Lowenberger C A, Ferdig M T, Bulet P, Khalili S, Hoffmann J A, Christensen B M
Animal Health and Biomedical Sciences, University of Wisconsin-Madison 53706, USA.
Exp Parasitol. 1996 Jul;83(2):191-201. doi: 10.1006/expr.1996.0066.
The effect of host immune activation on the development of Brugia malayi in one susceptible and four refractory strains of Aedes aegypti and in Armigeres subalbatus was assessed. A. aegypti that were immune activated by the injection of saline or bacteria 24 hr before feeding on a B. malayi-infected gerbil had significantly reduced prevalences and mean intensities of infection from those of naive controls when exposed to bloodmeals with low (105 mf/20 microliters) and medium (160 mf/20 microliters) microfilaremias. At a higher microfilaremia (237 mf/20 microliters) there were no significant differences in mean intensities, suggesting that the number of parasites ingested may affect the host's ability to mount an effective defense response. Because the major immune proteins in A. aegypti are defensins, we did Northern analyses of fat body RNA 8 hr after immune activation or bloodfeeding. All mosquitoes demonstrated rapid transcriptional activity for defensins following immune activation by intrathoracic inoculation with either saline or bacteria. However, no strain of A. aegypti, susceptible or refractory to B. malayi, nor Ar. subalbatus produced defensin transcripts after bloodfeeding on an uninfected or a B. malayi-infected gerbil. These data suggest that inducible immune proteins of mosquitoes can reduce the prevalence and mean intensity of infections with ingested parasites, but these proteins are not expressed routinely after parasite ingestion and midgut penetration and probably do not contribute to existing refractory mechanisms. Immune proteins such as defensins, however, represent potential candidates to genetically engineer mosquitoes for resistance to filarial worms.
评估了宿主免疫激活对马来布鲁线虫在一种易感和四种抗性埃及伊蚊品系以及骚扰阿蚊体内发育的影响。在以感染马来布鲁线虫的沙鼠血液为食之前24小时，通过注射生理盐水或细菌对埃及伊蚊进行免疫激活，当暴露于低微丝蚴血症（105条微丝蚴/20微升）和中微丝蚴血症（160条微丝蚴/20微升）的血餐时，其感染率和平均感染强度与未处理的对照相比显著降低。在更高的微丝蚴血症水平（237条微丝蚴/20微升）下，平均感染强度没有显著差异，这表明摄入的寄生虫数量可能会影响宿主产生有效防御反应的能力。由于埃及伊蚊中的主要免疫蛋白是防御素，我们在免疫激活或取食后8小时对脂肪体RNA进行了Northern分析。通过胸腔内接种生理盐水或细菌进行免疫激活后，所有蚊子的防御素均表现出快速的转录活性。然而，无论是对马来布鲁线虫易感还是抗性的埃及伊蚊品系，以及骚扰阿蚊，在以未感染或感染马来布鲁线虫的沙鼠血液为食后均未产生防御素转录本。这些数据表明，蚊子的诱导性免疫蛋白可以降低摄入寄生虫的感染率和平均感染强度，但这些蛋白在摄入寄生虫和中肠穿透后不会常规表达，可能对现有的抗性机制没有贡献。然而，诸如防御素之类的免疫蛋白是对蚊子进行基因工程改造以抵抗丝虫的潜在候选物质。
