Immunofluorescent detection of nuclear double-stranded RNA in situ in Vero and mosquito cells

Double-stranded RNA (dsRNA) was detected in situ by indirect immunofluorescence with antibodies to dsRNA. It was seen in nuclei of Vero and Aedes albopictus cells, but not in BHK cells, KB cells, chick embryo fibroblasts, or HeLa cells. Reactive dsRNA was present in the nucleoplasm, but not in nucleoli or cytoplasm. Extracted RNA from the whole cell contained from 0.08 percent (BHK) to 0.46 percent (HeLa) dsRNA, as estimated by serological methods. This dsRNA, found in molecules having the size distribution of heterogeneous nuclear RNA, did not renature rapidly after denaturation. The quantity of dsRNA in total extracted RNA did not correlate with the presence or absence of nuclear staining in situ.