Immunization and Immune Testing Why is this important?-Vaccination is the most efficient and cost-effective method of controlling infectious diseases-Many infectious diseases are now controlled or even eliminated vaccination-The administration of antibodies can further reduce incidence of disease and prevent deathImmunization-Active immunization: involves administering antigens to a patient so that the patient actively mounts a protective immune response-Passive immunotherapy: a patient acquires temporary immunity through the transfer of antibodies formed by other individuals or animalsA Brief History of Immunization-The Chinese noticed that children who recovered from smallpox did not contract the disease again (12th century)oThey infected young children with ground smallpox scabs to induce immunity in these children, a process known as variolationoThe use of variolation spread to England and America, but was stopped due to risk of death-Edward Jenner discovered process of vaccination by inoculating crusts from a person infected with cowpox (related but very mild disease)oVacccination, vaccineoNo one understood how this worked or whether similar techniques could protect against other diseases, but it did work -Practice of transferring antibodies was developed when it was discovered vaccines protected through the action of antibodies-By the late 1900s, there were vaccines that significantly reduced the number of cases of many infectious diseases-Have successful vaccines against some types of cancer-Eradication of smallpox-Hoping for worldwide eradication of polio, measles, mumps, and rubella-Decrease of disease following development of vaccines -A variety of political, social, economic, and scientific problems prevent vaccines from reaching all those who need them oIn developing nations worldwide, over 3 million children still die each year from vaccine-preventable infectious diseases-Effective vaccines have yet to be developed for some pathogens-Vaccine-associated risks (medical, financial, and legal) discourage investment in developing new vaccines-Active Immunization-In all active immunizations, the pathogen is altered or inactivated so it is less likely to cause illnessoSo the person won't develop diseaseNot all types of vaccines are equally safe or effectiveoEffectiveness is determined by checking the antibody tier (concentrations of IgG and IgM) in the blood-Wait 2-3 weeks before determining effectiveness Attenuated (Modified Live) Vaccines-Use pathogens that have reduced virulence so they do not cause diseaseoAttenuation: modified, live vaccines -Don’t cause disease, but may cause very mild infections, but no serious disease under normal conditions-Contain active microbes that stimulate a strong immune response due to the large number of antigen molecules that are availableoStimulate antibody and cell-mediated immunity-Vaccinated individuals can infect those around them, providing contact immunityoFlu mist -Usually very effective -Can be hazardous because modified microbes may retain enough residual virulence to cause disease in immuno-suppressed people-Pregnant women should not receiveoCan cause problems for a developing fetus-Organisms may revert to a wild type or mutate to a form that causes diseaseInactivated (Killed) Vaccines-Two types-both are safer than live vaccines because they cannot replicate, revert, mutate, or retain residual virus; they are antigenically weak-immune response isn't as strongoWhole agent vaccines-Deactivated, but whole microbesoSubunit vaccines-Antigenic fragments of microbes-Antigenically weak because the microbes don’t replicate and don’t provide many antigenic molecules to stimulate the immune response oHigh doses or booster doses often required for full immunityoOften contain adjuvants, chemicals added to increase the effective antigenicity - increase immune response, but sometimes cause inflammation-No contact immunity stimulated -Non-antigenic portions occasionally stimulate painful inflammatory response in some-Stimulate only antibody immune response (exogenous antigens) Toxoid Vaccines-Exotoxins-Organism secretes a toxin that is secreted through the bloodstream-Isolate toxin and modified to cause toxin to inactivate -Cause only antibody immune response (exogenous antigens)-Sometimes more efficient to induce an immune response against bacterial toxins that against cellular epitopes -Toxoid vaccines are chemically or thermally modified toxins used to stimulate active immunity-Require multiple childhood doses and re-inoculations every 10 years because they possess few epitopesCombination Vaccines-So children don’t get so many shots -Combine antigens from several toxoids and inactivated pathogens that are administered simultaneouslyoMMRoPentacel: immunizes against 5 different pathogensVaccines Using Recombinant Gene Technology-Takes pieces of DNA from a pathogen and put them in different vectors -Manipulate genetic material of pathogens to make safer and cheaper vaccines-Researchers are always seeking to make vaccines that are more effective, cheaper, and safer and to make new vaccines against pathogens that have been difficult to protect against -A variety of recombinant DNA techniques can be used to make improved vaccines oSelectively delete large quantities of very pure antigens for use in vaccinesoLive recombinant vaccinesoDNA vaccines Recommended Immunizations-Important that patients follow the recommended immunization schedule not only to protect themselves but also to provide society with herd immunity oThe protection provided all individuals in a population due to the inability of a pathogen to effectively spread when a large proportion of people (typically >75% ) are immune Vaccine Safety-Mild toxicity most commonoPain at injection site-More common with whole agent vaccines that contain adjuvantoIn rare cases, toxicity may result in general malaise and a high fever-This may be sufficient to discourage people from being immunized of having their children immunized-Risk of anaphylactic shock (allergic reaction)-Allegations that certain vaccines against childhood diseases cause or trigger autism, diabetes, and asthma oResearch has not substantiated these allegationsoModern vaccines are much safer than those in use even 10 years ago Passive Immunotherapy-Administration of preformed antibodies to a patient who needs immediate protection due to recent infection-Used to provide immediate protection against a recent infection