Jitrapakdee Sarawut, Unajak Sasimanas, Sittidilokratna Nusra, Hodgson Richard A J, Cowley Jeff A, Walker Peter J, Panyim Sakol, Boonsaeng Vichai
Department of Biochemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
CENTEX Shrimp, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
J Gen Virol. 2003 Apr;84(Pt 4):863-873. doi: 10.1099/vir.0.18811-0.
Yellow head virus (YHV) is a major agent of disease in farmed penaeid shrimp. YHV virions purified from infected shrimp contain three major structural proteins of molecular mass 116 kDa (gp116), 64 kDa (gp64) and 20 kDa (p20). Two different staining methods indicated that the gp116 and gp64 proteins are glycosylated. Here we report the complete nucleotide sequence of ORF3, which encodes a polypeptide of 1666 amino acids with a calculated molecular mass of 185 713 Da (pI=6.68). Hydropathy analysis of the deduced ORF3 protein sequence identified six potential transmembrane helices and three ectodomains containing multiple sites for potential N-linked and O-linked glycosylation. N-terminal sequence analysis of mature gp116 and gp64 proteins indicated that each was derived from ORF3 by proteolytic cleavage of the polyprotein between residues Ala(228) and Thr(229), and Ala(1127) and Leu(1128), located at the C-terminal side of transmembrane helices 3 and 5, respectively. Comparison with the deduced ORF3 protein sequence of Australian gill-associated virus (GAV) indicated 83 % amino acid identity in gp64 and 71 % identity in gp116, which featured two significant sequence deletions near the N terminus. Database searches revealed no significant homology with other proteins. Recombinant gp64 expressed in E. coli with and without the C-terminal transmembrane region was shown to react with antibody raised against native gp64 purified from virions.
黄头病毒（YHV）是养殖对虾疾病的主要病原体。从受感染对虾中纯化的YHV病毒粒子含有三种主要结构蛋白，分子量分别为116 kDa（gp116）、64 kDa（gp64）和20 kDa（p20）。两种不同的染色方法表明，gp116和gp64蛋白是糖基化的。在此，我们报告了ORF3的完整核苷酸序列，它编码一个由1666个氨基酸组成的多肽，计算分子量为185713 Da（pI = 6.68）。对推导的ORF3蛋白序列进行亲水性分析，确定了六个潜在的跨膜螺旋和三个胞外结构域，其中包含多个潜在的N-连接和O-连接糖基化位点。成熟gp116和gp64蛋白的N端序列分析表明，它们各自是通过多聚蛋白在分别位于跨膜螺旋3和5 C端的Ala(228)和Thr(229)以及Ala(1127)和Leu(1128)残基之间的蛋白水解切割而从ORF3衍生而来。与澳大利亚鳃相关病毒（GAV）推导的ORF3蛋白序列比较表明，gp64的氨基酸同一性为83%，gp116为71%，其在N端附近有两个明显的序列缺失。数据库搜索显示与其他蛋白无显著同源性。在大肠杆菌中表达的带有和不带有C端跨膜区域的重组gp64被证明能与针对从病毒粒子中纯化的天然gp64产生的抗体发生反应。
