Tests begin of flu vaccine grown in insect cell lines

10/25/04

Scientists are launching a research study to check the effectiveness of a new type of flu vaccine that is made differently than the conventional vaccine, which is grown in eggs. The experimental vaccine instead relies on a cell line drawn from insects known as fall armyworms, which are better known for their role as pests attacking crops such as corn, cotton, barley and alfalfa.

The study of FluBlOk, made by Protein Sciences Corp. of Meriden, Ct., was initiated by flu expert John Treanor, M.D., professor of medicine and director of the Vaccine and Treatment Evaluation Unit at the University of Rochester Medical Center. The study will include a total of 400 to 500 adults ages 18 to 49 at three sites: Rochester, the University of Virginia, and Cincinnati Children's Hospital.

Since the 1940s the chicken has been at the center of flu vaccination efforts, because fertilized chicken eggs are used to grow the flu viruses used in vaccines. Each egg contains less than a teaspoonful of material that will ultimately become part of a vaccine. Because of the complexity and sheer size of the process tens of millions of eggs must be produced, and vaccine material must be "harvested" from each it's typically a six-month process to produce enough vaccine for the public, when everything goes well.

Using a cell line instead of eggs to produce the vaccine would likely slice one or two months off the production process, says Treanor. That could reduce costs and also give scientists and physicians more time each year before they decide on that year's vaccine makeup, giving them crucial time to watch the spread of flu of around the globe and concoct a vaccine. Producing biological products in insect cell lines is common; the hepatitis B vaccine, for instance, is produced by human cell lines, and scientists from Rochester have developed an experimental vaccine against human papilloma virus using an insect cell line.

Reduced costs might also make it possible to boost the dose that patients receive. Last year in a study of the same product in 399 elderly people, Treanor found that people who had received more vaccine made twice as many antibodies to ward off flu than healthy people who got the conventional vaccine.

The new study is only for healthy people ages 18 through 49 who will not be getting a flu shot otherwise. The study will not include anyone from high-risk groups, such as pregnant women, people with pulmonary disease, the elderly, or health care workers. Those people should be vaccinated with conventional vaccine, which is known to work; the current study is testing an experimental vaccine to see whether it's effective.

Source: Eurekalert & others

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