Microbiology 8: Defence and vaccination against bacteria

Question 1

List features of Humoral Immunity

Answer 1

Humoral Immunity -directly mediated by antibodies -antibodies are produced by B lymphocytes -Plasma cells (terminally differentiated B lymphocytes) are the primary source of secreted immunoglobulins

Question 2

List features of cell mediated immunity

Answer 2

Mediated by T lymphocytes and NK cells

Particularly important for eliminating intracellular bacteria, e.g. tuberculosis, typhoid, legionella

Interaction of the reactive T lymphocytes and the macrophage is key to clearance of infection

Cell-mediated immunity is an immune response that does not involve antibodies, but rather involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.

Question 3

Name the two arms that acquired immunity can be divided into?

Answer 3

humoral immunity which is mediated by antibodies and cell mediated immunity.

Question 4

List the roles of antibodys

Answer 4

Toxin neutralisation, e.g. tetanus, diphtheria, botulism, anthrax etc. As a focus for complement binding (classical pathway) As an opsonin promoting phagocytosis

Question 5

What is a live attenuated vaccine

Answer 5

These contain mutations that affect the ability of the organism to thrive and/or cause disease in the host. Historically, the mutants were isolated by chemical mutageneisis or multiple passaging of the organism; more recently attenuated isolates have been rationally mutated using targetted molecular methods

Question 6

Give examples of live attenuated vaccines?

Answer 6

Viral: measles vaccine, mumps vaccine, rubella vaccine, Live attenuated influenza vaccine (the seasonal flu nasal spray and the 2009 H1N1 flu nasal spray), chicken pox vaccine, smallpox vaccine, oral polio vaccine (Sabin), rotavirus vaccine, and yellow fever vaccine.[2] Bacterial: BCG vaccine,[2] typhoid vaccine[3] and epidemic typhus vaccine.

Question 7

What is a conjugate vaccine?

Answer 7

A conjugate vaccine is created by covalently attaching a poor antigen to a strong antigen thereby eliciting a stronger immunological response to the poor antigen. Most commonly, the poor antigen is a polysaccharide that is attached to strong protein antigen.

Question 8

How does a conjugate vaccine work?

Answer 8

B cell response to a capsular polysaccharide is T cell independent, meaning that B cells can produce antibodies without T cell stimulation.[2] By conjugating the polysaccharide to a protein carrier, a T cell response can be induced T cell independent antigens like polysaccharides activate mature B cells, in the absence of antigen presentation, by cross-linking immunoglobulin receptors on the cell surface. The resulting immune response is not ideal for vaccination. It is typically characterised by poor immunological memory, low avidity antibodies(IgM (no affinity maturation) that are less likely to offer functional protection against disease, and in many cases repeated doses rather than boosting can lead to immunological hyporesponsiveness. .

Question 9

Name some examples of Conjugate Vaccines?

Answer 9

Hib Vaccine Pneumococcal Vaccine Meningococcal C conjugate vaccine Meningococcal A,C,W,Y vaccine

Question 10

What is a toxiod vaccine?

Answer 10

Toxoid vaccines are made from a toxin (poison) that has been made harmless but that elicits an immune response against the toxin.

Question 11

What disease do Toxiod vaccines prevent?

Answer 11

there are toxoids for prevention of diphtheria, tetanus and botulism

Question 12

List the differences between active and passive immunity

Answer 12

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Question 13

What is medical microbiology?

Answer 13

Medical microbiology is a branch of medical science concerned with the prevention, diagnosis and treatment of infectious diseases.