Establishment of a persistent infection by echovirus 6 in cloned human WISH cells (PI) was demonstrated. The cloned human WISH cells were maintained for 3.0 years (over 125 passages) and released virus continuously without cellular destruction. Neither temperature-sensitive virus mutants nor interferon appears to play a role in either establishment or maintenance of viral persistence. The majority of the virus produced by cloned human WISH cells is defective (2 X 10(6) particles per PFU) and differs from standard virus in its polypeptide profile and its inability to attach to parental WISH cells.
