Lecture 48 Flashcards
How can we acquire immunity?
Natural immunity: passively through one person receiving antibodies from another person or organism (typically mother to child), actively through actually contracting a disease and developing an adaptive response to it.
Artificial immunity: Active immunity through vaccines or passive immunity through antibodies (e.g immune globulin therapy using monoclonal antibodies).
What is the immunoglobulin distribution in the body? What form is IgA in the blood?
IgE in throughout the body (particularly surrounding organs), dimeric IgA in the mucosal surfaces, IgM and IgG in the blood circulation. In the blood IgA is monomeric.
What is the relative antibody count following passive immunization? Relate this to why boosters are needed for vaccines.
Passive immunization leads to a rapid fall off in antibody concentration within a relatively short time frame (particularly if IgM, which has a short half life). In active immunity the antibody concentration starts low with the first vaccine shot. This increases over time until it hits a semi peak which is still a relatively small antibody concentration relative to the maximum. This means boosters are required to reach the actual peak (maximum antibody concentration) to provide decent protection.
What two vaccines were used for polio? Which was more effective?
The dead vaccine produced by Salk and the live (attenuated vaccine) produced by Sabin. The Sabin one was much more effective at stopping polio.
What are some main success stories of vaccines? What type of vaccine?
Measles, mumps and rubella (all found in the same attenuated vaccine), polio (both as a dead (Salk) and attenuated (Sabin version), diphtheria (toxoid) and tetanus (toxoid).
What disease was eliminated from humanity by vaccines?
Human smallpox.
What is the most important thing for vaccines to work?
Herd immunity, a large percentage of the population must have the vaccine to prevent spread of the disease in the population (upwards of 85%).
What vaccine types are there and what are their properties? Give some examples.
Killed whole cell vaccines: e.g pertussis (whooping cough, a bacteria), or rabies, influenza A and hepatitis (all viruses). These vaccines are limited as they only produce IgG responses, no IgA or cell mediated immunity, hence live vaccines are better if possible.
Attenuation: removal of virulence genes to prevent the pathogen from being pathogenic, but still causing an immune response. (mumps measles and rubella)
Recombinant (subunit) proteins as vaccines: Isolation of the DNA of a pathogen which codes for the antigen, placing of this into a yeast cell to grow them and then insertion of the antigen molecules. (hepatitis B)
Recombinant vector (cells/virus) vaccines: insertion of DNA coding for antigen into another, non pathogenic virus or cell (these can include multiple antigens in one, vaccinating for many diseases at a time). (experimental for HIV and measles)
DNA vaccines: Isolation of DNA coding for antigen into a plasmid vector. This plasmid vector enters human cells which synthesise the antigen and can then be acted against. (Possibly for zika virus).
Another possibility is virus like particles which contain no DNA or RNA but do contain capsid surface proteins. (Gardasil is this)
What do live vaccines stimulate compared to killed vaccines?
Live stimulate cell mediated immunity, IgA, IgM and IgG.
Killed only stimulate IgM and IgG.
What are chemical adjuvants?
A chemical added to vaccine which will increase inflammation, slow the release of antigen and macrophage and T cell interaction and increase antigen presenting cell activity. These increase the vaccines affectiveness in generating an immune response.
How many booster vaccinations are typically required?
2 for live vaccines, 3 for killed or subunit/conjugate vaccines. Possibly 4 if the vaccine is weak enough.
What are possible future vaccine uses?
stopping allergies, targeting cancer cells, preventing autoimmunity and immunocontraception.
What are the resistance reasons against vaccines?
Not my problem, underestimate the impact of the disease, side effects, misinformation or belief in alternative therapies.
