Tropism and innate host response of the 2009 pandemic H1N1 influenza virus compared with related swine influenza viruses and reassortants in ex vivo and in vitro cultures of the human respiratory tract and conjunctiva

Abstract

BACKGROUND: Pandemic influenza H1N1 (H1N1pdm) virus of swine-origin causes mild disease, but occasionally is associated with acute respiratory distress syndrome and death.1,2 It is important to understand the pathogenesis of this new disease. Previously we showed a comparable virus tropism and host innate immune responses between H1N1pdm and seasonal H1N1 influenza virus in the human respiratory tract,3 however H1N1pdm virus differed from seasonal H1N1 influenza virus in its ability to replicate in human conjunctiva, suggesting subtle differences in receptor-binding profile and highlighting the potential role of the conjunctiva as an additional route of infection. We now compare the tropism and host responses elicited by pandemic H1N1 with that of related swine influenza viruses and a pandemic-swine reassortant virus in ex vivo and in vitro cultures of the human respiratory tract and conjunctiva. We have used recombinant virus to investigate the role of the hemagglutinin (HA) and neuraminidase (NA) of H1N1pdm virus in its conjunctival tropism. These findings are relevant for understanding transmission and therapy …