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Boston, MA — Modern medicine discovered vaccination only two centuries ago-although its common use began more than a hundred years later, and then mainly in Europe and North America. For most people in the world, vaccination began less than fifty years ago.
Termites, however, probably began using the technique around two hundred million years ago, according to new research by Boston University professor of biology James F. A. Traniello and his co-researchers. Traniello and his team have found that termites exposed to pathogens somehow share their immunity with other members of their colony.
Inside termite colonies and the nests of other social insects it’s warm and the members of the colony mingle closely. This is an almost perfect environment for the rapid growth of bacteria, fungi, or other disease agents-something human beings discovered when they too began living closely together in large urban environments. History records the result: numerous epidemics that have caused the deaths of millions of people.
The BU research team showed that, contrary to expectation, termites develop a more protective immune response when part of a group. Traniello, along with assistant research professor Rebeca B. Rosengaus and graduate student Keely Savoie, exposed termites to low doses of a pathogenic fungus that stimulated immunity but didn’t kill the insects. The exposed termites were then maintained either in isolation or in groups. Later, they were given potentially lethal doses of the fungus. The termites placed in groups survived at a higher rate than those kept in isolation.
Even more surprising, the researchers discovered that this immunity can be transferred to other colony members who were not previously exposed to the pathogen. A second experiment found that termites that merely had contact with exposed-or “inoculated”-nestmates, but which had not been inoculated themselves, were also less susceptible to a lethal infection.
Traniello suggests that the presence of even a few exposed individuals may enhance the immunity of the unexposed insects in a nest. Despite the obvious risks of disease transmission, evolution seems to have bestowed a health advantage to insects that have taken to social living.
The researchers are continuing their investigation, trying to determine how termites transfer immunity. One possibility is that some amount of a pathogenic fungus gets carried into the colony, enough to initiate an immune response, but not so much as to do harm. Another possibility is that the termites spread inactivated spores throughout the colony. It is also possible that the termites share bodily secretions that contain substances that may stimulate or activate an individual termite’s immune system.
Traniello’s report, “The Development of Immunity In A Social Insect: Evidence For The Group Facilitation of Disease Resistance,” appears in the “Proceedings of the National Academy of Sciences” of May 14, 2002.