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Heterogeneous progeny viruses are produced by a budding enveloped phage
Abstract:
Infection of Acholeplasma laidlawii cells by the temperate enveloped mycoplasma virus L2 results in production of three morphological forms of progeny L2 virus: L2-I, L2-II, and L2-III. These morphological forms can be separated by velocity sedimentation and agarose gel electrophoresis. The latter technique was used to size the quasi-spherical particles: L2-I is 74 nm, L2-II is 88 nm, and L2-III is 132 nm in diameter. The protein composition of the three L2 forms is the same, although there are differences in protein stoichiometric ratios. L2-I, L2-II, and L2-III have the same 11.8 kilobase pair superhelical DNA genome. However, UV inactivation studies and restriction frequency measurements indicate that L2-I and L2-III each contain 1 genome copy, while L2-II contains 2-3 genome copies.
Insights
Mycoplasma virus L2 infection produces three progeny forms (L2-I, L2-II, L2-III) differing in size and genome copy number. These distinct virus particles share the same DNA genome but vary in protein stoichiometry and L2-II contains multiple genome copies.
Area of Science:
- Virology
- Molecular Biology
- Microbiology
Background:
- Mycoplasma virus L2 is a temperate, enveloped virus infecting Acholeplasma laidlawii.
- Viral infection can lead to the production of progeny with varying characteristics.
Purpose of the Study:
- To characterize the morphological and genomic differences between progeny forms of Mycoplasma virus L2.
- To investigate the protein composition and DNA content of the different L2 virus variants.
Main Methods:
- Separation of progeny virus particles using velocity sedimentation and agarose gel electrophoresis.
- Determination of particle sizes via gel electrophoresis.
- Analysis of protein composition and stoichiometric ratios.
- Assessment of genome copy number using UV inactivation and restriction frequency measurements.
Main Results:
- Three distinct morphological forms of Mycoplasma virus L2 progeny were identified: L2-I (74 nm), L2-II (88 nm), and L2-III (132 nm).
- All forms share an 11.8 kbp superhelical DNA genome but differ in protein stoichiometric ratios.
- L2-I and L2-III contain one genome copy, whereas L2-II contains 2-3 genome copies.
Conclusions:
- Mycoplasma virus L2 exhibits pleomorphism, producing progeny with distinct physical characteristics and genome multiplicities.
- The observed variations in progeny forms are linked to differences in particle size and the number of genome copies per virion.