Researchers at the Bacterial Diseases of Livestock Research Unit, part of the National Animal Disease Center (NADC) in Ames, used a DNA sequence analyzer and collaborated with the University of Minnesota (U-M) to sequence the chromosomes of microbes that cause Johne's disease and bovine brucellosis.

In addition, the sequencing of an agent that causes leptospirosis — a project being done completely within the unit — has entered the final phase.

The analyzer, operated by ARS veterinary medical officer David Alt, allows unit scientists to perform almost 800 reactions a day. It can automatically analyze multiple runs of 96 DNA samples, making unattended 24-hour operation possible.

Automated sequencing allows for rapid analysis of an organism's genes, speeding identification of those linked to superior characteristics — or to negative traits, such as susceptibility to disease.

Sequencing of Mycobacterium paratuberculosis, a microbe that causes Johne's disease, was led by ARS microbiologist John Bannantine and U-M pathogenomics scientist Vivek Kapur. Johne's is an intestinal disorder characterized by diarrhea and weight loss in infected cattle. It is found in seven percent of beef herds and 22 percent of dairy herds nationwide.

ARS microbiologist Shirley Halling and Kapur led sequencing work on Brucella abortus. That microbe causes bovine brucellosis, a highly contagious bacterial disease that induces late-term abortions and infertility in cows, as well as undulant fever in humans.

The sequencing of Leptospira borgpetersenii serovar hardjo, a cause of leptospirosis, is being led by ARS microbiologist Richard Zuerner.

Leptospirosis causes abortions, stillbirths and weak offspring in cattle and swine, and it can reduce milk production in cows. It also affects many other animals, including dogs.

More information about genome sequencing at NADC can be found in the April 2003 issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research

agency.