[cRNA probes (riboprobes) synthesized in vitro for detecting enterovirus by molecular hybridization]

Radioactively labelled RNA transcripts made in vitro of various fragments from cDNA clones of poliovirus type 1 and of hepatitis A virus under the control of bacteriophage T7 or SP6 promoters have been evaluated for diagnostic purposes. The RNA transcripts were 2 orders of magnitude more sensitive as hybridization probes than corresponding cDNA preparations labelled by the nick translation procedure. A combination of hybridization analysis and sequence comparison showed that some regions of the genome of a number of enteroviruses are highly conserved, while others show very little homology; the general order of conservation is: 5'-non-coding greater than 3'-terminal greater than central (2C) greater than VP3 greater than VP1. The 350 bases of the poliovirus VP1 region were highly specific for that virus, while the 450-bases of the 5'NC region showed extensive cross-reaction with other enteroviruses. However, these probes did not hybridize with HAV, which was detected only by HAV-specific riboprobes. The transcripts have been successfully applied as hybridization probes in diagnostic tests on supernatants of infected cell culture lysates and in clinical samples, mainly in stool extracts.