Clinical presentation and sequence analyses of HA and NA antigens of the novel H7N9 viruses

Recently, a novel H7N9 avian influenza A virus has led to a human influenza outbreak in China. Here we report a 64-year old man with possible history of chronic bronchitis died from the H7N9 infection in Huzhou City, Zhejiang Province in Eastern China. The patient had been exposed to poultry before disease onset. Phylogenetic analyses of hemagglutinin and neuraminidase genes showed a close genetic relationship between viruses from the patient and from poultry booths where he had visited, indicating that the patient may have been exposed from the infected poultry. Two poultry venders and close contacts of the patient were negative for H7N9, suggesting that there are some unknown mechanisms to prevent them from being infected by the novel H7N9 virus. Furthermore, we found five novel H7N9 virus-specific sequence variations in receptor-binding site of hemagglutinin, which may be associated with the acquisition of the ability to infect humans.