ICAR AICE-JRF/SRF (PhD) · 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%
How our questions for ICAR AICE-JRF/SRF spread across the units of Veterinary Immunology & Serology. Difficulty: 1 easy, 28 medium, 18 hard.
| Serological tests: ELISA and agglutination | 5 | |
| Adaptive immunity | 4 | |
| Immunoglobulins | 4 | |
| The major histocompatibility complex | 4 | |
| Serological tests: CFT, AGID and virus neutralisation | 4 | |
| Immunopathology | 4 | |
| Innate immunity | 3 | |
| Antigens and antibodies | 3 | |
| Complement | 3 | |
| Hypersensitivity | 3 | |
| Vaccine types | 3 | |
| Colostral immunity | 3 | |
| Adjuvants | 2 | |
| The vaccine cold chain | 2 |
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.
Monoclonal antibodies were first produced by fusing antibody-secreting B cells with which cell type?
B. Myeloma cells
A hybridoma combines the specificity of a single B cell clone with the immortal growth of a myeloma cell line. None of the other cell types provides an immortal, antibody-secreting partner.
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.
On serum protein electrophoresis, a dog has a narrow, tall spike in the gamma region. The most likely category of cause is:
D. A monoclonal gammopathy such as multiple myeloma
A narrow spike reflects one clone's immunoglobulin, typically a plasma cell tumour, although canine ehrlichiosis can occasionally give a narrow peak. Chronic infection usually gives a broad polyclonal rise; FPT lowers gamma globulin; CRP is not in the gamma region.
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.
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.
Aluminium salt adjuvants are thought to act partly by activating which innate sensor?
C. The NLRP3 inflammasome
Aluminium salts activate the NLRP3 inflammasome, releasing IL-1β, besides forming a depot and presenting antigen as particles. TLR9 responds to CpG DNA, TLR5 to flagellin and RIG-I to viral RNA.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
Four birds have HI titres of 16, 32, 64 and 128. The geometric mean titre is:
D. 45
GMT = (16 × 32 × 64 × 128)^(1/4) = 2^((4 + 5 + 6 + 7) ÷ 4) = 2^5.5 ≈ 45.3. 60 is the arithmetic mean, which overweights high titres; 48 is the median; 32 comes from rounding the mean log2 titre (5.5) down to 5.
Further reading: Tizard IR, Veterinary Immunology, 10th ed.
Ten here, 47 in the app. The Laisha app has every practice question we have written to ICAR AICE-JRF/SRF 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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