INTRACELLULAR-LOCALIZATION OF VIRAL-RNA IN EIMERIA NECATRIX OF THE DOMESTIC-FOWL

The intracellular localization of viral RNA in three different stages of Eimeria necatrix, namely, the first- and second-generation meronts and the macrogamonts, were examined at the light microscopy level by i n situ hybridization. Digoxigenin-labeled riboprobes generated from pa rtial cDNA clones from 5.6-kb and 4.5-kb dsRNA (pzenv1 and pzenv2) wer e used in this study. Viral RNA was found to be confined to the cytopl asm of the eimerian host; no viral RNA was detected in chicken tissue. The intense hybridization signal observed in the cytoplasm of the imm ature meronts with the SP6 riboprobe of pzenv1 or the T7 riboprobe of pzenv2 was probably due to their hybridization to positive strands tha t had been extruded from the virus during transcription. In mature mer onts the intensity of the signal is lower, signifying a decrease in tr anscription activity. Viral replicase activity may thus be synchronize d with the growth phase of the eimerian host.