Viruses

Viruses

Infectious particles

what are viruses made of

1. protein shell/capsid

2. nucleic acid (RNA/DNA)

types of RNA viruses

• measles

• aids

• coronavirus

• poliovirus

• influenza

types of DNA viruses

• herpesvirus

• hepatitus b

• chicken pox

Common features in viruses

• very small

• dont have ribosomes

• only reproduce in hosts

Virus Cycle

1. Attaches to a host by binding to receptors on cell surface

2. Enters cell and disturbs a cell’s functions by mass producing its own genetic info

3. new virus particles are produced

4. new virus particles leave host cell

Immune system

cell and tissues

act to defend the body against pathogens

Pathogens

basically viruses

infectious agents causing diseases

immunity

protection from threats

two types of immunity in cells

innate - fast response

adaptive - slower and steady repsonses

Innate immunity

• nonspecific defense present in body since birth

• always active and first responders

types of innate immunity

1. physical barriers

2. chemical defenses

3. Phagocytes

4. Inflammation

Innate immunity: Physical barriers

the skin prevents things from entering the body

Innate immunity: Chemical defenses

• enzymes destroy microorganisms

• fevers prevent bacterial growth

Innate immunity: Phagocytes

macrophages surround and swallow invaders

Innate immunity: inflammation

reactions generate
pain
swelling
heat
redness

Adaptive immunity

Long lasting immunity granted by targeting specific pathogens

• mediated by lymphocytes

Lymphocytes

specialized white blood cells

two types of lymphocytes involved in adaptive immunity

B cells (bone marrow)
T killer cells (thymus)

Lymphatic system

move lymphs and immune system cells around body

Antigens

specific molecules of viruses that immune systems recognize
like a name tag for immune system to recognize viruses

b cells

produce antibodies that bind specific antigens to viruses

How do b cells operate?

• block viruses from reaching cells

• flag viruses for phagocytes to swallow

• mark viruses for proteins to bind and destroy

Killer T cells

operate by forming hole sin infected cells to kill them

Adaptive immunity is better than innate immunity because

• they are able to recognize specific cells

• can create an immune response to any threat

• prevent reinfection with the same virus

Vaccines

• contain an inactive part of a virus that wont create a disease in the body

• Body fights it and gains immunity and memory through B and T cells

Herd immunity

Because there are so many people immune to the disease it can’t spread around 

Adaptive immunity examples

• Killer T cells

• B cells

• Vaccines

• Antibodies

Innate immunity examples

• fever

• mucus membrane

• phagocytes

• inflammation

• stomach acid

How do viruses spread?

• direct contact

• indirect contact

• airborne

• droplets

• substance contamination

Bats are often the sources to viruses because…

• human disturb their environment

• they are resilient to viruses but carry them

• only hardy viruses survive in bats

Cholera

Bacterial infection of the small intestine
Bacteria attaches to small intestine cells, releasing a toxin

Cholera is caused by…

vibrio chrloate

cholera is spread through

contaminated water and food

Cholera symptoms

• vomiting

• watery diarrhea

• abdominal pain

• Severe dehydration

John Snow

• Father of epidemiology

• Studied first case in England 1831 of cholera

• Believed it came from unsanitary conditions

Bacteriophage

virus that infects bacteria

they have to infect bacteria to reproduce

natural antibiotic

Lytic phage cycle

1. phage enters bacteria

2. disturbs bacteria function, forcing it to make lots of phages

3. so many phages are replicated, the bacteria bursts and dies

Lysogenic phage

1. Phage inserts its DNA in bacterias DNA

2. viral DNA (prophage) is copies every time bacteria divides

3. bacteria stays alive

Phage therapy

Phages are give in from of pill, nasal spray, injections, enemas, or ointments
safe and efficient
give multiple types of phages at a time
not FDA approved

Straphylaccoceous Aeurus

causes skin disease

Antibiotics

1928
discovery of a fungus releasing a chemical taht inhibits growth of bacteria