Chicken anemia virus strains with a mutated enhancer/promoter region sharereduced virus spread and cytopathogenicity

Plasmid pCAV/E contains an infectious cloned double-stranded CAV (chicken a nemia virus) DNA genome (Noteborn et al., J. Virol. 65 (1991) 3131-3139). W e have constructed mutated CAV genomes by introducing mutations into the CA V promoter/enhancer region of pCAV/E. Various mutated CAV strains were func tional and had a smaller cytopathogenic effect in chicken T cells than wild -type CAV. In particular, mutations within the '12-bp insert' of the promot er/enhancer region had this effect. PCR and sequence analysis showed that t he CAV mutants were stable under cell-culture conditions. Southern-blot ana lysis showed that all replication DNA intermediates were normally formed by the CAV mutants. All viable mutant CAV strains were able to produce a neut ralizing conformational epitope, which implies that they can trigger the re quired protective immune response. These features make these mutant CAV str ains potential candidates for the development of an attenuated CAV vaccine. (C) 1998 Elsevier Science B.V. All rights reserved.