AP-1/Fos-TGase2 axis mediates wounding-induced Plasmodium falciparum killing in Anopheles gambiae.

Anopheline mosquitoes are the only vectors of human malaria worldwide. It is now widely accepted that mosquito immune responses play a crucial role in restricting Plasmodium development within the vector; therefore, further dissection of the molecular mechanisms underlying these processes should inform new vector control strategies urgently needed to roll back the disease. Here, using genome-wide transcriptional profiling, bioinformatics, and functional gene analysis, we identify a new axis of mosquito resistance to monoclonal Plasmodium falciparum infections that includes the AP-1 transcription factor Fos and the transglutaminase 2 (TGase2), a cross-linking enzyme with known roles in wound responses. We demonstrate that Fos regulates induction of TGase2 expression after wounding but does not affect expression of the components of the well characterized complement-like system. Silencing of Fos or of TGase2 aborts the wounding-induced mosquito killing of P. falciparum. These results reveal multiple signaling pathways that are required for efficient Plasmodium killing in Anopheles gambiae.

Genetic clonality of Plasmodium falciparum affects the outcome of infection in Anopheles gambiae.

Mosquito infections with natural isolates of Plasmodium falciparum are notoriously variable and pose a problem for reliable evaluation of efficiency of transmission-blocking agents for malaria control interventions. Here, we show that monoclonal P. falciparum isolates produce higher parasite loads than mixed ones. Induction of the mosquito immune responses by wounding efficiently decreases Plasmodium numbers in monoclonal infections but fails to do so in infections with two or more parasite genotypes. Our results point to the parasites genetic complexity as a potentially crucial component of mosquito-parasite interactions.

Boosting NF-kappaB-dependent basal immunity of Anopheles gambiae aborts development of Plasmodium berghei.

Anopheles gambiae, the major vector for the protozoan malaria parasite Plasmodium falciparum, mounts powerful antiparasitic responses that cause marked parasite loss during midgut invasion. Here, we showed that these antiparasitic defenses were composed of pre- and postinvasion phases and that the preinvasion phase was predominantly regulated by Rel1 and Rel2 members of the NF-kappaB transcription factors. Concurrent silencing of Rel1 and Rel2 decreased the basal expression of the major antiparasitic genes TEP1 and LRIM1 and abolished resistance of Anopheles to the rodent malaria parasite P. berghei. Conversely, depletion of a negative regulator of Rel1, Cactus, prior to infection, enhanced the basal expression of TEP1 and of other immune factors and completely prevented parasite development. Our findings uncover the crucial role of the preinvasion defense in the elimination of parasites, which is at least in part based on circulating blood molecules.

Demonstration and quantification of "hyperchromic" erythrocytes by haematological analysers. Application to screening for hereditary and acquired spherocytosis.

The double laser beam diffraction of spherized RBC used in the ADVIA 120 haematological analyser allows quantitation of cells aberrant not only by their volume but also by their haemoglobin concentration. The present investigation provides arguments for the identification of hyperchromic RBC as spherocytes, mainly the close relation between % hyperchromic cells and % lysed by the cryohaemolysis test. The percentage of hyperchromic erythrocytes may no longer be considered an instrumental artefact. Without allowing a definite diagnosis of hereditary spherocytosis, an increased percentage of hyperchromic cells indicates the degree of spherocytosis, making it an excellent automated and cost-free screening parameter for inherited and acquired corpuscular haemolysis.