NEW YORK (GenomeWeb) — An independent study by researchers in Indonesia has shown that Focus Diagnostics' Simplexa Dengue test has a higher detection rate than conventional RT-PCR or SYBR Green real-time RT-PCR methods in clinical samples. The Focus test, which simultaneously detects and serotypes dengue virus, could be used for future dengue surveillance studies, the authors concluded.
The study of Simplexa Dengue, published in PLoS One last week, used 184 ELISA-confirmed clinical samples taken in eight different cities in Indonesia, a dengue-endemic country. In this sample, the detection rate for conventional RT-PCR was about 29 percent. SYBR green real-time RT-PCR had a rate of 44 percent, while the Simplexa test had a rate of about 76 percent.
Using virus isolation as the gold standard for viremia, the researchers then tested the three assays again on a subset of 40 samples. The Simplexa test achieved 100 percent sensitivity, while the conventional and SYBR green methods were around 95 and 98 percent sensitive.
While a previous published study used Simplexa Dengue for serotype surveillance of mosquitoes, this is the first study using the product on clinical samples.
"It's a relatively new product, so this could potentially help us to get more visibility and business," Mona Gross, marketing manager for the Simplexa line at Focus, a Quest Diagnostics subsidiary, said in an interview this week with PCR Insider.
Focus did not provide funding or reagents for the study, Gross confirmed. Instead, Sanofi Pasteur SA, which recently funded phase III clinical trials of its dengue vaccine in five countries in Asia, donated the assays, as provision of equipment was otherwise a hurdle, according to study author Tedjo Sasmono, an investigator at the Eijkman Institute for Molecular Biology in Jakarta.
In an email to PCR Insider, Sasmono said the Simplexa method minimized human involvement, so it will hopefully reduce errors. Having a closed system is also an advantage, he said, because it can be standardized to be used in research projects involving multiple centers or countries and is expected to generate uniform results.
In addition, Sasmono explained that his own lab initially used conventional RT-PCR for dengue detection, but he was impressed that Simplexa's detection rate was better than the conventional method. Simplexa was also useful for dengue detection in large numbers of samples. "When combined with automated RNA extraction, it delivers sensitive and rapid detection results compared to the conventional method," Sasmono said.
In addition to cost, initial set up was a drawback, because "it required skillful and qualified operators to ensure the ultimate integrity of the data generated," Sasmono said. Still, he said that he hopes this method will "further support dengue diagnosis and surveillance in Indonesia" in the future.
Papers like this one might help get the word out about Simplex Dengue. Outside the US, Focus works with partners in each country to promote and market its tests, Gross said. "They know their markets better, and they help with the regulatory process oftentimes as well."
She noted that Thailand does a lot of work with Focus using this particular kit in their public health labs. "Brazil has also shown a lot of interest in this product, but they're not yet using it routinely. A lot of times with these ministries of health it takes some time to convert over," she said. Simplexa Dengue was approved for use in Brazil in 2011.
In the US, however, dengue is not common, and public health agencies may in fact receive testing reagents from the Centers for Disease Control and Prevention free of charge, Gross suggested.
Still, publication of this independent study could give the test some visibility outside the US. "We hope this might promote more interest, but we're not banking on that," Gross said.
A growing menu
Michelle Tabb, vice president for research and development at Focus, noted that in addition to the Simplexa Dengue molecular test for acute virema, Focus offers three ELISA-based tests for antibodies against the virus and a protein made by the virus itself. And the firm is continuing to build a menu of tests for the Simplexa platform.
In the interview with PCR Insider, Gross and Tabb described three tests that Focus has in clinical trials and five in the development phases.
Earlier this year, Focus' test for herpes simplex 1 and 2 virus from cerebrospinal fluid — the Simplexa HSV 1&2 Direct molecular test on the 3M Integrated Cycler — received expedited 510(k) clearance from the US Food and Drug Administration and CLIA moderate complexity categorization.
The company is now in clinical trials to develop that test for assaying HSV in genital swabs.
The firm also has a product in development for detection and differentiation of enterovirus and parechovirus from CSF, Tabb said. In addition, a test for Group A Strep detection, and one for MRSA and Staphylococcus aureus detection are already in clinical trials, while tests for Clostridium difficile, norovirus G1 and G2, respiratory detection of Bordetella pertussis and B. parapertussis, and Chikungunya virus are in development, Tabb noted.
"All these products are in our direct amplification disc format — sample to answer in one hour, directly from the specimen, no extraction required," Tabb said.
Focus expects the MRSA, Group A Strep, and the additional claim on the HSV direct test all to be available at the beginning of 2015, Gross said.
While there are other companies with similar products, Tabb and Gross said the flexibility and ease of use of the Simplexa platform gives the product strength in the market. "It's really an all-in-one solution for the customer to do their molecular testing," Tabb said. "Our integrated cycler ... allows us to do high-throughput testing and also stat testing as well," Tabb said.
In addition, Focus leverages expertise obtained in other aspects of its business for test development.
The Focus reference laboratory has been in business for over 30 years, Gross said, and has been doing molecular testing for 20 years. "We have a heritage in infectious disease testing," she added.
"As we drive forward in our marketing and our product development, we're really looking at ease of use, direct testing, really fast sample to answer, but keeping the ability also for the customer to purchase our [analyte-specific reagents]" to develop their own tests, she said.
The Chikungunya test is an example of Focus' ability to apply its experience as a reference lab and supplier of ASRs to developing a clinical test.
"What we're looking at doing right now is taking our knowledge of the [Chikungunya] assay from the Focus reference lab and putting that into a product that can be sold," said Gross. "I'm not sure that there would be much sales in the US, but in the Caribbean, where this has become endemic, we have had a lot of demand for this material. It will be sold as an [ASR], which would then be used as a lab-developed test by hospitals in those areas that need it."
As reported yesterday in JAMA, US health officials are bracing for wider spread of Chikungunya after the recent arrival of the virus, and some experts suggest it may become a part of the blood plasma virome here. In December, an official notice to public health officials from the CDC about Chikungunya cited Focus Diagnostics as the sole commercial laboratory providing molecular diagnostic testing.