Concerns

The concerns regarding D225G and D225N began to increase whensequences were released from fatal cases in Sao Paulo Brazil. These samples were collected in July, when the flu season in the southern hemisphere was peaking. Two lung samples were positive for D225G, while a lung and throat sample were positive for D225N.

There already was interest in position 225 for a number of reasons. D225N was in seasonal H3N2 and linked to the fixing of adamantine resistance (S31N), while D225G was in 1918 and 1919 samples and linked to a change in receptor binding domain specificities which would target subsets of cells in the lung. In addition, the polymorphism was jumping from one genetic background to another signaling recombination and increased chances that the polymorphisms would continue to jump to new genetic backgrounds.