Effects of bacterial microflora of the lower digestive tract of free-range waterfowl on influenza virus activation

Marcus D. King, M. Neal Guentze, Bernard P. Arulanandam, Adria A. Bodour, Vinayak Brahmakshatriya, Blanca Lupiani, James P. Chambers

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Proteolytic cleavage activation of influenza virus hemagglutinin (HA0) is required for cell entry via receptormediated endocytosis. Despite numerous studies describing bacterial protease-mediated influenza A viral activation in mammals, very little is known about the role of intestinal bacterial flora of birds in hemagglutinin cleavage/activation. Therefore, the cloaca of wild waterfowl was examined for (i) representative bacterial types and (ii) their ability to cleave in a "trypsin-like" manner the precursor viral hemagglutinin molecule (HA0). Using radiolabeled HA0, bacterial secretion-mediated trypsin-like conversion of HA0 to HA1 and HA2 peptide products was observed to various degrees in 42 of 44 bacterial isolates suggestive of influenza virus activation in the cloaca of wild waterfowl. However, treatment of uncleaved virus with all bacterial isolates gave rise to substantially reduced emergent virus progeny compared with what was expected. Examination of two isolates exhibiting pronounced trypsin-like conversion of HA0 to HA1 and HA2 peptide products and low infectivity revealed lipase activity to be present. Because influenza virus possesses a complex lipid envelope, the presence of lipid hydrolase activity could in part account for the observed less-than-expected level of viable progeny. A thorough characterization of respective isolate protease HA0 hydrolysis products as well as other resident activities (i.e., lipase) is ongoing such that the role of these respective contributors in virus activation/ inactivation can be firmly established.

Original languageEnglish (US)
Pages (from-to)4119-4125
Number of pages7
JournalApplied and Environmental Microbiology
Volume77
Issue number12
DOIs
StatePublished - Jun 2011
Externally publishedYes

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

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