Army worm invasion. Image credit:ABC News: Scott Ross
Most people probably don't realize how flu vaccines are made - by injecting live flu virus into living chicken eggs, incubating the virus-infected eggs, etc. That 50-year old vaccine making process poses a potential risk to employees working with live virus, and also may offend animal rights activists. (Do PETA members accept flu vaccines; just wondering?) Could also be off-putting to persons for whom a very strict vegetarian diet is part of their religious practice. 'Who cares as long as I can get my seasonal flu vaccine on time' you may be thinking. Should an avian (chicken) flu epidemic occur, it could wipe out chickens and block human vaccine production. (The egg method takes months, as it is.) Hence, it is of some interest that Protein Sciences is working on a method of producing flu vaccines from army caterpillars (pictured).
The "green" connection
No matter how superficially repulsive, how obscure, or how economically destructive a "pest" insect seems, its presence on Earth may benefit us. Scientists tend to frame this idea as 'needing to conserve biodiversity.' My Grandma often said "God works in strange ways" when I resisted improbable, changed circumstances.. Looking back on it, that was her polite way of saying 'deal with it kid.' A bit of wisdom that still applies, even if it makes me feel all crawly after the inoculation.
Technology Review has the details in Caterpillar Flu Vaccine Delayed; The FDA wants further evidence that the novel approach is completely safe.
Today's egg-based vaccine technology is slow and unwieldy, requiring at least six months' of production time and millions of eggs to supply enough doses for a regular flu season. If a new virus appears unexpectedly, the antiquated system wouldn't be able to gear up fast enough to produce a new vaccine, many experts agree. What's more, if the virus itself were derived from birds, it might reduce the supply of eggs, hampering the country's main means of vaccine production.
For the past decade, Protein Sciences, along with a number of other companies, has been looking to cell-based vaccines as a more efficient and robust alternative. Instead of growing viruses in chicken eggs, researchers inject virus strains into insect cells. Both the virus and the cells then grow and multiply quickly in bioreactors. Scientists break the cell walls and harvest a key protein, called hemagglutinin, produced by the virus. This protein, found on the influenza virus's outer surface, is responsible for binding to cells in the body, causing a viral infection. Scientists purify and inactivate the harvested protein so that it can stimulate an immune response without causing an infection. The protein is the main ingredient in a vaccine.
Protein Sciences' technology is a slight variation on the conventional cell-based approach. Instead of growing live viruses, the company replicates viral DNA within cells. The genes for hemagglutinin are extracted from a dead flu virus and injected into baculovirus--a virus that infects a caterpillar called the armyworm. The baculovirus is then injected into ovary cells isolated from the armyworm. In a bioreactor, the virus eats away at cells, replicating DNA and producing hemagglutinin.
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