lec 15

Many parents bring their children to "chicken pox parties" to expose them to the virus. They claim that natural immunity is better than artificial immunity. Do you think this claim is true? Why or why not?

artificial immunity would be better because the virus would be weakened and less likely to die or prevent serious damage

Explain what antigenic drift is and its implications for influenza vaccinations.

higher mutation rate causes antigens to change and memory cell that were develop when exposes to the flu the first time wont recognize the pathogen

What is the role of Helper T cells in both humoral and cell-mediated immunity?

humoral: release cytokines and activate APC B cells cell-mediated: release cytokines and activate T c cells

Explain the concept of herd immunity, and why it is an important parameter in understanding disease transmission.

immune to a pathogen acts as a barrier to the spread of that pathogenic microorganism in a population; group benefit that helps protect others that haven't be immunized

Describe the principles of vaccination, including the 4 different types of vaccines discussed in lecture. Understand the advantages and disadvantages of each type of vaccine, and know at least one example of each type. Be able to explain why booster shots are needed for some types of vaccines.

1. Inactivated killed vaccine - contain surface antigens but are non-viable and not infectious, sometimes require booster doses e.g rabies, influenza 2. Live attenuated vaccine - uses attenuated pathogen for life long immunity e.g MMR 3. Subunit vaccine - uses only a part of the pathogen's antigen that elicit strongest immune response e.g hepatitis B 4. Toxoids vaccine - inactivated toxin e.g tetanus & diphtheria booster doses needed to make more memory cell for longer immunity

How does our immune system identify cancerous cells (i.e. what are the 3 different ways cancer cells can look unusual)? Explain how our immune system combats cancerous cells, and which pathway (TC or NK) is used for each type of cancer cell.

1. display unusual protein in MHC I, e.g protein expressed in incorrect cell, mutated proteins 2. Are missing MHC I in their cell membrane 3. some cancer cells over-express other cell surface molecules 1 display unusual protein in MHC I recognized as antigens and destroyed by Tc cells 2 & 3 destroyed by NK cells by using perforin

Differentiate between active and passive immunity, and artificial and natural immunity. Know an example of each of the 4 types of immunity.

2 types of adaptive immunity 1. active immune response our body is exposed to the antigens and memory cells, we can be exposed to them naturally: we get sick and artificial: vaccination 2. passive immunity: transfer of antibodies gives temporary immunity no memory cells (weeks or months) exposed naturally: mother to infant and artificial: anti-venom

Helper T cells are involved in both humoral and cell-mediated immunity. HIV infects & kills helper T cells. Using your knowledge of the immune system, explain why people infected with HIV contract infections by a variety of opportunistic microbes. Explain why people infected with HIV also are at increased risk of a variety of cancers.

HIV kills helper T cells that activate the adaptive immune response, B cells to secrete antibodies and T c cells to kill intracellular pathogens infections without helper T cell these other cells won't be activated and cause immunosuppression a lack of response from the immune system

Know the 2 types of vaccines that have (at least historically) been used for influenza. Be able to explain why flu vaccines only last one year, what causes the side effects of different types of flu vaccines, and who cannot have the live attenuated vaccine. Explain why the flu vaccine (and all vaccines) are not immediately effective. In other words, why do they take over two weeks to confer immunity?

live attenuated vaccine inactivated killed vaccine the RNA = higher mutation which changes their antigens every year

Why can we say that NK cells act "independently"?

they don't need antigen presenting or cytokine activation

Describe the mechanism by which cytotoxic T cells kill viral-infected cells. What are the roles of MHC I and perforin?

when activated by T h cells, T c cells secrete perforin that creates holes in cell membrane killing the cell MHC I display viral antigen perforin kills virus-infected cell