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Evidence for recombination between PCV2a and PCV2b in the field
Richard Hesse1, Maureen Kerrigan, Raymond R R Rowland
1Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS 66506, USA.
Virus Research
|December 7, 2007
Summary
Porcine circovirus type 2 (PCV2) genotypes, including PCV2a and PCV2b, have been identified in pigs. This study reveals natural co-infections and recombination between PCV2 genotypes in swine herds.
Area of Science:
- Veterinary Virology
- Molecular Epidemiology
- Swine Infectious Diseases
Background:
- Porcine circovirus type 2 (PCV2) causes significant economic losses in the swine industry.
- PCV2 isolates are classified into distinct genotypes, with PCV2a historically prevalent and PCV2b emerging in North America in 2005.
- The emergence of PCV2b coincided with increased reports of porcine circovirus disease (PCVD).
Purpose of the Study:
- To investigate the prevalence and genetic diversity of PCV2 genotypes in clinical swine samples.
- To identify potential recombination events between different PCV2 genotypes in naturally infected pigs.
- To understand the molecular epidemiology of PCV2 in contemporary swine herds.
Main Methods:
- Genomic sequence analysis of PCV2 isolates from diagnostic submissions.
- Development and application of differential PCR with genotype-specific primers for clinical diagnosis.
- Phylogenetic analysis using whole genome sequences to determine isolate relationships.
Main Results:
- Genomic analysis confirmed the division of PCV2 isolates into distinct genotypes.
- Differential PCR detected the presence of both PCV2a and PCV2b in 25% of 97 clinical samples.
- Phylogenetic and sequence analysis revealed a mosaic isolate (0737A) with ORF1 from PCV2a and ORF2 from PCV2b, indicating recombination.
Conclusions:
- Pigs can be naturally infected with multiple PCV2 genotypes simultaneously.
- Recombination events between PCV2a and PCV2b genotypes occur in field settings.
- These findings highlight the dynamic evolution of PCV2 and its implications for disease management.
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