AMHERST, Mass. - University of Massachusetts scientists are among those who have formulated a vaccine that prevents the disease chlamydia, the leading cause of female infertility in this country. A patent for the vaccine has been granted based on work by microbiology professor A. Bruce MacDonald, who died last September, and his colleague, Elizabeth Stuart, a lecturer in microbiology. The work was done in conjunction with Judith Whittum-Hudson, an immunologist at Johns Hopkins University, and William Mark Saltzman, a chemical engineer at Cornell University.
Chlamydia is a bacterium with many virus-like features, explains Stuart. Besides the form of the disease which causes female infertility, and which can be sexually transmitted, another form of chlamydia is a major cause of blindness in Third-World nations. Recent research indicates that chlamydia also may be responsible for some cardiac and joint disorders.
The vaccine has been tested on mice; Stuart cautions that it will be several years – perhaps as long as a decade – before clinical trials are completed that could bring governmental approval for the vaccine. Current work is focusing on development of a nasal vaccine as an alternative to a strictly oral medication.
Stuart and MacDonald worked together on the research beginning in 1979, in an effort to discover and characterize various traits of the bacterium. For many years, scientists believed that it was impossible to create a chlamydia vaccine; there are many types of chlamydia, and it was thought that a separate vaccine would be needed for each strain. Scientists would have had to pinpoint a different and precise molecule in each strain, "a daunting task for researchers," says Stuart.
So Stuart and MacDonald, along with their collaborators, took a different approach: they identified a molecule, GLXA, which is present in all types of chlamydia. But the discovery presented a problem: most vaccines, such as flu vaccines, are easy-to-handle proteins,or an inactive virus. These can be mass-produced. GLXA, on the other hand, is a glycolipid: a fat and carbohydrate molecule that is difficult to test for stability, or to produce in great quantities.
Vaccines generally work this way: a patient is treated with tiny amounts of a bacterium or the relevant portion of it. This material is seen as "foreign" by the recipient, prompting the body to generate specific antibodies, which result in immunity to disease. But the hard-to-handle GLXA led these scientists to use a two-step approach in creating a vaccine. MacDonald and Stuart immunized mice with GLXA, and ultimately were able to produce a hybrid cell that produces the correct antibody and reproduces itself endlessly. The body recognizes this antibody as the original GLXA itself.
"Essentially, we’ve created an easy-to-handle protein molecule which can mimic the harder-to-handle glycolipid," Stuart explains. "And the cells which make this antibody replicate endlessly, so we can make as much as we need."
The group has so far had two patents issued, one for "Chlamydial Vaccine and Processes" and a second one covering the specific oral vaccine, using the special antibodies. A third patent, for diagnosis of chlamydial infections in biological fluids, was accepted by the patent office. The patent is pending and is expected to be awarded within the next two months. Currently,work continues on the vaccine both at UMass and at Johns Hopkins. Here at UMass, two graduate students, one in biochemistry and one in microbiology, are actively engaged in additional research involving this vaccine.
Stuart is a lecturer in the microbiology department, where she teaches graduate-level courses in infection and immunity, and pathogenic bacteriology. She is also director of the microbiology lab support. She earned her bachelor’s degree at Wellesley College, and her doctorate at the University of Chicago, and did four years postdoctoral work at UMass. MacDonald was a graduate of Carroll College in Helena, Mont. He received his doctorate from Michigan State University and did postdoctoral work at Illinois Medical School in Chicago. He taught at the Harvard School of Public Health before joining the UMass faculty in 1978. He was head of the department from 1978 to 1984, and continued teaching until his death.