Gutiérrez-López Rafael, Martínez-de la Puente Josué, Gangoso Laura, Yan Jiayue, Soriguer Ramón C, Figuerola Jordi
Department of Wetland Ecology, Estación Biológica de Doñana (EBD-CSIC), Avda. Américo Vespucio s/n,, E-41092, Sevilla, Spain.
CIBER Epidemiología y Salud Pública (CIBERESP), Sevilla, Spain.
Parasit Vectors. 2016 Nov 28;9(1):609. doi: 10.1186/s13071-016-1903-9.
The life-cycle of many vector-borne pathogens includes an asexual replication phase in the vertebrate host and sexual reproduction in the insect vector. However, as only a small array of parasites can successfully develop infective phases inside an insect, few insect species are competent vectors for these pathogens. Molecular approaches have identified the potential insect vectors of blood parasites under natural conditions. However, the effectiveness of this methodology for verifying mosquito competence in the transmission of avian malaria parasites and related haemosporidians is still under debate. This is mainly because positive amplifications of parasite DNA in mosquitoes can be obtained not only from sporozoites, the infective phase of the malaria parasites that migrate to salivary glands, but also from different non-infective parasite forms in the body of the vector. Here, we assessed the vectorial capacity of the common mosquito Culex pipiens in the transmission of two parasite genera.
A total of 1,560 mosquitoes were allowed to feed on five house sparrows Passer domesticus naturally infected by Haemoproteus or co-infected by Haemoproteus/Plasmodium. A saliva sample of the mosquitoes that survived after 13 days post-exposure was taken to determine the presence of parasite DNA by PCR.
Overall, 31.2% mosquito's head-thorax and 5.8% saliva samples analysed showed positive amplifications for avian malaria parasites. In contrast to Haemoproteus DNA, which was not found in either the body parts or the saliva, Plasmodium DNA was detected in both the head-thorax and the saliva of mosquitoes. Parasites isolated from mosquitoes feeding on the same bird corresponded to the same Plasmodium lineage.
Our experiment provides good evidence for the competence of Cx. pipiens in the transmission of Plasmodium but not of Haemoproteus. Molecular analyses of saliva are an effective method for testing the vector competence of mosquitoes and other insects in the transmission of vector-borne pathogens.
许多媒介传播病原体的生命周期包括在脊椎动物宿主中的无性繁殖阶段和在昆虫媒介中的有性繁殖阶段。然而，由于只有一小部分寄生虫能够在昆虫体内成功发育出感染阶段，因此很少有昆虫物种是这些病原体的有效媒介。分子方法已经确定了自然条件下血液寄生虫的潜在昆虫媒介。然而，这种方法在验证蚊子传播禽疟原虫和相关血孢子虫能力方面的有效性仍存在争议。这主要是因为在蚊子中，寄生虫DNA的阳性扩增不仅可以从迁移到唾液腺的疟原虫感染阶段子孢子中获得，还可以从媒介体内不同的非感染性寄生虫形式中获得。在这里，我们评估了常见蚊子致倦库蚊在传播两种寄生虫属方面的媒介能力。
让总共1560只蚊子吸食五只自然感染血变原虫或同时感染血变原虫/疟原虫的家麻雀。在接触后13天存活下来的蚊子的唾液样本用于通过PCR确定寄生虫DNA的存在。
总体而言，分析的蚊子头胸部样本中有31.2%以及唾液样本中有5.8%对禽疟原虫呈阳性扩增。与在身体部位或唾液中均未发现的血变原虫DNA不同，疟原虫DNA在蚊子的头胸部和唾液中均被检测到。从吸食同一只鸟的蚊子中分离出的寄生虫属于同一疟原虫谱系。
我们的实验为致倦库蚊传播疟原虫而非血变原虫的能力提供了有力证据。唾液的分子分析是测试蚊子和其他昆虫传播媒介传播病原体能力的有效方法。
