Chlamydia, which can cause infertility when left untreated, has evolved a stealth operation to grow while evading the host's immune system. Its infectious form enters the host cell sheathed in a protective layer of host cell membrane. It then changes into a replicative form and multiplies. In the process, it somehow imports all necessary amino acids, energy, and other supplies from the host cell's cytoplasm, possibly with the help of the newly discovered protein Cap1 (black dots). Chlamydia reverts to its infectious form when the cell can no longer tolerate the growing vacuole (see light micrograph on right). The cell finally bursts, releasing infectious particles. Micrograph by Zarine Balsara |
Cloak partly lifted on tiny ChlamydiaScience moves closer to effective vaccineFebruary 9, 2001The Boston Public Health Commission released 1999 statistics showing 2 percent of the city's 15- to 19-year-olds have chlamydia. Boston's minority girls were reported to have infection rates of almost 6 percent, and a 1998 Journal of the American Medical Association study of sexually active teenage girls in Baltimore found infection rates approaching 30 percent. In this era of sex education and ample health information, teen-agers in the U.S. probably are more aware of the dangers of sexually transmitted diseases than any generation before them, but they know little about some STDs. Consider Chlamydia trachomatis, the most common bacterial STD in the developed world. Since infection with Chlamydia is often silent, it goes mostly undetected even though it is the leading cause of preventable infertility in this country. In the Jan. 30, 2001, Proceedings of the National Academy of Sciences, Michael Starnbach, Harvard Medical School assistant professor, and colleagues presented data that advance researchers' understanding of this mysterious pathogen and, at the same time, move them closer to developing a vaccine. |
