Porcine Circovirus Infection Study Guide

Overview and Clinical Importance

Porcine circovirus (PCV) belongs to the family Circoviridae, genus Circovirus. These are among the smallest DNA viruses known to infect mammals, measuring only 17-22 nm in diameter with a circular, single-stranded DNA genome of approximately 1,700-2,000 nucleotides.

Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus-associated disease (PCVAD), which represents one of the most economically important diseases affecting the global swine industry. In the United States alone, PCVAD costs producers an average of $3-4 per pig, with peak losses reaching up to $20 per pig in severely affected herds.

Etiology and Virology

Porcine Circovirus Types

PCV2 Genotypes

PCV2 has evolved into multiple genotypes with varying clinical significance. The genotypes PCV2a, PCV2b, and PCV2d are most commonly associated with clinical disease. A significant genotypic shift from PCV2a to PCV2b occurred around 2003, and more recently PCV2d has become predominant in many regions.