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Analysis of JC virus DNA purified directly from human progressive multifocal leukoencephalopathy brains
Abstract:
Human polyomavirus JC DNA was purified directly from the diseased brain tissue of two patients with progressive multifocal leukoencephalopathy (PML) by a method employing differential salt precipitation (B. Hirt, J. Mol. Biol. 26:365-369, 1967). Each of the viral genomes (JC-NIH-1 and JC-NIH-2) was molecularly cloned intact in Escherichia coli, using pBR322, at their unique EcoRI (0.00 map unit) and BamHI (0.51 map unit) sites. The JC-NIH-1 genome was approximately 50 base pairs larger and the JC-NIH-2 genome was approximately 50 base pairs smaller than the prototype human polyomavirus JC (Mad-1) DNA. Analysis of the restriction endonuclease cleavage fragments of these two DNAs and the human polyomavirus JC (Mad-1) DNA revealed only slight differences which mapped in a region of the genome extending from 0.67 to 0.74 map unit. From previous homology studies, this region of variance corresponds to the noncoding region to the late side of the origin of DNA replication.
Insights
Researchers isolated and cloned human polyomavirus JC DNA from progressive multifocal leukoencephalopathy (PML) patient brains. Genetic analysis revealed minor variations in the viral noncoding region, impacting DNA replication.
Area of Science:
- Virology
- Molecular Biology
- Neuroscience
Background:
- Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system.
- Human polyomavirus JC (HPyVJC) is the causative agent of PML.
- Understanding HPyVJC genome variations is crucial for studying PML pathogenesis.
Purpose of the Study:
- To molecularly clone and characterize HPyVJC DNA directly from PML patient brain tissue.
- To identify and map genetic differences between HPyVJC isolates from PML patients and the prototype strain.
- To investigate the implications of these variations on viral replication and pathogenesis.
Main Methods:
- Differential salt precipitation was used to purify HPyVJC DNA from diseased brain tissue.
- Molecular cloning of viral genomes into Escherichia coli using the pBR322 vector.
- Restriction endonuclease digestion and analysis of cleavage fragments to compare viral genomes.
- Mapping of genetic variations to specific regions of the HPyVJC genome.
Main Results:
- Two intact HPyVJC genomes (JC-NIH-1 and JC-NIH-2) were successfully cloned.
- JC-NIH-1 and JC-NIH-2 genomes showed slight size differences compared to the prototype Mad-1 strain.
- Restriction fragment analysis revealed minor genetic variations localized to a specific noncoding region (0.67–0.74 map units) of the HPyVJC genome.
- This region of variance corresponds to the noncoding area adjacent to the origin of DNA replication.
Conclusions:
- The study successfully cloned and characterized HPyVJC strains from PML patients.
- Identified minor genetic variations in the noncoding region of HPyVJC, potentially influencing viral replication.
- These findings contribute to the understanding of HPyVJC diversity and its role in PML.