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Rheonix Completes Initial Testing of Self-Confirming HIV Diagnostic on Automated System

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NEW YORK (GenomeWeb) – Molecular diagnostics firm Rheonix has completed initial development and testing of an HIV assay that detects host antigen response to infection as well as viral RNA.

The assay uses Rheonix's Chemistry and Reagent Device (CARD) disposable microfluidic and a portable instrument, and is fully automated following loading of reagents and sample. The firm recently collaborated with researchers at New York University to demonstrate the assay, with results published earlier this year in the Journal of AIDS & Clinical Research.

Positive HIV serology results are often backed up with PCR-based testing. The Rheonix test, however, "is actually serving as a self-confirming assay" said Richard Montagna, Rheonix's senior vice president for scientific and clinical affairs, in an interview.

Early diagnosis of HIV infection is critical because initial infection can have extremely high levels of viremia and is much more transmissible, Montagna said, but antigen response to the virus is not immediate so direct detection of virus is required during the seroconversion window.

However, in low-resource settings globally, or even HIV clinics in impoverished areas of the developed world, PCR-based testing can be prohibitively expensive. One clinical lab recently developed a method for pooled NAAT testing, while research labs have sought lower-cost isothermal methods using exothermic chemical reactions or body heat.

The Rheonix dual-path microfluidic test is also a lower-cost alternative to traditional PCR. It uses reverse-transcription loop-mediated isothermal amplification (RT-LAMP), which is generally less expensive than real-time PCR, which has been used in previous CARD assays by the firm. It also uses magnetic bead-based nucleic acid purification, and can process four samples per microfluidic device. The immunoassays within the device, meanwhile, consist of lateral flow test strips from OraSure Technologies.

Automation and ease of use are also important for HIV testing in low-resource settings, and fast turnaround of test results could reduce the number of patients who are unable to return to the clinic for follow-up. The Rhenonix test uses raw samples of blood or saliva, and is described in the recent study as easy to use and rapid.

Montagna noted that there are six months left in the $1.5 million in Phase II Small Business Innovation Research funding provided by the National Institutes of Health to develop the test. "Efforts are currently under way to further reduce the time frame and increase the level of analytical sensitivity," he said.

The recent study states the developers are striving to bring the 80-minute run time close to the limit for LAMP, or around 20 to 30 minutes. The substitution of heat-stabilized lyophilized reagents for liquid ones is also underway, according to the study. The test is currently only qualitative, but Montagna said that it could be modified to quantitate a viral load with additional standards.

Rheonix is considering working with non-governmental organizations or other collaborators to bring the test to patients, and Stephen Pemberton, vice president of marketing and sales at Rheonix, said the dual immunoassay and molecular tests could have additional applications. "The HIV test is a very viable product, but it's also a proof-of-concept of a new, orthogonal technology," he said.

The firm has been developing its CARD technology for other applications, as previously reported by GenomeWeb. Namely, last year it unveiled a system for user-customized CARD assays for research use, but has also been pursuing IVD development, applied markets applications, and next-generation sequencing sample prep uses.

After raising $28.6 million to increase the commercialization efforts around its MDx platforms, the firm is now pursuing a possible dual use of one of its instruments, such that it would be available for both in vitro diagnostic testing and creating lab-developed tests. The firm is in preliminary discussions with the US Food and Drug Administration about dual-use approval, Montagna said.

Specifically, Pemberton added that the firm envisions the Encompass MDx system may ultimately serve both the research-use and lab-developed testing markets, while the Encompass Optimum will be the offering for applied markets.

Other dual-use platforms on the market currently include Becton-Dickinson's BD Max Open System and the QuantStudio Dx from Thermo Fisher. The latter functions in Test Development Mode, enabling the development of custom tests and supporting clinical research projects, or IVD Mode, with pre-set run and analysis parameters.

The first test for Rheonix's potential dual-use platform will be a triplex sexually-transmitted infection assay, Pemberton confirmed, and the company will also develop additional undisclosed tests for the platform. These will likely depend on the level of multiplexing the technology can achieve, he said.

In the applied markets domain, the firm continues to develop assays for spoilage organism testing, specifically to test craft brews and microbrews.

Rheonix is now contemplating the next steps in the applied markets, "to see if this is an opportunity where we're going to partner with somebody that's dominant in that channel ... to help us commercialize," Pemberton said.

The company is currently developing the NGS sample-prep piece with academic collaborators at a New York State-funded program via a Center of Excellence at the University of Buffalo. "We have taken their benchtop method for library prep, which currently takes them about a day and a half to create the library, and we've reduced it to 146 minutes in a totally unattended manner using our CARD technology," Montagna said.

He further noted that subjecting an automatically-prepared Rheonix library and a manually-prepared library to Illumina sequencing led to indistinguishable metrics. The firm expects to continue work on that project for four or five more months. "The NGS is the long ball that we're playing as far as our value proposition," Pemberton said, adding that the firm is also looking for additional partners or academic centers for collaboration. 

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