Immunology

Question 1

What is DiGeorge’s Syndrome?

Answer 1

Failure to develop a thymus, results in severe immunocompromised person

Deletion in chromosome 22

Question 2

What is the primary purpose of T cell development?

Answer 2

To generate a repertoire of T cells that distinguishes between self and non-self; AKA Thymic Education

Question 3

What are the primary lymphoid organs?

Answer 3

Bone marrow and thymus

Question 4

Describe the thymus

Answer 4

Flat, bilobed organ situated above the heart. Each lobe is surrounded by a capsule and is divided into lobules, which are separated from each other by strands of connective tissue called trabeculae. Each lobule is organized into the cortex and medulla.

Dendritic cells and macrophages in the thymus are critical for T cell selection.

Question 5

What are the four cell types found in the thymus?

Answer 5

Developing lymphocytes, thymic epithelial cells that surround developing lymphocytes, DCs, and macrophages

Question 6

How does the thymus change over time?

Answer 6

The ability of the thymus to produce functional T cells is greatest during childhood. As we age, the thymus goes through involution process in which it becomes increasingly fatty and decreasing in cellular composition. As a result the ability to produce new naive mature T cells decreases with age.

Question 7

Are bone marrow transplants more successful in children or adults?

Answer 7

Children–

Children have significant thymic tissue and have a high capacity for making functional T cells. As we age, the ability to make functional T cells is diminished.

Question 8

Describe the two major types of virion structures. the components of these structures, their roles in virus interactions with the host cell and virion stability.

Answer 8

• The nucleocapsid forms either an icosohedral structure or a helical structure. The icosahedron contains 20 facets with 12 corners or vertices and is made of repeating subunits. The helix is a coiled, ribbon-like structure that can be rigid or flexible. Either one can be surrounded by an envelope depending on the species of virus.
• Icosohedral viruses can be enveloped or non-enveloped, helical viruses must be enveloped
• Enveloped viruses can only be maintained in aqueous solutions and is readily disrupted by drying agents, acidic conditions, detergents and solvents.

Question 9

What are the major steps in virus replication?

Answer 9

1. Attachment
2. Penetration
3. Uncoating
4. Synthesis, translation, genome replication
5. Assembly
6. Release (budding or release)

Question 10

Describe how a virus recognizes its target cell and the role that this plays in tropism

Answer 10

Attachment is mediated by the virus interacting with specific cell surface markers. The cell surface markers and the attachment proteins of the virus determine its tropism. Most viruses are very specific in the kinds of species of hosts they can infect, and also which tissues/cells they can infect.

Question 11

What is the effect tropism has on the development of disease?

Answer 11

Some virus receptors are not specific, so it leads to broad virus infection in a lot of different kinds of tissues

Question 12

Where does assembly of new virions occur?

Answer 12

Cytoplasm

Question 13

What is fomite?

Answer 13

Some inanimate object in the environment which can harbor infectious organisms and thus serve as a source of passing a virus from one person to another in an indirect fashion.

Question 14

What is an arbovirus?

Answer 14

a virus that is arthropod-borne.

Question 15

What are roboviruses?

Answer 15

rodent-borne viruses.