UF Scientists Use New Research Technology To Understand Ancient Human Foe – Cholera

June 25, 2003

GAINESVILLE, Fla. — University of Florida scientists have invented a way of teasing out the genes bacteria use to outwit their human hosts, a discovery that could prove to be a boon for researchers brewing new vaccines and designing drugs for many serious afflictions.

In one of the first studies to put the new technology to the test, UF experts, working closely with researchers from Harvard Medical School, have isolated the proteins uniquely expressed in people by the cholera pathogen, an ancient intestinal scourge now sweeping the globe on its seventh pandemic wave since 1817. The report of their findings, which showcase the importance of a group of previously discounted genes in the infection process, will be published this week in the online edition of the Proceedings of the National Academy of Sciences.

The discovery could lead to a cheaper, more effective vaccine not only for the rampant deadly cholera bacteria, but also for other potential bioterrorism agents for which there currently are no preventive treatments.

UF researchers, with major funding from the National Institutes of Health and the National Institute for Dental and Craniofacial Research, developed the study’s screening tool, which allowed them to detect proteins expressed by bacterial genes during human infection. These proteins differed from those the bacteria produced when raised in laboratory cultures. The technology is patented by Gainesville-area iviGene Corp., founded by its UF inventors to patent and market the discovery under the trade name IVIAT, for In Vivo-Induced Antigen Technology.

“Prior to IVIAT, we were able to study only those genes identified when the bacteria were growing in the laboratory or in animal models,” said study investigator and IVIAT co-inventor Ann Progulske-Fox, a professor of oral biology at UF’s College of Dentistry who also serves as chairwoman of UF’s bioterrorism task force and is a member of the iviGene board of directors. “We realize now that the shortcoming of laboratory study is that the repertoire of genes a bacterium uses to survive and reproduce in the living host environment are very different from those it uses to survive and reproduce in a laboratory environment.”

The World Health Organization, which has called for development of an improved vaccine to combat cholera, estimates the ailment kills hundreds of thousands every year, plowing through unsanitary, crowded communities in poor, underdeveloped nations with deadly regularity. Health experts say outbreaks have been fueled by rapid population growth and the increasing popularity of international travel to developing countries. Oral vaccines aimed at preventing cholera are available, but they are expensive, provide only short-term immunity and do little to protect children under 2 years of age.

Developing an improved vaccine has proved arduous, however, because humans are the only known host for the cholera bacterium, making laboratory and animal studies problematic.

“IVIAT technology takes advantage of the antibodies made by humans when they become infected with the cholera bacterium,” said Jeffrey D. Hillman, a professor of oral biology at UF’s College of Dentistry and chief scientific officer of iviGene Corp. “After first subtracting out the uninteresting antibodies, the remaining ones serve as probes to identify the best potential targets for development of new vaccine and diagnostic strategies.”

In the study, researchers collected blood samples from 10 patients who were recovering from cholera at the International Centre for Diarrhoeal Disease Research in Dhaka, Bangladesh. The samples were screened to identify proteins uniquely expressed by the cholera bacterium when it is growing in the human host.

Researchers found the cholera bacterium produces a toxin that is not significantly expressed in laboratory cultures but is prominently expressed during human infection.

Identifying good diagnostic targets using IVIAT is a critical step before researchers can conduct additional studies to validate the findings and justify the cost and time involved in developing a new cholera vaccine.

The technology also could be used in the study of an array of other diseases and pathogens, including anthrax and E. coli, Progulske-Fox said. Hamburger-loving Americans are especially at risk for contracting E. coli, identified in 1982 after an outbreak of acute bloody diarrhea was traced to contaminated ground beef. The federal Centers for Disease Control and Prevention estimates E. coli sickens more than 70,000 U.S. citizens, killing dozens, every year.

“IVIAT is perfect for the study of the infectious biological agents used in bioterrorism, about which very little is known,” Progulske-Fox said. “The same is true for emerging pathogens, about which even less is known. With IVIAT, you can get right to work on identifying important genes of the infectious agent with no previous knowledge of its pathogenesis (origin) or genetic system. It’s universally applicable.”

In addition to their research on cholera, researchers are developing ways to identify the body’s genetic response to a host of cancerous, infectious and autoimmune diseases, such as diabetes and multiple sclerosis. These ailments are good research candidates for a related iviGene-designed, patent-pending technology named ISIAT, for In Situ-Induced Antigen Technology, Progulske-Fox said. ISIAT could potentially enable researchers to identify genes the body switches on to fight illness or those that abnormally turn on, thereby causing disease, such as in the case of cancer, where cells begin to reproduce helter-skelter. Drugs then could be developed to suppress malfunctioning genes or to boost the efficiency of genes the body activates to attack an illness.

The technology also could have agricultural applications, and preliminary studies are under way in plants at UF and iviGene. Ultimately, the research could help scientists develop crops with inherent resistance to plant pathogens, increasing crop yield and reducing dependence on insecticides and fungicides, Progulske-Fox said.

“Although antibiotics and various other technological breakthroughs over the past 50 years have had an enormous impact on human health and well-being, infectious diseases, cancer and autoimmune diseases are still extremely prevalent, accounting for a vast amount of human deaths and suffering worldwide,” Hillman said.

Yet useful vaccines only exist for a handful of the dozens of infectious diseases scientists have identified, Hillman said.

“IVIAT technology is the fastest, simplest and most comprehensive method available for identifying good targets that may lead to new treatments and diagnostic tools,” he said.