Receptor Binding Specificity of a Bovine A(H5N1) Influenza Virus

Abstract

Outbreaks in the US of highly pathogenic avian influenza virus (H5N1) in dairy cows have been occurring for months creating new possibilities for direct contact between the virus and humans. Eisfeld et al. examined the pathogenicity and transmissibility of a bovine HPAI H5N1 virus isolated from New Mexico in a series of in vitro and in vivo assays. They found the virus has a dual human- and avian virus-like receptor-binding specificity as measured in a solid phase glycan binding assay. Here, we examined the receptor specificity of a bovine HPAI H5N1 virus (A/bovine/OH/B24OSU-432/2024, H5N1, clade 2.3.4.4b) employing four different assays including glycan array technology, bio-layer interferometry (BLI), a solid phase capture assay and hemagglutination of glycan remodeled erythrocytes. As controls, well characterized avian (A/Vietnam/1203/2004, H5N1, clade 1) and human (A/CA/04/2009, H1N1) IAVs were included that bind α2,3- and α2,6-sialosides, respectively. We found that A/bovine/OH/B24OSU-432/2024 preferentially binds to "avian type" receptors (α2,3-sialosides). Furthermore, sequence alignments showed that A/bovine has maintained amino acids in its HA associated with α2,3-sialoside (avian) receptor specificity. We conclude that while we find no evidence that A/bovine has acquired human virus receptor binding specificity, ongoing efforts must be placed on monitoring for this trait.

Fig. 1.. Receptor binding specificity of bovine H5N1.

(a) Structures of glycans printed on the microarray. All N-glycans (A-X) have an α-amine at the reducing end asparagine moiety and O-glycans (1-5) have a N-terminal α-amine. (b) Glycan array binding analysis of the receptor binding specificities of H5N1 and H1N1 viruses. The fluorescence signals for each glycan are presented as mean ± SD (n = 4). (c) Bio-layer interferometry (BLI) sensorgrams demonstrating the sialic acid linkage-specificity of H5N1 and H1N1 viruses. Virus binding (association, in the presence of Oseltamivir,) and virus elution (dissociation, in the absence of Oseltamivir, gray highlighted) are shown. Representative data of at least two replicate experiments are shown.