Infection Science & Immunology – Fungal / Parasitic Infections, Immunisation & Diagnostics

Vocabulary flashcards covering key immunology, parasitology, vaccination and diagnostic terms from the lecture transcript.

Fungal infection

Disease caused by pathogenic fungi; may involve yeast or hyphal forms and provoke innate and adaptive immune responses.

Hyphae

Long, branching filamentous structures of a fungus; typical of mould-type growth.

Yeast

Unicellular growth form of fungi that reproduces by budding or fission.

NETosis

Process by which neutrophils expel DNA and granule proteins to form neutrophil extracellular traps (NETs) that immobilise microbes.

PAMP (Pathogen-Associated Molecular Pattern)

Conserved microbial structure recognised by the immune system’s pattern-recognition receptors (PRRs).

PRR (Pattern-Recognition Receptor)

Host receptor (e.g., TLRs, lectins) that detects PAMPs and initiates innate immunity.

Complement system

Cascade of plasma proteins that opsonise pathogens, induce inflammation and form membrane-attack complexes.

Parasite

Organism that lives on or within another organism (host) and draws nutrients at the host’s expense.

Malaria

Protozoan infection caused by Plasmodium spp., transmitted by Anopheles mosquitoes.

Schistosomiasis

Helminth infection caused by Schistosoma spp.; cercariae penetrate skin during freshwater contact.

Schistosoma mansoni

Blood fluke species responsible for intestinal schistosomiasis; eggs excreted in stool.

Cercaria

Free-swimming larval stage of Schistosoma released from snails; infective to humans.

Schistomulum (schistosomula)

Post-penetration larval stage of Schistosoma that migrates through host tissues to the liver.

Miracidium

Ciliated larval stage that hatches from Schistosoma egg and infects freshwater snails.

Sporocyst

Asexual developmental stage of Schistosoma inside the snail host producing cercariae.

Immunisation

Process of inducing protective immunity by vaccination or natural exposure.

Herd immunity

Indirect protection of susceptible individuals when a large proportion of the population is immune.

Live attenuated vaccine

Vaccine containing weakened but replicative microorganisms that elicit strong, long-lasting immunity.

Inactivated (killed) vaccine

Vaccine composed of pathogens rendered non-replicative; safer but often requires boosters.

Toxoid

Inactivated bacterial toxin used as vaccine antigen (e.g., tetanus toxoid).

Subunit vaccine

Vaccine containing purified antigenic components rather than whole organisms.

Recombinant vector vaccine

Vaccine using engineered viruses/bacteria to deliver genes encoding protective antigens.

DNA vaccine

Plasmid DNA encoding antigen injected to provoke in-situ antigen expression and immunity.

Serology

Laboratory detection of antibodies or antigens in serum for diagnostic or epidemiological purposes.

Radial immunodiffusion

Unlabelled immunoassay where antigen diffuses into antibody-containing gel forming precipitin rings.

Agglutination test

Assay in which particulate antigens clump upon antibody binding, indicating presence of specific antibodies or antigens.

Radioimmunoassay (RIA)

Highly sensitive assay using radio-labelled antigens or antibodies to quantify analytes.

ELISA (Enzyme-Linked Immunosorbent Assay)

Enzyme-based colourimetric assay to detect and quantify antigens or antibodies.

Western blot

Technique that separates proteins by electrophoresis, then probes with antibodies for detection.

Flow cytometry

Laser-based technology that measures physical and fluorescent properties of individual cells in suspension.

Hematopoietic stem cell (HSC)

Multipotent bone-marrow progenitor that gives rise to all blood and immune cells.

Myeloid lineage

HSC-derived cell lineage producing red cells, platelets, granulocytes, monocytes, macrophages and dendritic cells.

Lymphoid lineage

HSC-derived lineage generating B cells, T cells and natural killer (NK) cells.

Granulocyte

Leukocyte with cytoplasmic granules; includes neutrophils, eosinophils and basophils.

Monocyte

Circulating precursor that differentiates into macrophages or dendritic cells in tissues.

Lymphocyte

Adaptive immune cell category encompassing B cells, T cells and NK cells.

Neutrophil

Most abundant granulocyte; performs phagocytosis and NET formation to combat bacteria and fungi.

Eosinophil

Granulocyte critical for defence against helminths; mediates degranulation and ADCC via IgE.

Basophil

Granulocyte releasing histamine and mediators during allergic and parasitic responses.

B cell

Lymphocyte that recognises antigen via BCR and differentiates into antibody-secreting plasma cells.

T cell

Lymphocyte recognising antigenic peptides via TCR; includes helper (CD4⁺) and cytotoxic (CD8⁺) subsets.

Natural Killer (NK) cell

Innate lymphoid cell capable of killing virus-infected or transformed cells without prior sensitisation.

B cell receptor (BCR)

Membrane-bound immunoglobulin on B cells that binds specific antigen.

T cell receptor (TCR)

Heterodimeric receptor on T cells recognising peptide-MHC complexes.

MHC class II

Major histocompatibility complex molecule on APCs presenting extracellular antigens to CD4⁺ T cells.

CD4

Co-receptor on helper T cells that binds MHC II during antigen presentation.

CD8

Co-receptor on cytotoxic T cells that binds MHC I to identify infected cells.

Perforin

Pore-forming protein released by cytotoxic T cells/NK cells facilitating granzyme entry.

Granzyme

Serine protease entering target cells to trigger apoptosis following perforin pore formation.

Antigen presentation

Display of processed antigenic peptides on MHC molecules for T-cell recognition.

Opsonisation

Coating of pathogens with complement fragments or antibodies to enhance phagocytosis.

Toll-like receptor (TLR)

Family of PRRs that sense distinct PAMPs and activate innate immunity.

Macrophage polarization (M1/M2)

Functional differentiation: M1 pro-inflammatory, microbicidal vs. M2 anti-inflammatory, tissue repair.

Antibody-dependent cellular cytotoxicity (ADCC)

Killing of antibody-coated targets by effector cells (e.g., NK cells, eosinophils) via Fc receptors.

Lewis X antigen

Fucosylated carbohydrate PAMP on Schistosoma recognised by C-type lectin receptors.

Th1 response

T helper subset producing IFN-γ/TNF; promotes macrophage activation against intracellular pathogens.

Th2 response

T helper subset producing IL-4/IL-5/IL-13; key in defence against helminths and allergy.

Th17 response

T helper subset producing IL-17/IL-22 involved in neutrophil recruitment and fungal defence.

Treg (Regulatory T cell)

CD4⁺FoxP3⁺ subset producing IL-10/TGF-β to suppress excessive immune responses.

Nuocyte (ILC2)

Innate lymphoid cell type 2 producing IL-5/IL-13 contributing to Th2 and anti-helminth immunity.

Lymphatic filariasis

Mosquito-borne nematode infection (Wuchereria bancrofti, Brugia spp.) causing lymphedema and elephantiasis.

Brugia malayi

Filarial nematode species causing lymphatic filariasis; microfilariae circulate in blood.

Wuchereria bancrofti

Primary filarial worm responsible for most lymphatic filariasis cases worldwide.

Microfilaria

Sheathed larval stage of filarial worms found in peripheral blood; diagnostic form.

Diethylcarbamazine (DEC)

Antifilarial drug used, often with albendazole, for mass treatment of lymphatic filariasis.

Albendazole

Broad-spectrum anthelmintic disrupting worm microtubules; used in combination therapy.

Wolbachia

Intracellular bacterial endosymbiont of many filarial worms that modulates host immunity.

Granuloma

Organised aggregate of immune cells (e.g., macrophages, eosinophils) surrounding persistent antigen or parasite.

Luminex assay

Bead-based multiplex immunoassay allowing simultaneous quantification of multiple cytokines.

Direct sandwich ELISA

ELISA format where capture antibody coats plate, antigen binds, then enzyme-conjugated detection antibody binds the captured antigen.