Project description:. Here we provide a deeper insight into Xenopsylla cheopis salivary glands contents pairing transcriptome and proteomic approaches. Sequencing of 99 pairs of salivary glands from adult females X. cheopis yielded a total of 7,432 coding sequences functionally classified into 25 classes, in which the secreted class was found to be the most abundant one. The translated transcripts also served as a reference database for the proteomic study, which identified peptides from 610 different proteins.
Project description:XC-43 is a small peptide identified in the sialome of the flea Xenopsylla cheopis and act as a fast, tight-binding inhibitor of thrombin with a dissociation constant of less than 10 pM. The crystal structure of XC-43 in complex with thrombin shows that despite its substrate-like binding mode, XC-43 is not detectably cleaved by thrombin and that it interacts with the thrombin surface from the enzyme catalytic site through the fibrinogen-binding exosite I. The low rate of hydrolysis is verified in solution experiments with XC-43 which show the substrate to be largely intact after two hours of incubation with thrombin at 37°C. The potential of XC-43 as an anticoagulant is suggested by increased arterial occlusion time, tail bleeding time, and blood coagulation parameters in rat models of thrombosis.
Project description:Yersinia pestis, the causative agent of plague, is endemic in certain regions due to a stable transmission cycle between rodents and their associated fleas. In addition, fleas are believed to serve as reservoirs that can occasionally cause enzootic plague cycles and explosive epizootic outbreaks that increase human exposure. However, transmission by fleas is inefficient and associated with a shortened lifespan of the flea and rodent hosts, indicating that there remain significant gaps in our understanding of the vector-animal cycle of Y. pestis. Here, we show that laboratory-reared, infected fleas (Xenopsylla cheopis) can transmit viable Y. pestis from adults to eggs, and the bacteria can be passed through all subsequent life stages of the flea. Thus, our data raise the possibility that transovarial transmission in fleas might contribute to the persistence of Y. pestis in the environment without detectable plague activity in mammals.