Changes

These can be purified proteins such as a single envelope protein separated from a purified virus by detergent and then centrifuged (traditional method) - genetic engineering can now make single protein vaccines quickly and accurately.  

These can be purified proteins such as a single envelope protein separated from a purified virus by detergent and then centrifuged (traditional method) - genetic engineering can now make single protein vaccines quickly and accurately.  

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  

Recombinant or synthetic proteins 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 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).

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.

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 can be vaccinated directly into the host.

===Adjuvants===

===Adjuvants===