Animal diseases exam 2

Virion makeup and function

nucleic acid genome surrounded by a protein coat, facilitates transmission from one host to another

DNA classes

ssDNA, dsDNA, ssRNA, dsRNA, ssRNA retrovirus, sDNA hepadnavirus

What is the average size of a virus

0.02-0.3 micrometers

capsid

the protein shell surrounding the genome of a virus particle. repetitive and precise pattern around the nucleic acid

capsomere

subunit of the capsid, smallest morphological unit visible on a microscope

nucleocapsid

complete complex of nucleic acid and protein packaged in the virion

enveloped virus

virus that contains additional layers around the nucleocapsid

Virus enzymes

lysozyme, nucleic acid polymerases, neuraminidases (cleave glycosidic bonds and allow viruses to leave cell)

titer

number of infectious units per volume of fluid

plaque assay

analogues to the bacterial colony, allows for virus infectivity to be measured, plaques develop on lawns of host cells

phases of viral replication

attachment, entry, synthesis of virus nucleic acid, assembly of capsids, release (lysis)

Permissive cell

a host cell that allows the complete replication cycle of a virus to occur

Baltimore naming scheme

Based on the relationship of the viral genome to its mRNA. class I = ds DNA, class II = ss DNA. class III = dsRNA, class IV/V = ssRNA (+ or -), class VI = retroviruses which use reverse transcription, class VII = dsDNA which have an RNA intermediate

positive-strand RNA virus

single stranded RNA with the same orientation as mRNA

negative-strand RNA virus

single stranded RNA with complementary mRNA orientation

Retroviruses

animal viruses responsible for some cancers and AIDS, VI and VII class, require reverse transcriptase

Persistent infections

release of virions from host does not result in cell death

latent infections

delay between infection and lytic events

transformation

conversion of normal cell into tumor cell

cell fusion

two or more cells become one cell with many nuclei

viral metagenome

sum of all viral genomes in an environment

poliovirus/picornaviridae

small virus with direct translation of RNA producing a polyprotein which cleaves into smaller proteins. positive strand RNA

rhabdoviruses

rabies, vesicular stomatitis, enveloped viruses. negative strand RNA

influenza

orthomyxoviridae, enveloped, polymorphic, negative strand RNA. segmented genome allowing for quick mutation. hemagglutinin and neuraminidase

hemagglutinin

causes clumping of red blood cells

neuraminidase

breaks down sialic acid components of host cytoplasmic membrane

T cells

lymphocyte which produces a T cell receptor (TCR) which interacts with a single antigen

B cells

lymphocyte which produces antibodies or immunoglobulins

major histocompatibility complex (MHC) proteins

necessary for T cell to recognize antigen

T-cytotoxic (TC) cells

directly kill antigen bearing target cells when presented by MHC protein

T-helper (TH) cells

promote immune reactions by releasing cytokines. MHC II complexes

TH1 cells

activate macrophages to initiate inflammation and immunity

TH2 cells

stimulate antigen reactive B cells to produce antibodies

Antibodies

proteins made by B cells in response to antigens. directly interact with antigens to cause B cells to ingest antigen

Clonal selection

helper T cell releases cytokines which activate B cells in lymph node or spleen. become plasma cells which can release antibodies

IgG

most common antibody (80%). 2 heavy and 2 light chains result in antigen-binding sites

lgM

pentamer, aggregate of 5 Ig attached by a J chain, first in adaptive response, agglutination

lgA

dimer which is present in body fluids, protects mucous membranes

IgE

in serum and binds to eosinophils

IgD

in serum and function is unknown

Antibody production

somatic recombination, hypermutation, gene rearrangement

Opsonization

antigen is coated in opsonins to cause phagocytosis of bacteria by immune cells

agglutination

antibodies coat virus and block binding to host. more sensitive than precipitation tests. blood typing

Adaptive immune response timeline

after the second infection, inductive period drops to 2 days, lgM releases faster and lgG levels are elevated

enzyme-linked immunosorbent assay (ELISA)

detects specific proteins through antibody-antigen binding

polyclonal antibodies

made by many B cell clones, not precisely reproducible

Monoclonal antibodies

made by a single B cell clone, produced in vitro

hybridoma technology

provides specific antibodies for clinical and research purposes. combines plasma cells with cancer cells

Serology

the study of antigen-antibody reactions such as neutralization, precipitation, and agglutination in vitro, used for immunology tests. specificity and sensitivity are important.

precipitation

the interaction with a soluble antibody and antigen to form an insoluble complex

immunofluorescence

chemical modification of antibodies with dyed. rhodamine B (red) and fluorescein isothiocyanate (yellow-green). direct and indirect (based on whether desired antibody is dyed or not)

Enzyme Immunoassay (EIA)

covalently bonded enzymes label antibody molecules. Indirect EIA detects antibody, competitive detects antigen through the inverse of the color

radioimmunoassay (RIA)

radioisotopes label antibody molecules. used as conjugates instead of enzynes. iodine-125. can measure rare serum proteins

Immunoblots (western blotting)

basically gel electrophoresis then addition of specific antibodies

immunoglobulin (Ig)

antigen binding molecules produced by B cells

antibody (Ab)

secreted immunoglobulin

Antigen

any molecule that binds to immunoglobulin or T cell receptor

Types of phagocytic cells

Dendritic cells, neutrophils, macrophages

Leukocytes

nucleated white blood cells, 0.1% of blood cells

Lymphocytes

specialized leukocytes that are involved in adaptive immune response. B and T cells

Where to B and T cells originate

Both originate in bone marrow, but T cells mature in thymus - primary lymphoid organs

Lymphatic system

A circulatory system involved in draining lymph fluid from extravascular tissues

Lymph nodes

hot spots for lymphocytes and phagocytes

Antigen-presenting cells (APCs)

myeloid cells which engulf, process, and present antibodies to lymphocytes. monocytes, macrophages, and dendritic cells

Granulocytes

myeloid cells which contain toxins or enzymes that are released to kill target cells. neutrophils, basophils, eosinophils

Innate immunity

the ability to recognize and destroy a pathogen based on common pathogen associated molecular patterns (PAMPs). mediated by phagocytes using pattern recognition receptors (PRRs)

Neutrophil

a type of phagocyte which is an actively mobile granulocyte

Monocyte

a type of phagocyte which is a precursor of macrophages and is found in lymph nodes and spleen

Dendritic cells

A type of phagocyte which functions in phagocytosis and antigen presentation. Brings antigen to lymph node to present to T cells

pathogen evasion of innate response mechanisms

neutralizing toxic phagocytic products, leukocidins which kill phagocyte, hard resistant capsule

Inflammation

nonspecific reaction to noxious stimuli. Mediated by cytokines and chemokines

Diapedesis

Emigration of the leukocyte via blood vessels to sites of inflammation

Interleukins

attract neutrophils to infection which release chemokines for macrophage recruitment

cytokines

regulate cellular functions and activate various cell types. lymphokines or interleukins (ILs). Interferons (IFNs) and tumor necrosis factors (TNFs) act on cells other than B and T

chemokines

function as chemoattractants for phagocytes and lymphocytes. produced by lymphocytes in response to bacterial products

Fever response steps

pyrogens are released by pathogen digestion → pyrogenic cytokine release → interleukin-1 reaches hypothalamus and releases prostaglandin → prostaglandin raises body temp

Compliment proteins

Innate and adaptive immunity, marks pathogens, lyses many gram negative bacteria

Membrane-bound components of compliment (MAC)

compliment protein component which forms a pore in a pathogen

opsonization

enhanced phagocytosis by antibody or compliment binding

Natural killer cells (NK cells)

distinct cells which use granzymes and kill in the absence of the normal major histocompatibility complex (MHC) proteins

Adaptive immunity

the aquired ability to recognize and destroy a pathogen. directed towards antigens. Requires specificity, memory, and tolerance

T-cytotoxic cells

recognize antigen presented by MHC I protein on an infected cell, direct kill

T-helper cells

interact with MHC II complexes and promote immune reactions via cytokines. macrophage activation or antibody production