Investigation of the Causes of Post-weaning Multisystemic Wasting Syndrome and Phylogenetic Analysis of Porcine Circovirus Type II isolates
Date Issued
2006
Date
2006
Author(s)
Tu, Chi-Hua
DOI
zh-TW
Abstract
Post-weaning multisystemic wasting syndrome (PMWS), first described in Canada in 1991, has been now reported in most swine-producing countries and has become a significant problem for the pig industry. Porcine circovirus type 2 (PCV2) is the necessary cause of PMWS in swine; however, a variety of co-factors, including other infectious agents, are thought to be necessary in the full expression of disease. The aim of this study is to find out if other co-infection is necessary in the PMWS cases in Taiwan. The PMWS cases were diagnosed by three criteria described in previous study: (1) the presence of compatible clinical signs, (2) the presence of the characteristic microscopic lymphoid lesions, and (3) the detection of PCV2 within these tissues by PCR. Also, we detected Porcine circovirus typee I (PCV1), Pseudorabies virus (PRV), Porcine parvovirus (PPV), Classic swine fever virus (CSFV), Porcine reproductive and respiratory syndrome virus (PRRSV), Actinobacillus pleuropneumoniae (APP), Mycoplasma hyopneumoniae, Salmonella from different biological specimens of growth retarded pigs by RT-nPCR or PCR. In 62 pigs examined, 55 pigs were PCV2 positive (88.71%), 29 pigs were PPV positive (46.77%), 25 pigs were PRV positive (40.32%), 6 pigs were PCV1 positive (9.68%), 36 pigs were Mycoplasma hyopneumoniae positive (58.06%), 11 pigs were APP positive (17.74%), 42 pigs were PRRSV positive (67.74%), 10 pigs were CSFV positive (16.13%), 0 pigs were Salmonella positive and there were 30 PMWS cases. After statistic analysis, we found that co-infection with CSFV (p=0.04), PRRSV (p=0.0027), and PPV (p=0.0047) can increase the probability to induce PMWS. The nucleotide sequences of full-length genome of 8 Taiwan isolates were also analyzed by PCR and sequencing. After comparing nucleotide sequences of Taiwan strains published on GenBank, the PCV2 strains shared 93.1% to 99.8% identity. Comparing the amino acid sequences translated from ORF2 of PCV2 among the Taiwan strains, their amino acid sequences shared 88.5% to 100% similarity. The nucleotide sequences of PCV2 isolates shared 93.4% to 99.8% identity with other isolates world wide.
Subjects
豬環狀病毒
豬離乳後多系統性消耗性症候群
PCV
PMWS
Type
thesis
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