| Porcine circovirus type II can cause swine Post-weaning multisystemic wasting syndrome (PMWS), Porcine respiratory disease complex(PRDC), Porcine dermatitis and nephropathy syndrome (PDNS), Granulomatous enteritis, Necrotizing lymphadenitis and so on. It is an immunosuppressive viruses. By Porcine circovirus type II (PCV2) cause enteritis is one of PCVAD, clinically manifested by growth of piglet diarrhea, growth retardation or weight loss; in lymphoid tissues and intestinal tissues of pathogen detected significant amounts of PCV2, and a characteristic histological lesions. Aiming 2013-2014 PCV2 infection of diarrhea in piglets,13, Sichuan Group conducted a comprehensive epidemiological surveys, the main findings are as follows:1. PCV2 infection of diarrhea of piglets in Sichuan area statisticsThis study on diarrhea of piglet from 13 cities in Sichuan province,436 samples using PCR methods for detection and analysis of results showed that Positive samples for 312, the positive rate was 71.55%. This sampling of diarrhea of piglets in the 13 cities of PCV2 positive rate was highest in panzhihua city,88.89%, lowest in the deyang city was detected in 64.51%, PCV2 and TGEV, PEDV mixed infections are 4.35%,42.88%.1-6 week-old piglets diarrhea PCV2 positive rates were 82.88%,86.66%,57.38%,44.11%, and 36.84%. Positive rate of the final quarter of the yearto collect samples of PCV2 in turn,66.9%,65.78%, and 81.52%. PCV2 positive diarrhea piglets full blood, serum, feces of total seized out rate respectively for 36.67%,30%, and 83.33%, each organization organ PCV2 total seized out rate by high to low followed by for 76.92% (IN), and 71.15% (SMN), and 61.53% (intestinal), and 54.81% (spleen), and 47.11% (lung), and 29.8% (liver), and 25% (SmaN), and 14.42% (kidney), and(brain).These results indicate that, diarr hea of piglets group of PCV2 in the high infection rate, and in addition to the lymphatic organs and lymph tissue, the intestines may be another important target organ foe PCV2 infection.2. PCV2 molecular epidemiology of diarrhea in piglets group in Sichuan regionMolecular cloning and PCR methods, collected 312 PCV2 positive tissue specimen for analysis of different genotypes. of PCV2. It was found that PCV2a infection 15.12%, PCV2b Simplex Simplex infections accounted for 63.44%, both mixed infection 21.84%. Show 2014 diarrhea in piglets in the PCV2b of Sichuan province for the advantages endemic genotypes, in the form of simple infection and mixed infection of PCV2a and PCV2b. Amplified and measured 19 strains of the whole genome of PCV2 virus in Sichuan province, and molecular genetic evolution were analyzed. Homology analysis shows that determined in this study between 19 strains of PCV2 virus homology for 94.3%～100%.19 strains of PCV2 DNA sequences on GeneBank and comparative analysis of the different strains around the world. Results showed that the 19 strains of PCV2 virus in Sichuan province 16 strains belonging to Groupl,3 strains belonging to Group II.19 strains of PCV2 in Sichuan province Rep protein amino acid homology among strains of up to 96.8%-100%, that Rep genes are highly conserved PCV2 sequences far less variation than gene sequence. Cap protein, nucleotide sequence analysis revealed 19 strains of PCV2 virus in Sichuan province ORF2 nucleotide homology to 91.3%-99.9%, deduced amino acid homology is 94.5%-100%. With the world and the largest reference strains of Kimura distances are 6.09% and 4.84%; average transition/transversion (r) of 0.94 and 0.68; amino acid substitutions preference index for 3.8% and 2.5%. United States plant (FJ218000) compared to a total of 25 amino acid mutations. Cap protein amino acid mutations to the cumulative effect of these loci may be caused by antigenic drift, PCV2 immunogenic may be altered.. |
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