A PERSISTENT INFECTION IN MDCK CELLS BY AN INFLUENZA TYPE-B VIRUS

A persistent infection in Madin Darby Canine Kidney (MDCK) cells by an influenza B virus (B/Tecumseh/63/80) has been established and charact erized. Virus recovered from the persistent state titrated lower in re lation to the parental wild-type (wt) that initiated the infection as measured by hemagglutination and egg and tissue culture infectious dos e, suggesting that the virus is a less cytopathic variant of the origi nal wt virus. The persistent virus (pv) has decreased cytopathology fo r both MDCK and primary chick kidney (PCK) cell lines, and exhibits di fferent RNA and protein electrophoretic migrations. Plaques of the per sistent virus are smaller and take longer to appear, indicating that t he pv is a slower growing variant of the wt. The small plaque mutant p henotype may play a role in the maintenance of the persistent infectio n in MDCK cells. The pv differs from the wt antigenically and in its a bility to form deposits of uric acid-like crystals beneath the culture monolayers.