Beating two infections with one vaccine

From Baltimore, Md., at the Annual Conference on Vaccine Research

Identifying key similarities between related bugs could enable researchers to coax some vaccines to do double duty.

Immunity to one virus sometimes confers protection against a related microbe. Such cross-protection is the case with cowpox and smallpox, and a vaccine currently in use for Japanese encephalitis protects some animals against the closely related West Nile virus.

Cross-protection could occur in part because related viruses share many molecular parts that trigger immune cells to attack, says Anne S. De Groot of Brown University and the company EpiVax, both in Providence, R.I.

De Groot and her colleagues compared the genomes of a Japanese encephalitis virus and a strain of West Nile virus that killed several people in New York in 1999.

The researchers found that the viruses share at least 300 parts, or epitopes. This suggests that an immune cell primed to attack an epitope in one virus would respond to the other virus, as well.

Identifying other pairs of pathogens with many cross-reactive epitopes may reveal more double-duty vaccines, the researchers say.

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