High-Temperature Inducible Cell-Free Transcription and Replication of Double-Stranded RNAs within the Parasitic ProtozoanCryptosporidium parvum

• Published in: Virology (New York, N.Y.) Vol. 245; no. 2; pp. 331 - 337
• Main Authors: Khramtsov, Nikolai V., Upton, Steve J.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 05.06.1998
• ISSN: 0042-6822; 1096-0341
• DOI: 10.1006/viro.1998.9181

Sporozoites of the protozoan parasite,Cryptosporidium parvum,were found to contain free, full-size plus strands transcribed from two extrachromosomal, cytoplasmic, virus-like double-stranded RNAs (dsRNAs). Cell-free transcription and replication of both dsRNAs were observed in crude sporozoite lysates. RNA polymerase activity was found to be dependent upon addition of Mg2+or Mn2+, as well as the four ribonucleoside triphosphates, and was insensitive to inhibitors of cellular DNA-dependent RNA polymerase. Semiconservative transcription of the dsRNAs (plus strand synthesis) was observed at a wide range of temperatures, with an optimum of 50°C. In contrast, replication (minus strand synthesis) was detected only at 50 and 60°C.