| To master the epidemic situation about the porcine respiratory disease complex (PRDC) of Luchuan Pigs mainly raised in Luchuan County, whose related pathogens mainly include Porcine Circovirus Type2(PCV2), Mycoplasma hyopneumoniae (Mhp), Porcine Reproductive and Respiratory Syndrome Virus(PRRSV), Streptococcus Suis (SS), Swine Eperythrozoon (E.suis), Haemophilus parasuis (HPs), Actinobacillus Pleuropneumonia (APP), the newer and synergistic virus, Torque torque sus virus (TTSuV), and to provide theoretical basis for regulatory technology of prevention and diagnosis about PRDC and meet the practical application for raising Luchuan Pigs, during the period from2012March to2013December,650serum samples which we collected from23pig farms in Luchuan County of Guangxi were determined by enzyme-linked immunosorbent assay (ELISA) to monitor the antibody levels of PCV2, Mhp, PRRSV and APP. The the positive antibody rates of PCV2, Mhp, PRRSV and APP were74.67%,34.38%,41.82%and12.00%respectively in piglet herd without realted vaccines,76.72%,57.89%,60.00%and17.24%respectively in nursery herd without realted vaccines,91.06%,79.36%,68.00%and12.34%respectively in finishing herd without realted vaccines,85.71%,27.66%,40.00%and47.77%respectively in adult herd without realted vaccines. At the same time,131tissue samples collected from23pig farms in Luchuan County of Guangxi were determined by RT-PCR or PCR to monitor the antigen levels of PCV2, Mhp, PRRSV, SS, E.suis, HPs, APP and TTSuV. The pathogen detections indicated that the positive rates were50.38%(66/131),21.37%(28/131),9.92%(13/131),12.21%(16/131),27.48%(36/131),4.58%(6/131),0.00%(0/131),28.24%(37/131),42.75%(56/131) respectively. Among the pathogens, PCV2, E.suis, TTSu V1and TTSuV2were the most harmful. In all of99positive samples, there were only26single infections, therefore, PRDC was the multi-factorial disease mainly. The positive rate of multiply infections was73.74%(73/99). The main ways of multiply infections were double infections and triple infections. Tthe positive rate of double infections was accounted for34.25%(25/73) and triple infections accounted for32.88%(24/73). Within multi-factor pathogens, combining PCV2with other pathogens was the most important and common infection type-accounted for73.97%of the total multiply infections. However, Mhp, the most sensitive pathogen for Luchuan Pigs, only accounted for34.35%of the total multiply infections. According to the results of the test for antigens and pathogens, we could know that PRDC was very common in Luchuan Pig farms, and infected rates were different from different stages.To provide basic material for the prevalence and provide usefull reference for taking control of the related diseases of PCV2, we used the PCV2positive samples of Luchuan Pigs in Luchuan County detected by PCR and then dealt with mycillin and filters to inoculate PK-15cells without any PCV contamination. The DNA extracted from cells of the eighth generation was identified by PCR and indirect immunofluorescent assay. The results suggested that two infectious strains named LCa and LCb had been isolated and identified. The complete genomes of the isolated strains were sequenced and and analysed, then the result showed that the PCV2isolates were all1767bp and the isolated strains shared99.0%nucleotide sequence identidy to another and the total nucleotide sequence has94.9%-99.1%identidy with other published strains. There was no obvious difference between these isolated strains and the other published sequences, therefore, PCV2nucleotide sequences had less pertinence in geography. The isolated strains’ORF1genes were945bp. Their nucleotide sequences identidy and amino acid sequences identidy were all above99.9%, therefore, the isolated strains’ORF1genes were conservative. The isolated strains’ORF2genes were702bp. Their nucleotide sequences identidy and amino acid sequences identidy were999.3%and98.7%respectively, thus the isolated strains’ORF2genes were conservative. The evolutionary genetics analysis suggested that LCa and LCb belonged to sub-gene type2b. |
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