Scientists have taken an important step toward creating a vaccine against Alzheimer’s disease, customizing the response of the immune system with unprecedented precision.Using a harmless form of the herpes virus, scientists at the University of Rochester Medical Center put into mice a payload of genetic information that created a carefully crafted immune response, one that muted the type of toxic side effects seen in a previous study in people of a vaccine against Alzheimer’s. The work was published on-line June 25 in Neurobiology of Aging.