. Malaria and other vector-borne diseases pose an immense burden on mankind. To date, control campaigns to stop transmission of the Plasmodium parasites that cause malaria have relied on the distribution of drugs to treat those infected, and on the use of insecticide-impregnated bednets and indoor residual sprays to stop Anopheles mosquitoes from transmitting the infection. Historically targeting the mosquito vector with these insecticide-based methods has been our best weapon for controlling the spread of the disease, but mosquito populations are developing resistance to insecticides at an alarming rate, making disease control increasingly challenging. In the search for new powerful strategies aimed at controlling malaria-transmitting Anopheles populations, we can now exploit novel powerful genome engineering tools. In this project I am to use CRISPR/Cas technology in Anopheles gambiae to enable studies into critical aspects of mosquito basic biology and to enable a new generation of genetic control strategies. During my studies I have validated the function of CRISPR/Cas in A. gambiae and developed a powerful set of genetic engineering tools that I will use to study a novel crosstalk between reproduction and vectorial capacity, as well as to generate and test novel genetic control strategies for population suppression and replacement. Using CRISPR I have generated a line of mutant mosquitoes with large deletions in Zero Population Growth (ZPG), a gene critical for germ cell development. Resulting female mutants have atrophied ovaries while males show no sperm in the testes. In infection experiments with Plasmodium falciparum, the most deadly malaria parasite, females that are unable to develop eggs become less infected with parasites, suggesting a link between signaling from the ovaries and Plasmodium development. Therefore in this proposal I aim to elucidate the role of ovary-based signaling on P. falciparum development (Aim 1A). Furthermore I aim to explore the potential for the ZPG mutant spermless males to be used in Sterile Insect Technique (SIT) for population suppression campaigns (Aim 1B). CRISPR/Cas can also be used to facilitate gene drive systems capable of spreading desired traits to fixation in natural mosquito populations. Using my expertise in this technology, in Aim 2 I will develop an ?evolutionarily stable? gene drive system to robustly spread desirable traits to facilitate the fight against malaria. This drive system will guarantee drive spread by targeting two essential genes clustered together in the A. gambiae genome, making incorrect drive copying inviable. Further the system will be easily editable to enable testing of a wide variety of drive architectures and different anti-malarial or sterilizing cargoes. The findings of this project will be instrumental for expanding our knowledge of mosquito biological processes shaping vectorial capacity, and will expand the genetic toolkit available for the manipulation of wild Anopheles populations.
I have demonstrated successful implementation of CRISPR/Cas genome engineering technology in the primary malaria vector Anopheles gambiae. Malaria infects over 200 million people every year, and our tools currently used to control wild mosquito populations are becoming less effective, making studies into mosquito basic biology and development of new vector control tools an urgent endeavor. In this proposal I develop and employ CRISPR reproductive mutants to study a previously undescribed crosstalk between mosquito reproduction and vector capacity, and propose to use CRISPR to generate artificial selfish genetic elements that can spread anti- malarial traits through wild populations in order to stop malaria transmission.
| Smidler, Andrea L; Scott, Sean N; Mameli, Enzo et al. (2018) A transgenic tool to assess Anopheles mating competitiveness in the field. Parasit Vectors 11:651 |
