1

Speaker(s)：

Sue-Min Huang*, Chien Tu

Topic

Development of bivalent vaccine of iridovirus and nervous necrosis virus in grouper

Abstract

We selected the field isolates with high virulence and antigenicity of grouper iridovirus (GIV) and nervous necrosis virus (NNV) as the seed virus for immersion vaccination used in field tests. The safety tests of the bivalent vaccine demonstrated that the vaccine groups were better than control group in weight gain of fish. The efficacy of the bivalent vaccine in NNV was evaluated by intramuscular injection with 109TCID50/mL NNV and the result revealed significant protections at 14, 45 and 60 days post-vaccination (p < 0.05), respectively. In addition, the efficacy of the bivalent vaccine was evaluated by intraperitoneal injection with 107TCID50/mL GIV virus and the result revealed the significant protection only at 60 days post-vaccination (p < 0.05). These results demonstrated the effective protections of immersion types bivalent vaccine against NNV in giant grouper (Epinephelus lanceolatus) lasted for 60 days post-vaccination and against GIV only started at 60 days post-vaccination. Future study may be undertaken in the future.

2

Speaker(s)：

Jen-Chieh Chang

Topic

Application of the rapid fluorescent focus inhibition test (RFFIT) for the evaluation of rabies vaccine efficacy and the detection of rabies neutralising antibodies in wild animals of Taiwan

Abstract

For understanding the efficacy of commercially available inactivated rabies vaccines as well as an oral vaccine and the serological surveillance of rabies in wildlife, the rapid fluorescent focus inhibition test (RFFIT), for determining the levels of antibodies to rabies virus in serum, was introduced. Ferret badgers were vaccinated with each of four commercially available inactivated rabies vaccines (vaccines A, B, C, and D, prescribed for dogs and cats) and their titers of antibodies to rabies were monitored. Seroconversion in the vaccinated ferret badgers were detected two weeks post-vaccination. The seropositive rates (titer >0.5 IU/mL) of ferret badger groups A, B, C ranged from 50 to 100% 12 months post-vaccination; in comparison, ferret badgers in group D showed a decrease in antibody titers over time and most titers were less than 0.5 IU/mL starting at four months post-vaccination. Our data indicates that some commercially available inactivated rabies vaccines may be useful for ferret badger vaccination. Application of inactivated rabies vaccines using trap-vaccine-release tactics for immunizing wildlife was proposed as a rabies control strategy. In the application of an oral vaccine, seroconversion rate (titer >0.05 IU/mL) was 80% (12/15) two weeks post-vaccination, and then decreased down to 66.7% (10/15) two months post-vaccination. Fifty-one sera from 23 ferret badgers, 5 crab-eating mongooses, 6 gem-faced civets and 17 Formosan macaques were tested by the RFFIT. Five sera of the 23 ferret badgers (21.7%) tested positive and three of them showed nervous clinical signs and illness. Four of the five seropositive ferret badgers (80%) showed nervous clinical signs and tested positive by the fluorescent antibody test. We found seroconversion in rabid ferret badgers but couldn’t conclude if the rabid ferret badgers have longer incubation times before death. Further surveillance of serology in Taiwan ferret badgers should be carried out, especially in the buffer zones between rabies-epidemic and rabies-free areas.

3

Speaker(s)：

Yu-Liang Huang, Ming-Chung Deng

Topic

Methods training for the diagnosis and prevention of highly pathogenic porcine reproductive and respiratory syndrome at the Japan National Institute of Animal Health

Abstract

Highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRS) is an important transboundary swine disease. Since 2006, the disease has spread into Southeast Asia and damaged not only large commercial farms but also the backyard industry. In order to learn the effective methods for the diagnosis and prevention of HP-PRRS in swine, Dr. Yu-Liang Huang and Ming-Chung Deng visited the Japan National Institute of Animal Health from 4 August through 11 August, 2016. During this period, biosafety training was firstly carried out. Dr. Tagaki provided this training course which covered animal experiments, pathological examination, virus isolation, serological tests, and nucleic acid detection methods for HP-PRRSV. In addition to HP-PRRSV training, the epidemiology and prevention of PRRS in Japan was also discussed.