2 virus;
H3N2 influenza viruses circulating in humans and European pigs originate from the pandemic A/Hong Kong/68 virus. Because of slower antigenic drift in swine, the antigenic divergence between swine and human viruses has been increasing. It remains unknown to what extent this results in a reduced cross-protection between recent human and swine H3N2 influenza viruses.
We examined whether prior infection of pigs with an old [A/Victoria/3/75 (A/Vic/75)] or a more recent [A/Wisconsin/67/05 (A/Wis/05)] human H3N2 virus protected against a European swine H3N2 virus [sw/Gent/172/08 (sw/Gent/08)]. Genetic and antigenic relationships between sw/Gent/08 and a selection of human H3N2 viruses were also assessed.
After challenge with sw/Gent/08, all challenge controls had high virus titers in the entire respiratory tract at 3 days post-challenge and nasal virus excretion for 5–6 days. Prior infection with sw/Gent/08 or A/Vic/75 offered complete virological protection against challenge. Pigs previously inoculated with A/Wis/05 showed similar virus titers in the respiratory tract as challenge controls, but the mean duration of nasal shedding was 1·3 days shorter. Unlike sw/Gent/08- and A/Vic/75-inoculated pigs, A/Wis/05-inoculated pigs lacked cross-reactive neutralizing antibodies against sw/Gent/08 before challenge, but they showed a more rapid antibody response to sw/Gent/08 than challenge controls after challenge. Cross-protection and serological responses correlated with genetic and antigenic differences.
Infection immunity to a recent human H3N2 virus confers minimal cross-protection against a European swine H3N2 virus. We discuss our findings with regard to the recent zoonotic infections of humans in the United States with a swine-origin H3N2 variant virus.