During the first reporting period, MALVECBLOK implemented joint research efforts addressing fundamental topics of mosquito biology, and achieved the following objectives:

 (i) The molecular bases of reproductive biology of the mosquito vector, and its effects on immunity and Plasmodium transmission. We have characterized the composition of the male mating plug and the key coagulation enzyme, transglutaminase, crucial for mosquito fertility. In the females, we identified a cluster of three serine proteases that contribute to the efficient plug digest in the atrium and a gene that triggers oviposition. These discoveries may provide new targets for vector control. Importantly, we confirmed the relevance of laboratory studies for natural populations of An. gambiae. Most of the genes induced by mating in the laboratory were also induced in the field populations. Although mating per se does not affect development of the rodent malaria, it does induce expression of a number of immune genes.

(ii) The molecular mechanisms, which determine the mosquito immune status and regulate Plasmodium sporogony and transmission, both in laboratory settings and in natural populations. We have characterized the TEP1/LRR complex and revealed that it comprises an inactive form of TEP1. We uncovered that genetic diversity of P. falciparum enables parasites to survive immune responses in the vector; this discovery has important consequences for design of future vector control measures. Functional analysis of two major yolk proteins crucial for mosquito fertility revealed their role in TEP1 binding to parasites. Strikingly, expression of vitellogenin but not of lipophorin, is negatively regulated by Rel1/Rel2 immune pathway, suggesting that activation of immune responses represses reproduction in the mosquitoes.

(iii) The role of genetic polymorphism in genes controlling reproduction and immunity on the structure of mosquito populations and malaria transmission in Africa. We characterized polymorphisms in reproductive genes and gene families, which reveal evolutionary relationships between subspecies of the An. gambiae complex. Whereas some genes are under strong purifying selection in different species, others are subject for extensive variation with no signs of species-specific signatures.

The major achievement of this work package is the establishment of experimental infections in Kenya (Mbita station) and Mali (Bamako). Ethical authorizations to perform these experiments were obtained from local authorities. In Kenya, significant differences in Plasmodium development were identified in the mosquitoes grown on two types of local soils. Comparison of a number of breeding sites in different areas of Cameroon did not reveal major correlations between expression of immune genes and malaria transmission. Currently, correlations between susceptibility to P. falciparum and TEP1 genotype are being analysed in all three countries using SOPs established by MALVECBLOK.

In conclusion, during the reporting period the project identified new potential targets for control of mosquito populations. Our results suggest that Plasmodium developed means to cope with the vector immune responses, especially in the areas of high transmission, and instruct the future studies on immuno-modulated mosquitoes. Special attention of the consortium was given to cutting-edge training opportunities and sharing of resources between the partners. The knowledge acquired in the project has a strong impact on European scientific competitiveness, and addresses societal issues in the endemic countries by recruitment of young researchers and by disseminating the study principles and knowledge of socio-economic impact of malaria in the research centres and, more importantly, among the local population involved in the study. As a result of the project, children of at least three villages in Africa benefit from regular medical surveillance and timely antimalarial treatment.