Graczyk T K, Cranfield M R, Skjoldager M L, Shaw M L
Department of Immunology and Infectious Diseases, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, Maryland 21205.
J Parasitol. 1994 Feb;80(1):60-6.
An enzyme-linked immunosorbent assay (ELISA) utilizing 3 Plasmodium falciparum antigens, R32tet32, P.F.R27, and crude red blood cell extract, was developed for the detection of circulating anti-Plasmodium relictum or anti-Plasmodium elongatum antibodies in sera from naturally infected adult African black-footed penguins (Spheniscus demersus) at The Baltimore Zoo, Maryland. A concentration of 2.0 micrograms/ml of each antigen was optimal in terms of specificity, sensitivity, and test speed. It was possible to detect anti-Plasmodium spp. antibodies at a dilution of 10(-4.11). Low absorbance values (less than 0.050) of nonspecific background were observed. The binding efficacy of anti-penguin IgG coupled to alkaline phosphatase to antibodies in the penguin sera was significantly higher than the binding efficacy of anti-chicken IgG. All penguins, bled in the winter time, in controlled mosquito-free conditions had anti-Plasmodium spp. antibodies reactive with P. falciparum antigens. The penguins showed age-dependent variation in antibody levels. There was a decrease in antibody titration units that was significantly correlated with the number of outdoor exposure years experienced by the birds, despite the season-comparable epizootiologic conditions in their summer open-air habitat. We concluded that the decrease of anti-malarial antibodies could be explained by an antibody-mediated equilibrium of immunity in naturally immunized birds harboring endothelial-stage parasites. The ELISA described is sensitive, and it requires a minimal amount of equipment to collect the blood samples. The assay can be used for detecting and monitoring levels of anti-Plasmodium spp. antibodies in selected groups of penguins.
利用3种恶性疟原虫抗原（R32tet32、P.F.R27和粗制红细胞提取物）开发了一种酶联免疫吸附测定（ELISA），用于检测马里兰州巴尔的摩动物园自然感染的成年非洲黑脚企鹅（斑嘴环企鹅）血清中循环的抗残疟原虫或抗延长疟原虫抗体。就特异性、敏感性和检测速度而言，每种抗原2.0微克/毫升的浓度是最佳的。在10（-4.11）的稀释度下能够检测到抗疟原虫属抗体。观察到非特异性背景的吸光度值较低（小于0.050）。与碱性磷酸酶偶联的抗企鹅IgG与企鹅血清中抗体的结合效力显著高于抗鸡IgG的结合效力。在无蚊控制条件下于冬季采血的所有企鹅都有与恶性疟原虫抗原反应的抗疟原虫属抗体。企鹅的抗体水平呈现年龄依赖性变化。尽管其夏季露天栖息地的流行病学条件在季节上具有可比性，但抗体滴定单位的下降与鸟类户外暴露年数显著相关。我们得出结论，抗疟疾抗体的下降可以通过在携带内皮阶段寄生虫的自然免疫鸟类中抗体介导的免疫平衡来解释。所描述的ELISA具有敏感性，且采集血样所需设备最少。该测定法可用于检测和监测选定企鹅群体中抗疟原虫属抗体的水平。
