Meantime, Potomac Falls, Va.-based Tessarae said its Resequencing Pathogen Microarray-Flu was capable of detecting Swine Flu prior to the outbreak of the pandemic. The Affymetrix GeneChip-based array uses 956,000 array probes to interrogate 117,000 base pairs of pathogen gene sequences to detect and identify known and unknown upper respiratory pathogens, both viral and bacterial, according to the firm.
"We are very confident that our current RPM-Flu assay will definitively detect and identify the outbreak swine flu strains without any modification," said Matthew Lorence, vice president of marketing and sales at the firm. "There is also the additional benefit of detecting any co-infecting viral and bacterial pathogens that may be exacerbating morbidity and mortality in the Mexican cases, which seem to be more severe than the US cases," he told BioArray News last week.
Like CombiMatrix, Tessarae's main RPM-Flu customers have been military and foreign public health labs using its technology for surveillance. He said that the US public health system has not shown any interest in Tessarae's technology to date, but suggested that the swine flu epidemic could change things.
He acknowledged that RT-PCR and culture have been the "gold standard" methodologies for the CDC in the past, but said that Tessarae's technology offered some advantages. "RPM generates sequence data as the result, so pathogens present in the specimen are definitively identified based on the genomic sequences detected, versus accumulation of fluorescent signal from simple hybridization of probes to an intended pathogen target," Lorence said.
"Our assay definitively detected swine flu in five out of five specimens so far, and was able to do so without modification," he said. "This illustrates again the power of the technology to detect and identify unknown or emerging pathogens, something that PCR cannot do well or consistently, if at all."
At the same time, he noted that it took more than 10 years for PCR to become a standard diagnostic methodology in microbiology labs, and admitted that companies with array-based tests faced "resistance to new technologies." Still, Lorence said that it was in the labs' interests to adopt newer technology, like the RPM-Flu.
"Clinicians were not trained to expect multiple agents as the cause for infectious disease, so educating them on the benefits of being able to detect all pathogens present as opposed to the single pathogen that they suspect will enable better diagnosis and more appropriate treatment of patients," Lorence said.
Singapore and India
Outside of North America, companies with array-based flu identification assays have also touted the strengths of their platforms over the past week.
Singapore-based Veredus Laboratories said that its VereFlu chip, launched last year,
is able to detect H1N1, using a combination of PCR and array hybridization in a lab-on-chip system manufactured by partner ST Microelectronics.
VereFlu is portable and automated and the firm claims its platform can rapidly detect "all major influenza types at the point of need." CEO Rosemary Tan said in a statement that the company is now verifying the "efficacy of the tests on human samples" and plans to make its system available for swine flu identification over the next few weeks.
Tan told BioArray News last week that it is relatively simple for the company to upgrade VereFlu to include new strains, such as H1N1. "We align the sequences and design primers and probes to be able to detect, differentiate, and identify a particular strain or subtype," Tan said. "We use multiple gene targets with multiple probes to ensure that the detection is precise and specific," she said. "Optimization will be done to ensure that the multiplex PCR is working with high sensitivity and specificity and then we test the microarray panel for cross reactivity, sensitivity, and background noise level."
According to Tan, the firm is using synthetic sequences to test its assay for use. Once ready, Veredus will also collaborate with labs in Asia that can conduct the test on real samples. She declined to name the firm's collaborators.
In India, another company has also announced the availability of an array-based flu test. Ocimum Biosolutions said that it has upgraded its OciChip array platform to include probes for H1N1. The chip was originally developed three years ago during the avian flu outbreak.
Like Veredus, Ocimum is also validating its updated test. Ocimum said that it can also provide an RT-PCR based molecular diagnostic assay for use in India and Asia.
CEO Anu Acharya said in a statement that Ocimum is "ready to work with various public health labs in the India and the region that need help in setting up these assays, or running the samples in our labs."
