Porcine Circovirus 3: A New Member of the PCVAD Complex? [Edited]

July 4, 2018 — 

Current diagnostic tests are capable of detecting PCV3 in tissues but more information is necessary to understand the specific role of the virus in these clinical syndromes.

Circoviruses are small viruses with a circular, single-stranded DNA genome of approximately 2,000 bases, belonging to the family Circoviridae, genus Circovirus. Three types of porcine circovirus -- PCV1, PCV2 and PCV3 -- have been described thus far. PCV1 is a cell culture derived virus and is considered nonpathogenic for pigs1. In contrast, PCV2 is the primary etiological agent of porcine circovirus-associated disease which causes severe economic losses in the swine industry worldwide2. [Source: National Hog Farmer, By Piñeyro Pablo, Bailey L. Arruda, Eric R. Burrough, Phil Gauger and Rodger G. Main, Iowa State University, July 3, 2018]

Recently, collaborators from Iowa State University and Kansas State University reported the detection of a new species, PCV3, in typical lesions of porcine dermatitis and nephropathy syndrome, porcine circovirus associated disease and cases of reproductive failure3. Shortly after this description, PCV3 was also detected in a case of multisystemic disease without detection of any other significant pathogen4. PCV3 has subsequently been detected in pigs in most of the swine-producing countries worldwide. Despite the wide distribution of PCV3 and the apparent association with clinical disease similar to PCV2, the clinical implications of PCV3 are still being debated.

Based on the diagnostic case submissions received by the ISU VDL, it seems that PCV3 is being more consistently detected in aborted fetuses and tissue with PDNS lesions. The current diagnostic tests are capable of detecting the virus in tissues but more information is necessary to understand the specific role of PCV3 in these clinical syndromes. More research is required to understand the clinical relevance of PCV3, the potential role of PCV3 in abortion and PDNS cases, the impact of PCV2 and PCV3 coinfection, the prevalence and seroprevalence of PCV3, and the role that previous exposure to PCV3, PCV2 or PCV2 vaccination may have on clinical observations.

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