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DuPont Qualicon Bolstering Capabilities of Benchtop PCR-Based Food Testing System


By Ben Butkus

DuPont's microbial diagnostics division, DuPont Qualicon, has been bolstering the capabilities of its benchtop PCR-based testing platform through licensing agreements, and is looking to expand use of the system beyond food testing and into pharmaceutical testing and other public health markets, company representatives said this week.

Known primarily as a global materials science and chemical company, DuPont does business in a wide range of markets including agriculture, nutrition, electronics, communications, safety and protection, home and construction, transportation, and apparel.

But DuPont's Qualicon unit, which offers a variety of products for microbial testing, has been of "growing importance" to the company, Megan DeStefano, DuPont's global marketing manager, told PCR Insider this week, a statement underscored by a pair of announcements in the last week related to DuPont Qualicon's PCR-based testing products.

First, DuPont, acting through the Qualicon business, late last week inked a licensing agreement with Idaho Technology for reagents or methods using SYBR Green I and post-PCR melting curve analysis technology (see related story, this issue).

And this week, DuPont said that it is working with the US Department of Agriculture to develop a PCR-based test for six strains of Escherichia coli that have recently been increasingly implicated in food contamination and human illness.

Although the announcements were not directly linked, they both involve DuPont Qualicon's BAX System, an automated, benchtop PCR-based detection system for pathogen and food quality testing, which DuPont began selling in the mid 1990s and which has since "evolved into a more sophisticated platform," Amy Smith, technical and regulatory specialist at DuPont Qualicon, told PCR Insider.

"The BAX System … was initially designed to bring high-tech capabilities [like] PCR to the world of food testing," Smith said. "It basically provides an easy-to-use system that can be implemented in a food testing, government, service, or research laboratory."

The company's latest generation of the instrument, the BAX System Q7, was developed in collaboration and is sold under a license with Applied Biosystems, now part of Life Technologies. According to the company's website, the Q7 is compatible with currently available assays and offers faster processing than its predecessor along with real-time PCR and probe-based detection.

The system can detect multiple targets in the same well, with as many as 96 samples per batch, and can provide information beyond presence or absence of a microbe, such as quantitation or species differentiation.

In recent years DuPont has licensed TaqMan technology from Applied Biosystems/Life Technologies, as well as Scorpions probe technology from DxS (now Qiagen); and the company's agreement with Idaho Tech further expands the platform's capabilities.

"SYBR Green is the original platform for our original BAX assays for [microbes] such as Salmonella, E Coli 0157:H7, and Listeria monocytogenes," Smith said.

"Now we've expanded upon that product platform to include PCR assays that are based on real-time technologies," Smith added. "We have a platform with a variety of products including SYBR Green-based assays; but we've also expanded that to include TaqMan and Scorpions-based chemistry with a focus on real-time technology."

Smith did not detail how the company would incorporate the post-PCR melting curve technology licensed from Idaho Tech, but in general, the technology is often licensed in conjunction with SYBR Green to verify results from SYBR Green-based PCR, which can sometimes produce misleading results due to mispriming and the formation of primer-dimers, Jill Powlick, legal counsel for Idaho Technologies, told PCR Insider.

"When a dsDNA-binding dye is used for something like diagnostics, [researchers] always do a post-PCR melt to confirm," Powlick said. "With some of the more robust tests where there isn't a lot of mispriming, you might not do the melt … so they are mostly licensed together, but not always."

Smith noted that DuPont's goal in aggregating SYBR Green and other real-time PCR technologies has been to "take a technology that wouldn't have been available otherwise to laboratories that don't have molecular biologists and highly trained scientists … and provide an easy-to-use system. We've found this works really well in the world of food testing. These folks are using high-tech, modern technology to do their food testing. The ultimate goal is to have a safe food supply."

Meantime, this week's announcement by DuPont that it will collaborate with USDA to develop tests for emerging E. coli serotypes builds on a prior agreement under which the partners developed a test on the BAX System for the most well-known E. coli strain, O157:H7, a shiga toxin-producing strain most commonly associated with food contamination outbreaks.

"We have worked really well with USDA in the past, and have co-developed an assay for real-time detection of E. coli 0157:H7," Smith said. "Really the goal of that was to deliver an easy-to-use system for food companies to use to check their products and deliver safe products to the marketplace."

USDA currently uses the BAX System E. coli O157:H7 test, as well as tests for L. monocytogenes and Salmonella, Smith said. In addition, DuPont Qualicon sells its tests to various "top-50 food companies globally" and to third-party service labs that offer testing services to food companies.

However, in recent years, concern has grown within the food safety testing market about the so-called “big six” serotypes — E. coli O26, O111, O145, O103, O121, and O45 — which are commonly referred to as non-O157 shiga toxin-producing E. coli, or STEC.

The US Centers for Disease Control and Prevention estimate that non-O157 STEC are responsible for 36,000 illnesses, 1,000 hospitalizations, and 30 deaths annually.

"These six strains of E. coli are definitely a public health concern and they can cause human illness," Smith said. "And this increased prevalence has been recently noted. So should there be an increased surveillance? These six are really the focus, because right now there are extremely limited detection methods for these particular pathogens. And there is a need in the marketplace."

Smith also said that the new non-O157 STEC assays developed with USDA will utilize real-time PCR technology on the BAX System, and will help "expand the diagnostic tools offered for use" on the BAX System.

DuPont did not provide a timeline for the development of the test.

And although DuPont's recent announcements revolve around food-testing applications, the company may be looking to expand the reach of its system, especially into areas where there is a need to bring "high-tech, accurate tests to users who don't need to be highly skilled," DeStefano said.

"We are looking to expand into markets where contamination and safety are critical," she said. "Right now we're focusing on pharmaceuticals and public health as expanding markets."