篇名:
台灣分離豬瘟病毒株之演化樹分析Phylogenetic analysis of classical swine fever virus isolated from Taiwan
作者:
鄧明中;黃金城;黃天祥;張家宜;林育如;簡茂盛;鍾明華
中文摘要:
分析1993至2001年間台灣分離之豬瘟病毒株E2基因片段,可以明顯地區分出三個不同基因型的病毒株,分別為一個古典型(3.4基因亞型)及兩個外來型(2.1基因亞型)。其中2.1基因亞型病毒株首先於1994年被分離到並於1996年開始散播。而利用演化樹分析豬瘟病毒E2基因片段可以成功將台灣分離的2.1基因亞型病毒再區分為兩個不同的基因型(分別命名為2.1a及2.1b)。而2.1b病毒只於2001年間被分離到,且與2.1a病毒株間只有94.8%的核酸相似度。這樣的結果說明2.1a及2.1b病毒株間可能來自不同的來源。
英文摘要:
By analyzing the E2 sequences of classical swine fever virus from field outbreaks in Taiwan during 1993–2001, three virus populations with distinct genotypes were determined including one historical (subgroup 3.4) and two exotic (subgroup 2.1) strains. The first subgroup 2.1 virus was isolated in 1994 and further sporadic outbreaks occurred after 1996. Phylogenetic analysis using the E2 region has segregated the Taiwanese strains of 2.1virus into two different genotypes (termed 2.1a and 2.1b). The 2.1b viruses were only isolated in 2001 and shared approximately 94.8% nucleotide identities to the 2.1a viruses in the total genomic sequences. The results suggest that the 2.1a and 2.1b viruses may be introduced from different origins.
備註:
年份:西元 2004 年
期別:第 40 期
詳細內容:
Classical swine fever (CSF) is the most insidious and devastating disease of swine and wild boars, causing significant economical losses in the pig industry over most regions of the world. CSF is caused by classical swine fever virus (CSFV), a member of the genus Pestivirus within the family Flaviviridae. The genome of CSFV comprises a single open reading frame (ORF), approximately 12.3 kb in length (Meyers et al., 1989; Meyers and Thiel, 1996). This ORF, flanked by a 50-untranslated region (UTR) and a 30-UTR, encodes a polyprotein composed of about 3898 amino acids, which is processed by viral and cellular enzymes into four structural (C, E0, E1 and E2) and eight nonstructural (Npro, p7, NS2, NS3, NS4A, NS4B, NS5A and NS5B) proteins (Thiel et al., 1991; Meyers and Thiel, 1996).  CSF viruses consist of one serotype, reflecting a narrow range of evolutionary divergence (Vanderhallen et al., 1999). Therefore, genetic typing of the virus has been used in understanding the evolution, spread of viruses and the origins of disease outbreaks. Three regions, 50-UTR, E2 and NS5B, in the viral genome are most extensively used for genetic analysis and for studying virus diversity on the basis of sequence homology (Hofmann et al., 1994; Lowings et al., 1996; Stadejek et al., 1996; Greiser-Wilke et al., 1998; Paton et al., 2000). Analysis using a 96 nt region of the 50- UTR, a 190 nt region of the E2 and a 409 nt region of the NS5B has resulted in similar resolution to classify CSFV into three major groups and their subgroups. Group 1 and its three subgroups (1.1, 1.2 and 1.3) comprise most of the historical strains (Lowings et al., 1996; Paton et al., 2000) distributed in most regions of the world. Group 2 containing most of the current viruses, which segregates into subgroup 2.1, 2.2 and 2.3, has increased activity and caused epidemic infection since the 1980s (Paton et al., 2000). The earliest 2.1 strain (VRI2277) was isolated from Malaysia in 1986 (Vilcek et al., 1996; Paton et al., 2000). In the 1990s, the 2.1 viruses have caused epidemic of outbreaks in Germany (Oleksiewicz et al., 2003), The Netherlands (Widjojoatmodjo et al., 1999; Stegeman et al., 2000), Switzerland, Austria, Italy, Belgium, Spain (Paton et al., 2000), China (Tu et al., 2001) and Taiwan. Nevertheless, Group 3 contains disparate viruses distributed in regions such as Taiwan, Korea, Japan, Thailand and the United Kingdom (Sakoda et al., 1999; Paton et al., 2000).  Although an attenuated lapinized live vaccine (LPC) has been used to protect pigs from CSF since the 1950s in Taiwan, outbreaks occur endemically. We have genetically analyzed the viruses obtained during 1993– 2001. Our results not only identify that the 3.4 strains are the historical strains in Taiwan, which may become silent strains in fields after 1996, but also reveal that there has been a switch in the virus populations from the 3.4 to the 2.1 strains circulating wild types.
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台灣分離豬瘟病毒株之演化樹分析
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