Johnson P C, Mathewson J J, DuPont H L, Greenberg H B
University of Texas Health Science Center, Houston 77030.
J Infect Dis. 1990 Jan;161(1):18-21. doi: 10.1093/infdis/161.1.18.
In a multiple-challenge study of US adult volunteers with low or high levels of serum antibody to Norwalk virus, Norwalk inoculum 8FIIa was administered to 42 subjects, 22 were challenged 6 months later, and 19 received a third challenge after 6 more months. All 12 with high (greater than or equal to 1:200) but only 19 of 30 with low (less than 1:100) prechallenge titers experienced illness or a fourfold increase in titer after the first challenge (P less than .025). Only 4 of those challenged twice became ill; all had low initial titers but 3 had high titers before the second challenge. None became ill after a third challenge. Nine (47%) had high titers immediately before the third challenge; 3 had low titers before and after each challenge and remained asymptomatic. Thus, preexisting serum antibody to Norwalk virus does not seem to be associated with protective immunity, but antibody levels become associated with protection after repetitive exposure. Short-term resistance lasts greater than or equal to 6 months after challenge, and a small percentage of resistant individuals maintain low antibody titers even after multiple challenges.
在一项针对血清抗诺如病毒抗体水平低或高的美国成年志愿者的多次激发研究中，将诺如病毒接种物8FIIa给予42名受试者，6个月后对22名受试者进行激发，再过6个月后19名受试者接受第三次激发。所有12名激发前滴度高（大于或等于1:200）的受试者，但激发前滴度低（小于1:100）的30名受试者中只有19名在首次激发后出现疾病或滴度升高四倍（P小于0.025）。两次激发的受试者中只有4人患病；所有人初始滴度都低，但第二次激发前3人滴度高。第三次激发后无人患病。9人（47%）在第三次激发前即刻滴度高；3人每次激发前后滴度都低且无症状。因此，预先存在的血清抗诺如病毒抗体似乎与保护性免疫无关，但反复接触后抗体水平与保护作用相关。激发后短期抵抗力持续大于或等于6个月，一小部分有抵抗力的个体即使多次激发后仍保持低抗体滴度。
