Ticks are obligatory external parasites that feed on the blood of hosts, and often transmit pathogens, including bacteria, protozoa, and viruses. Tick-borne diseases cause huge economic losses in the animal industry as well as health risks to humans. The salivary secretions of the ticks play an important role in blood feeding by modulating the host response. We propose to investigate the peptidergic system as it relates to control of the salivary gland in the black-legged tick, Ixodes scapularis, which is one of the most important ticks in the northern U.S. as a risk to human heath. Our preliminary study suggests that at least two peptidergic systems are involved in neural control of the salivary gland: putatively, myoinhibitory peptide (MIP) and pigment dispersing hormone (PDF).
Specific Aim 1 is to identify candidate neuropeptides relevant to salivary functions. While we already identified candidate neuropeptides in our preliminary study, we will expand the survey by using more comprehensive and combinatorial approaches, proteomics, bioinformatics and immunohistochemistry.
Specific Aim 2 will further characterize the MIP which is the neuropeptide strongly supported for the function controlling the salivary glands in the preliminary studies. Cloning of the genes encoding MIP and its receptor will be followed by investigation of their expression patterns and function. This study will provide the first description of neuropeptides controlling the tick salivary gland and will provide a foundation for investigations into the roles of the peptidergic systems in salivary secretion in the next tier of study. The fundamental knowledge obtained from this research is expected to lead to the design of compounds and vaccines that disrupt the tick salivary function. The outcome of the proposed research will have high impacts on the studies in other tick species that have large negative impacts on the economy and health.
The outcome of the proposed work will provide an understanding of the basic biology of neural control of the tick salivary gland, which will provide the principles for studying other species of tick, and provide rational approaches to develop environmentally benign acaricidal compounds/strategies. This research is eventually expected to lead to the design of compounds and vaccines to disrupt the salivary functions and to prevent disease transmissions by ticks, ultimately improving human health.
