The castor bean tick (Ixodes ricinus), common in Europe, is closely related to the black-legged tick, I scapularis, commonly found in the United States. These ticks are vectors for human and animal diseases (eg, Lyme borreliosis, anaplasmosis, babesiosis, tick-borne encephalitis). Current research focuses on preventing tick-borne diseases by searching for suitable tick antigens that may be used for vaccine development, which is easier and less expensive than acaricide production. This study focused on 11 tick genes that encode proteins potentially involved in iron and heme metabolism.
Quantitative real-time PCR was used to determine gene expression profiles in different tick stages and tissues to identify target proteins that are upregulated during the blood meal. RNA interference technology was then used to assess the genes’ importance in tick physiology. Immunization experiments were then performed on rabbits with recombinant proteins. The authors reported that 2 new antigens, ferrochelatase (FECH) and ferritin1 (FER1), showed an effect on tick fecundity, although to a lesser extent than previously seen with ferritin2 (FER2) vaccination. FER1 and FER2 are iron-metabolism genes; the specific function of FECH is unknown. Further research is needed into whether a vaccine with a combination of these antigens could increase efficacy of antitick and antitransmission vaccines.