Growth of avian and human influenza viruses in organ cultures of duck and chicken colons.

Colons from ducks and chicken 1, 7, 14 and 28 days old maintained near-normal morphology up to 48 and 96 hours respectively in a system using NCTC135 medium (a part) + Dulbecco's modified Eagle's medium (9 parts ), at 37 degrees C and 95 per cent O2/5 per cent CO2. In the colon of 1 and 28 day-old ducks, duck influenza virus (Hav7N2) and budgerigar influenza virus (Hav4Nav1) grew to peak titer by hour 72, whereas human influenza virus (H3N2) did not grow. In the colon of 1 day-old chicken, the three viruses grew in the order of first duck virus, then budgerigar virus and then human virus, but in the colon of 28 day-old chicken, the growth of human virus was much less. Specific fluorescence was demonstrated in the mucosal epithelium of the colon of ducks and chicken, and intensity of fluorescence correlated with virus yield. THe fact that the avian and not the human influenza viruses showed good growth in the duck colons coincided with the fact that influenza viruses possessing avian hemagglutinin subtypes have frequently been isolated in nature from duck intestines.