The Current Status of Porcine Circovirus Vaccine Development and the Introduction of Testing Standards
Chiao-Chien Chu
Abstract
Porcine circovirus type 2 (PCV2) is a significant viral disease in pigs, primarily causing porcine circovirus-associated disease (PCVAD). The clinical symptoms include wasting, increased post-weaning mortality, and an elevated risk of co-infection with other pathogens, leading to immense economic losses in the pig industry. PCV2-inactivated vaccines can prevent or alleviate the clinical symptoms caused by PCV2, decreasing pig mortality and consequently reducing economic losses. There are two types of PCV-inactivated vaccines, and they are produced using different manufacturing methods. One is a whole-virus inactivated vaccine, and the other is a recombinant vaccine, which is produced by expressing the open reading frame 2 (ORF2) gene of PCV2 in the cell line or appropriate expression systems, followed by inactivation and the addition of suitable adjuvants. Due to the various forms and manufacturing processes of PCV2 vaccines, the choice of different examination methods for efficacy are based on their characteristics, such as relative potency, content of antigen, and antibody titer test, etc.
Important diseases inspection activity of Emerging Animal Disease Division for imported breeding pigs and TAF certification
Tsu-Han Chen
Abstract
In the past three years, a total of 1,347 samples of breeding pigs have been imported from the United States, Denmark, Canada, and France have been submitted to VRI. These samples were tested by the swine vesicular disease virus (SVDV) antibody competitive enzyme-linked immunosorbent assay (C-ELISA), the SVDV neutralizing antibody test (VNT), and the African swine fever virus (ASFV) real-time polymerase chain reaction (qPCR) test. These methods were applied to detect SVDV antibodies and ASFV nucleic acids, with results showing sensitivity and specificity over 95%. The SVDV-C-ELISA was used as a screening test, while the SVDV-VNT served as the final confirmatory test. During participation in the annual inter-laboratory and intra-laboratory proficiency test program, the results demonstrated high levels of consistency, specificity, and reproducibility. As a result, our laboratory currently passed 12 certifications under TAF ISO/IEC 17025:2017 and CNS 17025:2018, including certification for ASFV qPCR. Additionally, we are focusing on achieving TAF certification for three methods this year, including the SVDV-C-ELISA, the SVDV-VNT, and the pseudo-rabies virus antibody ELISA. These efforts aim to enhance the quality assurance of our laboratory, strengthen diagnostic technology, and support prevention and quarantine policies of Taiwan. By integrating these efforts, we contribute to the testing of imported breeding pigs, playing a key role in safeguarding food safety, and strengthening bio-security measures of our country.
A report on technique visit in US for genetic manipulation of classical swine fever virus and African swine fever virus
Wei-Cheng Hsu
Abstract
Classical swine fever and African swine fever are two critically important diseases affecting global pig industry. Prevalent in Asia, these diseases are known for their rapid transmission and high mortality rates among pigs. The potential invasion of these diseases poses significant risks to the industry and could lead to substantial economic losses, highlighting the urgent need for research in viral genetic manipulation to effectively combat these pathogens. In response to this need, two researchers from Veterinary Research Institute were assigned to Professor Yung-Fu Chang’s laboratoryat the Department of Population Medicine and Diagnostic Sciences, Cornell University College of Veterinary Medicine, from May 5 to May 18, 2024. During this period, they gained advanced skills and knowledge in vaccine design principles and techniques, including virus genome editing and recombination technologies such as mRNA vaccines and multi-epitope vaccines. These techniques enhance the efficiency and efficacy of vaccine development while also reducing the use of experimental animals, in line with humane research practices. Additionally, the researchers visited the Cornell University Animal Health Diagnostic Center, which is equipped with advanced diagnostic technologies and strict safety protocols. Overall, this training has significantly improved our expertise in relevant technologies and is expected to facilitate future breakthroughs in vaccine development, thereby strengthening our country's ability to defend against foreign animal diseases.