Microbiology Unit 5 - Vaccination

3 types of vaccines

1. Whole agent vaccine

2. Subunit

3. Toxoid

Whole agent vaccines

• Contain entire cell/virion

• Microorganism can be living/dead

Subunit vaccines

• contain only chemical component of mircobe

• specific protein/carbohydrate

Toxoid

• contain an inactivated bacterial exotoxin

• don’t alter antigenic properties

• strong antigens

• strong immune response

Attenuated whole agent vaccines

Contain a living but weakened microbe

2 examples of Attenuated whole agent vaccines

1. Oral Polio/Sabin (OPV)

2. Measles, mumps, & rubella (MMR)

How are the viruses attenuated

by serial passage through a poor host for virus

Pros of Attenuated whole agent vaccines

• Set up active infections, multiply inside the patient

• Antigen dose increased + maintained for a time

• strong immunity

• immunizes contacts, good for entire population

Cons of Attenuated whole agent vaccines

• Attenuated pathogen can harm immunosuppressed individuals

• Can back-mutate to virulent form

Inactivated whole agent vaccines

contain a “killed” microbe by chemical treatment

OPV

• Oral polio vaccine

• Sabin vaccine

• Attenuated whole agent vaccines

• No longer recommended

IPV

• inactivated polio vaccine

• Salk vaccine

• Now recommended

2 examples of inactivated whole agent vaccines

1. Polio

2. Influenza

Influenza

• 8 different RNA molecules = can be shuffled

• Gives rise to new strain = new vaccine per year

Pros of Inactivated whole agent vaccines

• Can’t cause disease

• Can’t harm immunosuppressed individuals

Cons of Inactivated whole agent vaccines

• Can’t multiply in host

• Antigen “dose” doesn’t rise

• Stimulation of the patient’s immune system is not as strong

• Not as strong immunity

• Don’t immunize contacts

• Don’t “revaccinate” population

3 examples of Subunit vaccines

1. Hepatitis B virus

2. Pneumococcal pneumonia

3. Hib vaccine

Hepatitis B virus

• childhood immunization

• healthcare workers

• recombinant

Pneumococcal pneumonia

• capsular polysaccharide

• Streptococcus pneumoniae

Hib

• Haemophilus influenza type b

• capsular polysaccharide

• diphtheria toxoid

Pros of Subunit vaccines

• Can’t cause disease (non-living)

• Made quickly and cheaply

Cons of Subunit vaccines

Immune response to vaccine (immunity) may be weak

3 types of subunit vaccine

1. Capsular

2. Conjugated'

3. Recombinant

Capsular subunit vaccine

bacterial capsule polysaccharides

Conjugated subunit vaccine

• capsule polysaccharides + toxoid

• toxoid = co-stimulant (improves immune response)

Recombinant subunit vaccine

virus proteins

Which vaccine is capsular subunit

pneumococcal pneumonia vaccine

Which vaccine is conjugated subunit

Hib vaccine

Which vaccine is recombinant subunit

hepatitis B vaccine

Recombinant DNA technology

• process where gene is isolated from one organism → given to another'

• genetic engineerings

Protein human insulin is made by

• E.coli cells

• (given human insulin gene in lab)

The Hepatitis B vaccine and its envelope proteins were made using

Recombinant DNA technology

hepatitis B vaccine

only viral envelope protein molecules

HBsAg

• hepatitis B surface antigen

• HBV envelope spike proteins

what was isolated from the Hepatitis B virus to make the vaccine

gene coding for envelope protein

the envelope protein gene was spliced into what

• Yeast artificial chromosome (YAC)

• plasmid-like

What was induced to take up the Yeast artificial chromosome (YAC)

Yeast cells

Cells with the Yeast artificial chromosome (YAC) use flow of genetic information (DNA→RNA→protein) to make

envelope protein (HBsAg)

The genetically-engineered yeast cells

make + secrete the HBsAg into growth medium

What is used to remove yeast cells

• Membrane filtration

• HBsAg passes through filters

The HBsAg solution is

• purified

• sterilized by radiation

• made into “doses”

Hepatitis B immunization - 3 key events in body

1. antigen molecules contact B-cells with IgD molecules specific for HBsAg → B-cell clonal selection

2. antigen molecules may be phagocytized by APCs → displayed to T-cells with IgD molecules specific for HBsAg

3. Circulating antibodies formed

Unlike exotoxin, toxoid molecules don’t

• poison the host

• cause disease

what 2 things does the DT vaccine contain

• diphtheria toxoid

• tetanus toxoid

Strong immunity to tetanus lasts about

10 years

3 examples of exotoxin

1. Staphylococcus aureus exotoxin

2. Diphtheria exotoxin

3. Vibrio exotoxin

Staphylococcus aureus exotoxin

• toxic shock syndrome (TSS)

• fever

• vomiting

• burn-like rash followed by shock

Diphtheria toxin

• inhibits protein synthesis

• can affect nervous & cardiovascular systems

Vibrio exotoxin

• cholera toxin

• excess fluid loss from epithelial cells in small intestine

• loss of smooth muscle control

• rwatery diarrhea

Escherichia coli endotoxin

• weak

• mild illness (travelers’ diarrhea)

Salmonella typhi endotoxin

• very potent

• severe diarrhea

• kidney damage

what is pooled from donors immune to disease to create immune serum globulins

serum

What is purified from the donor’s serum

• Antibody fraction

• IgG

• IgM

What provides immediate protection once injected into a patient risk for a disease

immune serum globulins

immune serum globulins are used as preventative for

hepatitis A virus

Example of immune serum globulin

Rabies vaccine