Anopheline anti-platelet protein from a malaria vector mosquito has anti-thrombotic effects in vivo without compromising hemostasis

Identification of the active region responsible for the anti-thrombotic activity of anopheline anti-platelet protein from a malaria vector mosquito

“…The encoded protein, anopheline anti-platelet protein (AAPP), binds directly to type-I and type-III collagen, and has in vitro anti-platelet activity in platelets from humans, rats, and mice [9,10]. AAPP inhibited whole blood aggregation induced by collagen at 10 mg/kg body weight (bw) and prevented pulmonary death at a lower dose (3 mg/kg bw) without prolongation of bleeding time in a mouse tail-cut model compared with aspirin (100 mg/kg bw), which compromised hemostasis [10]. Thus, based on a new concept (i.e., achieving anti-thrombotic effects by counteracting the thrombogenic property of collagen), developing AAPP as an anti-thrombotic agent is potentially useful.…”

The Crystal Structure of the Active Domain of Anopheles Anti-platelet Protein, a Powerful Anti-coagulant, in Complex with an Antibody

“…Inhibition of Collagen Binding of AAPP by the 8H7 Fab-AAPP inhibits platelet aggregation via direct binding to collagen (7,14). Experiments were carried out to determine whether the 8H7 Fab can block this interaction.…”

“…Cloning, Expression, and Purification of AAPP-Cloning and purification were essentially carried out as for the AAPP protein described previously (7,14,17). The gene sequence from A. stephensi mosquitoes was cloned into pET22 with a hexahistidine tag and tobacco etch virus cleavage site at the C terminus.…”

“…These proteins are the first anti-coagulants found to have this mode of action. Earlier work by us has shown AAPP is able to inhibit blood aggregation without prolonging bleeding time, which holds out the promise of safer treatments for thrombotic disease (14). Other types of anti-platelet medication such as cyclooxygenase inhibitors have a risk of leading to excessive bleeding (15).…”

Immunization with AgTRIO, a Protein in Anopheles Saliva, Contributes to Protection against Plasmodium Infection in Mice

“…The saliva contains biologically active molecules, which modulate host responses, including coagulation, platelet aggregation, thrombin activation, and vasodilation (Fontaine et al, 2011; Hayashi et al, 2012; Ribeiro et al, 1994; Ronca et al, 2012). Indeed, the saliva of arthropods can enhance the infectivity of diverse pathogens (Edwards et al, 1998; Limesand et al, 2000; Schneider and Higgs, 2008; Schneider et al, 2006), including Aedes and Culex mosquito saliva and arboviruses (Le Coupanec et al, 2013; Reagan et al, 2012; Styer et al, 2011), sand fly saliva and Leishmania (Kamhawi, 2000; Norsworthy et al, 2004; Ockenfels et al, 2014; Theodos and Titus, 1993), tick saliva and Borrelia (Wikel et al, 1997), or tsetse fly saliva and trypanosomiasis (Caljon et al, 2006).…”