Vaccines stimulate immunity Cary High

Objectives Understand the purpose of a vaccine Explain the three lines of natural immunity Describe the four types of vaccine development strategies Identify the advances made by the early vaccines developed in the US

Deadly Childhood Diseases in US Were common in your grandparent’s childhood. Many of them got diseases such as diphtheria, whooping cough, polio and small pox. Many of them lost friends to these diseases The ones that got the diseases and survived developed PERMANENT immunity

Childhood Diseases in the US Are rare today due to vaccines that activate the IMMUNE SYSTEM. This gives the body the ability to fight off the germs causing the disease

Scientists working on vaccines Immunologists Molecular biologists Biochemists others

Body’s Natural Immunity IMMUNE SYSTEM: 3 lines of defense Barrier defenses Internal defenses: starts with the production of WBCs in the bone marrow which become specialized and circulate throughout the body. They often collect in the lymph nodes (located in armpits, neck and groin). This is why you have swollen glands when fighting off a cold.

First Line of Defense Nonspecific Barriers to Infection Skin Mucous Membranes Cough Sneeze

Second Line of Defense EATER CELLS: Macrophages – special WBCs that attacks invading microorganisms, engulfs it and breaks it down into pieces. This results in a surface-antigen notification system being sent out to the rest of the immune system.

Third Line of Defense SMART CELLS: The antigens cause the formation of specific antibodies by the B-cell lymphocytes T-cells support B-cells for rapid enemy antigen recognition with future exposures (memory T cells)

Vaccines imitate the invader and stimulate immune response Using several strategies: Live “attenuated” viruses / bacterium (too weak to cause the disease but strong enough to activate immune response) Inactivated or killed viruses / bacterium (microorganism is killed using chemicals but leave the surface antigen in tact; antigen recognition stimulates immune system) Recombinant DNA-based used for viruses that will not grow in cultured cells Experimental Vaccines from engineered viruses and bacteria

Recombinant DNA - based Because these viruses/bacteria do not grow in cultured cells, it is impossible to develop live or inactivated vaccines for them. Scientists identify a subunit of the virus/bacterium and use recombinant DNA technology to produce vaccine. The subunits activate the body’s immune response, but do not cause the disease.

Recombinant DNA

Experimental Vaccines Scientists are: Trying to engineer viruses / bacteria with specific genes deleted that will stimulate immune response without causing the disease They could also carry the antigens for several diseases, making them a SUPER VACCINE. Pharming: developing pharmaceutical vaccines in plants may provide more efficient and safer vaccine that is more stable for distribution. They are working creating new antigens that form antibodies to trigger specific immune response to cancer.

Early Vaccines Small Pox – in 1776 Edward Jenner developed a vaccine used an attenuated virus (cowpox) Polio – virus that infected spinal fluid and led to paralysis; many put on iron lung machines to breath. In 1950, Jonas Salk discovered an injectable inactive vaccine. In 1961, Albert Sabin advanced this by creating an attenuated vaccine that is delivered orally

Recombinant Vaccines Hepatitis B – attack the liver and can cause death. Mild cases improve with in 6 months. However, 10% of those cases become carriers and can transmit the disease to others. This virus refuses to grow in a cultured dish so scientist engineered the vaccine using recombinant DNA technology (cloned gene put into the DNA of a yeast cell). Hep-B vaccine is the FIRST BIOENGINEERED VACCINE

Goal of vaccination program to achieve Herd (Community) immunity When a critical portion of a community is immunized against a contagious disease, most members of the community are protected against that disease because there is little opportunity for an outbreak. Even those who are not eligible for certain vaccines—such as infants, pregnant women, or immunocompromised individuals—get some protection because the spread of contagious disease is contained.

Vaccination schedule: US children Age Hep B Oral Polio DPT Heameophilus MMR 2 months X 4 months 6 months 12-15 months 15-18 months 4-6 years 14-16 years

Q/A If a child gets an infectious disease, before he gets his routinely scheduled vaccine, and survives, does he still need the vaccine? A nursing home patient is experiencing a pervasive case of psoriasis on her skin. Is she more susceptible to an infectious disease? Why or Why not?

More Q/A Name the first recombinant DNA vaccine made available in the US. What is the difference between a vaccine made with an attenuated virus and one made with an inactive virus? Can you catch the disease from the vaccine (live or inactive)? What is the purpose of a vaccine? What is the purpose of a vaccination program?