Identification of two regions within the subtype A avian metapneumovirus fusion protein (amino acids 211–310 and 336–479) recognized by neutralizing antibodies

The fusion (F) protein of a subtype A AMPV was expressed in sections in Escherichia coli. Six genome sections were selected which encoded the majority of the protein. These were cloned then expressed from a His tag expression plasmid and, following purification on nickel columns, identities were confirmed by Western blot analysis. The interactions of each fragment with AMPV neutralizing antisera were determined. Purified fragments were mixed with AMPV sera raised against A–C subtypes by a natural route, in order to determine any reduction in their neutralizing capacities. Two fragments covering regions of the F ectodomain reduced neutralizing capacities of both subtype A and B antisera to a highly significant degree (p < 0.001) while no effects were seen with subtype C antiserum. Previous studies of similar viruses had identified neutralization as being associated with equivalent F regions. Findings are likely to be useful in guiding future vaccine design.