Brucellosis field test in development at UW

Laramie – Over the last several years, UW Associate Professor of Veterinary Sciences Gerard Andrews has dedicated his work to the development of a brucellosis field test.

Brucellosis in cattle, elk and bison has troubled Wyoming cattlemen since the initial loss of the state’s brucellosis class-free status in 2004, and the resulting testing requirements are costly.

Andrews says B. abortis is of interest to the state, and thus he was asked to work on his current project. Andrews says there are two general arms of the research in this project: diagnostics and vaccine development. With the opening of the Biosafety Level Three (BSL-3) lab in the Wyoming State Veterinary Lab, Andrews predicts vaccine development will progress forward.

Today, when cattle are tested for brucellosis the blood samples are sent to the Wyoming State Veterinary Laboratory in Laramie and analyzed by lab technicians before results are produced. If Andrews’s rapid test is released after successful validation, producers should be able to quickly determine whether their cattle are positive for infection by Brucella abortis, the bacteria responsible for brucellosis..

“It is based on a diagnostic cassette, almost like a pregnancy test,” says Andrews of his work. “You don’t have to take a lot of sample, or move the sample from the field to the laboratory or spend hours on a laboratory test. It is a very simple procedure.”

At this point, Andrews says the team has used molecular approaches and techniques in his research to understand how the bacteria survive, cause disease and persist during infection. The field test developed by Andrews is based on published results from these approaches. Andrews and his team of graduate students at UW have identified over a dozen B. abortis proteins that appear to be involved in the virulence of the bacteria, or its ability to persist in the host. These proteins can be used to distinguish between infected elk and/or cattle and naïve animals, or those that have never been exposed to B. abortis.

Through his research, Andrews will be able to further explore the applicability and feasibility of use of the proteins identified, and he says this will help determine which proteins are useful candidates for the assay they are developing.

Currently, one protein has been selected as particularly promising, and it works in the assay, but Andrews and his team are looking for more candidate proteins. The use of more than one protein in the assay will increase the accuracy of the test.

“We have a protein now, and it’s just a matter of a year or so before we can identify more candidates that we can really use in the assay,” explains Andrews. “Our ultimate goal is to combine two or more proteins to distinguish between animals that are immunized, vaccinated or naïve.”
“It has taken us about four years to get to this point,” says Andrews. “I’m working with students, and it’s labor intensive and takes a lot of man power.”

Developing tests or vaccines isn’t a simple or fast process. Andrews says he and his team are probably at least five years away from having a test developed that can be distributed to the public for use. Full development of an assay or vaccine can take anywhere from 10 to 20 years, which can be sped up slightly when working with non-human animals.

Andrews clarifies this estimate with the caveat that the test passes validation.    

In validation, Andrews says highly specific and highly sensitive results are sought. Specificity protects against false positives by only identifying the proteins associated with B. abortis while sensitivity prevents false negatives by recognizing very small quantities of protein.

“We have to look at a lot of samples – hundreds – to validate the test. Then, we have to deploy to the field,” says Andrews about the next steps in getting the test ready.

It is important to have people who don’t work in a laboratory also conduct the test in field trials, explains Andrews. In this phase of testing, the same samples will be tested in both the field and the lab to make sure results are accurate.

“It’s been a little frustrating,” continues Andrews. “What works in the lab in one type of detection methodology doesn’t necessarily mean it will work in a different kind of assay.”

“Proof of concept it one thing in the laboratory,” says Andrews. “We will have to convince folks who will use the assay that it will work for them accurately.”

This assay may also be used with a variety of other dangerous pathogens, according to Andrews, and specifically with select agents, which are considered potential bioterrorist agents by both the Centers for Disease Control and the USDA.

Andrews’s experience working with bacterial pathogens is extensive. In 20 years of working for the Department of Defense, nine of those were spent working with select agents, and he says he has studied infectious disease agents since 1983.

“I’ve always been fascinated with bacterial pathogens that are able to survive in the host and not necessarily cause disease for a long time,” say Andrews. “When I got here, I naturally fell into working with Brucella.”

“I like working with different microorganisms – working with different pathogens helps you understand the interactions between bacteria and their hosts better – and understanding the commonalities and differences” says Andrews.

Andrews was recently tenured as an associate professor and was asked to chair the microbiology program at UW.

“Things are going to get a little busier for me in a different direction,” says Andrews, “But I’ll also continue to move forward with my research.”

Saige Albert is assistant editor of the Wyoming Livestock Roundup and can be reached at saige@wylr.net.