Comparison of the virologic and immunologic responses of volunteers to live avian-human influenza A H3N2 reassortant virus vaccines derived from two different avian influenza virus donors

We compared the abilities of the six internal RNA segments of two avian influenza viruses, A/Mallard/Alberta/88/76 (H3N8) and A/Mallard/NY/6750/78 (H2N2), to confer attenuation on wild-type human influenza A/Bethesda/1/85 (H3N2) virus in seronegative adult volunteers. Live avian-human influenza A reassortant virus vaccines derived from either avian virus parent were comparable in the following properties: safety, infectivity, immunogenicity, and genetic stability. Since the avian influenza A/Mallard/Alberta/76 virus offered no clear advantage as a donor virus, we will conduct our future evaluations on live influenza A virus reassortants derived from the more extensively characterized avian influenza A/Mallard/NY/78 virus.