Changes

1:4000 formaldehyde is used in the preparation of killed vaccines; inactivants containing azuridines and beta propiolactone are being developed which do not leave a persistent infectious viral fraction (like formaldehyde).

1:4000 formaldehyde is used in the preparation of killed vaccines; inactivants containing azuridines and beta propiolactone are being developed which do not leave a persistent infectious viral fraction (like formaldehyde).

===Subunit Vaccine (part of the organism)===

===Subunits (part of the organism)===

*Purified protein

Recombinant or synthetic protein can also be used as a subunit - the gene for the antigen required is inserted into a virus vector or cloned into bacteria allowing endogenous expression of the antigen. Small antigens, such as peptides, can be produced synthetically where necessary e.g. with

**Single envelope protein separated from a purified virus by detergent then centrifuged (traditional method)

Influenza viruses that are constantly mutating, and Canary pox vaccines encoding rabies or FeLV spike proteins (canary pox is safe as it undergoes incomplete replication in mammalian skin cells).

Subunit antigens can also be isolated using the DNA coding for antigenic proteins; circular DNA plasmids are expanded in disabled E.coli strains and then purified - the plasmids expressing the foreign gene are inserted at the site of injection which can be vaccinated directly into the host.

**Small antigens, such as peptides, can be synthetically produced

**E.g. Being developed constantly to fight the Influenza viruses

 

*DNA coding for proteins (antigens)

**Circular DNA plasmids expanded in disabled E.coli strains and then purified

**Plasmids express the foreign gene insert at the site of injection

**Can be vaccinated directly into the host

===Adjuvants===

===Adjuvants===