ICAR AIEEA (PG): Master's entrance, Veterinary Science and Animal Sciences · India · NTA for ICAR
Original practice questions written to the published syllabus · not past papersInnate and adaptive immunity, antibodies and complement, hypersensitivity, vaccines and the cold chain, and the serological tests used in diagnosis and surveillance.
In the exams: ICAR AICE-JRF core group 06; ICAR AIEEA-PG 13 (Microbiology); NAVLE health maintenance and prevention 35%
ICAR AIEEA (PG) and AICE-JRF/SRF (core group 06: Microbiology)
Definitions and mechanisms: PRRs and TLR ligands, primary and secondary lymphoid organs by species (bursa, ileal Peyer's patch, haemal nodes, inverted pig nodes), immunoglobulin structure and classes, complement pathways and regulators, MHC processing, Gell and Coombs types with veterinary examples, adjuvants and vaccine types, and the principle of each serological test (CFT reading, AGID, HI, ELISA formats).
How our questions for ICAR AIEEA spread across the units of Veterinary Immunology & Serology. Difficulty: 1 easy, 27 medium, 5 hard.
| Adaptive immunity | 3 | |
| Immunoglobulins | 3 | |
| The major histocompatibility complex | 3 | |
| Serological tests: ELISA and agglutination | 3 | |
| Serological tests: CFT, AGID and virus neutralisation | 3 | |
| Immunopathology | 3 | |
| Innate immunity | 2 | |
| Antigens and antibodies | 2 | |
| Complement | 2 | |
| Hypersensitivity | 2 | |
| Vaccine types | 2 | |
| The vaccine cold chain | 2 | |
| Colostral immunity | 2 | |
| Adjuvants | 1 |
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
Unmethylated CpG DNA motifs, used as experimental adjuvants, act mainly through:
D. TLR9 in endosomes
Bacterial DNA is rich in unmethylated CpG, recognised by endosomal TLR9. TLR2 and TLR4 are surface receptors for lipoproteins and LPS; NLRP3 is triggered by aluminium salts and crystals, not CpG.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
Which cell is chiefly responsible for carrying antigen from tissues to lymph nodes and activating naive T cells?
B. Dendritic cell
Dendritic cells capture antigen, mature after pattern recognition receptor signalling and migrate to lymph nodes where they present peptide with co-stimulation to naive T cells. Neutrophils die at the site; mast cells and NK cells do not prime naive T cells.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
In young sheep, cattle and pigs, which tissue acts as a primary lymphoid organ for B cell diversification before involuting around puberty?
B. Ileal Peyer's patch
The continuous ileal Peyer's patch of young ruminants and pigs diversifies B cells and then involutes. Jejunal patches persist as secondary tissue; haemal nodes and mesenteric nodes are secondary organs.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
Gamma-delta (γδ) T cells are notable in domestic ruminants because:
B. They form a large fraction of circulating T cells in young calves and lambs
γδ T cells are a minority in humans and mice but make up a large proportion of blood T cells in young ruminants and pigs and are abundant in epithelia. They generally lack CD4 and circulate outside the thymus.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
Papain digestion of an IgG molecule yields:
C. Two Fab and one Fc
Papain cuts above the hinge disulphides, releasing two Fab and one Fc. Pepsin cuts below them, giving F(ab')2. Separation into heavy and light chains needs reduction, not papain.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
Which complement fragment is the most potent chemoattractant for neutrophils?
D. C5a
C5a is an anaphylatoxin and strong neutrophil chemotaxin. C3b is the main opsonin; C4b is part of the classical convertase; C1q is the recognition unit of C1.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
Genetic resistance to Marek's disease is classically associated with which MHC haplotype?
C. B21 of the chicken B complex
The B21 haplotype of the chicken MHC (B complex) is the textbook example of MHC-associated resistance to Marek's disease. DLA, SLA and ELA are the MHCs of dogs, pigs and horses, species that do not get Marek's disease.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
A disease has a basic reproduction number (R0) of 4. What minimum proportion of the population must be immune to prevent sustained transmission?
C. 75%
Herd immunity threshold = 1 − 1/R0 = 1 − 1/4 = 0.75, i.e. 75%. 25% is 1/R0 itself (a common slip). 80% and 40% do not follow from the formula.
Further reading: Thrusfield M et al., Veterinary Epidemiology, 4th ed.
Immune-stimulating complexes (ISCOMs) are cage-like particles made of:
A. Saponin, cholesterol and phospholipid with incorporated antigen
ISCOMs are formed by Quil A saponin with cholesterol and phospholipid, incorporating antigen, and favour cell-mediated and cytotoxic responses. The others describe aluminium, oil emulsion and Freund's adjuvants.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
The I-2 strain of Newcastle disease vaccine is valued in village poultry programmes mainly because it is:
D. Thermotolerant, reducing dependence on the cold chain
I-2 is a live thermotolerant strain developed for village chickens in hot climates with weak cold chains. It is not inactivated and not a gene-deleted marker vaccine.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
Ten here, 33 in the app. The Laisha app has every practice question we have written to ICAR AIEEA in this subject, marked as you go, with timed papers, a jump-to-unanswered list and a certificate when you pass at 70 per cent.
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