Studies of a recombinant which inherited the haemagglutinin from the human influenza virus A/Hong Kong/1/68 (H3n2) and other genes from influenza virus A/duck/Ukraine/1/63 (H3N8).

A recombinant (R3/3) has been obtained which inherited the gene coding for the haemagglutinin from human influenza virus A/Hong Kong/1/68 (H3N2), and seven other genes from influenza virus A/duck/Ukraine/1/63 (H3N8). The recombinant R3/3 had properties, a ts+ phenotype and a capability of reproducing in chick embryos, similar to those of the duck influenza virus, but, in contrast to this parent, had lost its ability to reproduce in organ cultures of colon of ducks and chickens as well as in monolayer cultures of chick embryo fibroblasts.