The goal of vaccine development is to produce a full-blown immune response without causing full-blown disease. However, when vaccines containing soluble proteins from the microorganisms are used to produce an immune response, the CTLs are rarely activated.
For decades, vaccine development experts have sought to find a simple and practical way to activate the killer cells or CTLs using soluble proteins, but finding a method that works has been a challenge.
"We were able to solve this problem by taking advantage of the observation that a class of proteins, called heat-shock proteins, are exceptions to the rule that soluble proteins are unable to stimulate CTL responses. In fact, heat-shock proteins are extremely potent in stimulating a CTL immune response," says Dr. Young.
Heat shock proteins, or stress proteins, are a family of proteins that cells produce in response to stress from heat, injury, germs, or toxins. Normally, these proteins act as molecular chaperones, binding to other proteins and ferrying them to and from various compartments of the cell. A few years ago, immunologists noticed that heat shock proteins are present on the surface of bacteria and are responsible for flagging the T cells and triggering the CTLs to attack.
Dr. Young and his colleagues found one particular protein from the
tuberculosis bacterium, called hsp70, that could elicit powerful immune
responses and could be used as an immune system booster. The special properties
Contact: Seema Kumar or Eve Nichols
Whitehead Institute for Biomedical Research