The impact of gene knock-down and vaccination against salivary metalloproteases on blood feeding and egg laying by Ixodes ricinus

Abstract

Two cDNAs coding homologous putative metalloproteases (Metis 1 and Metis 2, expected molecular weights of 55.6 and 56.0 kDa, respectively) were identified from the hard tick Ixodes ricinus. The expression of Metis genes was induced in salivary glands during tick blood meal. RNA interference was used to assess the role of both Metis 1 and Metis 2 in tick feeding. It was found that salivary gland extracts lacking Metis 1-2 had a restricted ability to interfere with fibrinolysis. RNAi against Metis 1-2 also induced a high mortality rate. An immune reaction was raised in repeatedly bitten animals against Metis 1 and 2. Vaccination of hosts with the recombinant Metis 1 protein produced in a eukaryotic system partially interfered with completion of the blood meal. Although vaccination did not alter the survival rate or feeding time of ticks, their weight gain and oviposition rate were reduced. This will affect their reproductive fitness in the field. We believe this is the first report of an anti-tick vaccine trial using a metalloprotease derived from I. ricinus.

Expression profiling, gene silencing and transcriptional networking of metzincin metalloproteases in the cattle tick, Rhipicephalus (Boophilus) microplus

“…As previously mentioned, vaccination with single metzincins did in fact result in some decrease of engorgement weight and ovipositioning, however, it did not have a great effect on tick mortality (Decrem et al, 2007;Imamura et al, 2009). Based on the differential transcriptional network observed between reprolysins and astacins, the results support use of a combinatorial metzincin-based vaccine, which will be evaluated in a subsequent study.…”

“…Spirochete dissemination through vertebrate tissues may similarly be aided by salivary metalloproteases and other salivary anti-haemostatic agents (Maritz-Olivier et al, 2007;Ribeiro, 1989), which prevent fibrin clot formation and dissolution of the fibrin clots eventually formed around the feeding cavity of ixodid ticks (Francischetti et al, 2003). For this reason both Decrem et al (2007) and Imamura et al (2009) selected salivary gland metalloproteases from I. ricinus and H.…”

“…To date six reprolysin-like metalloprotease coding sequences have been identified in Haemaphysalis longicornis (Harnnoi et al, 2007), five in Ixodes ricinus (Decrem et al, 2007; and three in Ixodes scapularis (Francischetti et al, 2003).…”

“…Accordingly, Decrem et al (2007) proposed that these salivary gland metalloproteases are adequate vaccine candidates, since an elicited antibody response would result in the inhibition of essential anti -heamostatic enzymes (Decrem et al, 2007). Subsequent vaccination against these salivary gland metalloproteases did in fact affect the engorgement weight and fecundity of I. ricinus (with 47% and 55.4%, respectively) (Decrem et al, 2007) and the mortality of H. longicornis (with 14.6%) (Imamura et al, 2009). These reports support the notion that tick metzincin metalloproteases are promising anti-tick vaccine candidates and require further investigation to fully explore their potential.…”

Molecular and biological characterization of the Amblyomma americanum organic anion transporter polypeptide

“…RNAi gene silencing was carried out according to previously published methods (Nijhof et al, 2007;Decrem et al, 2008;Hatta et al, 2007). Using the cloned AamOatp plasmid DNA as template and PCR primers (forward, 5ЈTAA TAC GAC TCA CTA TAG GGG GAC CCG GCA AGC ACT TGC TAG TT3Ј; reverse, 5ЈTAA TAC GAC TCA CTA TAG GGT GTT CTT GGA GAC CGC GTC CTC C3Ј) with added T7 promoter sequence (in bold), were used to amplify the template for AamOatp double-stranded RNA (dsRNA).…”