The intestine of ferret--a possible site of influenza virus replication.

Anal virus shedding and stimulation of the immune response were observed in ferrets after oral and rectal administration of influenza A/Hongkong/1/68 (H3N2) virus. Despite of the low pH in the stomach, the virus had reached the intestines after oral administration and was found in high concentration in faeces and in mucosal cells lining the colon. Using immunofluorescent staining, the virus antigen was detected in cytoplasm of columnar epithelial cells. Virus replication also occurred in the respiratory tract, probably as result of inhalation of anally shedded virus. However, the virus replication in the lungs did not seem essential for virus isolation from the intestines. Taking into account the very short food passage time in ferrets the results could indicate the replication of influenza A/Hongkong/1/68 virus in the digestive tract of ferrets.