Veterinary Parasitology- ICAR JRF/SRF 2024

• Type II (Antibody-Dependent Cytotoxic) Hypersensitivity:
• Mediated by IgG or IgM antibodies directed against surface antigens of target host cells, triggering complement-mediated lysis or opsonization/phagocytosis:
• Anemia in Malaria (Plasmodium): Antibodies against parasite antigens deposited on red blood cells cause bystander extravascular hemolysis.
• Megacolon/Cardiomyopathy in Chagas Disease (Trypanosoma cruzi): Autoantibodies cross-react with host nervous and cardiac muscle cells, destroying enteric autonomic ganglia.
• Hemoglobinuria in Babesiosis (Babesia): Immune-mediated destruction of parasitized and unparasitized erythrocytes triggers intravascular hemolysis.
• Glomerulonephritis in Malaria: Caused by circulating immune complex deposition in renal glomeruli, representing Type III hypersensitivity.
• nalysis:
• Conditions (A), (B), and (C) involve Type II hypersensitivity. Hence, Option 1 is correct.

• Dual-Action Tick Vaccine: 64 TRP (64-kDa Tick Recombinant Protein) is a truncated cement-cone salivary protein originally cloned from Rhipicephalus appendiculatus.
• Mechanism of Action: It acts as a dual-target vaccine candidate: (1) It damages the tick attachment cement cone, inducing local inflammatory rejection and disrupting blood feeding and reproduction across multiple ixodid species (Rhipicephalus, Amblyomma, Ixodes); (2) It cross-protects against transmission of tick-borne pathogens, notably tick-borne encephalitis virus (TBEV).
• Other Tick Antigens:
• Bm86 & Bm91: Concealed gut antigens from Rhipicephalus (Boophilus) microplus used in commercial anti-tick vaccines (TickGARD, Gavac), which damage gut digestive cells rather than acting as dual transmission-blocking cement targets.

Correct option: (3) 64 TRP.

• Breakthrough Subunit Vaccine: CoxAbic (developed in Israel by ABIC Biological Laboratories / Phibro Animal Health, launched in 2002) is the world's first non-living subunit anticoccidial vaccine for poultry.
• Mechanism of Action: CoxAbic is derived from native, affinity-purified gametocyte surface antigens (APGA, containing 56-kDa and 82-kDa glycoproteins) of Eimeria maxima. Inoculated into breeding hens, it stimulates high-titre protective IgG antibodies transferred via egg yolk to broiler chicks, providing maternal passive immunity against E. maxima, E. tenella, and E. acervulina.
• Contrasting Vaccines: Paracox, Nobilis COX ATM, and ADVENT are live or live-attenuated coccidiosis vaccines containing live sporulated oocysts.

Correct option: (3) CoxAbic

• Immunopathology of Filariasis: The severe chronic pathology of lymphatic filariasis (Wuchereria bancrofti, Brugia malayi)—manifesting as lymphangitis, lymphadenitis, and irreversible elephantiasis—is mediated by Type-IV (delayed-type / cell-mediated) hypersensitivity responses.
• Immunological Basis: Death of adult filarial worms triggers intense Th1/Th17 cell-mediated immune responses, macrophage accumulation, endothelial proliferation, and granulomatous fibrosis occluding lymphatic vessels.
• Hypersensitivity Types in Other Conditions:
• Self-cure phenomenon in haemonchosis: Type-I immediate hypersensitivity (IgE-mediated mucosal mast cell degranulation and histamine release).
• Haemoglobinuria in babesiosis: Type-II antibody-mediated cytotoxic hypersensitivity.
• Cercarial dermatitis: Initially Type-I IgE-mediated, followed by secondary Type-IV reaction upon repeat exposure.

Correct option: (1) Lymphatic filariasis in W. bancroft’ infection

• Orphan Vaccine Concept: An orphan vaccine is a biologically effective, proven vaccine that targets a neglected or commercially unviable disease condition, resulting in lack of commercial production and distribution.
• Case of To45W Vaccine: The To45W recombinant oncosphere antigen vaccine was developed to protect sheep against Taenia ovis metacestodes (sheep measles). While conferring $\gt 95\%$ protection against cysticercosis, T. ovis causes aesthetic carcass condemnation without acute clinical mortality or human health threat, so pharmaceutical companies ceased commercial production, classifying it as an orphan vaccine.
• Contrast with Commercial Vaccines: Rakshavac-T (Theileria annulata), Dictol (Dictyocaulus viviparus irradiated lungworm vaccine), and Paracox (Eimeria spp.) have established commercial markets.

Correct option: (1) To45W based vaccine