When A. albopictus, clone C6/36, cells were infected with chikungunya (CHIK) virus, high virus yield accompanied by a cytopathic effect in the acute stage of infection was followed by a relatively low yield of virus over a long period of time. Virus produced from persistently infected cultures became gradually of smaller plaque size and more temperature-sensitive; however, such virus still retained pathogenicity for suckling mice even after one year of infection. When the persistently infected cells were subcultured, a dissociation was observed between the time course of cell growth and that of virus production, suggesting some intracellular mechanisms that turn off virus production. The greater part of the interference against CHIK virus by the culture medium of the persistently infected cells appeared to be mediated by the infective virus in the medium. The infective virus was easily removed from the persistently infected cells either by subculture or by cloning in the presence of anti-CHIK serum, yielding cured cultures or virus-negative clones.