Porcine circoviruses are circular single-stranded DNA viruses that infect swine and wild boars. Two species of porcine circoviruses exist. Porcine circovirus type 1 is non-pathogenic, unlike porcine circovirus type 2, which is associated with the immuno-depressive disease known as Post-weaning Multisystemic Wasting Syndrome (PMWS).

Porcine circovirus DNA has been shown to replicate by a rolling circle mechanism. Several other studies have revealed similar mechanisms of rolling-circle replication in plasmids and single-stranded viruses such as Geminivirus.

Three elements are important in rolling-circle replication:

1. a gene-encoding initiator protein
2. a double strand origin, and
3. a single strand origin.

However, differences exist between viruses and plasmids and between viruses. Porcine circovirus replication probably involves a 'melting pot' rather than 'cruciform' rolling-circle mechanism.

This review provides a summary of current knowledge of replication in porcine circoviruses as models of the Circovirus genus. Based on various studies, the factors affecting replication are defined and the mechanisms involved in the different phases of replication are described or proposed.

Reference

Faurez F., D. Dory, B. Grasland and A. Jestin, 2009. Replication of porcine circoviruses. Virology Journal,6:60. doi:10.1186/1743-422X-6-60.

Further Reading

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You can view the provisional version of the full report by clicking here.

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Find out more information on Post-Weaning Multisystemic Wasting Syndrome (PMWS) by clicking here.