Serological and virological investigations fo orthomyxovirus in birds in South-East Asian area.

We have previously reported that some species of migrating ducks (pintail, mallard, widgeon and falcated teal) possess in their sera antibodies against H antigens of human or avian influenza viruses. Such findings have also been reported from other workers, and the appearance of new types of influenza viruses accompanied by outbreaks of new influenza pandemics, or circulation of influenza virus antigens in animals, birds and humans have been discussed on the basis of such findings. Recently a number of orthomyxoviruses have been isolated from wild birds such as myna, banded parakeets, etc. imported from India and some areas of South-East Asia. Some of them have H antigens not recognized previously, and some are found to have more or less common reactions with human H3 antigen, and consequently antigens Hav 7 and Heq 2, which are known to show cross-reaction with H3. The significance of such a fact in connection with the appearance of a new influenza pandemic is discussed.