Examination for a viral co-factor in postweaning multisystemic wasting syndrome (PMWS)

Area of Science:

• Veterinary Virology
• Molecular Epidemiology

Background:

• Postweaning multisystemic wasting syndrome (PMWS) is a significant disease in pigs.
• The role of viral co-factors in PMWS development is not fully understood.
• Porcine circovirus type 2 (PCV2) is implicated in PMWS, but strain-specific effects require investigation.

Purpose of the Study:

• To identify potential viral co-factors involved in PMWS development.
• To investigate if specific PCV2 genotypes influence the transition from infection to clinical disease.

Main Methods:

• Extensive virological examinations of organ material from PMWS-diagnosed pigs.
• Virus isolation attempts using a wide range of primary and established cell lines.
• Comparative analysis of complete PCV2 DNA genome sequences from PMWS-positive and -negative pigs.

Main Results:

• No specific virus other than PCV2 was identified as a contributor to PMWS.
• PCV2 isolates from PMWS-affected and unaffected pigs showed 95.5% genome identity.
• Sequence analysis revealed amino acid differences in replicase and capsid proteins between PCV2 groups.

Conclusions:

• The study did not find evidence for viral co-factors other than PCV2 in PMWS.
• PCV2 strain variations, particularly in capsid and replicase proteins, may influence the clinical outcome of infection.
• Findings support the hypothesis that specific PCV2 genotypes contribute to PMWS pathogenesis.