Saturday, September 14, 2013

H7N9 studies flesh out infectivity patterns in humans, pigs

[editing is mine]
Lisa Schnirring | Staff Writer | CIDRAP News  |
Sep 13, 2013
Researchers looking for molecular clues to help global health officials assess the risk from the new H7N9 virus in China reported this week that it is adept at attaching to human lower and upper respiratory tract cells and that it replicates efficiently in swine airway tissues.
In the first study, researchers from Erasmus University Medical Centre in the Netherlands explored airway attachment patterns of two genetically engineered H7 viruses that contained the hemagglutinin of either a Shanghai or Anhui H7N9 strain. They published their findings yesterday in the October issue of the American Journal of Pathology, published by Elsevier.

They used histochemical analysis to examine the patterns of attachment to different types of human airway tissues, and they compared patterns with those seen in other flu viruses that infect humans to different degrees, including H3N2, 2009 H1N1, and H5N1.

Similar to other avian influenza viruses, H7N9 attached more strongly to tissues in the lower than the upper airway, the authors found. But unlike other avian flu viruses, H7N9 had abundant attachments to epithelial cells in the bronchioles and alveoli and attached to a broader range of cell types.

Thijs Kuiken, DVM, PhD, said in an Elsevier press release, “These characteristics fit with increased virulence of these emerging avian H7 viruses compared to that of human influenza viruses.”

Another key finding from the experiments was more concentrated attachment of H7N9 viruses in ciliated cells in the nasal concha, trachea, and bronchi, which hint at the potential for efficient transmission in humans. However, Kuiken said the mainly sporadic pattern of H7N9 infections suggests that the virus hasn’t acquired all the properties it needs for efficient transmission among humans.



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