Submitted to: American Veterinary Medical Association Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 19, 1997
Publication Date: N/A
Technical Abstract: Attenuation of serotype 1 Marek's disease viruses (MDVs) at early passage levels is desirable to preserve antigenicity. Expansion of the 132 base pair repeat (bpr) region is a mutation induced during serial passage in cell culture that has been considered a marker for attenuation. In the present study, primers designed to amplify this region were used in PCR assays to identify mutant clones at early passage levels of two recent MDV isolates. Clones with altered phenotypes at 20-40 passages all retained virulence when tested by in vivo challenge. We conclude this technique offers no advantage over simple serial passage in deriving attenuated clones and that the linkage between 132 bpr expansion and attenuation is not absolute.