Wednesday, 27 October 2010

Circovirus linked to PCV2, PMWS, PDNS, PRRSV.

Everyone seems to be racing to publish.

This abstract helps explains the links between some of the various emerging pig diseases and circovirus.

It all comes back to circovirus and the often secret epidemics in pig herds, now being exposed all over the world.

The massive use of antibiotics to keep sick pigs alive created the dangerous MRSA st398

Abstract here

Molecular characterization of porcine circovirus 2 isolated from diseased pigs co-infected with porcine reproductive and respiratory syndrome virus

Jianzhong Yi and Chengqian Liu
Abstract (provisional)
Porcine circovirus type 2 (PCV2) is the causative agent of PMWS. healthy pigs experimentally inoculated with PCV2 developed the typical microscopic lesions of PMWS but only mild clinical symptoms. The co-infection of PRRSV,PPV and PCV2 have been reported in recent years, Experimental studies on co-infection with PRRSV and PCV2 resulted in the microscopic lesions associated with PMWS and/or porcine dermatitis and nephropathy syndrome (PDNS) and the development of severe disease.
In June 2008, severe disease, known as ''high fever'' occurred in several pig farms in shanghai, leading to a 57% death rate. We simultaneously detected PRRSV and PCV2,PPV in the tissue samples from diseased pigs by PCR technology, PRRSV was detected, genome sequence blast showed the strain belongs to genotype 2, 99.4% homologous to the PRRS virus strain JXA1 isolated in China, which has been proved to cause porcine high fever disease with high morbidity and mortality (Tian, et al.,2007). There was no PPV detected in all the samples, but we detected PCV2 from all the PRRS infected samples. The complete genome of PCV2 strains were sequenced, phylogenetic and polymorphic analyses were carried out. BLAST searches revealed the highest sequence identity (99.5% nt and 99.3% aa) to Guangxi strain EF675230.
The phylogenetic tree showed that clustering of the isolates didn't strongly correlate to clinical signs or geographical distribution. Polymorphic analyses demonstrated that the amino acids at most of the polymorphic sites in ORF1 and ORF2 belong to the same amino acid group according to chemical or structural properties, and revealed that highly polymorphic regions overlapped with the known immunoreactive epitopes of ORF2. Key words: PCV2, PMWS, PDNS, PRRSV.