1

Speaker(s)：

Shu-Chia Hu

Topic

2017 Rabies Diagnostic and Monitoring Conference in Japan

Abstract

The 2017 Rabies Diagnostic and Monitoring Conference was held at the National Institute of Infectious Diseases, Japan from Jan 5th - 17th, 2017. Rabies prevalence, monitoring, risk assesment, and control policies for each country were exchanged during the conference. Furthermore, a course for rabies detection techniques (using diagnostic techniques such as: real-time reverse transcription polymerase chain reaction, reverse transcription loop-mediated isothermal amplification, direct rapid immunohistochemical test) was scheduled during the visit. A vsit to the pathological laboratory of Dr. Park Chun-Ho in Kitasato University was also arranged, and Dr. Park Chun-Ho kindly shared with us his expertise on rabies pathology.

2

Speaker(s)：

Tzu-Ming Huang

Topic

Characterization of Bacillus cereus group isolates obtained from aquatic animals

Abstract

The Bacillus cereus group of microorganisms contains several species of Bacillus, including B. cereus, B. thuringiensis, B. anthracis, B. mycoides and B. weihenstephanensis. Members of the Bacillus cereus group are known to causes food poisoning outbreaks, and is thus an important pathogen of food-borne disease in Taiwan; moreover, they can be isolated from aquatic specimens. The objective of the present study was to identify the species, virulence factor, and pathogenicity of members of the Bacillus cereus group isolated from aquaculture. In total, 7 isolates from soft-shelled turtles (SST) and 3 isolates from fish were successfully cultivated. Sequencing of the16S rRNA gene revealed that all isolates belonged to the Bacillus cereus group. More specifically, sequencing of the gyrB gene indicated that the 7 isolates from SST were B. thuringiensis and the 3 isolates from fish were B. cereus. Detection of virulence factors by the polymerase chain reaction revealed the presence of genes encoding for the hemolysin BL and the non-hemolytic enterotoxin among SST isolates, as well as enterotoxin T among the fish isolates. The SST isolates demonstrated high sensitivity to oxytetracycline but resistance to sulfonamide. Intraperitoneal injection of B. thuringiensis isolate into SST at a dosage of 106 CFU (colony forming unit) resulted in a 83% mortality rate two weeks post-infection. We, thus demonstrate that members of the Bacillus cereus group can be isolated from aquaculture operations and that the B. thuringiensis isolated from SST was pathogenic and sensitive to oxytetracycline. In the future, the detection of crystal toxins in SST isolates will be necessary to confirm that it is a bona-fide B. thuringiensis.

3

Speaker(s)：

Sue-min Huang

Topic

A bivalent inactivated vaccine of viral nerves necrosis virus and grouper iridovirus applied to grouper broodfish (Epinephelus coioides) reduces the risk of vertical transmission

Abstract

Forty-one broodfish of orange-spotted groupers (Epinephelus coioides) were selected to ‎evaluate the effectiveness of the viral nerves necrosis (VNN) virus and the grouper iridovirus (GIV) inactivated bivalent vaccine in grouper broodfish. Real-time quantitative PCR analysis resulted in a detection rate of 4.1% (2/41) for both VNN and GIV in E. coiodes broodfish eggs. In addition, approximately 1780 copies of GIV viral DNA were detected in broodfish eggs pre-vaccination and thus confirmed vertical transmission of GIV in E. coiodes broodfish. A significant increase of the serum antibody titer of anti-VNN was >50% higher in the high titer level (1:1810 to 1:5120) and 45% higher in the moderate titer level (1:452 to 1:1280), which were both respectively higher than the serum antibody titer of the anti-GIV display 50% (10/20) in a titer of 1:57 to 1:320 and 40% (8/20) in a titer of 1:452 to 1:1280 one month post-vaccination. These results demonstrate that VNN is a highly antigenic virus and can effectively induce neutralizing antibodies better than GIV. Furthermore,the VNN and GIV viral copy numbers were 97.1 and 1780 copies/μg DNA, respectively, in broodfish eggs pre-vaccination. One month after the vaccination, the viral genomes of VNN and GIV were undetectable in egg specimens. These results indicate that immunization can induce a specific neutralized antibody conferring protection, and the infected antigen can thereby be eliminated by immunity in vivo. We therefore demonstrate that the specific antibodies of GIV and VNN induced by vaccination can reduce the risk of vertical transmission of VNN and GIV in E. coiodes broodfish.