Infectious diseases and vaccines Flashcards
Describe the main immune modules induced by the innate lymphoid cells.
Some pathogens use Vectors
Intermediate hosts
* carry infections
* often blodsucking
* Tics, Fleas, Flies, Mosquitos
Antibodies
Antibodies are protective proteins produced by your immune system. They attach to antigens (foreign substances) — such as bacteria, fungi, viruses and toxins — and remove them from your body.
Viral infections
binds to a surface receptor to infect a cell
– DNA or RNA (ds or ss) -Replicate within host cell
– Genome replication may be error-prone =>mutations – Protein or lipoprotein coat
– Lipid-envelope when extra-cellular (some)
Antibody (especially secretory IgA)
Blocks binding of virus to host cells; preventing infection or reinfection
IgG, IgM, and IgA
Block fusion of viral envelope with host cell’s plasma membrane
IgG and IgM
Enhance phagocytosis of viral particles (opsonization)
IgM
Agglutinates viral particles
Complement activated by IgG or IgM antibody
Mediates opsonization by C3b and lysis of enveloped viral particles by membrane-attack
complex
IFN-g secreted by TH or TC cells
Direct antiviral activity
Cytotoxic T lymphocytes (CTLs)
Kill virus-infected self cells
NK cells and macrophages
Kill virus-infected cells by antibody-dependent cell-mediated cytotoxicity (ADCC)
Hepatitis C
overcomes interferon antiviral effects by blocking/inhibiting PKR
HSV
inhibits TAP activity => shutting down MHC class I presentation to CD8+ T-cells
Influenza and HIV
change their surface Ag
Virus -Evasion strategies
Type I and III interferon pathways
* Peptide processing and presentation in MHC class I
* Cytotoxic T lymphocyte and NK-cell response
* Modulation immunresponse by producing or blocking cytokines, chemokines or receptors
* Latency – ceasing to replicate until immunity wanes
* Survival within Macrophages
* Antigen variation
Intracellular bacteria
Type1andcytotoxicimmune response
– Macrophages
– NKcells
Extracellular bacteria
Type3 immune response
– Neutrophils
– Antibodies
* Neutralization & opsonization
– Complement
* opsonization & lysis
Mycobacterium Tuberculosis
Intracellular bacteria
* Survive in macrophages
* Hard to eliminate – although often contained
* Th1 type immune response
* Recruits&acitvates
macrophages
* Granulomas
Parasitic infections
Very broad category
Giardia lamblia
SEM 8698 lores.jpg.
(2019 Wikimedia Commons.
* From small unicellular (protozoan) to large macroscopic worms
* Ways of infection
– Water–Giardia
– Vectors–Malaria
– throughintestinaltract(food,water,feces) – Somethroughskin(egSchistosomas)
* Immune response depends on
* Mode of immune detection
* Paracitic stage * Location
Parasitic infections - Helminths
Enter hosts- intestinal tracts
* Exclusively extracellular
* Type 2 immune response
– ILC2s
– IL-4, IL-5, IL13
– Mucosa
– Smooth muscle contraction
– induction of IgE
– mast cells, eosinophils
– M2 Macrophages -Alternatively activated
* Evasion:
– decrease external Ag expression
– wrap themselves in host proteins to limit immunity
Fungal infections
Type 3 Immune response
* Commensal fungal organisms
– May be pathogenic if dominant
– Ie:antibacterial medications–oral candidosis (oral thrush) or vulvovaginal candidiasis (yeast infections)
* Opportunistic infections – Not normally pathogenic – Immunodeficient patients
* Neutropenia, Immunesuppression, HIV/AIDS – Candidosis
* Pneumocystis Carini * Evasion:
Candidiasis
Shankargouda et al, Fron Microbiol 2015
– –
Capsules that prevent PRRbinding
Fungi-induced expulsion from macrophages
Vaccination
Aim:
– to generate protective immunity without having to go through the disease
* Active immunization
– Induce adaptive response by exposure to nonpathogenic or parts of a microbe
– Effectors:
* Antibodies
* ProtectiveTcells
Vaccines adjuvants
Adjuvants are included to enhance the immune response to a vaccine
– Alum — good at stimulating TH2 but not TH1 responses
– AS04 — alum plus a TLR4 agonist
* Encourages TH1 responses
– Virosome — reconstituted viral envelope with no genetic information
Vaccines – conjugate
Conjugate or multivalent vaccines can improve immunogenicity – Linking with something immunogenic
Passive immunisation
Passive immunity is provided when a person is given antibodies to a disease rather than producing them through his or her own immune system.
Influenza vaccines
Antigens form 4 different virus – 2 A and 2 B
* 3 forms approved in Norway:
– Inactivated virus (most)
– Inactivated with virus (for patients >65 yrs)
– Live attenuated virus (nosespray) (children 2-17 yrs)
