This standardization was chosen to enable users to scan both types of records with a single script. The CDC uses an abbreviated description of passage level, based on the codes in the table below. We believe that it is preferable not to filter out low-complexity regions when comparing influenza sequences. Clicking on the gi number retrieves the corresponding database entry. The table of matches is followed by individual alignments of the query sequence against each one of the sequences in the table.
Fractional values are acceptable.
Furthermore, in some cases, sequences are masked in their entirety, indicating that the statistical significance of any matches reported against the unfiltered query sequence should be suspect. For more information on low complexity filtering, click here . As a service to the user of this web site, we provide links to sources of 2D and 3D structural information about hemagglutinin and neuraminidase. In addition, H. Tao, a member of the Influenza Database Team, has generated 3D displays of the hemagglutinin monomer and trimer, showing antigenic and receptor-binding sites. We provide a tool for viewing an alignment of protein sequences with each residue color-coded to represent either a chemical classification or a degree of hydrophobicity.