! eg. cattle responses to Boophilus tick GROOMING AVOIDANCE PUSTULE IMMUNITY PARASITES MULTIPLE RESPONSES AGAINST PARASITE eg. cattle responses to Boophilus tick ! GROOMING AVOIDANCE PUSTULE EOSINOPHILS ANTIBODY GRANULOMA

• Rhipicephalus sanguineus infected with Babesia canis IMMUNITY PARASITES REFRACTORINESS / SUSCEPTIBILITY • Rhipicephalus sanguineus infected with Babesia canis • Ixodes ricinus infected with Borrelia burgdorferi Ab grooming wrong receptors phagocytosis (human is refractory) (human is partial refractory / susceptible) spirochaetes in joint grooming evasion of antibody evasion of phagocytosis

eg. Trypanosoma in blood plasma IMMUNITY PARSITES ANTIBODY ON EXTRACELLULAR PROTOZOA eg. Trypanosoma in blood plasma U surface antigen membrane lysis + C3b complement complement mediated lysis and opsonisation + phagocytosis Th B

Th B stimulatory factors secretory antigen antibody IMMUNITY PARASITES IMMUNE EXPULSION OF GUT NEMATODES B Th U secretory antigen antibody nematode inactivation nematode expulsion stimulation of goblet cells + type 1 hypersensitivity releasing mast cell amines aid expulsion of inactive worms stimulatory factors gut with goblet cells U U U U U U U

Types 1 and 4 are both active against mites, ticks, fleas IMMUNITY PARASITES CUTANEOUS HYPERSENSITIVITY - TYPE 1 Types 1 and 4 are both active against mites, ticks, fleas • TYPE 1 produces amines leading to eosinophil degranulation protein which is toxic to macro-parasites. Y IgE antibody antigen histamine serotonin eosinophils basophils neutrophils sensitised mast cell degranulates when exposed to antigen attraction of granulocytes

Types 4 and 1 are both active against mites, ticks, fleas IMMUNITY PARASITES CUTANEOUS HYPERSENSITIVITY - TYPE 4 Types 4 and 1 are both active against mites, ticks, fleas • TYPE 4 activates macrophages which stimulate fibroblasts to produce granuloma and neutrophils to form intra-epidermal pustules U T cell sensitised T lymphocyte releases lymphokines macrophage activation neutrophils lymphocytes antigen fibroblasts

Antibody mediated cytotoxicity against Schistosoma, Fasciola etc IMMUNITY PARASITES EOSINOPHILS AGAINST HELMINTHS IN TISSUE Antibody mediated cytotoxicity against Schistosoma, Fasciola etc • Secretory / excretory antigens stimulate production of antibody from B lymphocytes and eosinophil stimulation promoter from T lymphocytes. • Antibody opsonises helminth larva, eosinophils degranulate around it and kill it. B Th antigen Y Fc antibody eosinophil stimulation degranulation opsonisation

INTRACELLULAR PROTOZOA (eg Leishmania) IMMUNITY PARASITES MACROPHAGE ACTIVATION AGAINST INTRACELLULAR PROTOZOA (eg Leishmania) • Type 4 hypersensitivity: antigen stimulates T lymphocytes to produce interferon gamma. This activates infected macrophages to produce NO and H2O2 and extra lysosomal enzymes, all toxic to Leishmania APC T cell IFNg activated macrophage kills Leishmania antigen Leishmania in parasitophorous vesicle within macrophage

INTRACELLULAR PROTOZOA eg Theileria parva IMMUNITY PARASITES CYTOTOXIC T LYMPHOCYTES AGAINST INTRACELLULAR PROTOZOA eg Theileria parva • Antigen is presented to CTL and they proliferate. • Antigen + MHC receptors on CTL permit specific binding to infected lymphocytes. • Bound CTL release toxic granules to kill infected cell. APC CTL antigen released specific granule release T lymphocyte with Theileria schizont T lymphocyte killed

VARIATION in Trypanosoma IMMUNITY PARASITES EVASION OF ANTIBODY BY ANTIGENIC VARIATION in Trypanosoma • Trypanosoma antigens stimulate antibody production. • These antigens can vary in successive generations of Trypanosoma. • Each new variant can evade the preceding antibody response until new antibody is produced. a b c d Trypanosoma per mm3 of blood, variants a - d Titre of antibody to Time (each peak takes several weeks)