New principle for developing vaccines

Infections with a certain type of bacteria (group B streptococcus) can lead to severe, sometimes life-threatening, infections in newborn infants.

In Sweden some 100 children contract these infections each year.Now medical researchers at Lund University are on the track of a possible future vaccine. The method they are using may also be of significance for other new vaccines.

When a new vaccine is developed, it is often done by first selecting a certain protein that characterizes the bacterium or virus the vaccine will be targeting. In the next step a certain part of the protein is singled out that has an especially strong capacity to rouse the body’s immune defense.

The idea of a vaccine is for the immune defense to recognize and react to a future invader. Selected portions of a couple of different proteins are sometimes combined into a so-called fusion protein.

“But we tried another way of thinking. Perhaps the other parts of the protein that don’t provoke the immune defense as much are more important to the protein. They may have been hidden from the immune defense precisely because they are so important,” wonders Gunnar Lindahl, professor of medical microbiology.

A new fusion protein based on this idea turned out to have the very best effect on group B streptococci­just the opposite of the conventional principles.

“This discovery is significant not only for battling streptococci but also for developing new vaccines in general. The conventional way of going about it might not be the most effective,” maintains Gunnar Lindahl.

A vaccine against group B streptococci would probably be given to young women ahead of their first pregnancy. One possibility would be to do this in combination with the vaccine against cervical cancer that was launched earlier this year and targets teenage girls prior to their sexual debut.

The findings are published in Cell Host & Microbe, a new sister journal of the prestigious Cell.

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