Togavirus RNA: reversible effect of urea on genomes and absence of subgenomic viral RNA in Kunjin virus-infected cells.

Electrophoretic analyses showed that no RNase-sensitive RNA smaller than the genome was specified by the flavivirus Kunjin in infected Vero cells during the period of maximum RNA and protein synthesis. In contrast, RNA extracted from Sindbis virus-infected cells under similar conditions included the expected 42S RNA (equivalent to the genome) and the smaller 26S (interjacent) RNA. Treatment of the genome of both togaviruses with 12 M urea produced a reversible (possibly conformational) change; measurement of the molecular weights of the treated RNAs by co-electrophoresis with fully denatured ribosomal RNA markers in SDS-polyacrylamide gels yielded a value of 2.1 X 10(6) if 8 M urea was incorporated in the gels and 4.2 X 10(6) if urea was omitted from the gels. These results indicate that flavivirus messenger RNA is represented solely by the intact genome of m.wt. 4.2 X 10(6).