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Seminar 936

Date:2022-10-19 Update:2022-10-19

Evolution of H5 highly pathogenic avian influenza viruses circulating in Taiwan during 2015-2020

Yu-Ju Lin

 

Abstract

A novel H5 highly pathogenic avian influenza virus (HPAIV) of clade 2.3.4.4c has caused outbreaks in Taiwan since January 2015 and become an endemic virus. There were three waves of clade 2.3.4.4c H5Nx reassortants detected, occurring in the fall of 2016, the spring of 2018, and the autumn of 2019. With the third wave, new H5N5 reassortants appeared. Invading clade 2.3.4.4c of the H5Nx subtype was quickly replaced in 2022 by clade 2.3.4.4b of the H5N2 virus. The H5N1 subtype of clade 2.3.4.4b is currently the most common epidemic strain worldwide. The continuous circulation of HPAI H5Nx variants and the emergence of novel reassortants in Taiwan highlight that the surveillance, biosecurity, and management systems of poultry farms need to be improved and carefully executed.

 

Isolates of Anthrax-like Bacillus cereus group from diseased soft-shelled turtles

Tzu-Ming Huang

 

Abstract

Since 2014, several sample cases from soft-shelled turtles (SST) have been submitted to the Animal Health Research Institute from southern Taiwan. The clinical symptoms of the submitted cases included neck torsion and sudden death, with lesions caused by hyperemia in the laryngopharyngeal mucosa, edemas in the mesentery, and enlargements of the liver and spleen. Intracellular bacterial clusters were noted in the liver and kidney microscopically. Large whitish and waxy colonies with beta-hemolysis were obtained by bacterial overnight culture with blood agar plates and the bacterial isolates were determined to be Gram-positive bacilli. Biochemical characterization and comparison of 16s rRNA gene sequences, identified the isolates as belonging to the Bacillus cereus group, BCG. The Bacillus cereus group of microorganisms contains several species of Bacillus, including B. cereus, B. thuringiensis, B. anthracis, B. mycoides, and B. weihenstephanensis. BCGs are known to cause food poisoning outbreaks and are thus an important pathogen of food-borne disease in Taiwan. Moreover, they can be isolated from aquatic specimens. However, BCGs rarely cause severe infections in animals resulting in disease. Detection of virulence factors by the polymerase chain reaction (PCR) 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 isolates. To further investigate potential pathogenesis mechanisms, detection of the plasmids encoding the production of anthrax toxin and capsule in B. anthracis, pXO1 and pXO2, respectively, was conducted via PCR detection, according to the WOAH Terrestrial Manual 2018, and resulted in the positive detection of pXO1 in SST isolates. It therefore seems likely that anthrax-like BCG caused infections among SST in Taiwan.

 

 

To attend 2022 Bilateral Cooperation Meeting on Agricultural Science and Technology in USA and visit the Beltsville Agricultural Research Center

Jen-Chieh Chang, Tzu-Ming Huang, Ming-Chung Deng, Chwei-Jang Chiou

Abstract

The 2022 Bilateral Cooperation Meeting on Agricultural Science and Technology was held on August 2, 2022 by the U.S. Department of Agriculture (USDA) at Washington, D.C., the capital of the United States of America. Both sides discussed and concluded five research issues: Animal Health, Animal Production, Crop Production & Protection, Natural Resources & Sustainable Agriculture Systems, and Nutrition, Food Safety & Quality. The chairpersons of each research issue were a director general of research institutes of Council of Agriculture, Taiwan and a National Program leader of USDA. The project “Molecular epidemiology of Seneca Valley virus in Taiwan and development of its diagnostic kit” was proposed by the Animal Health Research Institute (AHRI).  With the collaboration of National Animal Disease Center, Agriculture Research Service (ARS), the project aims to obtain full-length genome sequences of Seneca Valley virus (SVV) and then to investigate sequence differences among SVV strains of Taiwan, the USA, and other countries. In addition, the ARS will assist the Taiwan side in evaluating an ELISA with field sera shared by the USA side when the prototype ELISA of SVV antibodies was developed by the AHRI. In addition, the ongoing program of Molecular Approach to Antimicrobial Resistance (AMR) was discussed. This program was involved in surveillance of AMR and whole genome sequencing (WGS) analysis, carried out by the guidance of the US expert. The Taiwan delegation visited the Beltsville Agricultural Research Center (BARC) and progresses and results of some ongoing projects were discussed with the experts of BARC on August 1, 2022. Animal Parasitic Diseases Laboratory (APDL) of BARC would like to assist AHRI to study the parasitic diseases and then to broaden understanding of the change of parasitic diseases as a result of climate change.

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