DHIA Detectives Have New DNA Tool at Their Fingertips

Chris Torres
Staff Writer

MANHEIM, Pa. — Mastitis testing is going the route of “CSI”-like technology, thanks to a new, first-of-its-kind machine Lancaster DHIA technicians are using.

Called PCR-based mastitis testing (Polymerase chain reaction), the technology can identify up to 11 major mastitis causing genes, along with a penicillin resistant gene.

The technology creates millions of copies from a single strand of DNA using a cycle of heating and cooling. The goal, in this case, is to check for various genetic markers that can potentially lead to a cow developing mastitis.

The technology was developed in 1984. It has been used in a variety of applications, including the cloning of animals, diagnoses of hereditary diseases and identifying various infectious diseases.

Kary Mullis, a world reknown biochemist, won the 1993 Nobel Prize in Chemistry for developing the technology.

Jere High, general manager of Lancaster DHIA, said the technology is already being used in Europe for mastitis testing. But as far as he knows, Lancaster DHIA is the first lab of its kind in the U.S. to be using it.

He found out about the technology after attending a conference in Croatia earlier this year on Johne’s Disease, where he was giving a speech.

Conventional mastitis testing requires a lab technician to replicate bacterial growth using a milk sample from an infected cow. But this test can be unreliable at times, according to High. Between 25 and 40 percent of tests coming from cows with clinical mastitis cannot be replicated in the lab.

It takes between two and seven days to get results from a conventional mastitis test. PCR testing and evaluation can be completed in less than two days.

“What I really like about this is that it takes the guess work out of it,” High said.

Along with this, he said that samples, unlike those used in conventional testing, do not need to be sterile and the same samples used to measure somatic cell counts can be used. Preserved samples at the DHIA lab can also be used.

A company out of Finland, Finnzymes Diagnostics, developed the “assay.”

During a tour of the DHIA lab last week, members of the Pennsylvania Center for Dairy Excellence’s Dairy Advocacy Resource Team (DART), got a chance to check out what High likes to refer to as “the lab’s toaster oven.” It literally looks like one. The surprisingly unimposing assay is controlled by a computer which collects data from the various tests it takes.

Finnzymes is collaborating with Agilent Technologies in the development of the assays.

It can handle between 22 and 90 DNA samples at one time and performs up to 88 different tests in about 90 minutes.

Getting the assay was not cheap. A typical one can cost over $50,000.

Lancaster DHIA members can get a full panel test done for $24. A “contagious test” will cost $19. Non-members will pay a little more for each test.

High said “the sky is the limit” when it comes to using the technology because not only will it provide markers for mastitis, it will enable farmers to make better decisions on herd selection and breeding.

“It is really exciting for us. The sky is the limit because everything has a genetic marker,” he said.