Acquisition of protective immunity in Geochelone pardalis against Amblyomma marmoreum (Acari:Ixodidae) nymphal ticks.

Significant increases in serum globulins (alpha 1, alpha 2, beta and gamma) were observed in mountain leopard tortoises (Geochelone pardalis) after they had been immunized with nymphal homogenates of Amblyomma marmoreum. There was a concomitant significant increase in the numbers of leukocytes (lymphocytes, basophils, monocytes and eosinophils). Resistance to nymphal-challenge infestations was manifested by reduced feeding time, lower engorgement masses, and significantly fewer (P < 0.0001) numbers of nymphs that moulted. These findings are contrary to the generally reported phenomenon, that ticks do not induce resistance in their natural hosts.