篇名:
黃牛感染O/Taiwan/99口蹄疫病毒後抗3AB抗體之發展Anti-3AB antibodies in the Chinese yellow cattle infected by the O/Taian/99 foot-and-mouth disease virus
作者:
黃金城;李 璠;杜文珍;李淑慧;黃天祥;林有良;鍾明華;林士鈺
中文摘要:
O/Taiwan/99口蹄疫病毒於1999年入侵台灣。黃牛在實驗室或野外感染此病毒都不會發展成水?性臨床症狀。我們使用ELISA的方法法,以口蹄疫病毒結構蛋白3AB為抗原,評估3AB抗體的發展及持續時間之長短,此評估可以了解病毒在黃牛體內增殖之情形。首先使用疫苗免疫產生之抗血清及未感染的陰性血清測得ELISA試劑的專一性約99%,而敏感性測試則使用黃牛自然感染之陽性血清測得為60%。在實驗動物的學習則顯示黃牛比其他動物發展較低的抗3AB抗體。另外我們追蹤天然感染的黃牛3AB抗體持續時間,發覺爆發感染後約維持6個月即消失。這些結果建議黃牛似有較強之抵抗性限制病毒之增殖及減少3AB抗體的發展。
英文摘要:
The O/Taiwan/99 foot-and-mouth disease virus (FMDV), a South Asian topotype of serotype O, was introduced into Taiwan in 1999. The Chinese yellow cattle infected by the virus did not develop clinical lesions under experimental and field conditions. A blocking enzyme-linked immunosorbent assay (ELISA) kit with the 3AB antigen, a polypeptide of FMDV non-structural (NS) proteins, was used to evaluate the development and duration of anti-3AB antibodies, proving active viral replication, in the Chinese yellow cattle. The specificity of the assay was 99%, as was established with negative sera from regularly vaccinated and from naive cattle. The sensitivity tested with sera from naturally infected animals was approximately 64% and it was lower than that obtained by serum neutralization (SN) test. Under experimental infection, the Chinese yellow cattle developed lower anti-3AB antibodies than that developed in other species. Duration of anti-3AB antibodies was traced in two herds of naturally infected animals, indicating that anti-3AB antibodies persisted for approximately 6 months after outbreaks. On the basis of this study, we propose that the Chinese yellow cattle may have natural resistance, which limits viral replication and reduces the development of anti-3AB antibodies. c 2002 Elsevier Science B.V. All rights reserved.
備註:
年份:西元 2001 年
期別:第 37 期
詳細內容:
Foot-and-mouth- disease (FMD) is widespread in many regions of the world including parts of Africa, Asia, Middle East and South America. Recently, FMD in ruminants caused by a strain of South Asian topotype of serotype O (Kitching, 2000) has spread to most regions of Asia, including China, Cambodia, Vietnam, Thailand, Lao, South Korea, Japan, Russia, Mongolia, and Taiwan. It has caused an economically devastating impact on affected countries mostly because of trade barriers, which are imposed where the disease occurs.  For those parts of the world where FMD is prevalent, commercial vaccines are widely used to control the disease. Intensive vaccination programs have the benefit of reducing the probability of spread to neighboring regions where vaccination is not practiced. Considering the ability of foot-and-mouth disease virus (FMDV) to establish persistent infection in ruminants (Kitching, 1992; Salt, 1994; Woodbury, 1995), a reliable tool to estimate the asymptomatic viral activity in animal populations should be an important contribution for monitoring the FMD situations. Recently, the possibility to differentiate infected from vaccinated animals based on the development of antibodies against non- structural (NS) proteins of FMDV has been intensely studied (Villinger et al., 1989; Rodriguez et al., 1994; Lubroth and Brown, 1995; Silberstein et al., 1997; Mackay et al., 1998a; Sorensen et al., 1998). Now there is agreement that the detection of antibodies to the NS polyproteins 3ABC and 3AB is the most reliable indicator of previous infection with FMDV (De Diego et al., 1997; Mackay et al., 1998a; Sorensen et al., 1998; Lubroth et al., 1998; Malirat et al., 1998; Brocchi et al., 1998). Enzyme-linked immunosorbent assays (ELISAs) based on recombinant FMD NS viral antigens produced by various expression systems (Sorensen et al., 1998; Mezencio et al., 1998; Mackay et al., 1998b; Bergmann et al., 2000) have been used to evaluate the development and duration of anti-NS proteins antibodies. One of these studies (Mackay et al., 1998b) indicates that the levels of anti-3ABC antibodies in infected animals may be related to the development of clinical signs. For example, all animals, which showed clinical lesions seroconverted to 3ABC by 1 month after experimental infection and remained seropositive for longer than 12 months. However, response to 3ABC in vaccinated and sub-clinically infected animals developed slowly and only 80% of the animals were seropositive at 2 months after infection (Mackay et al., 1998b). These studies have suggested that the detection of antibodies to 3ABC is optimal on a herd basis to test viral activity in an asymptomatically infected population.  The O/Taiwan/99 FMDV caused a series of outbreaks during 1999-2000 in Taiwan. It was introduced into Taiwan through the sub-clinical infection of the Chinese yellow cattle. In a previous study (Huang et al., 2001), we have reported that the Chinese yellow cattle, a native species of beef cattle, infected by the O/Taiwan/99virus do not develop clinical lesions under experimental and field conditions. As the Chinese yellow cattle may act as carriers to transmit virus to new hosts, a reliable approach to differentiate the infected from the vaccinated animals and to detect the dub-clinical infection in the Chinese yellow cattle is critical for practicing the FMD eradication programs. To establish the detection approach, we have used a 3AB-ELISA kit to evaluate the development and duration of anti-3AB antibodies in the infected Chinese yellow cattle.   The most surprising feature in this study was that the Chinese yellow cattle developed variable patterns of anti-3AB antibodies either in field or in experimental infections. Our study provided further data for understanding the immune response to 3AB in the sub-clinically infected animals.
附件下載:
附件名稱:
黃牛感染OTaiwan99口蹄疫病毒後抗3AB抗體之發展
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