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Seminar 851  

 

Seminar:  851

1

Speaker(s)

Kuo-Jung Tsai

Topic

Comparison of antibody initiation by two vaccines against Foot-and-Mouth disease virus

Abstract

Since the outbreak of foot-and-mouth disease (FMD), caused by Cathay topotype of serotype O in 1997 in Taiwan, the mandatory vaccination has been persistently used to control FMD until now. The efficacy of FMDV vaccine against various O/TWN strains in Taiwan has been persistently followed. The aim of the study is to compare the antibody initiation between homologous and heterologous vaccines in swine. The experiment I was focused on the difference of anti-FMDV antibody in maternal-derived antibody (MDA) by 10 heads of 90-days-pregancy sows vaccinated with homologous or heterologous vaccine. The experiment II was focused on the difference of anti-FMDV antibody in the growing pigs with homologous or heterologous vaccine. Comparison of anti-FMDV antibody of MDA showed that the viral neutralization (VN) titer of piglets in the homologous vaccine group was higher than that of heterologous group during 2 to 10 weeks of age. The similar pattern for VN titer was also found in the growing pigs with homologous or heterologous vaccine.

2

Speaker(s)

Yen-Ping Chen

Topic

Diagnosis of Botulism in Wild Birds

Abstract

Avian botulism, also known as limberneck, is a parsalytic, often fatal disease of birds resulting from ingestion of toxin produced by the bacterium Clostridium botulinum. Seven types of botulinum neurotoxin, designated as types A through G, have been identified. Almost all outbreaks in poultry are caused by type C, although types D or E are also involved. Clinically, paralyzed legs were usually the first symptom being observed in avian botulism, and the paralyses were later demonstrated in wings, neck, and eyelids. Death can result from water deprivation, electrolyte imbalance and respiratory failure. There are no characteristic gross lesions in birds dying of botulism. The most reliable test for avian botulism is the mouse protection test, although the PCR technique is also successfully applied in the detection and differentiation of the neurotoxin genes.

During January and June in 2015, our laboratory received five botulism-suspected cases of wild birds. Four of the cases were black-faced spoonbills. The sera of the cases were tested by the mouse inoculation test to detect the toxins; moreover, carcasses or organs of the cases were tested by the PCR to detect the botulism neurotoxin genes and to identify their types. The outbreak during February 27 and March 2 attacked 14 black-faced spoonbills and resulted in seven deaths. According to the clinical signs and the results of the mouse inoculation tests and the PCR tests, the mosaic C/D neurotoxin of botulism was the etiologic agent of this outbreak in the black-faced spoonbills. The fifth case occurred in Gaoping River during March 5 and 12. There were near 1,000 waterfowl affected, including teals, European wigeons, and shovelers. The mosaic C/D neurotoxin of botulism also contributed to this outbreak in Gaoping River. Detecting and typing Clostridium botulinum and their toxins by the mouse inoculation test and the PCR simultaneously could bring about rapid and definitive diagnosis and the treatment of sick birds, and could therefore prevent or minimize further cases.

3

Speaker(s)

Chia-Yi Chang

Topic

The epidemiology and pathogenesis of novel porcine epidemic diarrhea virus in Taiwan

Abstract

Between January 20 and July 30 of 2014, a total of 119 samples from 54 herds in 13 counties were submitted to the Animal Health Research Institute. In 20 of the 25 herds with detail histories, including severe diarrhea and vomiting occurred in pigs of all ages, with mortality approximately 100% in suckling pigs. The differential etiologies, including transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), and porcine group A rotavirus (GARV), were tested by reverse transcription polymerase chain reaction (RT-PCR). The RT-PCR of PEDV was positive in 86 cases of 39 herds. Attempts to isolate PEDV in Vero cells revealed that only 7 specimens from 7 herds showed the cytopathic effects (CPEs) of fusion and syncytia. These CPEs were indeed caused by PEDV, as confirmed by RT-PCR, sequencing, and electron microscopy. Sequence comparisons of diarrhea samples and isolated PEDV were assayed by MEGA 5.2 software. The newly isolated PEDV/Taiwan/2014 strains were clustered in group 2 as novel PEDV, together with strains PEDV/USA/2013, PEDV/ China/2011–2013, and PEDV/Korea/2014, whereas the classical CV777 strain and historic Taiwan strains were placed in a separate group 1. Further, the virulence of novel PEDV was examined in the suckling pigs with 7 days old. The diarrhea and vomiting were shown in all pigs inoculated with 107 TCID50 PEDV. The mortality reached to 50%. These results indicated that a novel PEDV was the cause of the recent new outbreak of diarrhea in Taiwan and was high virulence in pigs.