Medical Device Daily

The FDA took the fairly infrequent step this week of issuing a statement concerning a product clearance, this one reporting the okay of a license supplement for Gen-Probe (San Diego) to market the first fully automated West Nile Virus (WNV) nucleic acid test for donor screening. The system is designed to add full automation, and thus further efficiency and higher-throughput capacity, to test for the disease.

While WNV is typically spread by infected mosquitoes, transmission of the disease can occur through blood transfusions or organ transplantation — and the FDA noted that most infected individuals have “mild disease and recover spontaneously.”

But infection can, according to Gen-Probe, have symptoms ranging from those similar to the flu to severe encephalitis, that range making it fairly difficult to diagnose.

“Something like 1,500 units of blood infected with West Nile have been intercepted since investigational testing began back in 2003 . . . ,” Michael Watts, senior director of investor relations and corporate communications at Gen-Probe, told Medical Device Daily. “Blood is very safe today, but what this [system] does is [ that] it increases the efficiency of testing.”

The system can detect WNV’s genetic material in plasma specimens from individual donors of blood, tissue and organs, the FDA said. It is not intended for use on cord blood specimens or as a tool in the diagnosis of WNV infection

Watts said the advanced Tigris system provides a “lack of manual intervention,” and that this will be of special benefit to blood banks that previously using Gen-Probe’s Procleix eSAS – standing for Enhanced Semi-Automated System — along with the company’s Tigris System under an Investigational Device Exemption (IND) received in 2003, along with the company’s WNV Procleix assay.

The assay was approved by the FDA in December 2005 (Medical Device Daily, Dec. 5, 2005).

The FDA said the Procleix Tigris system is “capable of performing certain manual steps that were performed by technologists when using semi-automated systems.

‘”The difference between this assay system and the previously approved Procleix semi-automated platform is the degree of automation,” the FDA said.

The automated Procleix Tigris can process 1,000 blood samples in about 14 hours, Gen Probe said.

It said that blood banks approached it in 2004 after they began using the ESAS system, saying that it was “very difficult” to do individual donor testing on the semi-automated equipment.

That’s when Gen-Probe offered Tigris under the IND.

Gen-Probe said the first confirmed U.S. death resulting from transmission from donated blood was reported in 2002, although the disease was first detected in the U.S. in 1999. The FDA said the disease has recurred “each year since then,” and has become endemic in the U.S.

Typically, blood banks combine 16 units of blood together to test, with Watts calling this the “paradigm” for donor blood testing for years. But after Gen-Probe offered its Tigris system, blood banks, if they noticed a high incidence of WNV in a given geographic area, would switch from group combined testing to individual donor testing with the WNV Procleix assay.

“So rather than testing 16 different units of blood at once, they’d test each individual unit of blood, which increases the sensitivity of testing, obviously, by not diluting the sample as much,” Watts said.

The FDA said “it is estimated” that between 1 million and 3 million people have been infected with the virus. Watts said there are about 14-15 million units of blood donated each year in the U.S. The company’s blood screening products are marketed worldwide by Chiron (Emeryville, California), a Novartis (Basel, Switzerland) company, and it will be targeting blood banks across the country with this new Tigris system.

Gen-Probe said that according to the Centers for Disease Control and Prevention (Atlanta), more than 4,200 human cases of WNV infection occurred in the U.S. in 2006, and nearly 350 units of WNV-infected blood were intercepted.

The Procleix Tigris System also is approved for commercial blood screening use with the Procleix Ultrio Assay in “many” countries outside the U.S., the company said. T

he Ultrio Assay simultaneously detects HIV-1, hepatitis C and hepatitis B.

Watts told MDD that in January the company submitted to the FDA a request for approval for this same test for marketing in the U.S.

In the area of clinical diagnostics, the Tigris system was cleared in December 2003 for use with the Aptima Combo 2 assay to detect Chlamydia trachomatis and Neisseria gonorrheoeae (MDD, Jan. 4, 2004).