Abstract Title
Receptor binding evolution of A(H5) viruses
Abstract
Since its emergence in 1996, the A/goose/Guangdong/1/1996 lineage of A(H5N1) has spread globally. This widespread distribution has led to increased diversity among A(H5) viruses, including the establishment of local endemic clades in some regions. Most recently, the emergence of the 2.3.4.4b clade has resulted in a panzootic, leading to increased detections of A(H5) globally. Unlike previous epizootics, the emergent clade has led to mass mortality events in wild birds and mammals, including sporadic human infections. Why the emergent 2.3.4.4b has led to a panzootic, whereas previous clades have not, is poorly understood. We aimed to investigate whether this apparent fitness advantage may be at least partially due to changes to haemagglutinin receptor binding characteristics.
We selected contemporary A(H5) influenza viruses, representative of currently circulating HA clades (2.3.4.4b, 2.3.2.1a, and 2.3.2.1c), to assess wildtype, whole-virus avidity by biolayer interferometry. In addition to the contemporary influenza viruses, we selected historical A(H5N1) viruses (clades 1 and 2.2) representing significant ancestors of the contemporary clades.
Viruses were grown in cell culture and purified by centrifugation. Biotinylated sialic acid receptor analogues with either a2,3 or a2,6 linkages, were used to determine association kinetics using the Octet platform. Association curves were fitted using in-house software (Blivion) to determine virus avidity.
Preliminary data have indicated an isolate A(H5N1) of clade 2.3.4.4b showed improved binding to a2,3-linked sialic acid compared to that of a clade 2.3.2.1c virus isolated from a human in Cambodia. Neither showed binding to a2,6-linked sialic acid. Studies of the remaining viruses is ongoing.
We selected contemporary A(H5) influenza viruses, representative of currently circulating HA clades (2.3.4.4b, 2.3.2.1a, and 2.3.2.1c), to assess wildtype, whole-virus avidity by biolayer interferometry. In addition to the contemporary influenza viruses, we selected historical A(H5N1) viruses (clades 1 and 2.2) representing significant ancestors of the contemporary clades.
Viruses were grown in cell culture and purified by centrifugation. Biotinylated sialic acid receptor analogues with either a2,3 or a2,6 linkages, were used to determine association kinetics using the Octet platform. Association curves were fitted using in-house software (Blivion) to determine virus avidity.
Preliminary data have indicated an isolate A(H5N1) of clade 2.3.4.4b showed improved binding to a2,3-linked sialic acid compared to that of a clade 2.3.2.1c virus isolated from a human in Cambodia. Neither showed binding to a2,6-linked sialic acid. Studies of the remaining viruses is ongoing.
Co-Author(s)
Lorin Adams1,2; Simone Kunzelmann1; Antoni G. Wrobel1; John Skehel1; Steven Gamblin1; Nicola S. Lewis1,2
1. The Francis Crick Institute, London, UK
2. Royal Veterinary College, London, UK
Abstract Category
Avian influenza in mammals, pandemic preparedness, and one health