Production of Bacterial Vaccine

Production of Bacterial Vaccine 


Production of Bacterial Vaccine


These steps are followed in production of bacterial vaccines -

The Seed lot system:

A suitable strain of bacteria against a specific disease is cultured, called seed lot and it is stored at -70℃ to use as the seed to prepare a number of batches of vaccines.

From this seed lot vaccine is prepared following further procedures. The vaccines are tested for safety and efficacy.
In clinical trials, if the result is satisfied, the seed lot will be approved for routinely production of bacterial vaccines.

Fermentation:

The approved bacterial seed contained in an ampoule is stored at -70℃ or freeze-dried.
The bacteria are cultured in media through one or more passages. When the bacteria produced in sufficient numbers, they are inoculated into a batch of media contained in a fermenter.

The pH, temperature and redox potential of the medium is adjusted. The maximum bacterial yield is obtained after a day.
About one day is required for rapidly growing bacteria and for slow growing bacteria, more than two weeks is required.

Processing of Bacterial Harvest:

The bacterial harvest is a mixture of bacterial cells, metabolic products and exhausted medium.

This process involves these procedures:

a) Killing - The bacterial cells are killed by heating and using disinfectants.
for example, Bordetalla pertussis is killed by heating and formalin.
Vibrio cholerae is killed by phenol.

b) Separation - The bacterial cells are separated from the culture fluid by centrifugation, by reduction of the pH and then precipitation of the cells.
The bacterial cells are resuspended in a saline water and the culture fluid is discarded.

Fractionation:

The components are extracted from bacterial cells or from the culture media and then purified for bacterial cell component vaccine.
For example, the polysaccharide antigens are separated from Neisseria meningitidis cells by treating with hexadecyl trimethyl ammonium bromide, purified and then improved by resolubilization in a suitable solvent and precipitated.

Streptococcus pneumoniae cells are treated with ethanol.

Then the bacterial components are dried to powder, stored and incorporated into vaccines.

Detoxification:

This step is used for toxoid vaccines, in which bacterial toxins are detoxified.  Diphtheria toxin is detoxified with formalin. The detoxification is done in fermenter or after fractionation on the purified toxin.

Adsorption:

It is the adsorption of components of the vaccines to a mineral adjuvant to increase the immunogenicity and to decrease the toxicity.
 These mineral adjuvants are commonly aluminum phosphate, aluminum hydroxide, calcium phosphate.
Absorbed vaccines are diphtheria vaccine, DTP vaccine and tetanus vaccine.

Conjugation:

Conjugation is the linking of a vaccine component of poor immune response with a vaccine component of good immune response.
Example.  The immunogenicity of the vaccine Haemophilus influenzae type B is enhanced by  conjugation with polysaccharide of diphtheria,  tetanus toxoids and the outer membrane protein of Neisseriae meningitidis type A and type C.

" Production of Bacterial Vaccine"
Written By
Sadia Akhtar
Student of Department of Microbiology
Jagannath University.
Email- sadiabd810@yahoo.com

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