Home
 /  Seminar  /  Seminar 865
Seminar 865  
Date:2016-09-20
Update:2017-11-02

  

Seminar:  865  

1

Speaker(s)

Chun Wang

Topic

Development and application of serum neutralization test for porcine reproductive and respiratory Syndrome virus (PRRSV)

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most significant pathogens of swine herds worldwide. Several different cell populations, including high and lowpermissive cell clones to porcine reproductive and respiratory syndrome (PRRS) virus, were derived from the MARC-145 cell line (parent cell: P) by cell cloning. Maximum virus yields in MARC-145 of high permissive and P clones were 108 and 106 tissue culture infective dose 50 (TCID50)/mL, respectively. These results indicated that the MARC-145 cells of high permissive will be useful for PRRS virus replication. In addition, a PRRSV serum neutralization test (SNT) based on MARC-145 cells of high permissivity was developed for detecting neutralizing antibodies to PRRSV. A total of 537 porcine sera were tested using SNT, and the titer of anti-PRRSV neutralizing antibodies was at its lowest point from 7 weeks old, and was raised significantly after 12 weeks post-birth. 

2

Speaker(s)

Tsu-Han Chen

Topic

A comparison of methods for the detection of antibodies against swine vesicular disease

Abstract

Swine vesicular disease (SVD) is a highly contagious disease afflicting pigs. Swine vesicular disease virus (SVDV) is classified as belonging to the genus Enterovirus in the family Picornaviridae. All SVDV isolates are classified into a single serotype. Infection of SVDV in pigs is characterized by vesicles that progress to erosions in the mouth, muzzle, nares, teats, and feet. Antigenically, SVDV is related to the human Coxsackievirus B5. Although SVDV infection usually results in low mortality, diagnosis of SVD is important because this disease is clinically indistinguishable from other vesicular diseases, particularly foot-and-mouth disease (FMD). For SVD diagnosis, virus neutralization tests (VNT) and ELISAs are the techniques commonly used. The VNT is the standard test, but it has the disadvantage that it takes 2 to 3 days and requires tissue culture facilities. In addition, cross reaction between SVDV and other enteroviruses often complicates the interpretation of the VNT. Currently, competitive ELISAs employing the monoclonal antibodies 5B7 and UK-72 is used for detecting antibodies against SVDV, and the VNT is used as an additional confirmatory test. In our study, 48 sera samples collected from six SVDV infected pigs were tested in parallel with the VNT as well as with an ELISA employing monoclonal antibody 5B7 (5B7-MAC-ELISA). The agreement between the two methods was up to 100%. In order to evaluate an in-house indirect ELISA based on the VP1 structural protein of SVDV, 30 sera collected from three SVDV infected pigs were tested by this indirect ELISA. Both the diagnostic specificity and sensitivity of the indirect ELISA were more than 95%, and the agreement between the results of our indirect ELISA and the 5B7-MAC-ELISA was high, where the value was >95% and the Kappa value was >90%. This assay is highly specific, since cross-reaction of the antibodies against FMDV was not detected.

3

Speaker(s)

Yang-chang Tu

Topic

Study on pathogenesis of goose hemorrhagic polyomavirus in geese by in situ hybridization

Abstract

Hemorrhagic nephritis enteritis of goose is caused by goose hemorrhagic polyomavirus (GHPV) and the disease is one of the major diseases afflicting geese in Europe. In 2015, GHPV was identified in three farms in mid-southern Taiwan, and the majority of infected goslings in these farms showed sudden death without obvious clinical signs. When the cases were reported, the cumulative mortality rates were 7.5% (230/3060), 15.3% (550/3600), and 16.7% (400/2400) in the three infected farms, respectively. Clinically, the infected goslings developed normally and then the sudden onset of disease appeared. The bills, webbed feet and conjunctivas appeared pale in some infected goslings. Grossly, transudate effusions in the coelomic and pericardial cavities, hemorrhaging in the jejunum and ileum, and deposition of urate on the internal organs were observed. The kidneys were swollen, mottled pale to yellowish in color, and hard in texture. Histopathologically, acute transmural hemorrhaging in the small intestine was only found in the early stages. In the middle to late stages, renal tubular necrosis accompanied with hemorrhaging, gouty tophi, fibrosis, and mineralization were commonly observed and the necrosis was usually located around intralobular veins. Necrotizing vasculitis was also profound in the digestive tract in all affected geese. Hepatocyte degeneration, multiple necrosis of the adrenal gland, and lymphocyte depletion of the spleen were also seen. Notably, the GHPV VP1 gene was detected in the brain, heart, liver, spleen, lung, kidney, intestine, etc. Phylogenetic analysis of the amplified sequences indicated that strains of Taiwan were similar to those of France, Germany, Hungary, and China, giving a percent identities of >99%. The distribution and localization of viral nucleic acids was determined to be in the endothelial cells of the different sizes of arteries, veins, and even in the capillary (sinusoid and glomeruli) throughout the body, including brain, heart, aorta, liver, spleen, lung, kidney and digestive tracts. The positive viral signals were not found in the parenchymal cells of any organ. These results suggested that the pathogenesis of GHPV was consistent with viral replication in the endothelial cells, resulting in endothelial cell necrosis, the subsequent increase of blood vessel permeability, as well as secondary circulation disorders.

4

Speaker(s)

Deng, Ming-Chung

Topic

24th International Pig Veterinary Society Congress and the visiting of the OIE reference laboratory for African Swine Fever in the Pirbright Institute

Abstract

The International Pig veterinary society (IPVS) Congress is a important international congress every two years. The 24th IPVS and 8th European Symposium of Porcine Health Management (ESPHM) were held in Dublin, Ireland, during 7th-10th June, 2016. Beside the porcine reproductive and respiratory syndrome, the topics of this congress was one of focused on congenital tremor and seneca valley virus. The Pirbright Institute is a prestigious animal disease research center in the world. The purpose of this visiting was learned for ASF the diagnosis of African swine fever. Dr. Dixon, who was the leader of the OIE reference laboratory, arranges the course and taught me the basic methods of ASF diagnosis. It might be helpful in the setting ASF diagnosis in our institute.