AbstractSubgenomic fragments of cDNA from poliovirus type 1 were inserted downstream from the SP6 or the T7 promoter in a Gemini riboprobe vector and their in vitro synthesized RNA transcripts were used as radiolabeled probes for the detection of enteroviral RNAs by molecular hybridization. The cRNA transcripts appeared to be more sensitive probes than the corresponding cDNAs. In vitro transcripts of the 5′ noncoding region (5′ nc riboprobe) were able to detect all of 14 reference enterovirus strains tested, as well as human rhinovirus 2, by dot blot hybridization with infected cell lysates. The same riboprobe also detected the enteroviral RNAs present in 16 of 18 samples of successive passages of stools in tissue culture and in some cases even in crude stool extracts. A riboprobe from the VP 1 region detected specifically poliovirus types 1,2, and 3 in lysates of infected cells and in 50% of the infected stool specimens tested. These probes could be of particular interest for the epidemic survey of poliovirus infecti