Viruses and the Immune System

What are the different types of genetic material found in viruses?

DNA or RNA. The genetic material can be either single-stranded or double-stranded.

What surrounds the genetic material in viruses?

 a protein coat called a capsid.

What do we call the membrane that sometimes surrounds the capsid?

the viral envelope.

What do we call the proteins in the viral envelope?

envelope proteins

What is the infamous envelope protein in Covid virus?

SARS-CoV-2

Distinguish lytic from lysogenic cycle in viruses. (reproductive cycles)

In the lytic cycle, the viral genome takes over the host cell’s machinery to produce  new viral particles, ultimately causing the cell to burst open and release the new viruses. However, the lysogenic cycle involves the viral genome integrating into the host cell’s DNA, becoming part of it and replicating passively with the host.

Does HIV have both lytic and lysogenic cycles? What is the significance?

Yes. This allows HIV to persist in the host for extended periods, making it difficult to eradicate.

What do we call a global epidemic?

pandemic

Who was the father of epidemiology?

John Snow

What disease did John Snow study the spread of?  What was the source of the disease?

He studied cholera. He determined that the source of the disease was contaminated water.

Why were epidemics rare for 95% of human history?

Because of small population sizes, limited migration, and a lack of dense urban centers.

What does R naught tell us about epidemics?

how contagious a disease is

What virus has a high R naught?

Measles has a high R naught value of 12-18. This means that one person with measles will infect 12 to 18 other people on average (if no one is immune and no control measures such as vaccines or isolation are in place).

What virus are we close to eliminating?

polio

What do epidemiologists do when there is an outbreak?

When there is an outbreak, epidemiologists create a ring of eradication where they create a ring around confirmed cases and vaccinate everyone in it.

What virus have we eradicated from the human population?

We eradicated smallpox from the human population in 1980.

What is the term we use to describe the pathogens that we get from animals?

Pathogens that we get from animals are called zoonoses.

What animals does influenza jump from to infect humans?

several animals including birds and pigs

What animals harbor a lot of different viruses?

Bats, primates, and rodents are known to harbor a lot of different viruses.

Why is our skin good at protecting us from pathogens?

Because it acts as a physical barrier and has a low pH (making it inhospitable to many microbes).

What coating protects our epithelial cells (respiratory/digestive) from pathogens?

The mucous layer

What are the first cells to encounter pathogens in our blood stream?

white blood cells called phagocytes

How do macrophages ingest cells?

Macrophages ingest cells through a process called phagocytosis, where they recognize cells, attach to them, and engulf them into a pocket called a phagosome. Then, the phagosome fuses with a lysosome where enzymes break down the cell into smaller fragments. The antigens, are presented to helper T cells on the macrophage’s surface using MHC class II molecules, while the waste is expelled.

How do neutrophils kill pathogens? (think NETs)

Neutrophils kill pathogens by releasing NETs (Neutrophil Extracellular Traps) which are webs of DNA and proteins that trap and kill microbes outside the cell. They typically die during the process.

What are the 5 markers of inflammation?

redness, swelling, heat, pain, and loss of function.

How does the release of cytokines help direct the immune response?

The release of cytokines helps direct the immune response by signaling and coordinating the activity of immune cells

What cell does the Macrophage (and/or dendritic cell) activate by showing the antigen?

 T cells

What does the Helper-T cell do?

The Helper T cell identifies antigens on macrophage. Then multiplies. Then activates B-cells to make specific antibodies, activates specific killer T-cells, activates suppressor T-cells, and some become a memory T-cell.

What virus infects Helper
T cells? (thus making the person “immunodeficient”)

HIV

What cell makes antibodies?

B (plasma) cells

What type of T cell can kill cells?

Cytotoxic T cells (killer T cells) can kill cells

What type of T cell calls off the attack?

Regulatory (suppressor) T cells regulate the immune response and call off the attack.

What type of T and B cell will circulate in the blood in case of a second  infection?

Memory T and B cells will circulate in the blood in case of a second infection. They are primed to recognize and rapidly neutralize the pathogen.

Why can’t we make a permanent vaccine for HIV or Influenza virus?

Because they mutate rapidly.

The first vaccine: Who came up with the process?

 Edward Jenner

What was the first vaccine? What did it successfully prevent?

Edward Jenner inoculated a person with a substance from a cowpox blister. This vaccine successfully prevented smallpox.

Who coined the term: Vaccine? Why are vaccines called vaccines?

Edward Jenner coined the term vaccines. He used the Latin word “vacca” meaning cow to describe the cowpox virus that he used in his vaccine.

Who normally produces anti-snake venom?

Horses, sheep, and goats

What type of antibodies are used to fight cancer?

Monoclonal antibodies

What is considered the perfect vaccine?

A vaccine that just gives the antigen

What is the second best type of vaccine?

A vaccine that gives an attenuated (weakened/dead) virus.

Ig M

• pentameter

• First to the scene

• Mainly found in blood

• Can connect to up to 10 pathogens

Ig A

• Dimer

• Most abundant

• In mucus, sweat, and tears

Ig E

• Monomer

• Attaches to antigens of allergens

• Initiates inflammation

Ig G

• Monomer

• Can go through the placenta

• First one your born with

• First protection for baby