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Updated: Jul 8, 2026

Synthesis of Infectious Bacteriophages in an E. coli-based Cell-free Expression System
Published on: August 17, 2017
Phage formation in Staphylococcus muscae cultures; nucleic acid synthesis during virus formation
Abstract:
1. The total nucleic acid synthesized by normal and by infected S. muscae suspensions is approximately the same. This is true for either lag phase cells or log phase cells. 2. The amount of nucleic acid synthesized per cell in normal cultures increases during the lag period and remains fairly constant during log growth. 3. The amount of nucleic acid synthesized per cell by infected cells increases during the whole course of the infection. 4. Infected cells synthesize less RNA and more DNA than normal cells. The ratio of RNA/DNA is larger in lag phase cells than in log phase cells. 5. Normal cells release neither ribonucleic acid nor desoxyribonucleic acid into the medium. 6. Infected cells release both ribonucleic acid and desoxyribonucleic acid into the medium. The time and extent of release depend upon the physiological state of the cells. 7. Infected lag phase cells may or may not show an increased RNA content. They release RNA, but not DNA, into the medium well before observable cellular lysis and before any virus is liberated. At virus liberation, the cell RNA content falls to a value below that initially present, while DNA, which increased during infection falls to approximately the original value. 8. Infected log cells show a continuous loss of cell RNA and a loss of DNA a short time after infection. At the time of virus liberation the cell RNA value is well below that initially present and the cells begin to lyse.
Insights
Infected insect cells alter nucleic acid synthesis, releasing RNA and DNA. This impacts cellular RNA and DNA levels, affecting cell health and virus production.
Area of Science:
- Microbiology
- Molecular Biology
- Virology
Background:
- Understanding cellular responses to viral infections is crucial for developing antiviral strategies.
- Nucleic acid metabolism plays a pivotal role in host-pathogen interactions.
Purpose of the Study:
- To investigate the changes in nucleic acid synthesis and release in normal versus virus-infected *S. muscae* cells.
- To characterize the differential synthesis of RNA and DNA during viral infection.
Main Methods:
- Quantification of total nucleic acid synthesis in normal and infected *S. muscae* cell cultures (lag and log phases).
- Analysis of intracellular RNA and DNA content per cell.
- Detection and quantification of nucleic acid release into the culture medium.
Main Results:
- Infected cells exhibit altered nucleic acid synthesis, with decreased RNA and increased DNA compared to normal cells.
- Infected cells release both ribonucleic acid (RNA) and desoxyribonucleic acid (DNA) into the medium.
- Cellular RNA levels decrease significantly in infected log-phase cells, preceding lysis and virus liberation.
Conclusions:
- Viral infection profoundly disrupts host cell nucleic acid metabolism, leading to the release of cellular nucleic acids.
- The observed changes in RNA/DNA ratios and release patterns indicate a significant metabolic reprogramming during infection.
- These alterations in nucleic acid dynamics are closely linked to the progression of viral infection and host cell viability.
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