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Seminar 935

Date:2022-09-28 Update:2022-12-30

Development of a Marek’s disease vaccine for poultry

Chia-Chia Chang



Marek's disease (MD) is a highly contagious viral disease of poultry, and chickens are the most important natural host for Marek’s disease virus (MDV). MDV is a lymphoproliferative disease caused by oncogenic (serotype 1) strains of Marek’s disease herpesvirus (MDV) belonging to the Herpesviridae family. This disease is marked by the presence of T-cell lymphomas as well as lymphocytic infiltration of nerves and organs. Marek’s disease can be successfully controlled by vaccination with attenuated or non-pathogenic MDV strains to reduce depression, paralysis, and death in infected chickens. Current commercially available vaccines against MD are not only a combination of different serotypes, but also include virally vectored recombinant vaccines and these various vaccine types can be combined into one. In today’s talk, I will introduce the current development status of a Marek’s disease vaccine and the protocols for the determination of its safety and efficacy.

Activity of wild type classical swine fever virus in swine herds subjected to varying vaccine regimens

Yu-Liang Huang



Classical swine fever (CSF) is a highly contagious and hemorrhagic disease which is listed as an important infectious diseases affecting pigs worldwide, by the World Organization for Animal Health (WOAH). There has not been a single CSF case during the past 10 years in Taiwan. Therefore, following FMD elimination in Taiwan, CSF is the next disease planned for elimination. Currently, the administration of a CSF vaccine is the primary method for CSF prevention on Taiwanese pig farms. The protective efficacy of vaccine immunization, will therefore directly affect the successful prevention of CSF in in the commercial pig herds. To understand the protection conferred to pigs vaccinated under varying dosage regimens, we monitored live animals with varying levels of maternally-derived antibodies (MDA) subjected to the attenuated CSF vaccine or without the vaccine. Attenuated CSFV vaccines were administered to pigs exhibiting high MDA, and after the parity pigs came into contact with CSFV-infected pigs, they displayed a short period of viremia and shedding of CSFV. On the other hand, pigs exhibiting high MDA but which were not administered the CSFV vaccine, demonstrated severe clinical signs, viremia, shedding of CSFV and were able to transmit CSFV to the other pigs. In conclusion, CSFV vaccination should be administered to herds exhibiting CSFV activity in the form of MDAs.

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