EMERGING TESTS

CDC and the Diagnostics Industry Continue to Battle Zika

While summer has ended, the battle against the mosquito-borne virus Zika continues. The Centers for Disease Control and Prevention (CDC) updated prior travel and testing guidance on Zika transmission to cover all of Miami-Dade County in Florida, as mosquito transmission of the virus continues to be reported in that region. The number of locally acquired cases of the virus is low in the United States at 137 according to the CDC’s Oct. 19 update, but there are a total of 4,016 cases in the U.S. with 3,878 related to travel. One reported case was laboratory-acquired.

While locally mosquito-transmitted cases in the United States have only occurred to date in Florida, travel related cases have been reported in all 50 states with the most occurring in California, Florida and New York. Just as virus transmission has not abated, efforts to develop better diagnostics continue in earnest. The FDA has issued a total of 12 Emergency Use Authorizations for diagnostics. Here’s an update on some recent developments concerning available testing.

Hologic EUA Expanded to Urine Samples
Earlier this year, an Emergency Use Authorization (EUA) was granted to Hologic for its Aptima® Zika Virus Assay for use with serum and plasma. In September, the FDA expanded that EUA to allow use of the assay with urine samples collected with the patient-matched serum or plasma. Hologic’s new authorization "expands the window in which an individual can be tested and we can get results from a 7-day window to a 14-day window," explains Tom West, Hologic’s Division President of Diagnostic Solutions. That affords "better ability to identify if an individual is impacted by Zika and take appropriate measures and to see if Zika is expanding in the population," he added.

As discussed in DTET‘s June 2016 issue, according to the CDC, Zika virus RNA is unlikely to be detected in serum after the first week of illness, but Zika virus RNA can be detected in urine for at least two weeks after onset of symptoms. See "Urine Becoming Preferred Zika Sample as Testing Industry Prepares for Summer Mosquito Season," DTET, June 2016 p. 1. The CDC says urine "should always be collected with a patient matched serum specimen."

Hologic’s assay is run on its Panther system—which West indicates is a laboratory- based system that is "very successful … in the clinical environment and the blood screening environment because of the speed with which it can process a sample"— processing can occur within hours. West adds that what distinguishes the Panther system is its "high level of specificity and sensitivity." "The CDC identified this specificity and sensitivity as one reason to move this forward as quickly as it did," West notes.

Roche’s LightMix
In August, EUA was also granted to Roche’s LightMix® Zika rRT-PCR test to detect Zika in EDTA plasma or serum samples. The test utilizes Roche’s LightCycler 480 Instrument II or cobas z 480 Analyzer. "The LightMix Zika test is an easyto- use molecular diagnostic test that enables healthcare professionals to quickly detect the virus," Head of Roche Molecular Diagnostics Uwe Oberlaender said in a statement. Roche distributes the test manufactured by TIB MOLBIOL GmbH. "The end-to-end automated process from sample preparation to results for up to 96 samples can be performed in just 2.5 hours," according to the Roche statement. Roche previously announced availability of the cobas® Zika Test for use with cobas® 6800/8800 Systems to screen blood samples under an Investigational New Drug Application protocol.

Vela Diagnostics’ Sentosa
Another assay granted an EUA was the Sentosa® SA ZIKV RT-PCR test from Sinapore-based Vela Diagnostics, for use with serum, EDTA plasma and urine (with patient-matched serum or plasma). The FDA granted the EUA in September. Vela indicates the test can process 22 samples in three hours, its detection limit "enables detection of samples with low viral load," and it is "authorized to run on the automated Sentosa® SX101 real-time PCR workflow, along with the Sentosa® SX Virus Total Nucleic Acid Kit v2.0."

ARUP Laboratories’ Zika Virus Detection by RT-PCR
Also receiving EUA from the FDA in September was the ARUP Laboratories Zika Virus Detection by RT-PCR test. That test is used for "in vitro qualitative detection of Zika virus with specified instruments" to detect Zika virus RNA "in human serum, EDTA plasma, and urine (collected alongside a patient-matched serum or plasma specimen)," according to the company’s website. The test is authorized for use on the QuantStudio 12K Flex real-time PCR instrument (Thermo Fisher)–or other authorized instruments.

Quest’s MAC-ELISA
In September, Quest Diagnostics introduced an antibody test service to help detect Zika infection based on the CDC-developed Zika Immunoglobulin M (IgM) Antibody Capture Enzyme-Linked Immunosorbent Assay (Zika MAC-ELISA). Quest is operating under a CDC license to offer the service with EUA approval from the FDA. Earlier this year in April, Quest became the first commercial lab with FDA EUA approval for a Zika test—which provided qualitative detection of RNA from Zika in serum. Then in September, Quest announced availability of an RT-PCR-Zika test to detect the virus in serum and paired urine specimen. Quest explained in a statement that molecular testing "is most useful up to 14 days after" symptoms appear and "IgM antibody testing is most useful two to 12 weeks following the onset of symptoms."

"Not every lab provider has our level of expertise or scale. We believe our leadership positions us to aid clinical and public health response to emerging infectious diseases such as Zika," says Quest spokesperson Wendy Bost. "This is why Quest fast tracked development and FDA emergency use authorization for its first molecular Zika test earlier this year and has now introduced an antibody Zika test service. By providing these services, we significantly broaden physician and patient access to quality Zika virus test services in the United States and internationally."

Takeaway: While locally transmitted cases of Zika virus are limited so far to Florida, travel related cases continue to rise and the diagnostics sector continues to seek ways to improve virus detection.

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