Acquired immunity
What are cytotoxic T cells
Main function is to kill targeted cells by programming them to undergo apoptosis
Apoptosis is a normal cellular response that is important to tissue remodeling that occurs during development in multicellular animals
T cells use this normal function, apoptosis as a method to trigger the death of infected cells
What are the clinical signs associated with musculoskeletal disease
All lame cattle and sheep are not foot rot cases
Most lameness in ruminants involves the foot
Eventually to diagnose you may have to pick up or examine a foot
gait and lameness score
posture - are they able to bear weight?
What are the characteristics of bacteria
Bacteria are transparent and require staining
Standard stain is based on gram - Gram pos it blue/purple, gram neg is red
Require special stains to see capsule or flagella
size 0.25 to 50um
Morphology - spherical, rods, spiral, filamentous
What is the difference between endotoxins and exotoxins
- Host: fever, shock, death
- Outer membrane of gram negative bacteria, generally less toxic, cannot be converted into toxoids
Exo - Proteins actively secreted by live bacteria, often encoded in plasmids (virulence factors)
- Host: toxemia
- Secreted by gram neg and gram pos bacteria, highly toxic, converted into toxoids for vaccination
What are the basic concepts of viruses
Different viruses have different structures and different patterns of infection and replication
Outcome of viral infection can vary depending on the virus and the host
Dependence on host cell functions make viral infections difficult to control by chemical intervention
What are cytotoxic CD8 t cells
Many viruses and some bacteria are intracellular pathogens
A lifestyle likely developed to evade innate immunity and possibly antibody responses - it is difficult to identify intracellular pathogens because of their locaiton
What are the clinical signs associated with the nervous system
often symptoms obvious but cause not -> many neurologic conditions look similar - Blindness, circling, head carriage or tilt, response to stimuli, unusual gaits, depression, head pressing, seizures
Metabolic and nutritional diseases can affect the nervous system
What is the similarities and difference in bacterial cell walls between gram pos and gram neg
Gram + = 1 cell membrane, plasma membrane and thick peptidoglycan layer
Gram Neg = 2 cell membranes, inner plasma membrane and thing peptidoglycan layer and outer (LPS) membrane
How does bacterial growth happen
Requires nutrients, enzymes
Aerobic - grows in the presence of oxygen
Anaerobic - only grows in the absence of oxygen
Reproduce by binary fission
Speed of multiplication varies by species - E. Coli can divide every 20 mins
What is the correlation between bats and viruses
A study found 12,333 bats from latin america, africa and asia all carried 9% of at leas one of 91 distinct coronaviruses
It is estimated that there are at least 3200 coronaviruses that infect bats
Almost 1400 different species of bats with different susceptibilities
Intermediary hosts are often involved in the leap from bats to humans but arent necessary
Several other zoonatic diseases have been linked to bats
How do cytotoxic cells identify target cells
Infected cells can process the antigen of the pathogen and present it on their surface
CD8 T cells then identify protein complexes on the infected target cells
What are the clinical signs associated with reproductive diseases
Abnormal breeding behaviour and estrus activity
- bulls = lack of libido is often due to physical causes like lameness and spondylosis
- cows = lack of estrus activity is often associated with poor body condition, continual estrus activity is often associated with an ovarian cyst
How does cell wall structure affect antibiotic sensitivity
Gram positive bacteria more sensitive to most antibiotics, especially penicillin group
Gram negative bacteria is less sensitive to many antibiotics
How do you diagnose or identify bacteria
Gram stain - doesn't always tell us exactly what it is
Special stains
Bacterial culture and antibiotic sensitivity testing
Serology (measuring antibody titer)
Fluorescent antibody test
PCR; molecular microbiological methods
What is MERS CoV
Middle east respiratory syndrome
First reported in saudia arabia in 2012
All cases have been linked to travel through the arabian peninsula
What are helper T cells
CD4 cells
Associated with another MHC pathway - MHC class 2
expressed on antigen presenting cells
Linked to innate immunity through some of the antigen presentation
Mainly concerned with extracellular pathogens
What are the clinical signs associated with the cardiovascular system
Exercise intolerance - reluctant to move, weak, lethargic, may go down if moved any distance
Peripheral edema - brisket area, abdomen under jaw
Jugular vein distension
Coughing, foam from mouth
Problems with extremities - ear tips, tail, feet
What are bacterial spores
Some bacteria like costridium spp. and Bacillus anthracis form spores when the going gets tough
-> dormant, highly resistant survival capsule for genetic material
What are viruses?
A non-cellular infectious agent
- nucleic acid usually surrounded by a protein coat = contains NA < protein, sometimes lipids, enzymes, no cellular organization, totally inert outside host cell
- Metabolically inert
- Reproduce only within a living cell
What is host range
Viruses tend to have host specificity
Will usually only infect one type of cell or host
However are capable of jumping to other susceptible species
There are various viruses that focus on - animals as hosts, plant animals, Viruses of eukaryotic microbes, viruses of bacteria
Host specificity is often determined by - presence of receptors on host cell to which virus attaches, presence of suitable metabolic machinery in host cell which viruses can use
What is the helper T cell pathway
Extracellular antigen detected
Ensosome/lysosome degrade antigen
Degraded antigen is also loaded onto MHCII molecules
Helper T cell recognize antigen and coordinate immune response - B cell then antibody production, helper signals to activate CD8, activate and enhance macrophage function
What are the steps you should consider when looking at signs of sickness
Consider animals history - age, production stage, source, feeds and feeding, vaccinations, previous treatments or disease
Consider the environment - pasture, barn, feedlot, stocking density, ventilation, bunk space, water source
Clinical examination
treatment
What are the different antigenic structures on bacterial cells
Cell wall - O antigens
Capsule - K antigens
Flagella - H antigens
Fimbriaa - F4; F5
E. Coli O157 H7
What are the key ways in which viruses differ from bacteria and other living cells
Much smaller in size
Simple structure and organization
Contain either DNA or RNA but never both
Not capable of independent reproduction
Two distinct phases in life cycle
Main receptor for SARS-CoV-2 is angiotensin 1 converting enzyme 2
Researchers evaluated ACE2 sequences in 410 vertebrate species including 252 mammals