Shaojian Xu

A mouse model to study infection against porcine circovirus type 2: viral distribution and lesions in mouse

BackgroundLittle information is known about viral distribution and transmission of porcine circovirus type 2 (PCV2) in species other than swine. It is still a debated topic whether the PCV2 could be infected and caused clinical lesions. Our study is aimed to estimate the susceptibility of Kunming mouse to PCV2. Forty-eight, 6-week-old Kunming mice were randomly divided into four groups. Group A (C1-C12) was inoculated with PK-15 cell culture as a control group. Group B (sPCV1-12) was inoculated orally and intramuscularly with PCV2 (106.2TCID50/ml). Group C (mPCV1-12) was inoculated orally and intramuscularly with PCV2 (106.2TCID50/ml) and a booster inoculation at days 14 and 28 after the first inoculation. Group D (MixPCV1-12) was unvaccinated but released into Group C. Each group was sacrificed at 7, 14, 28, and 42 days post-inoculation, respectively. Necropsy was checked on every mouse. Sera samples were collected for the test of PCV2 specific antibody. Tissues were collected for histopathology study and polymerase chain reaction (PCR).ResultsThe results showed that viral replication, seroconversion, and microscopic lesions were found in inoculated mice. Continuous existence of PCV2 viruses in lymph nodes have been confirmed by PCR, which took at least seven days for the virus to be transferred into other organs from the primary interface, and the diffusion to thymus had been retarded for seven days. Special PCV2 antibody could be found in PCV2 inoculation mice and was significantly higher than that in the control. Further more, microscopic lesions and the main target of PCV2 focused in the lymph nodes with a characteristic depletion and occasional necrosis of lymphocytes in the cortex and paracortex were found in inoculated mice.ConclusionsThe Kunming mouse could be infected by PCV2 virus and used as a PCV2 infected experimental model.

Loop-mediated isothermal amplification for detection of porcine circovirus type 2

BackgroundPorcine circovirus type 2 (PCV2) is the primary causative agent of the emerging swine disease known as postweaning multisystemic wasting syndrome (PMWS). Nowadays, polymerase chain reaction (PCR) is still the most widespread technique in pathogen detection. Loop-mediated isothermal amplification (LAMP), a novel nucleic acid amplification method developed in 2000, will possibly replace PCR in the field of detection. To establish a LAMP method for rapid detection of PCV2, two pairs of primers were designed specially from the open reading frame 2 (ORF2) sequences of PCV2. A LAMP method for rapid detection of PCV2 was established. To compare with PCR, sensitivity and specificity of LAMP were evaluated using the optimized reaction system. The LAMP products could be determined by agarose gel electrophoresis or adding SYBR Green I dye.ResultsThe amplification of LAMP could be obtained at 63°C for 60 min. The detection limit was nearly 1 copy of DNA plasmid, more sensitive than PCR. There was no cross-reaction with porcine circovirus type 1 (PCV1), porcine pseudorabies virus (PRV) and porcine parvovirus (PPV) under the same conditions.ConclusionsLAMP is an useful rapid detection method with high sensitivity and specificity for PCV2.

Immunogenicity of porcine circovirus type 2 nucleic acid vaccine containing CpG motif for mice

BackgroundThis study aimed at reseaching the immune effect of porcine circovirus type 2 (PCV2) DNA vaccine containing CpG motif on mice.MethodsA total of 40 6-week-old female BALB/c mice were randomly divided into four groups which were immunized by 18CpG-pVAX1-ORF2, pVAX1-ORF2, pVAX1 and PBS, respectively, and immunized again 2 weeks later. All mice were challenged with 0.2 mL PCV2 cells virulent strain SD (106.0 TCID50/mL) after 4 weeks. Average daily gain, blood antibody levels, microscopic changes and viremia were detected to estimate the effect of DNA vaccine.Results and DiscussionThe results showed that compared to those of the control mice, groups immunized with pVAX1-ORF2 and 18CpG-pVAX1-ORF2 could induce PCV2-specific antibodies. The PCV2-specific antibodies level of 18 CpG-pVAX1-ORF2 groups was higher significantly than other groups and decreased slowly along with time. There was no distinct pathological damage and viremia occurring in mice that inoculated with CpG motif DNA vaccines. The results demonstrated that the DNA vaccine containing 18 CpG could build up resistibility immunity and reduce immune organ damage on mice.

Complete Genome Sequence of Porcine Circovirus 2b Strain Shandong

ABSTRACT Shandong is a porcine circovirus 2b (PCV2b) strain that was isolated and purified from tissue samples from pigs with postweaning multisystemic wasting syndrome (PMWS) in the Shandong Province of China. Here, we report the complete genome sequence of strain Shandong, which may aid in understanding the molecular characteristics of this strain.

Complete Genome Sequence of Recombinant Porcine Circovirus Type 2 Strain SD-3

ABSTRACT We report here the genome sequence of a recombinant porcine circovirus type 2 strain SD-3, isolated from a commercial swine farm with an outbreak of postweaning multisystemic wasting syndrome (PMWS) in pigs in Shandong Province of China. The complete circular genome of this isolate is 1,767 nucleotides in length. This recombinant isolate has the ORF1 regions from PCV2a viruses and ORF2 regions from PCV2b. The findings will help us to understand the molecular evolution of porcine circovirus type 2 and the relationship between porcine circovirus type 2 and disease.