One of Harvill’s colleagues, post-doctoralscholar Dan Wolfe, focuses on the lesser known of the two Bordetella species: parapertussis. Like pertussis, this strain is present in humans and can cause whooping cough, but its extent isn’t known.“While parapertussis isn’t thought to be much of a problem in the United States,”he says, “that’s probably because of poor surveillance—it’s not monitored nearly as closely as pertussis.”

A few years ago, biomedical scientists began to suggest that, because today’s DTaP (diphtheria, tetanus, and pertussis) vaccine doesn’t protect against parapertussis, this pathogen might be becoming more prevalent. Wolfe’s research has also shown that, while a host’s immune response to pertussis protects the host only from pertussis, the immune response to parapertussis protects against both. Wolfe’s current research focuses on what is required for a host to have immunity to parapertussis, as well as why host immune systems react differently to these two pathogens. “We know these two species are co-existing. What effect could that have on the future of both species, as far as their relative prevalence?”

Harvill notes that there are a lot of questions about the behavior of Bordetella.“To look for answers, we're dissecting the tools, the genes, that these bacteria use to interact with their host—in this case, in experimental mice,” he says. “Bordetellae have a large set of genes that interact with
host immunity in different ways, and so essentially we knock out certain genes one at a time to figure out their function and then to compare them with other genes.” Harvill’s lab is able to use all the tools of mouse molecular immunology, together with genetic manipulation of Bordetella, to examine the interactions between host and pathogen.