Date of Award

4-1-1989

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Microbiology & Immunology

Abstract

Cattle and laboratory animals display acquired immunologically based resistance to ixodid tick feeding. Antibody, cell mediated, and complement dependent effector mechanisms are involved in this immunological response. The current study was concerned with the isolation and characterization of ixodid tick molecules involved in the host immune response to infestation.Ixodid ova extracts were fractionated by membrane ultrafiltration and Sephadex G 200 gel permeation chromatography. The whole ova extract and defined molecular weight fractions obtained were analyzed for their ability to interact with immune effector elements of tick resistant hosts.Amblyomma americanum whole ova extract induced both immediate and delayed skin hypersensitivity in larvae infested guinea pigs. Membrane ultrafiltration fractions of Amblyomma americanum extract elicited delayed hypersensitivity responses in larvae infested guinea pigs. Sephadex G 200 gel filtration fractions of Amblyomma americanum ova extract did not induce an antigen specific hypersensitivity response in nymph infested guinea pigs. Cross reactivity was demonstrated by D. albipictus whole ova extract and membrane ultrafiltration fractions thereof, all of which induced a delayed hypersensitivity response from A. americanum larvae infested guinea pigs.Unfractionated A. americanum ova extract did not stimulate lymphocytes from larvae, nymph, or adult infested guinea pigs to proliferate in an antigen specific manner. Both the 100 kdal and above and the 30 to 100 kdal ultrafiltration fractions stimulated lymphocyte blastogenesis in larvae infested guinea pigs. Sephadex G 200 fractions did not stimulate antigen specific proliferation in lymphocytes from larvae, nymph, or adult infested guinea pigs.Amblyomma americanum whole ova extract and Sephadex G 200 fractions of ova extract were further characterized by two dimensional electrophoresis. Isoelectric focusing-2DGE and NEPHGE-2DGE of whole ova extract resulted in complementary gels with polypeptides ranging from 10 kdal to 205 kdal and 12 kdal to 245 kdal, respectively. Serum from tick infested and naive rabbits recognized ova extract components from 46 kdal to 80 kdal of IEF-2DGE immunoblot. Only the 43 kdal component was recognized in blots from more than one fraction.A presumptive monoclonal antibody was raised to immunogenic molecules contained in ixodid ova extract. This antibody displayed heterogenous reactivity on IEF-2DGE immunoblot.

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