FIG 1.

53C10 neutralizes multiple H1 clades of influenza A virus. (A) Monoclonal antibody 53C10 recognizes HAs from the alpha clade and pdm09 clade. The baculovirus-expressed HAs of A/California/04/2009 and A/Iowa/15/1930 were subjected to ELISA with monoclonal antibody 53C10. 53C10 was 2-fold serially diluted. The baculovirus-expressed HA of strain B/Florida/4/2006 was used as negative control. (B) Neutralization activity of 53C10 against representative strains from different clades of H1 viruses. The online swine H1 clade classification tool (https://www.fludb.org) was employed to classify the virus strains. (C) Phylogenetic analysis of the H1 representative stains by maximum likelihood method in MEGA X. The phylogenetic tree with the highest log likelihood (−9917.90) was generated in the Jones-Taylor-Thornton (JTT) model with a bootstrapping of 1,000 replicates using the global swine H1 clade classification reference sequences (27). In the phylogenetic tree, strain name, isolated species and country, subtype, and H1 clade are shown. The H1 clades are labeled as alpha, beta, delta1, delta2, delta like, gamma, gamma2, alpha beta gamma2 like, gamma2 beta like, other, pdm09 (npdm), NA (not applicable), and ND (not determined) (www.fludb.org).