Scott A L, Ibrahim M S, Tamashiro W K
Department of Immunology & Infectious Diseases, Johns Hopkins University School of Hygiene, Baltimore, MD 21205.
Acta Trop. 1990 Jul;47(5-6):339-53. doi: 10.1016/0001-706x(90)90035-x.
The surface-associated molecules of the second (L2), third (L3) and fourth (L4) larval stages of Dirofilaria immitis were characterized employing radiolabeling techniques and SDS-PAGE analysis. Major labeled components of 35 kDa and 6 kDa were present in extracts from IODO-GEN-labeled L2 and L3 parasites. The results of lactoperoxidase-catalyzed reactions also demonstrated that L2 and L3 stages of D. immitis have a similar repertoire of surface-associated antigens. However, in contrast to the results obtained with IODO-GEN, lactoperoxidase reactions labeled components with apparent molecular weights of 66, 48, 25, 16.5 and 12 kDa. The similarities in the molecular weights of the L2 and L3 surface-associated components and the results of immunoprecipitation experiments which demonstrated that antibodies produced against the 35 kDa molecule from D. immitis L3s also recognize the 35 kDa component from L2 parasites suggest that synthesis of the molecules found at the surface of mature infective larvae begins as early as day 6 of development in the mosquito, D. immitis L4s emerged from the molting process with a repertoire of surface-associated antigens distinct from those found on L2s and L3s. IODO-GEN labeling of D. immitis L4s showed major surface-associated molecules with apparent molecular weights of 57, 40, 25, 12 and 10 kDa when analyzed under non-reducing conditions. In addition to molecules of 57, 40, 25, 12 and 10 kDa, extracts of D. immitis L4s labeled with lactoperoxidase contained additional major bands at 45, 43 and 8 kDa. Metabolic labeling experiments demonstrated a shift in the amount and complexity of the excretory/secretory products released by D. immitis during L3 to L4 development.
采用放射性标记技术和SDS-PAGE分析对犬恶丝虫第二（L2）、第三（L3）和第四（L4）幼虫阶段的表面相关分子进行了表征。在碘酰基苯（IODO-GEN）标记的L2和L3寄生虫提取物中存在35 kDa和6 kDa的主要标记成分。乳过氧化物酶催化反应的结果也表明，犬恶丝虫的L2和L3阶段具有相似的表面相关抗原谱。然而，与碘酰基苯标记的结果相反，乳过氧化物酶反应标记的成分表观分子量为66、48、25、16.5和12 kDa。L2和L3表面相关成分的分子量相似，免疫沉淀实验结果表明，针对犬恶丝虫L3的35 kDa分子产生的抗体也能识别L2寄生虫的35 kDa成分，这表明在蚊子体内发育至第6天，成熟感染性幼虫表面发现的分子就已开始合成。犬恶丝虫L4从蜕皮过程中出现时，其表面相关抗原谱与L2和L3不同。在非还原条件下分析时，碘酰基苯标记的犬恶丝虫L4显示主要表面相关分子的表观分子量为57、40、25、12和10 kDa。除了57、40、25、12和10 kDa的分子外，用乳过氧化物酶标记的犬恶丝虫L4提取物在45、43和8 kDa处还含有额外的主要条带。代谢标记实验表明，犬恶丝虫在L3到L4发育过程中释放的排泄/分泌产物的数量和复杂性发生了变化。
