High-tech vaccines may be more likely to aggravate, rather than prevent, disease than traditional vaccines, Swiss scientists suggest.

University of Zurich researchers found that genetically engineered vaccines designed to protect mice against a virus called lymphocytic choriomeningitis virus, or LCMV, may under some circumstances actually heighten vulnerability to disease.Reporting in the journal Science Thursday, Rolf Zinkernagel and his colleagues said their findings suggest disease-aggravating immune responses "may be an unwanted consequence" of high-tech vaccines now under development to protect against AIDS, leprosy and many other infections.