Making Vaccines

Effective Vaccines

• Have low levels of side effects or toxicity.• Protect against exposure to natural, or wild

forms of the pathogen.• Should stimulate both an antibody (B-cell)

response and a cell mediated (T-cell) response.• Have long term, lasting effects that produce

immunological memory.• Should not require numerous doses or boosters• Are inexpensive, have a long shelf life and are

easy to administer.

Routes of Administration

• The majority of vaccines are administered by injection– Subcutaneous– Intramuscular– Intradermal

• Oral vaccines are available for only a few diseases

Administration Routes

Live, attenuated (weakened) cells (viruses)

– Vaccines are longer-lasting and require fewer boosters

– However, the disease agent could mutate back to pathogenic strain

– Harder to make this type for bacteria – usu. viruses

– Example: MMR, Varicella zoster

Killed whole cells or inactivated viruses

– Even though they are harmless, they still contain recognizable antigens on their surface

– Because the microbe does not multiply, a weaker immune response is stimulated vs. live vaccines

– larger doses and more boosters are required.

– Example:Polio virus

Toxoid vaccines

– A purified toxin produced by the antigen is used to elicit immune response.

– Example: DTaP• Diptheria,

Tetanus and acellular Pertussis

Subunit Vaccines

• Subunit vaccines contain just the antigens of the microbe that best stimulate the immune system.

• Antigens that have been separated from the rest of the microbe

• Examples: Hepatitis B, Gardasil, Influenza

Genetically engineered microbes or microbial antigens

– Genes for microbial antigens are inserted into a plasmid vector and are cloned in appropriate hosts.

– The resultant protein product is used to provoke immune system.

DNA vaccines– These

vaccines contain all or part of the pathogen DNA, which is used to “infect” a recipient’s cells.

Herd Immunity• More individuals that are

immune decreases the incidence of the disease and the occurrence of the pathogen.

• With greater numbers immunized, it is less likely that an unimmunized person will encounter the pathogen.

• Mass vaccination confers indirect protection for those who do not receive the vaccine resulting in “herd immunity”.