Effect of actinomycin D on simian rotavirus (SA11) replication in cell culture

Abstract

Rotaviruses are the major cause of viral diarrhea in humans and animals. Actinomycin D (Act D) is an antibiotic that intercalates DNA and therefore inhibits DNA-dependent transcription. The current study was carried out to assess the influence of Act D on the replication of simian rotavirus (SA11) in cell culture. Virus-infected MA-104 cell cultures were studied in the presence of Act D at concentrations of 1.25 and 2.5 µg/ml. Treatment of rotavirus-infected cells with 2.5 µg/ml Act D 48 h post-infection reduced the cytoplasmic metachromasia after staining with acridine orange by 25%. Viral RNA labeled with 3 H-uridine in the presence of the drug was separated by polyacrylamide gel electrophoresis. Viral RNA replication was not affected by Act D, but increased 3 H-uridine uptake was demonstrable by infected cells in the presence of the drug. This possibly was due to the inhibition of cellular RNA synthesis by Act D, which thus enhances incorporation of the radionuclide into the viral RNA. Act D reduced the number of infected cells presenting virus-specific fluorescence 48 h post-infection by more than 50%. These data suggest that Act D may have complexed with viral RNA and prevented newly synthesized mRNA from being translated, but may not have prevented early replication. Rotaviruses are classified as a genus within the family Reoviridae. These viruses are the major causal agents of acute diarrhea in mammals and fowl. The virions are nonenveloped 75 nm in diameter, and the genome consists of eleven segments of double-stranded RNA that encode six structural (VP1-VP4, VP6 and VP7) and five nonstructural (NSP1-NSP5) proteins (1). They have a triple-layered double capsid and replicate in the cytoplasm. Virion uncoating is followed by penetration into susceptible host cells and productive infection depends on the function of viral transcriptase in the synthesis of mRNA and double-stranded RNA segments of the progeny. The minus RNA strands act as templates for the synthesis of full-length plus strands (2,3). Both newly synthesized and pre-existing plus strand RNA act as templates for minus strand synthesis.Actinomycin D (Act D) is an antibiotic that binds noncovalently to DNA and strongly inhibits transcription in eukaryotic and prokaryotic cells (4,5). Due to its toxicity, Act D has not been used clinically as an

Therapeutics and Immunoprophylaxis Against Noroviruses and Rotaviruses: The Past, Present, and Future

“…Interestingly, Neomycin and other aminoglycosides have also been shown to exhibit inhibitory effects on rotavirus plus- and minus-strand RNA synthesis [ 184 ]. Actinomycin D, an antineoplastic antibiotic, has been proposed to complex with viral RNA and prevent newly synthesized mRNA from undergoing translation [ 185 ].…”