Pathogens & Immunity Text Chapter

What is a pathogen Anything that causes harm to your body –Bacteria, virus, protista and fungi are all kingdoms that contain common pathogenic organisms –Animals (mosquitos, tapeworms) and plants (poison ivy, poison oak) are larger pathogenic organisms

Pathogenic Fungus

Animal pathogens Roundworms, heartworm & tapeworms

Transmission of pathogens Contaminated food, water Bodily fluids via unprotected sex, sharing of needles during drug use Mother to unborn child Airborne –Attach to dust or water droplets

Vectors Mosquitoes –West Nile Virus, Malaria Houseflies, tse tse fly (African Sleeping Sickness) Ticks – Lyme disease (bacteria) Animals - Rabies (virus)

How do they work? Transmitted or vectored by a number of ways… Propagated Spread person to person Common source All get sick from one source point, i.e. contaminated water

How to stop a pathogen… Prevent entry to body –Good hygiene, insect repellent, boil water, throughly cook food, do not engage in risky behaviors Promote a rapid immune response –Healthy lifestyle – diet, sleep, exercise Medicines –Anitibiotics, antivirals, fungicides Vaccines –Teach your immune system to recognize invaders

The immune response Antigen –nametags for all cells and cell-like organisms Host –the organism or cell that is under attack; has a particular receptor site for antigens Antibody –a protein made by the body to prevent attachment of pathogen to host cell

vaccine A little bit of virus (weakened or dead) that “teaches” your body to make antibodies Your body remembers how to fight pathogens by “memory B cells”

T4 Bacteriophage Viruses

Is it Alive? NO! –Do not perform the 6 characteristics of life 1. cells 2. organization 3. energy use 4. homeostasis 5. growth & development 6. reproduction Influenza Virus

What is a Virus? Obligate intracellular parasite –Piece of DNA or RNA covered with a capsid Protein “coat”

Classification of Viruses No Kingdom! classify based on the host they invade –Plants, animals, bacteria Genetic material –DNA or RNA –RNA viruses are called retrovirus morphology

Viral Shapes

How do Viruses work? Must have host Lytic or virulent cycle 1. Finds specific host – antigen “name tags” matches a host “docking station” 2. Injects its nucleic acid into host cell 3. Host cell becomes a viral “factory” to make new viruses 4. Host cell bursts  releases viruses, kills host

Lysogenic or Temperate Cycle Some viruses enter host and become dormant –Inactive Can become activated by another virus –Example – cold sore viruses made active by common cold

Beneficial Virus?! Control of other diseases Useful in Genetic Engineering as a vector of new DNA –Gene therapy to cure genetic disorders –Ie. Cystic fibrosis

Effects of Viruses Harmful - pathogenic

HIV – AIDS Pandemic Human Immunodeficiency Virus –Causes Auto Immune Disorder Syndrome (AIDS) –Spread through blood, semen, vaginal fluid, and breast milk –Attacks immune system – Helper T cells, which controls the rest of your immune system

Spread of HIV

25 million dead to date

Control of HIV Education! Protection –Vaccines –Interferon Keep it dormant – control trauma, stress Boost immune system