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ARS Home » Plains Area » Kerrville, Texas » Knipling-Bushland U.S. Livestock Insects Research Laboratory » LAPRU » Research » Publications at this Location » Publication #365056

Research Project: Cattle Fever Tick Control and Eradication

Location: Livestock Arthropod Pests Research

Title: Vitellogenin receptor as a target for tick control: a mini-review

item MITCHELL, ROBERT - US Department Of Energy
item SONENSHINE, DANIEL - Old Dominion University
item Perez De Leon, Adalberto - Beto

Submitted to: Frontiers in Physiology
Publication Type: Review Article
Publication Acceptance Date: 5/2/2019
Publication Date: 5/21/2019
Citation: Mitchell, R., Sonenshine, D.E., Perez De Leon, A.A. 2019. Vitellogenin receptor as a target for tick control: a mini-review. Frontiers in Physiology. Volume 10: Article 618.

Interpretive Summary: Ticks are parasites that can transmit a wide variety of harmful disease-causing microbes to humans, livestock, and other animals. The discovery and validation of molecular targets is required to innovate tick control technologies. A target that remains to be fully explored is the vitellogenin receptor (VgR). Nearly 100 VgRs have been identified in various insect species, but only 4 have been described so far in ticks. VgR is involved in tick egg formation and maturation. Research showed that disabling VgR prevented ticks from laying viable eggs. Further research is needed to find practical ways to disrupt VgR. Molecules could be designed to specifically alter the function of the VgR gene. Applied biotechnology presents the opportunity to research vaccines that elicit antibodies against the VgR in infested hosts, which would prevent the proliferation of ticks in the environment and decrease the multiplication of the microbes they transmit.

Technical Abstract: While much effort has been put into understanding vitellogenesis in insects and other organisms, much less is known of this process in ticks. There are several steps that facilitate yolk formation in developing oocytes of which the vitellogenin receptor (VgR) is a key component. The tick VgR binds vitellogenin (Vg) circulating in the hemolymph to initiate receptor-mediated endocytosis and its transformation into vitellin (Vn). The conversion of Vg into Vn, the final form of the yolk protein, occurs inside oocytes of the female tick ovary. Vn is critical to tick embryos since it serves as the nutritional source for their development, survival, and reproduction. Recent studies also suggest that pathogenic microbes, i.e., Babesia spp., that rely on ticks for propagation and dissemination likely “hitchhike” onto Vg molecules as they enter developing oocytes through the VgR. Suppressing VgR messenger RNA synthesis via RNA interference (RNAi) completely blocked Babesia spp. transmission into developing tick oocytes, thereby inhibiting vertical transmission of these pathogenic microbes from female to eggs. To date, VgRs from only four tick species, Dermacentor variabilis, Rhipicephalus microplus, Amblyomma hebraeum, and Haemaphysalis longicornis, have been fully sequenced and characterized. In contrast, many more VgRs have been described in various insect species. VgR is a critical component in egg formation and maturation that can serve as a precise target for tick control. However, additional research will help identify unique residues within the receptor that are specific to ticks or other arthropod disease vectors while avoiding cross-reactivity with non-target species. Detailed knowledge of the molecular structure and functional role of tick VgRs will enable development of novel vaccines to control ticks and tick-borne diseases.