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New Process Tackles Difficult Bacteria
Submitted by smithgll on Tue, 01/21/2014 - 3:02pm
Chlamydia is the most common sexually transmitted disease in America. The Center for Disease Control estimates 2.86 million infections occur annually and 1 in 15 sexually active females, aged 14-19 years, has chlamydia. Untreated, it can damage a woman’s reproductive organs.
Chlamydia is zoonotic; that is, it can be spread among different species and it’s a particularly serious health concern for sheep and sheep farmers. It can cause lameness, pneumonia, and spontaneous abortion throughout a herd.
With the primary objective of developing a chlamydia vaccine for sheep, a team of OSU researchers, led by Dan Rockey at the College of Veterinary Medicine, has developed a new process that will lead to faster, less expensive, and more accurate tests for chlamydia.
Chlamydia is a tough bug to grow in a traditional test tube culture. That means testing for chlamydia is either slow and expensive, or not very accurate. The most commonly used test in medical clinics, the enzyme-linked assay or ELA test, is quick and inexpensive, but is only about 70% accurate. That means, 3 out of 10 patients are incorrectly diagnosed as chlamydia-free. Clearly, there is a need for something better.
In the past decade, advances in technology have made the use of genome sequencing (mapping an organism’s DNA) a quick and relatively inexpensive process for identifying bacteria and other bugs. “The first chlamydia genome was funded in 1998,” says Rockey. “It took five years and over a million dollars. Now we can take DNA from swabs and have a complete genome in less than three weeks for about $800; and it’s going down all the time.” At OSU, genome sequencing is done in the Center for Genome Research and Biocomputing. “There are a lot of researchers on campus using genomics,” says Rockey. “It’s important to note that OSU did a great job establishing and funding the CRGB to the point where it has become a leader in genomics biology. We’re right at the forefront.”
Rockey and graduate student Tim Putman have developed a new process for extracting and ‘growing’ difficult bacteria like chlamydia so it can be genome sequenced. You might expect the process to involve some futuristic, high-tech gizmo but, surprisingly, they just use a magnet.
Rockey’s lab takes some infected tissue and uses chlamydia-specific antibodies to attach an iron particle to a tiny amount of the bacteria. Then they liquify the mixture and use a run-of-the-mill magnet to shoot the bacteria out of the solution. “It sounds crazy, but it works,” says Rockey. “It is a great needle in a haystack finder.”
Once they have separated out the pure chlamydia, they multiply the sample by copying it’s DNA in a lab process called ‘Whole Genome Amplification’; then it is ready for genome sequencing. “We just take our test tube, walk across the street to the CGRB, and they do the sequencing for us,” says Rockey.
The Rockey lab recently published a method for using this technique on humans. “We took swabs from patients, used the magnets to grab the chlamydia, and then genome sequenced it,” says Rockey. We got a lot of biological information quickly without having to culture the organism.” This, and other new technologies, may eventually lead to a better chlamydia test that can be used by clinics and diagnostic laboratories.