Unique Double-Stranded RNAs Associated with the Trichomonas vaginalis Virus Are Synthesized by

Most Trichomonas vaginalis isolates are carriers of the multi segmented double-stranded RNA ( dsRNA) virus. In vitro polymerase assays were performed to demonstrate the RNA-dependent RNA polymerase (RDRP) activity of purified particles. Transcripts which comigrated with the dsRNAs of the virus were readily detected as synthesized products, indicating viral RDRP activity. In addition, smaller-sized dsRNA species, possibly two of approximately 700 bp (sI) and one of 500 bp (s2), were synthesized by purified virus particles of the CsCI gradient surrounding the virus peak. No cross-hybridization with either sI or s2 and the dsRNA segments occurred, suggesting that sI and s2 were synthesized from dilferent templates. An RNase A protection assay revealed that the synthesized sI and s2 polymerase products were double stranded. Furthermore, hybridization of products with strand-specific RNA of sI generated from cDNA indicated that only one strand was synthesized in vitro. sI and s2 were not visualized in ethidium bromide-stained agarose gels of dsRNA of infected trichomonads grown in batch cultures. However, dsRNA profiles of the same infected organisms cultivated under.defined continuous-flow conditions contained readily detectable levels of sI and s2, indicating that amplification of sI and s2 occurred under specific environmental conditions. These newly discovered dsRNAs were not detected in all of the virus-carrying isolates. Finally, it is noteworthy that the sI and s2 dsRNAs and the RDRP activity were not detected in trichomonal isolates without virus or in virus-negativ