Nucleic acid-based analyses of non-group A rotaviruses.

Simple genome profile studies on polyacrylamide gels allow all non-group A rotaviruses isolated so far to be recognized by the absence of the tight triplet (7-9) of RNA segments seen in all group A viruses. However, reliance solely on genome profile studies for rotavirus grouping can be misleading and, for virus group definition, additional corroborating nucleic acid and serological studies are essential. Terminal fingerprint analysis was the first generation of nucleic acid-based assays that allowed discrimination between the various rotavirus groups. By means of this technique the clear definition of five rotavirus groups (A-E), correlating exactly with those found by a serological assay, has been possible, with preliminary evidence for at least two additional groups. The technical sophistication of fingerprinting techniques prevents their widespread use in epidemiological studies; the development of a second generation of nucleic acid-based assays is therefore under way. These employ molecularly cloned cDNA probes to the genomes of non-group A viruses which can be widely distributed for use in 'dot-blot' screening of faecal samples and, if expressed as protein in Escherichia coli, should provide a ready source of viral antigen for use in surveying viral prevalence through the screening of serum antibody levels.