journey of the avian influenza virus H5N1 through 30 years of evolutionary events, geographical locations, and animal species

Influenza viruses have caused outbreaks and pandemics throughout human history and have until Covid-19 been considered the group of viruses with the largest potential for pandemics. Avian influenza viruses cause zoonotic diseases, including birds, mammals, and humans. This review focuses on H5N1 because it is highly pathogenic and generated the most common clades among the current ones (e.g. 2.3.4.4). Since the first goose that was infected in Guangdong, China by A/Goose/Guangdong/1/96 (H5N1) in 1996, H5N1 has undergone many events of reassortment with other influenza viruses and accumulated many amino acid substitutions on the 10 proteins that are encoded by the H5N1 genome. The review will follow H5N1 through examples of such evolutionary events that permitted the virus to spread across the world, as well as through many animal species. Hallmark mutations that permit or prevent the selective binding to receptors on bird or mammal host cells will be identified. The journey through the NorthAtlantic fly way from Europe to North and South America, culminating in the first reported death from H5N1 in the United States will be explained. The review concludes with the current state of vaccines and anti-virals and an assessment by the author of the current situation.