Naturally Acquired Resistance to Ixodes scapularis Elicits Partial Immunity against Other Tick Vectors in a Laboratory Host

ABSTRACT In many regions where ticks negatively impact public health or economic production, multiple medically important tick species may have overlapping geographic distribution, and in North America, this includes members ofIxodes,Dermacentor, andAmblyommagenera. Acquired tick resistance is the process by which some animals develop an immune response against feeding ticks after one or more exposures. This form of immunity can restrict the ability of ticks to feed and may inhibit transmission of pathogens. Likewise, many proteins present in tick saliva are conserved among tick species, and prior studies have reported cross-protective host immunity against certain combinations of ticks. In this study, we used a guinea pig model to assess whether host resistance againstIxodes scapulariscould confer protection against two other medically important tick vectors,Dermacentor variabilisandAmblyomma americanum. Tick challenges using nymphs were used to induce host resistance against a primary species, followed by additional challenge using a secondary tick species. Tick attachment to hosts and engorgement weights were reduced significantly forD. variabilisandA. americanumfeeding onI. scapularis–sensitized hosts. Reciprocally,I. scapularisengorgement weights were reduced to a lesser extent, and attachment was unaffected when feeding on hosts sensitized with eitherD. variabilisorA. americanum. These results indicate that immunity againstI. scapulariscould potentially be exploited for use in an anti-tick vaccine targeting multiple tick species and their associated pathogens.