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Published on: September 13, 2018
Biochemical and biological variation of Cydia pomonella (codling moth) granulosis virus
1Department of Entomology and Parasitology, University of California, Berkeley, California 94720, USA.
Abstract:
Cydia pomonella granulosis viruses (CpGV) from three different sources were compared biochemically and biologically. Restriction enzyme profiles of a CpGV isolated in Mexico and propagated for 9 years in a laboratory in Darmstadt, Germany (CpGV-MD) were compared with those of the same isolate propagated for 9 years at a Berkeley, California, laboratory (CpGV-MB). Only one of six enzymatic digests revealed a difference in the DNAs, which were subsequently calculated to be 99.94% homologous. No differences were found in molecular weights of enveloped virion polypeptides with SDS-polyacrylamide gel electrophoresis. In contrast, the restriction profiles of a CpGV isolated in Russia (CpGV-R) differed from that of CpGV-MB and CpGV-MD in five of six enzymatic digests due to what appeared to be a deleted fragment of DNA of about 1 x 10(6) in the CpGV-R genome. SDS-PAGE indicated a small difference in mobility of a high-molecular-weight protein in CpGV-R as compared to CpGV-MB and CpGV-MD. Two low-molecular weight proteins present in both CpGV-MD and CpGV-MB were missing completely in CpGV-R. Southern blot hybridization of restriction endonuclease gels using (32)P-labeled CpGV-MB DNA showed homology for all three isolates. A radioimmune protein blot assay revealed no differences in serological reactivity among the three CpGVs. LD(50) values for first and fifth instar larvae showed CpGV-MB and CpGV-MD to have similar virulence, while CpGV-R had significantly less.
Insights
Biochemical analysis revealed Cydia pomonella granulosis viruses (CpGV) isolates maintained in different labs are highly homologous. However, a Russian CpGV isolate showed genetic differences and reduced virulence in codling moth larvae.
Area of Science:
- Molecular Virology
- Insect Pathology
- Biochemistry
Background:
- Cydia pomonella granulosis viruses (CpGV) are crucial biological control agents for codling moth.
- Long-term laboratory propagation can potentially induce genetic drift in viral isolates.
- Understanding isolate variability is essential for maintaining efficacy in pest management programs.
Purpose of the Study:
- To biochemically and biologically compare CpGV isolates from different geographical origins and laboratory maintenance histories.
- To assess the genetic relatedness and virulence of CpGV isolates after prolonged laboratory propagation.
Main Methods:
- Restriction endonuclease digestion and analysis of viral DNA.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein profiling.
- Southern blot hybridization for DNA homology assessment.
- Radioimmune protein blot assay for serological comparison.
- Determination of lethal dose 50 (LD50) values in codling moth larvae.
Main Results:
- CpGV isolates from Mexico (Darmstadt and Berkeley labs) exhibited 99.94% DNA homology, with minimal differences in restriction profiles and protein composition.
- A Russian CpGV isolate (CpGV-R) showed significant differences in restriction profiles, likely due to a DNA fragment deletion, and lacked two low-molecular-weight proteins.
- All isolates demonstrated DNA homology via Southern blot, and serological assays revealed no differences in reactivity.
- CpGV-R exhibited significantly lower virulence against codling moth larvae compared to the laboratory-maintained isolates.
Conclusions:
- Long-term laboratory maintenance of CpGV isolates results in minimal genetic and biochemical divergence.
- Geographical origin can be associated with significant genetic variations in CpGV, potentially impacting virulence.
- The study highlights the importance of monitoring viral isolate characteristics to ensure consistent biological control performance.
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