Oct. 1, 1997 MANHATTAN -- For Kansas cattle, getting vaccinated may become as simple as eating fodder. Researchers at Kansas State University are developing a vaccine for calf enteric disease that will not be delivered as a shot. It will instead immunize cattle through the alfalfa they eat.
Sanjay Kapil, assistant professor of diagnostic medicine, heads the effort to genetically express proteins for the bovine corona and bovine rota viruses in plants. With traditional vaccinations, farmers directly inject cattle with non-infective virus protein. This produces antibodies that help fight disease. However, Kapil explains that this process is a hassle for ranchers.
"If you inject too much of the virus, the cattle will get sick. But by delivering vaccines with plants, the cattle will never get sick." This is because the plant vaccines do not have concentrations of infectious virus. Anyone who has struggled with capturing and injecting a calf with a needle will recognize the convenience the new vaccines will provide.
Researchers must first insert the genes of the virus into the plant chromosomes so that it will become a permanent part of the plant's genetic code. The ultimate goal is expressing the new vaccination gene in successive generations of plants, which can then be fed to animals.
Kapil explains that smaller trials represent the first step in the overall process. "Before we go into large scale animal trials, we need to do it in a lab system. So we chose tobacco plants and the mouse, which are easier to work with in the lab." The team has successfully integrated the vaccine in tobacco plants and fed those plants to mice. Now, they are simply waiting for the results.
Though the Kansas State team moved first in bovine vaccinations, researchers had already begun expressing vaccination genes in plants for human consumption. Knowing the results of their trials, Kapil expects the same positive results for cattle. The next step will be actual field trials, taking vaccines into fodder crops, like alfalfa, and giving it to cattle. Field trials could be as little as five years away.
Plant vaccines will help Kansas farmers and ranchers, but the significance of this research stretches far beyond its cattle ranches. Enteric diseases like corona and rota cost more than $3 billion worldwide, infecting and killing young cattle with diarrhea. Ranchers in the United States lose $250 million annually to the viruses.
Kapil expects this research to help many related projects.
"We have crossed the boundaries of just the animal group." He explains that a similar rota virus invades human babies, as well as cattle, leading to infection in 750 million children each year. If the bovine vaccination proves effective, a similar technique may be developed for children.
Because of this exciting potential, the K-State team is applying for a patent. While similar procedures have been patented, Kapil feels this his team's genetic engineering is unique. "Every system is different: which gene to go after, how to deliver it, which crop, how to deliver it in the crop. We're very lucky. The initial results are very promising."
Kapil says his team's research is "a storybook of daydreams." For cattle and farmer alike, gene vaccines would be a dream come true.
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