An ELISA Based on a Truncated Soluble ORF2 Protein for the Detection of PCV2 Antibodies in Domestic Pigs / 中国病毒学·英文版

Postweaning multisystemie wasting syndrome (PMWS) is an important swine disease that is closely associated with porcine circovirus type 2 (PCV2). The capsid protein (Cap protein) is a major structural protein that has at least three immunoreactive regions, and it can be a suitable candidate antigen for detecting the specific antibodies of a PCV2 infection. In the present study, an indirect enzyme-linked immunosorbent assay (TcELISA)based on a truncated soluble Cap protein produced in Escherichia coli (E.coli) was established and validated for the diagnostic PCV2 antibodies in swine. The TcELISA was validated by comparison with an indirect immunofluorescence assay (IIFA). The diagnostic sensitivity (DSN), specificity (DSP), and accuracy of the TcELISA were 88.6%, 90.7% and 89.4%, respectively. The agreement rate was 89.38% between results obtained with TcELISA and IIFA on 113 field sera. A cross-reactivity assay showed that the method was PCV2-specific by comparison with other sera of viral disease. Therefore ,the TcELISA will be helpful for the development of a reliable serology diagnostic test for large scale detection of PCV2 antibodies and for the evaluation of vaccine against PCV2 in swine.

Genetic Variation Analyses of nsp2 Gene of PRRSV in Ningxia Hui Autonomous Region of China / 中国病毒学·英文版

To gain a better understanding of the genetic diversity and evolution of PRRSV in the Ningxia Hui Nationality Autonomous Region (Ningxia) of China, the nsp2 genes from a series of PRRSV strains collected from the region in 2007 were partially sequenced. These sequences were then analyzed along with the classical strain (ch-la) and two other epidemic strains SD (3) and SD2006. Comparison of the nucleotide sequence with ch-la indicated that nsp2 genes of seventeen Ningxia isolates (NX strain) have deletions of 87 nucleotides. Sequence analysis indicated that homology between the Ningxia strain and ch-la was 60.3%-79.9% in the nucleotide sequence, and homology between the NX strains and SD strains was 80.3%-98.8% in the nucleotide sequence. The nsp2 genes of the seventeen isolates had 74.9%-100% nucleotide sequence identities with each other. This study was undertaken to assess the regional variation of prevalent PRRSV and to establish a sequence database for PRRSV molecular epidemiological studies.