Jahrling P B, Frame J D, Rhoderick J B, Monson M H
Trans R Soc Trop Med Hyg. 1985;79(3):380-4. doi: 10.1016/0035-9203(85)90388-8.
The efficacy of passive immunization for treatment of Lassa Fever (LF) is believed to depend on the titre of the neutralizing antibody infused. For the purpose of identifying optimal donors of LV-immune plasma, a population of LF-convalescent patients in Liberia was tested for prevalence of neutralizing antibody. Minimally protective titres, expressed as a log10 neutralization index, (LNI), were established in animal models as LNI greater than 2. LNI titres for 26 donors, tested eight or more months after illness, were modest: 16 titred 1 less than LNI less than 2, 4 titred 2 greater than LNI less than 3, and only 4 titred LNI greater than 3. Sequentially obtained plasma from six donors indicated that the LNI response was delayed relative to the indirect fluorescent antibody (IFA) response, that high titres (LNI greater than 3) occurred only after seven months and in only two of six patients. Most of the unselected LV-immune plasma will require concentration to therapeutically useful LNI titres. In a passive immunization experiment, guinea-pigs were protected by a late convalescent plasma (LNI = 4.8, IFA = 320) but not by an early plasma, (LNI = 0.6, IFA = 640), thus supporting the selection of immune plasma on the basis of the LNI. Cross serological testing with LV strains and convalescent plasma from patients in Sierra Leone, Liberia and Nigeria suggested that these LV strains were indistinguishable by cross-IFA, but were readily distinguishable by cross neutralization tests. Geographical matching of LV and plasma origins may thus be a factor in selection of optimal plasma for passive immunization of Lassa fever.
被动免疫治疗拉沙热（LF）的疗效被认为取决于输入的中和抗体滴度。为了确定最佳的拉沙病毒免疫血浆供体，对利比里亚一群拉沙热康复患者进行了中和抗体流行率检测。在动物模型中确定的最低保护滴度，以log10中和指数（LNI）表示，为LNI大于2。对26名在患病八个月或更长时间后接受检测的供体的LNI滴度进行了测定，结果适中：16人的LNI滴度为1小于LNI小于2，4人的LNI滴度为2大于LNI小于3，只有4人的LNI滴度大于3。从六名供体依次获取的血浆表明，LNI反应相对于间接荧光抗体（IFA）反应延迟，高滴度（LNI大于3）仅在七个月后出现，且六名患者中只有两名出现。大多数未经筛选的拉沙病毒免疫血浆需要浓缩至具有治疗作用的LNI滴度。在一项被动免疫实验中，豚鼠受到晚期康复血浆（LNI = 4.8，IFA = 320）的保护，但未受到早期血浆（LNI = 0.6，IFA = 640）的保护，从而支持基于LNI选择免疫血浆。对来自塞拉利昂、利比里亚和尼日利亚患者的拉沙病毒株和康复血浆进行的交叉血清学检测表明，这些拉沙病毒株通过交叉IFA无法区分，但通过交叉中和试验很容易区分。因此，拉沙病毒和血浆来源的地理匹配可能是选择用于拉沙热被动免疫的最佳血浆的一个因素。
