2002-2004年台南縣牛流行熱抗體監控及病毒分離鑑定

Virus Identification and Serum Antibody Monitoring of Bovine Ephemeral Fever in Tainan County during 2002-2004

謝耀清(Yao-Ching Hsieh,) ； 陳世輝(Shih-Hui Chen) ； 黃晉瑩(Jing-Ying Huang) ； 李儼峰(Yen-Feng Lee) ； 蔡耿宇(Keng-Yu Tsai) ； 劉宏仁(Hung-Jen Liu)

《臺灣獸醫學雜誌》 31卷3期 (2005/09) Pp. 208-216

https://doi.org/10.7009/TVJ.200509.0208

摘要

台南縣在2001年10月爆發牛流行熱疫情後，即進行全面疫苗注射，為了定期監控牛流行熱血清中和抗體的變化情形，本研究在台南縣選取5場牛場，每場選取5頭未成年牛隻及10頭成年牛隻，以血清中和抗體試驗進行三年之監測，共檢測2700個樣品。結果顯示，在2002年成牛平均血清中和抗體力價（159.12±43.99倍）高於2003年（142.04±49.04倍）與2004年（101.06±35.23倍）（P＜0.0025），有顯著差異。經疫苗補強免疫後，血清中和抗體力價約維持4-5個月後開始消退，但成牛牛群整年平均血清中和抗體力價為134.07±29.8倍，且血清中和抗體均呈週期性的變化，而未成年牛群整年平均血清中和抗體力價為69.56±39.97倍。經調查發現血清中和抗體週期性消退的情形以2004年最為顯著，在7月份成牛抗體消退至32倍以下的百分比為28%，而未成年牛約72%。於2004年8月份爆發疫情後，進行病毒分離並以DNASTAR軟體進行親源關係分析比較，發現2004年分離株與2001年及1999年之差異度在0.3-0.4%，而與1984及1996年差異度在1.2-2.5%。經分析發現（1）牛群抗體隨著疫情爆發後有逐年消退趨勢，（2）牛群抗體消退的時間點在每年6-7月份與11-12月份最為明顯，（3）牛流行熱疫情的爆發與群體牛隻血清抗體週期性消退具關聯性，（4）疫情發生的間歇期有逐年縮短的現象，與疫情爆發的強度有關，（5）1996年以後病毒分離株與1984年之分離株在抗原決定位上的胺基酸發生變異。本研究可供牛流行熱新式疫苗研發及國內防疫之參考。

關鍵字

牛流行熱 ； 中和抗體 ； 親源關係分析

並列摘要

Due to the 2001 bovine ephemeral fever (BEF) outbreak, cows in Tainan county were vaccinated against BEFV infections. To monitor the serum neutralizing (SN) antibody profiles of BEF, five farms in Tainan county were monitored monthly during 2002-2004. Five immature calves and 10 mature cows in each farm were monitored during these years. The mean SN titers of mature cows were 159.12 ± 43.99 in 2002 that was higher than that in 2003 (142.04 ± 49.04) and 2004 (101.06 ± 35.23) . After booster, the SN titers were maintained at the mean levels for 4-5 months and then declined. Mature cows had the mean SN titers of 134.07 ± 29.8, while immature calves had the mean SN titers of 69.56 ± 39.97. In this study, we found the periodic decline of SN in 2004 was the most remarkable. In July 2004, the SN titers of 28% of mature cows and 72% of immature calves were lower than 1:32. Three BEFV strains have been isolated since the 2004 outbreak. Sequence and phylogenetic analysis by DNASTAR software package indicated that the 2004 isolates were closely related to the 2001 and 1999 isolates, sharing 99.6-99.7% homology. The 2004 isolates were distantly related to the 1984 and 1996 isolates and shared 98.8-97.5% identity with these isolates. Our results indicated that (1) the gradual decline of SN titers follows the BEF outbreaks, (2) the decline of SN titers was most remarkable in June-July and November-December, (3) the BEF outbreaks were correlated with the periodic decline of SN titers, (4) the shorter epizootic intervals were related to the incidence and scale of BEF, and (5) variations within epitopes on the G protein of BEFV occurred between 1984 isolates and strains isolated after 1996.

並列關鍵字

bovine ephemeral fever ； neutralizing antibody ； phylogenetic analysis