S-Space College of Veterinary Medicine (수의과대학) Dept. of Veterinary Medicine (수의학과) Theses (Ph.D. / Sc.D._수의학과)
Evaluation of Type 1 Porcine Reproductive and Respiratory Syndrome Virus Vaccines based on Clinical, Virological, Immunological and Pathological Analyses
유럽형 돼지 생식기 호흡기 증후군 바이러스 백신의 임상학적, 바이러스학적, 면역학적, 병리학적 분석을 통한 평가
- 수의과대학 수의학과
- Issue Date
- 서울대학교 대학원
- Boar; Piglet; Cross-protection; Porcine Reproductive and Respiratory Syndrome Virus; Semen; Vaccine; Vaccine efficacy
- 학위논문 (박사)-- 서울대학교 대학원 : 수의과대학 수의학과 수의병인생물학및예방수의학전공, 2016. 2. 채찬희.
- The Porcine Reproductive and Respiratory Syndrome Virus was first recognized in the early 1900s as a cause of reproductive losses in sow and severe respiratory disorders in growing pigs. PRRSV is recognized by 2 genotypes: Type 1 (European genotype) and Type 2 (North American genotype). Although these two PRRSV genotypes produce the same disease symptoms, they are significantly different antigens. Until late 2000s, Type 2 PRRSV was the main genotype in Korea. After the first detection of Type 1 PRRSV in 2005, the proportion of Type 1 PRRSV has continuously increased. Until 2013, Type 2 PRRSV vaccines were the only vaccines available in Korea. However, the modified live virus (MLV) vaccines for Type 1 PRRSV became available in 2014. Therefore, in order to evaluate the efficacies of commercial vaccines, it is reasonable to measure the cell-mediated immunity, humoral immunity, pathological and clinical responses against these two types of PRRSV.
A study was performed to compare the efficacies of two commercial Type 1 PRRSV MLV vaccines against heterologous Type 1 and Type 2 PRRSV challenge in growing pigs and boars. For the study of growing pigs, a total of 112 pigs were randomly divided into 7 groups
4 vaccinated and challenged groups, 2 non-vaccinated and challenged groups, and a negative control group. According to this study, commercial Type 1 PRRSV MLV vaccines could reduce the level of viremia against Type 1 PRRSV, but it could not reduce the level of viremia against Type 2 PRRSV. Low level of IL-10 and high level of Type 1 PRRSV-specific IFN-γ-SC were both detected within Type 1 PRRSV challenged groups, whereas high level of IL-10 and low number of Type 2 PRRSV-specific IFN-γ-SC were detected in vaccinated pigs within Type 2 PRRSV challenged groups. Type 1 PRRSV vaccines effectively reduced the lung lesions and Type 1 PRRSV nucleic acids in Type 1 PRRSV challenged groups. However, both the lung lesions and Type 2 PRRSV nucleic acids did not reduce in Type 2 PRRSV challenged groups. Accordingly, the Type 1 PRRSV commercial vaccines can provide partial protections against Type 1 PRRSV challenge but cannot provide effective protection against heterologous Type 2 PRRSV challenge.
For the study of boars, a total of 35 purebred Landrace boars were randomly divided into 7 groups
4 vaccinated and challenged groups, 2 non-vaccinated and challenged groups, and a negative control group. In this study, the clinical symptoms were reduced by Type 1 PRRSV MLV vaccines after challenging with Type 1 and Type 2 PRRSV. Seminal shedding of PRRSV was independent of viremia. The reduction of Type 1 PRRSV seminal shedding coincided with the appearance of Type 1 PRRSV-specific IFN-γ-SC in Type 1 PRRSV-challenged groups. The frequencies of Type 1 PRRSV-specific IFN-γ-SC induced by Type 1 PRRSV vaccine were relatively high compared to Type 2 PRRSV-specific IFN-γ-SC induced by the same vaccine. The PRRSV MLV vaccine can provide a more effective protection against the same genotype than a different genotype in terms of seminal shedding of PRRSV in boars.