Abstract
A total of 212 arbovirus serotypes, representing 29 arbovirus serogroups, were screened for their plaque-forming ability and titrated in two continuous simian kidney cell lines (VERO and LLC-MK2). Plaquing data were obtained with 205 viruses in either one or both of these cell lines; seven viruses failed to plaque in either line. Both cell lines were susceptible to 169 arbovirus serotypes. Seventeen viruses failed to plaque in VERO and 18 in LLC-MK2. Plaques appeared as early as 2 days, and as late as 18 days (Triniti virus in VERO) Plaque diameters ranged from 1 to 28 mm. during a 24-day observation period.