Two clade 2.3.4.4b H5N1 viruses formed reassortants with human influenza A in vitro: 20 of 2,698 clones
In cell culture, reassortants formed with human H1N1 and H3N2 viruses, but rarely. Polymerase compatibility alone does not appear to explain their recovery.
Researchers reported in Proceedings of the National Academy of Sciences that two contemporary clade 2.3.4.4b H5N1 viruses can exchange genome segments with human-adapted influenza A viruses (IAV) in cell culture pnas.org
Proceedings of the National Academy of Sciencespnas.orgOpen source ↗. They used a biosafe reassortment system and coinfected cells with human H1N1 and H3N2 viruses under several conditions.
The authors genotyped 2,698 plaque-purified viral clones and recovered 20 reassortants, or 0.74%.
Polymerase assays showed that some human IAV subunits, particularly H1N1 PA or H3N2 PB2, increased H5N1 polymerase activity. The authors conclude that factors beyond polymerase compatibility may limit recovery of reassortants. All experiments were performed in vitro.
