Can we use the antibody-antigen interaction to develop diagnostic tests to detect either the antibody or the antigen?
Serological” assays (Serology)
Ab-Ag interaction is highly specific - if have one, can use to detect the other
Hep C virus cant be grown, use ELISA tech. (Enzyme Linked Immunosorbent Assay) to find antibodies
Enzyme Linked Immunosorbent Assay
4 steps
- Antigen attached to solid support
- Patient sereum added - antibodies (if present) bind to attached antigen
- Add second antibody (anti-human lg) which recognized human immunoglobulin nd is tagged with an enzyme
- Add substrate for tagged enzyme -> coloured reaction product is produced if anti-human lg has bound to antibody- antigen complex
A positive ELISA result indicates that antibodies against a certain microorganism are present in a patient’s blood serum.
But - Antibodies in the serum may be due to:
Patients may have a negative ELISA result (no antibodies detected) even if they are truly infected with the microbe if:
Positive:
- current active infection
- previous infection in fully recovered pt (AB remain)
- Vaccination
Says negative but is Positive:
-no antibodies yet just recently got disease
-tests during window period (time between contact and AB appear)
3-4 days to 2 weeks
Can we alter immune system function by external manipulation? (3)
- Pharmaceuticals (2)
- Nutritional supplements
- Pharmaceuticals
Immunosuppressive drugs
-suppressing autoimmunity (rejection of transplants)
-act y inhibiting cell-mediated immunity, blocking cell division (T cells) or blocking cytokines
Immunostimulatory drugs
- stimulate prod. of lymphocytes in bone marrow
- purified cytokines
act non-specifically and often have unwanted side effects
Can we alter immune system function by external manipulation? (3)
- Pharmaceuticals (2)
- Nutrients
- Nutritional supplements
Can we alter immune system function by external manipulation? (3)
- Nutrients
- Nutrient deficiencies impair immune system function
Most studied nutrients include: zinc, selenium, copper, vitamins, folic acid
Can we alter immune system function by external manipulation? (3)
- Nutritional supplements
Boost immune function
evidence of effectiveness is controversial
COLD-fX (extract of North American Ginseng
What COLD-fX claims are supported by studies?
2
- Effects on innate immunity
- stimulates macrophage production and activity - Effects on acquired immunity:
- increased amounts of cytokines
- increased production of B-cells and higher levels of lgG
Is the concept of “boosting” your immune system scientifically valid?
Immune system designed to be balanced and Immune system cells and signalling is regulated
Can we create a protective immune response against a microbe without having to go through a natural infection first?
Vaccines
Vaccines
Produce memory B/T cell so future exposure to same microbe rests in rapid immune response
Passive Immunization (2)
Immune Globulin 2
Post exposure prophylaxis
Intravenous immune globulin
Maternal antibodies
Temp, short term immunity using pre-existing antibodies from someone
(3-4 weeks life span)
Immune Globulin- IgG Purified (pre form antibodies give immediate protection)
Eg. Post exposure prophylaxis = Known recent exposure to specific microbe (before disease)
HBIG Hepatitis B Immune Globulin
Eg. Intravenous Immune Globulin (IVIG) = lower production of AB because of IMD(protects from environment)
Maternal Antibodies = Transferred from mother to fetus protection for first 4-6 mo. of life
- gives protection while immune system forms
- influence schedule of vaccination
Active Immunization
2 types of vaccines
Long Term immunity due to an immune response exposure to an antigen = Vaccination
(Microbe or part that cant cause disease but produces Humoral/cell-mediated immunity
- Whole Cell(entire microbe and antigenic parts)
- killed or live attenuated whole cell vaccines - Sub unit Vaccines
- parts of microbe that are most antigenic/ need to cause disease
Whole Cell Vaccines (Salik Poli vaccine, Cholera Vaccine)
- Killed whole cell vaccines
(Salik Poli vaccine, Cholera Vaccine)
- earliest developed, easy to make, little knowledge of microbe needed
- antigenic properties remain
- will not grow in person, no risk, boosters needed for strong immunity
-risk due to toxic parts (Lipopolysaccharide)
Inflamm at injection, fever
Whole Cell Vaccines
- Live attenuated whole-cell vaccines (Measles, Mumps, Rubella)
(Measles, Mumps, Rubella)
- living but weakened (attenuated)
- grown in lab until mutates and reduce ability to grow inside host
- multiply briefly but not enough for disease, enough to trigger humoral and cell-mediated immunity
mimics natural infection (life long immunity)
risk of back mutation (non attenuated)
Not for Immunocompromised
Sub unit (acellular) vaccines
Whooping cough, Diphtheria, Tetanus, etc.
(Whooping cough, Diphtheria, Tetanus, etc.)
Individual purified bacterial components (not whole cell)
-pick parts that give strong immune reaction or cause disease-capsular polysaccharide
pilli/attachment proteins
bacterial toxins (inactivated)
-no LPS
Vaccines give little side effects
-less likely to give cell-mediated immunity
-less likely to give life long immunity (booster)
Tetnaus every ten years
Vaccine Formulations
“Adjuvants”
formulated to include non-antigenic components(“Adjuvants”) that enhance the immune response to the antigen
(Aluminum Sulfate, Oil + water emulsions)
- trap antigen and promote slow, sustained release
- trigger activation of T-cells
- act as non specific immune stimulants
- useful for sub-unit vaccines and to improve vaccines of newborns, elderly, Immunocompromised
- mild side effects at injection (inflamm. discomfort)
Vaccination Strategies
Timing important for best immune response varies on vaccine
Mom antibodies remain for a year and interfere with immune response to vaccine if 1st dose early
Herd Immunity
Protection by being part of large group that vaccines
don’t need to vaccine everyone only enough to stop spread
High enough to infected and susceptible are less likely to meet
Side effects of vaccination
Concern of older ones
Oral Poliovirus Vaccine (live, attenuated)
- Back mutation
-OPV replaced with killed (Salk) Vaccine
Side effects are mild and due to additives in formulation not actual antigen (preservatives, stabilizers, adjuvants)
- allergic reaction to egg protein (flu vaccine)
- fever, inflamm at injection, general malaise
No evidence towards serious complications
Challenges in Vaccine Development
- Finding right microbial antigen to put into vaccine (no effects)
- Bundling vaccines (more parts weaker response)
- Getting life long immunity
- Stability
- delivery systems
- public health issues (getting her mentality up, perception)
