NEW YORK, May 12, 1955 (UP) -What the U.S. scientists now visiting the laboratories of drug companies are trying to find out is whether any of the companies, either by hurrying or through carelessness, let live viruses slip into their anti-polio vaccines.
The official scientific prescription for making the vaccine, prepared by the National Institutes of Health of the U.S. Public Health Service, and called "minimum requirements," eliminates any possibility of live viruses slipping into it, provided it is followed to the letter.
In outline, the prescription is:
Take healthy monkeys, kill them and examine their bodies for any sign of any disease. If they pass, take the kidneys and mince them. Put this mince into sterile tubes, along with a specially prepared food -"Mixture 199"-which will keep the cells alive and flourishing.
Add viruses of one of the three types which cause polio in the human body. Put the sealed tubes in slots inside a steel drum. Slowly revolve the drum to keep the kidney cells constantly bathed in the liquid food. Keep this up for four to seven days, and then "harvest." For each virus that went into each tube, there now are some 1,000,000 viruses.
Put the tubes into a machine which whirls them at very high speed, to throw out the heavier particles of kidney tissue. Pour off the clear fluid at the top, which contains the viruses. Filter it to get out bacteria and any remaining kidney cells.
Now take samples. Put some in tubes and try to culture bacteria. Watch tubes for results for 14 days. Inject some in two or more rabbits and four or more guinea pigs.
These animals do not develop polio but will develop other infectious diseases if the causative organisms are in the virus soup. Watch the rabbits for 21 days, the guinea pigs for 42 days. If any sicken and die of unknown cause, throw out the whole batch and start all over again.
But if it passes, add formaldehyde and keep at body temperature. This will "kill" or deactivate the viruses.
Now put samples in at least five tissue culture tubes and see if viruses will reproduce. If they do, it can only mean that some "live" viruses have survived the formaldehyde. Give each tube at least 14 days to develop living viruses. Make sub-cultures from each tube and watch them for at least seven days.
If these tests are passed, put the soups containing the three types of polio viruses together and you have the Salk anti-polio vaccine.
Now repeat the tissue culture tests. Also inject samples into 10 or more mice to test against incidental infections, and observe mice for 21 days.
Inject vaccine into the brains of at least 12 healthy monkeys and into the muscles of at least six healthy monkeys. Watch monkeys for 28 to 32 days for any symptoms resembling polio. If there are none, the vaccine is okay.
You may add a preservative, but you must show that it will not lessen the potency of the vaccine. Having put the vaccine into sterile containers for marketing, you must label them with an expiration which cannot be more than six months later.
These are "minimum requirements." Any drug house may exceed them. Each is required to file "protocols" - that is, a detailed run-down of its methods for comparison with the standard.
The National Institutes of Health may analyze any batch -- and the makers are required to take and keep samples of each batch for possible inspection.
