Pandemic swine-origin H1N1 influenza A virus isolates show heterogeneous virulence in macaques

David Safronetz, Barry Rockx, Friederike Feldmann, Sarah E. Belisle, Robert E. Palermo, Douglas Brining, Don Gardner, Sean C. Proll, Andrea Marzi, Yoshimi Tsuda, Rachel A. LaCasse, Lisa Kercher, Anthony York, Marcus J. Korth, Dan Long, Rebecca Rosenke, W. Lesley Shupert, Celia Alpuche Aranda, John S. Mattoon, Darwyn KobasaGary Kobinger, Yan Li, Jeffery K. Taubenberger, Jürgen A. Richt, Michael Parnell, Hideki Ebihara, Yoshihiro Kawaoka, Michael G. Katze, Heinz Feldmann

Research output: Contribution to journalArticlepeer-review

84 Scopus citations


The first influenza pandemic of the new millennium was caused by a newly emerged swine-origin influenza virus (SOIV) (H1N1). This new virus is characterized by a previously unknown constellation of gene segments derived from North American and Eurasian swine lineages and the absence of common markers predictive of human adaptation. Overall, human infections appeared to be mild, but an alarming number of young individuals presented with symptoms atypical for seasonal influenza. The new SOIV also showed a sustained human-to-human transmissibility and higher reproduction ratio than common seasonal viruses, altogether indicating a higher pathogenic potential for this newly emerged virus. To study the virulence of the SOIV, we used a recently established cynomolgus macaque model and compared parameters of clinical disease, virology, host responses, and pathology/histopathology with a current seasonal H1N1 virus. We here show that infection of macaques with two genetically similar but clinically distinct SOIV isolates from the early stage of the pandemic (A/Mexico/4108/2009 and A/Mexico/InDRE4487/2009) resulted in upper and lower respiratory tract infections and clinical disease ranging from mild to severe pneumonia that was clearly advanced over the mild infection caused by A/Kawasaki/UTK-4/2009, a current seasonal strain. Unexpectedly, we observed heterogeneity among the two SOIV isolates in virus replication, host transcriptional and cytokine responses, and disease progression, demonstrating a higher pathogenic potential for A/Mexico/InDRE4487/2009. Differences in virulence may explain more severe disease, as was seen with certain individuals infected with the emerged pandemic influenza virus. Thus, the nonhuman primate model closely mimics influenza in humans.

Original languageEnglish (US)
Pages (from-to)1214-1223
Number of pages10
JournalJournal of virology
Issue number3
StatePublished - Feb 2011
Externally publishedYes

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Insect Science
  • Virology


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