Nucleotide and deduced amino acid sequence of the influenza neuraminidase genes of two equine serotypes.

This research article is an analysis of the neuraminidase (NA) genes which affect equine influenza, finding similarities between these genes and previously observed subtypes, particularly in relation to the enzyme active site of the NA molecule.

Nucleotide Sequence of Two Equine Serotypes

• This research has successfully sequenced the complete neuraminidase (NA) genes of two serotype viruses, EIV-A1 and EIV-A2, which cause equine influenza.
• The NA genes were cloned into pBR322, a very common plasmid (DNA molecule) often used in cloning procedures.

Comparison to Previous Neuraminidase Subtypes

• Through comparison of the deduced amino acid sequences, the N7 and N8 genes of the EIV-A1 and EIV-A2 serotypes showed significant homology (similarity in sequence) with the previously sequenced subtypes N1, N2, and N9.
• This homology can be seen in the basic structure of the gene and protein, conservation of cysteine residues (amino acids), potential glycosylation sites (where a sugar molecule is added to a protein), and the active site of the NA molecule (the region where the enzyme functions).

Relationship Between Neuraminidase Molecules

• The study also shed light on how different NA molecules are related. The N1 and N8 molecules seem to be more closely related in terms of their total amino acid sequences than any other two subtypes. Similarly, the N7 and N9 molecules show high homology.
• This area of homology is especially strong in the region of residues 100-205, equivalent to the amino terminal one-third of the “head” of the NA protein. The “head” region of the NA molecule is a key area for its functionality, so this homology suggests similar behaviors between these subtypes.