Adaptation of Marek's disease virus to the Vero continuous cell line

Marek's disease virus (MDV) is a highly infectious, cell-associated oncogen ic herpesvirus. Production of MD vaccines has been limited to primary chick en and duck embryo fibroblast (CEF and DEF) cultures. These have a limited life span and cannot be readily stored in liquid nitrogen. Moreover, the ne ed to prepare CEF and DEF cells on a regular basis from 10 to 11 day-old em bryos derived from a flock that must be tested continuously for the presenc e of avian pathogens adds to the cost of vaccine production. A continuous c ell line that would support MDV replication could have significant advantag es for the rapid large-scale preparation of MD vaccines. In this report, we describe the adaptation to growth of CEF-grown preparations of serotype 1 and serotype 3 (herpesvirus of turkeys; HVT) strains of MDV in cells of the Vero continuous cell line. Although both viruses produced typical CPE, hig her levels of infectious progeny and more extensive virus-specific immunofl uorescence were obtained for HVT than for the serotype 1 virus. PCR and pul sed field electrophoresis (PFE) analysis of the DNA from Vero cells infecte d with either virus confirmed the presence of virus-specific DNA. (C) 2001 Elsevier Science B.V. All rights reserved.