Immunodeficiency disease Flashcards
Immunodeficiency is defined as
Absent or impaired immune function resulting in increased susceptibility to infection or neoplasia
May be a problem with the innate or adaptive immune system
What is immunodeficiency caused by
Usually because of problems with the numbers or function of neutrophils or lymphocytes
Genetic
Acquired
Nutritional
Toxic
Infection
Affected animals are more susceptible to infections and parasitic disease
Severe Combined Immunodeficiency (SCID) is and affects
A congenital immunodeficiency of the adaptive immune system
A genetic disease of Arabian horses
Affects about 2-3% of arabian foals
Autosomal recessive
The most important congenital immunodeficiency syndrome in horses
But NOT the most important immunodeficiency in foals
Severe combined immunodeficiency is caused by
No lymphocytes or Ig
Foals cannot produce functional B or T lymphocytes: hence ‘combined’
What would you see in diagnostics for SCID
Persistently low numbers of lymphocytes
<1.0 x 109/L (1.2-4.9 x 109/L)
Absence of circulating IgM after 25 days of life
Failure to mount an immune response
Death by 5-6 months of age
-often due to pneumonia caused by unusual pathogens
Why does SCID show later in life
Takes time for colostral antibody to clear
First clinical signs often appear between 2-8 weeks of age
Signs of SCID in necropsy
Lymph nodes – lack lymphoid follicles and germinal centers, few cells present
Spleen – absence of germinal centers and lymphoid sheaths around arterioles
Thymus – small
Thymic Aplasia in Nude Animals is caused by what and affects what
A congenital immunodeficiency
Mice, calves, cats and others
Born hairless AND no (or limited number of ) T cells
Thymus – aplasia or non-functional
What is the thymic aplasia effects on the immune system
B Cells and Ig present
Less Ig produced
Why?
No stimulation to respond to
T cells help to stimulate Ig production
Die of viral disease
Autosomal recessive
Canine Cyclical Neutropenia is and effects who
Congenital immunodeficiency of the innate immune system
“Gray Collie Syndrome”
Autosomal recessive genetic condition that affects stem cells of smooth and rough collies
Canine Cyclical Neutropenia is physically presented as and how to test
Recognize by light coat and persistently gray or brown nose
Collies should always have black noses
Genetic test available
Canine Cyclical Neutropenia cycles what
Cyclic problem with production of
Neutrophils
Platelets
Other WBC
Drastic drop of neutrophils every 11-12 days then come back up
Canine Cyclical Neutropenia can cause what in dogs
Prone to infection
Usually die as puppies, rarely live beyond 2-3 years of age
Immunodeficiencies can include
Common variable Ig deficiency
-Variable decrease in Ig, more susceptible to infections
Functional deficiencies
-Cell appearance and numbers normal
Seconday immunodeficiencies can be caused by
Toxins
- Enviro
-complex organic molecules
Nutrition
- Starvation depresses immune function
-Obesity promotes inflmmation
Viral infections of immunodeficiencies may cause
Have no adverse effect on immune system
Transiently suppress the immune system
Short term lymphopenia is common in many viral infections
Specifically target immune organs with severe or long-lasting consequences
Targeting the immune system favours survival of the virus
Canine distemper effects what parts of the body
Virus has a predilection for:
Epithelial tissue
Nervous Tissue
Lymphocytes
Secondary lymphoid organs
Canine distemper affects what of the immune system
Destruction of lymphocytes
Profound immunosuppression
Secondary infections- major contributing factor to clinical signs
FeLV is what type of virus
A type of retrovirus infection
How many cats are affected with FeLV
About 70% of cats exposed to FeLV become infected
About 40% of the infected become viremic
About 90% of the viremic cats become persistently infected
If 100 cats exposed, 70 will become infected, 28 will become viremic, and 25 will become persistently infected
How does FeLV work
Virus become inserted in cats DNA
Causes tumors and immunosuppression
How is FeLV spread
Infected cats shed virus in saliva, nasal and all other secretions
In-utero infection of fetus
Who is most at risk for FeLV
Free ranging cats most at risk of becoming infected
Especially young animals
About 30% of cats are resistant to infection
Initially invades lymphoid tissue of URT
Become viremic
Infects other lymphoid organs and granulocyte precursors
Following infection of FeLV, the immune response may:
Completely clear the infection
Suppress infection but virus remains latent in bone marrow
Activated by steroids/stress
Viremia
Allow active infection with viremia
But produce antibodies that prevent tumor development
Still susceptible to FeLV immunosuppressive disease
Or susceptible to both tumors and other diseases
Disease effects of FeLV
Immunosuppression
Suppression of bone marrow stem cells
Lymphosarcoma
Leukemia
How does FeLV cause immunosupression
Following infection virus mutates into variants that kill T Cells
Lymphopenia
Depressed cell mediated immunity
More susceptible to infections
B cells and antibody production intact
Immune complex disease
Highly immunosuppressive variant may develop
Fatal T cell immunodeficiency
Suppression of bone marrow stem cells of FeLV does what
Nonregenerative anemia
Lymphosarcoma in FeLV is
Generalized LN enlargement
Organ involvement: small intestine, kidneys, CNS, mediastinal
FeLV types o vaccination
Canarypox vector
Inactivated (killed) FeLV virus
Vaccination does not help cat if already affected
Canarypox vaccination of FeLV is
Contains FeLV DNA coding for parts of the virus
Called PureVax FeLV (Boehringer Ingelheim)
No adjuvant so decreased risk of injection site reactions and sarcomas
Not as effective as some killed vaccines
Inactivated (killed) FeLV virus types
Nobivac Feline 2-FeLV (Merck) – 2-year vaccine
Leukocell 2 (Zoetis)
Feline Immunodeficiency Virus (FIV) is caused by and spread by
An infection
An RNA lentivirus (also a retrovirus)
Related to HIV
Spread by deep bites- territorial, free roaming toms
Also, through mating and in-utero infection
FIV is most common in
Most common in old male cats that live outdoor
Pathogenesis of FIV
Localized lymph node infection
Virema
Viremia of FIV
Fever
Lymphopenia and neutropenia
(Diarrhea, respiratory signs)
Usually recover but persistently infected
Reactivation in some cats of FIV
Gradual depletion of lymphoid tissue and macrophages
Gradually increasing risk of infections
Prevention of FIV
Vaccination
Test
Vaccination of FIV effectiveness
Not completely effective
Interferes with testing
Discontinued in North America
Why to test for FIV
e.g. feral cat health program
Isolate
Euthanasia
How did Severe Combined Immunodeficiency Disease (SCID) get its name?
Both T and B lymphocytes are affected
What is the life expectancy of a gray collie pup, why, how is this prevented?
Short, die as puppies
Cyclic problem with production of neutrophils and other WBC
prone to infections.
Genetic test – don’t breed carriers
How can you protect against FIV?
Don’t let your cat roam
Test new cats that are brought into the home
genetic immunodeficiencies can affect
Any part of the immune system
Acquired immunodeficiencies are
Viruses are most important
Often temporary
Some are lifelong/progressive
