Evolution of the possibility of establishing a caprine arthritis encephalitis virus (CAEV) free flock and study on the mechanism of CAEV-induced chronic arthritis

• Main Authors: I.Ting.Chao, 趙怡婷
• Other Authors: W.C.Lee
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/24090969744456463098

碩士 === 國立中興大學 === 獸醫學系 === 88 === Abstract Caprine arthritis encephalitis is a chronic progressive debilitating disease. Taiwan has become a high prevalent area. The first aim of the experiment was to evaluate the possibility of establishing a CAEV free flock. A dairy goat farm which had been regular surveillance on CAEV infection in our laboratory was used to evaluate the possibility of establishing CAEV free flocks. Two flocks, 17 months old (F1-1) and 4 months old (F1-2) both which were born from the same dam (F0) and fed by heated pooled colostrum were used in this study. Blood were regularly sampled and tested every 3-4 month interval and CAE seropositive goats were culled or separated. After one year intensive surveillance and culling test, the accumulative seropositive rate of F1-1 and F1-2 flocks were 40.1% and 14.8%, respectively, which were compared to 67.9% of F0 dam tested before the experiment. Comparison the accumulative seroconversive rate at the age of 9 - 10 months old of F1-1 , F1-2 , and F2 (kids delivered from F1-1, F1-2) were 16.7 %, 8.3 %, and 4.4 %, respectively. Moreover, a cross-section serological surveillance on 6 dairy goat farms using heated colostrum to feed neonate kids, the average seropositive rate of 10 months old goat for CAE were 42.3+29.0 % (0 - 81.8 %), which was significant higher than the farm with intensive serological surveillance and culling system (P<0.05). In contrast to another 4 dairy goat farms using non-heated colostrum to feed neonate kids, the average seropositive rate of 10 months old goat were 74.1+27.2% (42.9 — 100 %), which was significant higher than previously heat treated colostrum groups (P<0.05). The results suggest that it is possible to establish a CAE free farm by gradually decreasing the reservoirs, feeding kids using heated colostrum, culling or separating system by intensive serological surveillance, and obtaining the full cooperation by raiser. On the other hand, the immunopathological appearance of CAEV-induced arthritis is similar to the lesion of rheumatoid arthritis (RA) in human. Thus, in order to understand the mechanism of CAEV-induced chronic progressive arthritis, the experiment was studied on the phenotype of peripheral blood mononuclear cells (PBMC) and synovial fluid (SF) using flow cytometry and the change of cellular compartment of elbow lymph nodes using computer-assisted morphometric analysis. The result showed that the relative number of CD4+ T lymphocytes in PBMC was significantly increased with the lesion of arthritis, whilst, IgG+ B cells in PBMC was significantly decreased (P<0.05) as compared to negative control. Markedly increasing CD8+ T lymphocytes in synovial fluid was noted in those CAEV- infected goats with swollen joints. There was a significant increasing IgG concentrations in synovial fluid from CAEV infection with or without swollen joints as compared to unifected controls. T cell dependent area (paracortex) in elbow lymph nodes from CAEV infected goats with marked synovial lesion were marked hyperplasia, when compared to uninfected goats without synovial lesion. Moreover, virus antigen expression in lymph nodes and synovial membrane were markedly increased with lesion of synovial membrane. Those results suggest that an abnormal regulation in controlling viral replication may be the crucial point in the formation of progressive arthritis during CAEV infection.