Mancini Maria Vittoria, Spaccapelo Roberta, Damiani Claudia, Accoti Anastasia, Tallarita Mario, Petraglia Elisabetta, Rossi Paolo, Cappelli Alessia, Capone Aida, Peruzzi Giulia, Valzano Matteo, Picciolini Matteo, Diabaté Abdoulaye, Facchinelli Luca, Ricci Irene, Favia Guido
Scuola di Bioscienze e Medicina Veterinaria, Università di Camerino, Camerino, Italy.
Department of Experimental Medicine, Centro di Genomica Funzionale, University of Perugia, Perugia, Italy.
Parasit Vectors. 2016 Mar 10;9:140. doi: 10.1186/s13071-016-1427-3.
Malaria still remains a serious health burden in developing countries, causing more than 1 million deaths annually. Given the lack of an effective vaccine against its major etiological agent, Plasmodium falciparum, and the growing resistance of this parasite to the currently available drugs repertoire and of Anopheles mosquitoes to insecticides, the development of innovative control measures is an imperative to reduce malaria transmission. Paratransgenesis, the modification of symbiotic organisms to deliver anti-pathogen effector molecules, represents a novel strategy against Plasmodium development in mosquito vectors, showing the potential to reduce parasite development. However, the field application of laboratory-based evidence of paratransgenesis imposes the use of more realistic confined semi-field environments.
Large cages were used to evaluate the ability of bacteria of the genus Asaia expressing green fluorescent protein (Asaia (gfp)), to diffuse in Anopheles stephensi and Anopheles gambiae target mosquito populations. Asaia (gfp) was introduced in large cages through the release of paratransgenic males or by sugar feeding stations. Recombinant bacteria transmission was directly detected by fluorescent microscopy, and further assessed by molecular analysis.
Here we show the first known trial in semi-field condition on paratransgenic anophelines. Modified bacteria were able to spread at high rate in different populations of An. stephensi and An. gambiae, dominant malaria vectors, exploring horizontal ways and successfully colonising mosquito midguts. Moreover, in An. gambiae, vertical and trans-stadial diffusion mechanisms were demonstrated.
Our results demonstrate the considerable ability of modified Asaia to colonise different populations of malaria vectors, including pecies where its association is not primary, in large environments. The data support the potential to employ transgenic Asaia as a tool for malaria control, disclosing promising perspective for its field application with suitable effector molecules.
疟疾在发展中国家仍然是一个严重的健康负担，每年导致超过100万人死亡。鉴于缺乏针对其主要病原体恶性疟原虫的有效疫苗，以及该寄生虫对现有药物库的耐药性不断增加，同时按蚊对杀虫剂的抗性也在增强，因此开发创新的控制措施对于减少疟疾传播至关重要。共生生物转基因技术，即通过改造共生生物来传递抗病原体效应分子，是一种针对疟原虫在蚊媒中发育的新策略，显示出减少寄生虫发育的潜力。然而，基于实验室的共生生物转基因技术证据在实际应用中需要在更接近现实的封闭半野外环境中进行。
使用大型笼子评估表达绿色荧光蛋白的阿萨亚属细菌（阿萨亚（绿色荧光蛋白））在斯氏按蚊和冈比亚按蚊目标蚊群中扩散的能力。通过释放转基因雄蚊或设置糖水喂食站，将阿萨亚（绿色荧光蛋白）引入大型笼子。通过荧光显微镜直接检测重组细菌的传播，并通过分子分析进一步评估。
在此，我们展示了在半野外条件下对转基因按蚊进行的首次已知试验。改造后的细菌能够在斯氏按蚊和冈比亚按蚊这两种主要疟疾传播媒介的不同群体中快速传播，通过水平传播方式并成功定殖于蚊中肠。此外，在冈比亚按蚊中还证明了垂直和跨龄期扩散机制。
我们的结果表明，改造后的阿萨亚属细菌具有在大型环境中定殖于不同疟疾传播媒介群体的强大能力，包括那些原本与其没有主要关联的物种。这些数据支持了将转基因阿萨亚属细菌用作疟疾控制工具的潜力，并为其与合适的效应分子一起在实地应用揭示了广阔前景。
