High-temperature inducible cell-free transcription and replication of double-stranded RNAs within the parasitic protozoan Cryptosporidium parvum.
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 degrees C. In contrast, replication (minus strand synthesis) was detected only at 50 and 60 degrees C.
Khramtsov
N V
NV
Division of Biology, Kansas State University, Manhattan 66506, USA. podolsk@ksu.edu
Upton
S J
SJ
D000818:Animals; D002474:Cell-Free System; D016785:Cryptosporidium parvum / Q000235:genetics* / Q000821:virology; D012367:RNA, Viral / Q000235:genetics*; D013696:Temperature; D014158:Transcription, Genetic
D012367:RNA, Viral