A scientific team, armed with genetic engineering techniques, says it is moving closer to creating a safer vaccine for whooping cough, a disease that kills more than 1 million babies worldwide each year.

In a study published Thursday in the journal Science, a team of American and Japanese scientists reported they have made major steps toward producing a "genetically detoxified" pertussis toxin, or PTX.The current vaccine for pertussis, commonly known as whooping cough, uses killed, whole cells of Bordetella pertussis, which is the bacteria that cause the disease.

Using techniques to alter genetic material, or DNA, from the whooping cough bacteria, the team developed mutant bacteria that make an altered segment of PTX protein that induces very little of the harmful enzyme activity believed to cause the current vaccine's harmful side effects.