Detection of beet necrotic yellow vein virus strains, variants and mixed infections by examining single-strand conformation polymorphisms of immunocapture RT-PCR products.

Single-strand conformation polymorphism analysis was found to be a powerful tool for rapidly assigning large numbers of beet necrotic yellow vein virus (BNYVV) isolates to a known strain group as well as for detecting mixed infections, minor variants or new strain groups. The prevalence of the B-type in Germany and France and the A-type in most other countries was confirmed. Minor variants with a very restricted distribution were detected occasionally. New rhizomania outbreaks in Great Britain were caused either by the A- or B-type or mixtures of both suggesting introduction of BNYVV from several sites abroad. An entirely different BNYVV type (P-type) was identified in a small area in France. Evidence for further strain groups in China was also obtained.