Genetic characterisation of an influenza A virus of unusual subtype (H1N7) isolated from pigs in England

An H1N7 influenza A virus, isolated from pigs in England in 1992, was examined genetically to determine the characteristics and probable origin of the eight gene segments. Six of the RNA segments encoding PB2, PB1, PA, HA, NP and NS were related most closely to those of human viruses, whilst two of the RNA segments (NA and M) were related most closely to those of equine viruses. The HA gene was most similar to that of A/USSR/90/77 (H1N1) but amino acid differences suggested independent genetic drift. In contrast, there were relatively few changes in the NA and M genes compared to those of A/equine/Prague/1/56 (H7N7).