Towards a semen proteome of the dengue vector mosquito: protein identification and potential functions

Background

No commercially licensed vaccine or treatment is available for dengue fever,a potentially lethal infection that impacts millions of lives annually. Newtools that target mosquito control may reduce vector populations and breakthe cycle of dengue transmission. Male mosquito seminal fluid proteins(Sfps) are one such target since these proteins, in aggregate, modulate thereproduction and feeding patterns of the dengue vector, Aedesaegypti. As an initial step in identifying new targets fordengue vector control, we sought to identify the suite of proteins thatcomprise the Ae. aegypti ejaculate and determine which aretransferred to females during mating.

Methodology and Principal Findings

Using a stable-isotope labeling method coupled with proteomics to distinguishmale- and female-derived proteins, we identified Sfps and sperm proteinstransferred from males to females. Sfps were distinguished from spermproteins by comparing the transferred proteins to sperm-enriched samplesderived from testes and seminal vesicles. We identified 93 male-derived Sfpsand 52 predicted sperm proteins that are transferred to females duringmating. The Sfp protein classes we detected suggest roles in proteinactivation/inactivation, sperm utilization, and ecdysteroidogenesis. We alsodiscovered that several predicted membrane-bound and intracellular proteinsare transferred to females in the seminal fluids, supporting the hypothesisthat Ae. aegypti Sfps are released from the accessory glandcells through apocrine secretion, as occurs in mammals. Many of theAe. aegypti predicted sperm proteins were homologous toDrosophila melanogaster sperm proteins, suggestingconservation of their sperm-related function across Diptera.

Conclusion and Significance

This is the first study to directly identify Sfps transferred from maleAe. aegypti to females. Our data lay the groundwork forfuture functional analyses to identify individual seminal proteins that maytrigger female post-mating changes (e.g., in feeding patterns and eggproduction). Therefore, identification of these proteins may lead to newapproaches for manipulating the reproductive output and vectorial capacityof Ae. aegypti.