Serine Proteinase Inhibitors (Serpins) in Tick Feeding and Physiology

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DESCRIPTION (provided by applicant): In the United States (US) ticks transmit more vector borne disease agents than any other vector arthropod. Limitations associated with current acaricide based tick control strategies that threaten the future sustainability of tick borne illnesses containment programs, have necessitated the need for development of alternative tick control strategies. Our long-term goals are to identify important tick proteins, which if blocked, can compromise the tick's ability to feed, acquire and transmit disease agents. One important such class of proteins, are serine proteinase inhibitors that are commonly referred to by its acronym "serpin", which is the largest class of proteinase inhibitors that have been found in most forms of life. In humans, serpins are involved in regulation of important of proteolytic pathways that are essential to life such as blood coagulation with serpin malfunctions arising from natural mutations causing numerous debilitating diseases. We have recently described a family of 19 Amblyomma americanum serpins that we have named as "Lospins", an acronym for Lone Star tick serpins. Sequence and expression data analyses have revealed that 10 of the 19 Lospin cDNAs encode for Lospin proteins that are potentially secreted into tick saliva during tick feeding. Our hypothesis is that, the 10 Lospins are secreted into the host during tick feeding to facilitate the tick's escape from host defense and that disrupting their function will prevent the tick from feeding. In this proposal we will characterize six of the 10 Lospins via two specific aims. The first is to validate secretion into tick saliva of six selected Lospin proteins. The rationale is that Lospins detected in tick saliva will represent candidates that are secreted into the host during tick feeding and will be selected for further study. We will raise specific polyclonal antibodies to candidate Lospins and use them in standard western blotting analyses of collected tick saliva. The second, we will be to suppress expression of Lospins selected in aim 1 and study the effects on tick feeding. The rationale is that suppression of an essential Lospin will prevent the tick from feeding and it will be selected for future study. A. americanum is an important public health pest that is commonly encountered tick species particularly in southern and Atlantic states. The immediate utility of results from this proposal will be advancing our knowledge on the physiology of this important pest. This data will position us to rationale new methods to control this tick. PUBLIC HEALTH RELEVANCE: In the United States ticks transmit more vector borne disease agents than any other vector arthropod. Limitations associated with current acaricide based tick control strategies that threaten the future sustainability of containment programs for tick borne illnesses, have necessitated the need for development of alternative tick control strategies. Identification of important tick proteins that regulate tick physiology and facilitate tick feeding is important before alternative tick control methods can be developed.