Hayward, CA - March 4, 2009 -A major breakthrough publication, published last Friday in the February 27 early edition of the Proceedings of the National Academy of Sciences,.describes studies that were greatly aided by utilizing Biolog Phenotype MicroArray technology to advance our understanding of an important class of pathogenic bacteria.
At the Rocky Mountain Laboratories of the NIH, NIAID division, Anders Omsland, Robert Heinzen and colleagues have succeeded in culturing the bacterium that causes Q Fever, a disease that can be transmitted to humans from animals. Most commonly it is transmitted from cattle, sheep or goats, but sometimes even cats and dogs. A typical human infection usually results in flu-like symptoms and a fever lasting one to two weeks. However the infection can be more serious, progressing to an atypical pneumonia or becoming a chronic infection of an organ such as the heart. It is usually transmitted by inhalation or by tick bite.
The causative agent of Q fever is the bacterium Coxiella burnetii which was first discovered in 1937. It has been particularly difficult to study this bacterium and find possible ways to cure infections because, until the work of Omsland, Heinzen, and colleagues, it has only been possible to grow these bacteria inside of animal cells. Growth in animal cells is difficult, costly, time consuming, and produces low yields. The group at Rocky Mountain reported that, using their specially devised culture medium, ACCM, they can now obtain 3 logs of growth without using animal cells as hosts.
Biolog’s Phenotype MicroArray technology, allows scientists to study the growth properties and nutritional needs of bacterial cells, fungal cells, and even human cells. As such it is becoming a core technology for cell assay and many other cellular studies. Instead of measuring cell growth, the technology employs a colorimetric redox dye to measure the stimulation or inhibition of cell energy production under different test conditions. It was extremely helpful in these studies of C. burnetii because it allowed the scientists to assay the effect of various environmental and nutritional factors without requiring the cells to grow. They found that C. burnetii requires special conditions in order to grow it outside of cells, for example a low pH (4.5), low oxygen (2.5%), and unusually high levels of the amino acid L-cysteine. With the Biolog PM-1 plates they were also able to determine that it can use a diverse assortment of at least 17 substrates to produce energy.
This is an important breakthrough because it has taken over 70 years to determine a method of culture and because researchers can now generate enough supplies of the cells to allow more and better studies to go forward. There are a number of other important bacteria that grow inside of other cells and have not been culturable outside of cells including, for example Chlamydiae and Rickettsiae. Now there is hope that they can be cultured with a medium similar to ACCM or that researchers can follow the example of Omsland, Heinzen, and coworkers and use Phenotype MicroArray technology to dissect and determine their special requirements.
C. burnetii undergoes a transformation between two discernable forms during the course of infection, forming metabolically dormant small cell variants (SCVs) and metabolically active large cell variants (LCVs). Both of these forms are seen in the cell free culture, and future studies can help determine the factors influencing the important transformation between these two forms.
In fact, work in the laboratory of Michele Swanson at the University of Michigan medical school has successfully employed Biolog Phenotype MicroArrays to look at similar transitions in another intracellular pathogen, Legionella pneumophila, the causative agent of Legionnaire’s disease. This work by Edwards, Dalebroux, and Swanson, just published in the January 16, 2009 issue of Molecular Microbiology, identified fatty acids as a key nutritional signal that the cells respond to.
Phenotype MicroArray technology, developed with SBIR funding from NIH and NASA, is more and more proving to be an important breakthrough technology. A press release in November, 2008 described breakthroughs in using PM to study other medically important and difficult to culture bacteria such as Mycobacterium, and Nocardia, as well as the readily cultured pathogen, Cronobacter sakazakii.
Biolog is a privately held company based in Hayward, CA, that continues to pioneer in the development of powerful new cell analysis tools for solving critical problems in biological, pharmaceutical, and biotechnological research and development. It is the world leader in cell phenotyping technology. Biolog’s respiration-based technology is unique in its broad applicability to cells – this includes bacterial cells and fungal cells as well as animal cells. More than 200 scientific publications and presentations document the effectiveness and productivity of PM technology. The PM product line adds to the innovative microbial identification products offered by the company, such as the new GEN III System. Biolog products are available worldwide, either directly from the company or through its extensive network of international distributors. Further information can be obtained at Biolog's website, www.biolog.com.