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Seminar 873  
Date:2017-05-25
Update:2017-11-06

  

Seminar:  873

1

Speaker(s)

Wan-Chen Li

Topic

Identification and genomic characterization of avian bornavirus isolated from an African grey parrot

Abstract

Avian bornavirus (ABV) can infect a variety of birds including a variety of rare and endangered parrots, canaries, Canada geese, mallards, and munia. Avian bornavirus is a neurotropic virus and its infection can lead to chronic andfatal proventricular dilatation disease (PPD) in parrots. According to the differences between ABV genomes, the International Committee on Taxonomy of Viruses (ICTV) reclassified the genus Bornaviruses into five species in 2015. Parrot bornavirus 2 (PaBV-2) and parrot bornavirus 4 (PaBV-4) are the most common types detected in parrots with PPD. In 2016, we detected and isolated an ABV from an African gray parrot which was reared in a breeding farm and had clinical signs of PPD. The viral genome sequence of the isolated ABV was most closely related to PaBV-4, (full-length genome similarity of ~95%). Since this case of PDD was discovered, the breeding farm has improved its sanitation practices, and no similar case have been reported.

2

Speaker(s)

Re-Shang Chen

Topic

Research and development of a Porcine Epidemic Diarrhea Virus Vaccine

Abstract

Porcine epidemic diarrhea virus (PEDV) was first discovered in the UK in 1971, and was identified throughout Europe in the 1980s and 1990s. In the 2010s, a new variant strain of PEDV (nvPEDV) emerged in the Southeast Asian countries, Thailand, Vietnam, Philippines, as well as China. In April 2013, the first outbreak of nvPEDV occurred in the United States and spread rapidly, leading to the death of more than 8 million piglets, resulting in disarray among the world's pork suppliers, affecting prices considerably. In October, 2013 an outbreak also occurred in Taiwan caused by a similar strain of nvPEDV (PEDV Taiwan / 2014) to that of the US. The virulence and shedding duration of this nvPEDV outbreak strain was stronger and longer compared with the older CV777 strain of PEDV viruses. In general, nvPEDV infected piglets display more pronounced symptoms of severe diarrhea, vomiting and dehydration, accompanied with high mortality. At present, there are a few commercialized PEDV vaccines designed to combating classical PEDV. In order to control nvPEDV re-emergence among pig farms, a new PEDV vaccine by traditional virus attenuating methods or genetic engineering technology, is heavily required by the market. As the PED virus mainly invades the small intestinal villi cells, an effective vaccine should ideally protect the piglets within the first 10 days post-birth against the highest potential nvPEDV challenge. This nvPEDV vaccine will be developed using traditional methods to develop a live attenuated virus vaccine as well as an inactivated vaccine, and to inoculate sows and piglets, thereby reducing the economic losses of PEDV. This nvPEDV vaccine will take the PEDV / Taiwan / 2014 isolates and adapting them to Vero cells in order to develop safe, effective, and high-titre PEDV vaccine strains. We will then compare the PEDV sequences between the field strains and the attenuated strains. Based on these results, we will select and screen the strains producing highest nvPEDV virus titers. Further studies are then planned concerning the adjuvant, antigen preparations, administration routes and laboratory tests (e.g., characterization tests, aseptic tests, viral contamination tests, safety and efficacy trials, etc.). Finally, safety and efficacy tests for the nvPEDV vaccine in field trials will be performed according to regulations in Taiwan. To develop an effective and safe nvPEDV vaccine, we are constantly innovating and using a variety of new technologies in order to protect swine from nvPEDV infection and thus help reduce economic losses for Taiwanese pig farmers.