The following is excerpted from:


Product Qualtiy Control Testing for the Oral Polio Vaccine


B. Brock, L. Kelleher, B. Zlotnick
Dev Biol Stan, 1998, 94:217-9

"INTRODUCTION
The oral polio vaccine is a trivalent preparation comprising attenuated Sabin strains of polio virus types 1, 2, and 3 in an oral dosage form. The vaccine induces an immune response comparable to the natural disease and is credited with the control and eradication of wild-type polio disease in the United States... The viral content of the vaccine is specified by FDA regulations. The three individual polio virus types are combined in specific ratios to assure that all three strains immunize effectively.

MATERIALS AND METHODS
Cell culture preparation
The cell culture substrate is prepared in primary monkey kidney cells obtained from green monkeys that do not harbour SV40 virus. The monkeys used as a source of kidney tissue are purpose- bred in isolated breeding colonies. These animals are tested for tuberculosis and viral antibodies and are held in isolation quarantine under strict veterinary supervision until use. A kidney perfusion process is performed under aseptic conditions which liberates kidney (renal epithelial) cells in preparation for cell culturing...

Cells are grown and observed for at least 11 days in the cell culture laboratory. After cell growth is completed, 75% of the roller bottles are sent to the virus production laboratory for polio virus inoculation. The remaining 25% of the roller bottles are sent to quality control for testing.

Cell culture testing
Fluids from all the roller bottles of a single kidney are pooled and tested to detect the presence of any transmissible, microbial agent ...
Therefore, every individual cell batch is observed for a total of more than 50 days in culture. The appearance of an adventitious agent at any stage of testing results in rejection of the cell batch.

Virus production
The remaining 75% of the cell culture bottles are sent to production for virus inoculation. One of the Sabin attenuated strains is prepared to inoculate the production bottles. Master polio virus seed stocks are maintained in a viable state in liquid nitrogen storage. Master viral strains have been prepared in the presence of SV40 virus neutralizing antiscrum. All subsequent working seed strains have been prepared in CMK cells and screened to assure they are free of SV40 virus. The same level of virus is used for each group of bottles inoculated...

Viral harvest testing
Viral harvest samples are sent to the Quality Control laboratory for evaluation and the rest of the harvested fluids are stored frozen until testing is completed. Fluids collected from these bottles are tested to detect the presence of any transmissible microbial agent in CMK cells....(and) in Rhesus monkey kidney cells, rabbit kidney cells, and BSC-1 cells, all for 14 days. Additionally, samples are tested to demonstrate the absence of mycoplasma. ...

Monopool testing
When the appropriate number of harvests for a single polio virus type are released by Quality Assurance, they are thawed and combined to form a monopool. Samples from an unfiltered, prorata monopool are tested to ensure freedom from adventitious agents in rabbits, guinea pigs, adult mice, and newborn mice. .. The appearance of any adventitious agent at any stage of testing results in rejection of the monopool. This process is repeated for each monopool virus type.

Monopool release
A document is prepared containing the production history and test results on the monopool by Quality Assurance. This document is submitted to the FDA Center for Biologics Evaluation and Research, along with monopool samples for testing. The FDA reviews the manufacturer's test results, performs tests as appropriate, and provides notification of the release of the monopool for further manufacture.

Trivalent vaccine release
Released monopools, of each type, are combined with diluent to make a trivalent vaccine bulk preparation. Samples are tested by Quality Control for potency and sterility. The vaccine is aseptipally filled into single dose final containers. Samples are tested by Quality Control for potency, identity, and safety. Final container samples are also sent to the FDA with a final protocol for the release of the final filled container vaccine for distribution.

CONCLUDING REMARKS

Extensive quality control testing of the Sabin oral polio vaccine is performed throughout the multi-stage manufacturing process. Testing of the cell culture and viral harvest preparations to assure the absence of adventitious agents uses large cell production volumes (25% of total), multiple detection systems, repetitive testing, and lengthy observation periods (cumulatively beyond 50 days). Over 4,000 individual cell culture observations are made during the quality control testing of a single trivalent bulk lot. Any product contamination with an adventitious agent observed at any point results in rejection of the materials for product use.
   Monopool and trivalent vaccine testing is performed to assure the safety and potency of the product. This testing includes well-established and sensitive animal mice, adult mice, guinea pigs, rabbits and rhesus monkeys, as well as in vitro laboratory assays.  Samples from every product monopool and final trivalen vaccine lot are provided to the FDA government laboratory for concurrent testing.   The FDA Center for Biologics Evaluation and Research reviews the testing and manufacturing protocol and provides component or product release to the manufacturer for every individual product monopool and final trivalent vaccine lot before commercial distribution for use in humans.

REFERENCE
Polio Virus Vaccine Live Oral Trivalent, Subpart B, Title 21 Code of Federal Regulations, April 1, 1996, 630.10-630.19. "

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