Lecture 15- Immune Response to Viruses and Parasites Flashcards
What is the primary mechanism in the defense against viruses
Killing of virus infected cells by cytotoxic T cells
What is an obligate pathogen
Uses host cell machinery and may be host adapted- making it easier to evade immune system
What are the steps in viral pathogenesis
- Virus binds receptor
- Enters cell via endocytosis or fusion
- Nucleic acid released from capsid
- Replication occurs
- New nuclei acids packaged into new capsids
- New virons are released or cell disintegrates to release virons
What are the steps in DNA Virus replication
Infectious viral DNA undergoes replication to form new viral DNA then undergoes transcription to become new viral RNA then translation to become viral protein and then viral assembly
What are the steps in RNA replication
Infectious viral RNA will replicate and form new viral RNA then will undergo translation to viral protein and then protein assembly
What are the steps in lentivirus replication
Infectious viral RNA will undergo reverse transcription to form viral RNA then transcription to form viral rna then translation to viral protein and then virus assembly
What is an example of DNA virus
Canine parvovirus
What is an example of RNA virus
Influenza
What is an example of lentivirus
Equine infectious anemia, HIV
What TLRs detect nucleic acids
3, 7, 8, 9w
Hat detects intracellular nucleic acid sensors in all nucleated cells
RIG-1, MDA-5
What are some innate responses to viruses
Interferons, lysozyme, bile/intestinal enzymes, conglutinin, mannose-binding lectin, surfactant proteins A&D, defensive, apoptosis of host cells
What are interferons
Glycoproteins secreted by virus infected cells, trophoblasts
What is interferon alpha
Plasmatyic dendritic cells via TLR7/9, lymphocytes, monocytes and macrophages
How many isoforms of interferon-alpha do pigs, cattle, horses and dogs have
Pigs and cattle: 12
Horses: 4
Dogs: 2
What is interferon Beta
Virus infected fibroblasts
What is interferon-w/all
Lymphocytes, monocytes, trophoblasts of many species
What is interferon T
Ruminant trophoblasts
What is interferon delta
Pig trophoblast
What is interferon kappa
Keratinocytes
What is interferon gamma
Antigen stimulated T cells, pig trophoblasts
What is interferons a, beta
Produced very rapidly by virus infected cells
What stimulates NK cells
Interferons
What do NK cells produce
Interferon gamma
Who has more rapid response natural killer cells to cytotoxic t cells
Natural killer cells
Interferons activate many ____
Anti-viral mechanism
What is 2’5 OAS
Antiviral protein, activated by exposure to dsRNA and upregulated by interferons
What are Mx proteins
GTPase that inhibit influenza viruses
What does 2’5 OAS degrade
RNA
What does protein Kinase R prevent
Translation
What does Mx GTPase block
Viral assembly
What are some antibody responses to viruses
Block absorption into cell, stimulate phagocytosis, initiate complement
What diseases is antibody mediated destruction of host cells important
Rabies, new castle disease, FLV, BVD, avian infectious bronchitis
What are cell mediated mechanism responses to viruses
Viral antigens expressed on infected cell before new virus is reassembled can be presented on cell surface by MHC I, Tc cells recognize viral peptide as foreign, Tc cells kill infected cell
Antigenic variation number for swine flu
H1N1
Antigenic variation number for equine flu
H3N8
Antigenic drift
Change in structures of H/N molecules
Antigenic shift
Recombination of two strains
What are ways viruses can evade immune system
Antigenic variation, reduced effectiveness of antibodies, blocking interferons, downregulating MHC I- reduced effectiveness of NK cells and Tc cells
How does equine herpesvirus type 1 evade immune system
Has latent phase
Enters multiple cell types in horses- endothelial, epithelial and mononuclear
Users MHC I as entry molecule
Cell associated viremia allows rapid spread- neurologic disease and abortion
Can hide envelope proteins, down regulate MHC I, and gG proteins inhibit cytokines
Immunity to parasites is characterized by a ___ response and __ production
Th2 response and IgE production
Helminths are ___parasites
Obligate
What is the function of thick cuticle in helminths
Can’t be destroyed efficiently by MAC or complement
What plays a role in destruction of helminths
Eosinophils
What do L-arginines do
Drive granuloma formation and reduce availability of arginine which is anti-inflammatory by decreasing T cell activity
What is the primary response to helminths
Th2 as well as IL-4, IL-10, IL-13, IgE, mast cells, eosinophils
What is IgE mediated self cure reaction to helminths
Worms secrete antigens in saliva and triggers mast cell degranulation and vasoactive molecules released
This stimulates smooth muscle contractions and vascular permeability-dislodges and flushes worms, IL-13 stimulates epithelial proliferation, sloughs worms
Degranulating mast cells produce chemotactic substances for
Eosinophils
Th2 cells produce ___ that mobilizes eosinophils from bone marrow
IL-5
What are the four components in eosinophil
Major basic protein
Eosinophilia neurotoxin
Catatonic protein
Eosinophilic perioxidase
What are the two mechanisms typically used in cell mediated immunity against parasites
Delayed type hypersensitivity (type IV)-T cells and NK cells
Direct attack
What are some ways parasites evade immune system
Immunosuppression, protease inhibitors, immunoglobulin splitting proteins, prostaglandins, antioxidants
What re taeniastatins
Protease inhibitors produced by taenia taeniaformis
What are some functions of taenia taeniaformis
Inhibits neutrophil chemotaxis, inhibits complement activation, inhibits T cell proliferation, inhibits IL-2 production
