Presenter of 2 Presentations
ESTABLISHMENT OF THE TICK BIOBANK FOR THE APPLICATION TO VECTOR BIOLOGY RESEARCH AND THE DEVELOPMENT OF TICK CONTROL METHODS (ID 1499)
PRE-RECORDED: THE ROLES OF OOGENESIS-RELATED MOLECULES IN BABESIA-INFECTED HAEMAPHYSALIS LONGICORNIS (ID 753)
Abstract
Introduction
The phenomenon of the transovarial transmission of Babesia parasites in ticks has been demonstrated experimentally, however, the molecular mechanisms are still unclear. To find the key tick factor(s) for Babesia transmission, we focused on molecules involved in yolk protein precursor (vitellogenin; Vg) synthesis and Vg uptake, which are crucial events in tick oogenesis.
Methods
With a tick–Babesia experimental model, the expression profiles of Haemaphysalis longicornis Vg synthesis-related genes and Vg uptake-related genes were examined after the semiartificial mouse skin membrane feeding of Babesia-infected bovine red blood cells. Based on the expression profiles, Vg gene silencing was conducted and the existence of Babesia DNA in the ovary and hemolymph was assessed.
Results
The expression levels of Vg-2 and Vg-3 decreased in the fat body of Babesia-infected ticks at 1 day after engorgement (DAE). In the ovary, Vg-2 mRNA expression was significantly higher in Babesia-infected ticks than in uninfected ticks at 1 and 2 DAE and decreased at 3 DAE. VgR expression was significantly lower in Babesia-infected ticks than in uninfected ticks at 2 and 4 DAE. ATG6 had a lower gene expression in Babesia-infected ticks compared to uninfected ticks at 2 DAE. Western blot analysis revealed that H. longicornis Vg-2 accumulates in the fat body and hemolymph of Babesia-infected ticks. Moreover, Vg-2 knockdown ticks had a lower detection rate of B. ovata DNA in the ovary and a significant reduction of B. ovata DNA in the hemolymph compared with control ticks.
Conclusions
Vg uptake from the hemolymph to the ovary was suppressed in the presence of B. ovata and that accumulated Vg-2 is associated with Babesia infection or transmission in the tick body.