Johansen K, Svensson L
Department of Women and Child Health, St. Göran Hospital, Karolinska Institute, Stockholm, Sweden.
Arch Virol. 1997;142(7):1491-8. doi: 10.1007/s007050050175.
Rotavirus is an important cause of gastroenteritis in young children. Locally produced antibodies in the intestinal mucosa are proposed to play an important role in the defence against rotavirus infection, but it is not established whether IgA alone can neutralize rotavirus, nor if IgA antibodies recognize epitopes involved in protective immunity. To evaluate whether human IgA plays a role in virus neutralization, serum IgA was purified from nineteen rotavirus seropositive individuals and examined for its neutralizing capacity by a peroxidase focus reduction test. In all nineteen sera IgA neutralizing antibodies against serotype 3 (rhesus rotavirus) were demonstrated. Purified IgA was further investigated and shown not only to neutralize rotavirus in solution but also to neutralize rotavirus already pre-bound to epithelial cells (MA-104). IgA epitope blocking assays with monoclonal antibodies directed against heterotypic epitopes on VP4 and VP7, revealed that IgA antibodies from 4/16 sera recognized epitopes on VP4, while 5/16 sera recognized a VP7 epitope. When whole sera were investigated for comparison 7 and 9/16 sera recognized epitopes on VP4 and VP7 respectively.
轮状病毒是幼儿肠胃炎的一个重要病因。肠道黏膜中局部产生的抗体被认为在抵御轮状病毒感染中起重要作用，但目前尚未确定单独的IgA是否能中和轮状病毒，也不确定IgA抗体是否识别参与保护性免疫的表位。为评估人IgA在病毒中和中是否起作用，从19名轮状病毒血清阳性个体中纯化血清IgA，并通过过氧化物酶灶点减少试验检测其中和能力。在所有19份血清中均证明存在针对3型（恒河猴轮状病毒）的IgA中和抗体。对纯化的IgA进行进一步研究，结果表明其不仅能中和溶液中的轮状病毒，还能中和已预先结合在上皮细胞（MA - 104）上的轮状病毒。用针对VP4和VP7上异型表位的单克隆抗体进行的IgA表位阻断试验表明，16份血清中有4份的IgA抗体识别VP4上的表位，而16份血清中有5份识别VP7表位。当对全血清进行检测以作比较时，16份血清中分别有7份和9份识别VP4和VP7上的表位。
