Bovine H5N1 binds poorly to human-type sialic acid receptors

Highly pathogenic H5N1 avian influenza (HPAI) viruses started circulating in lactating dairy cattle in the USA at the end of 2023 (ref. 1) and these viruses are now rapidly spreading between cows2. Eisfeld et al.3 found that a clade 2.3.4.4b H5N1 virus from this cattle outbreak can bind to α2,6-linked sialyl-glycopolymers on microtitre plates. Here we show that the haemagglutinin from a clade 2.3.4.4b H5N1 virus binds poorly to glycans that terminate with α2-6 sialic acids. 

This is an important finding, as α2,6 sialic acid is abundant in the upper respiratory tract of humans, and acquisition of α2,6 sialic acid receptor specificity is believed to be required for efficient transmission of influenza virus in humans and is considered a risk factor for the emergence of a new pandemic virus4.