Prof Peter Palese's group has been busy publishing several papers in the Journal of Virology. One report describes the creation of cross-reactive antibodies to H7N9 by making Newcastle disease virus (NDV; a very contagious bird virus that has already been established as a poultry vaccine backbone) produce the H7 haemagglutinin from North American birds (H7N1-3).
They did this by inserting a representative H7 protein coding sequence in between normal NDV genes. The serum collected from mice immunized with this recombinant virus could block a range of H7-containing influenza A viruses. A new vaccine candidate in the making.