From the outside, the OSU Veterinary Research Laboratory (VRL) doesn’t look like a high-tech center of advanced disease testing, but behind the drab, cement-block walls, are highly-trained experts and hundreds of thousands of dollars’ worth of state-of-the-art equipment.
There are several teams working in the VRL, which is managed by the Oregon Veterinary Diagnostic Laboratory (OVDL). On the Molecular Diagnostic (MD) team are Section Head Manoj Pastey, Supervisor Donna Mulrooney, and Microbiologists Andree Hunkapiller and Noah Lawler. They use DNA to find the causes of disease in all kinds of critters, from chickens to llamas. “Basically we are looking for specific gene sequences that identify a pathogen – a virus, bacteria or parasite – in a sample,” says Mulrooney. “The sample can be anything from a piece of lung, to fecal samples, to blood,” she says.
Most of the customers for the lab are Oregon veterinarians, many of whom work in the OSU Veterinary Teaching Hospital, but there are also customers from other states. “We have tests that are unique to our lab, so we get samples from across the U.S.,” says Mulrooney. “For instance we have a test for Mycoplasma haemolamae, a blood parasite that can cause severe anemia in alpacas and llamas.” That test was developed right here at the OSU College of Veterinary Medicine by Dr. Susan Tornquist and Dr. Chris Cebra
The molecular diagnostics lab also works with state and federal agencies. They receive weekly samples from Oregon’s state veterinarian for screening of avian influenza. “We test samples from the live bird market in Woodburn,” says Mulrooney. Avian influenza is a serious problem for farmers because it spreads very quickly and is deadly to poultry.
The OVDL is a member of a national surveillance network, under the U.S. Department of Agriculture, that works to respond quickly to disease outbreaks. That means the MD team has to be prepared to take on heavy loads of extra testing on a moment’s notice. “In the event of a multi-state outbreak of something like avian influenza, we have to cancel vacations and work long hours,” says Hunkapiller.
Molecular diagnostic testing usually yields faster and more specific results than using a microscope to identify disease. “With a traditional tissue culture, you are trying to find a broad class of pathogen. In this lab, every assay is designed to find something specific. It could be a certain species of bacteria or a certain strain of that species,” says Hunkapiller.
The exact process for testing varies from sample to sample, but the first step is extracting the DNA. That was once a long laborious job, but new technology makes it much easier. “We can extract up to 96 samples in a few hours as opposed to a few samples in a day,” says Hunkapiller. The technology that provides this speed is called a magnetic particle processor, and one machine costs as much as a new car.
The magnetic particle processor breaks down samples to release the DNA, then starts a process where magnetic beads attract the DNA, and the machine washes out the rest. A chemical process releases the DNA from the beads. Then a reagent is used to separate out a DNA segment unique to the pathogen in question. That bit of DNA is increased exponentially using a thermal cycler, and a process called polymerase chain reaction (PCR). The increase in the DNA segment is what allows it to be detected.
Because both machines are so expensive, buying more to accommodate increased business is not a good option. Therefore, Mulrooney and her team are working on streamlining their processes by tweaking the tests for a variety of samples so that they can run on the thermal cycler at the same time. But every time a test is slightly altered, it needs to be validated. “We group tests that have really similar settings, but we still need to make sure the slight changes do not affect sensitivity and accuracy,” says Mulrooney.
The molecular diagnostics team also works on developing new tests. “There are so many specific pathogens we could test for,” says Hunkapillar, “so we try to provide what our customers need.” Creating a new test is time-consuming and complicated. “We have to gather many samples,” says Lawler. “Sometimes we have to try different extraction techniques, or a new PCR might need to be set up. There is a lot of problem solving involved.”
One of the MD team’s biggest customers is the OSU Veterinary Teaching Hospital, and the lab strives to provide speedy results for them. For example, in the past, when a horse in the hospital had respiratory infections, the doctors sent samples to an outside lab for testing. The MD team spent many months developing an equine respiratory panel and now provides that service.