Prospects for a sequence-based taxonomy of influenza A virus subtypes

Area of Science:

• Virology
• Genomics
• Bioinformatics

Background:

• Influenza A virus (IAV) infections are classified into subtypes based on Hemagglutinin (HA) and Neuraminidase (NA) proteins.
• Traditionally, subtypes were defined by antibody cross-reactivity, but genetic sequencing is now crucial for characterizing IAV diversity.

Purpose of the Study:

• To determine if serologically defined influenza A virus subtypes can be reproduced using sequence-based criteria.
• To establish a robust genetic taxonomy for HA and NA subtypes.

Main Methods:

• Comparative analysis of over 1.1 million IAV protein sequences from Genbank, reduced to 272,292 unique sequences.
• Phylogenetic reconstruction and partitioning based on the longest internal branches to cluster HA and NA subtypes.

Main Results:

• A robust genetic taxonomy for HA and NA subtypes was successfully obtained using a simple clustering method.
• The genetic taxonomy requires amendments to current nomenclature, including separating two bat IAV isolates into their own subtype.
• Phylogenies of other genomic segments generally do not support major subtype partitions, except for small, divergent lineages.

Conclusions:

• Genetic sequencing provides a reliable method for classifying influenza A virus subtypes.
• A revised, sequence-based nomenclature is proposed to improve the accuracy of IAV classification.
• Further research may be needed to refine the classification of IAV genomic segments.