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Genomic variations among wildtype and mutant strains of pseudorabies virus
N A Zeenathul1, M L Mohd-Azmi, A S Ali
1Faculty of Veterinary Medicine, University Putra Malaysia 43400 UPM, Serdang, Selangor, Malaysia. zeenatnba@hotmail.com
Abstract:
Both wild-type virulent and mutant strains of pseudorabies virus (PrV) were used in this study. Mutants used were derived from the plaque purified strain PrVmAIP. A total of six drug resistant mutants, three bromodeoxyuridine (BUdR) resistant and three iododeoxyuridine (IUdR) resistant, respectively, were isolated and passaged in chicken embryo fibroblast (CEF) cells. The DNA of these PrVs were compared with the wild-type isolates by means of the restriction fragment pattern (RFP) findings produced with Bam HI, Kpn I, Hind III and Bgl II restriction enzymes (RE). Compared to the wild-type PrVs (PrV-VBA1-parental strain of PrVmAIP; PrV-VBA2; PrV-VBA3), the RFP of PrVmAIP showed the presence of mutations within the RE sites studied. Both PrV-VBA1 and PrV-VBA2 appeared to be closely related but their RFPs differed from PrV-VBA3. Significant differences either in the number, size or migrations of the DNA fragments could also be detected in the BUdR resistant strains. Even though different features of cytopathic effect (GPE) were observed in the IUdR resistant PrVs, the RFP findings remained identical. The PrVs studied showed considerable differences from the reference PrV (PrV-CD).
Insights
This study compared drug-resistant pseudorabies virus (PrV) mutants to wild-type strains using DNA restriction fragment patterns. Bromodeoxyuridine-resistant mutants showed significant DNA differences, while iododeoxyuridine-resistant mutants did not, despite varying cytopathic effects.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Pseudorabies virus (PrV) is an important pathogen in swine.
- Understanding PrV genetic diversity is crucial for disease control.
- Drug-resistant mutants offer insights into viral genome stability.
Purpose of the Study:
- To characterize the genetic differences between wild-type and drug-resistant PrV strains.
- To investigate the impact of drug resistance mutations on viral DNA.
- To compare the utility of restriction fragment patterns (RFP) for differentiating PrV strains.
Main Methods:
- Isolation and propagation of six drug-resistant PrV mutants (3 BUdR, 3 IUdR) in chicken embryo fibroblast (CEF) cells.
- Analysis of PrV DNA using restriction fragment pattern (RFP) analysis with Bam HI, Kpn I, Hind III, and Bgl II restriction enzymes.
- Comparison of RFPs between wild-type PrV strains (PrV-VBA1, PrV-VBA2, PrV-VBA3) and mutant strains (PrVmAIP).
Main Results:
- Mutations were identified within restriction enzyme sites in the PrVmAIP strain compared to wild-type PrVs.
- PrV-VBA1 and PrV-VBA2 showed relatedness, distinct from PrV-VBA3 based on RFP.
- Significant DNA fragment variations were observed in BUdR-resistant strains, but not in IUdR-resistant strains despite differing cytopathic effects.
- All studied PrVs exhibited substantial differences from the reference PrV (PrV-CD).
Conclusions:
- Restriction fragment pattern analysis is effective in detecting genetic variations in PrV.
- BUdR resistance is associated with detectable genomic alterations, unlike IUdR resistance.
- PrV strains display significant genetic diversity, impacting their molecular profiles.