Roche's TaqScreen West Nile Virus Blood Screening Test Can Also Detect Other Members of the Potentially Deadly Japanese Encephalitis Virus Group


PLEASANTON, Calif. -- Roche Diagnostics, a leading provider of nucleic acid-based blood screening products, announced

today that its new assay for detecting West Nile virus in donated blood can

simultaneously detect other members of the Japanese Encephalitis virus group,

of which West Nile virus is a member. Roche's studies have shown that its

TaqScreen West Nile Virus Test can detect West Nile virus (including the

Kunjin and New York strains), St. Louis Encephalitis virus, Japanese

Encephalitis virus, and Murray Valley Encephalitis virus. Roche's test

represents an important milestone in local and international efforts to

prevent the spread of these potentially deadly viruses through the transfusion

of blood and blood products.

Although mosquitoes remain the most common means of transmission of these

viruses, the Food and Drug Administration (FDA) and Centers for

Disease Control and Prevention (CDC) last year indicated that a small number

of West Nile virus cases had likely spread through blood transfusions and

tissue donations. Because incidence of infection with West Nile virus is

expected to increase in North America in 2003, the FDA and CDC last September

called on industry to have a blood screening test for West Nile virus ready

for the 2003 mosquito season. Canada issued similar guidance to blood banks in


To date, Roche is the only company to announce a nucleic acid test capable

of detecting West Nile virus and other members of the Japanese Encephalitis

virus group in donated blood. In addition, Roche's West Nile virus test will

be the first and only fully automated nucleic acid testing system to be

introduced under an Investigational New Drug Application into the blood

screening market. Full automation is an important feature for blood banks

trying to manage the costs and workflow associated with the new testing


"Roche responded in record time to the FDA's call to action," said Richard

Thayer, vice president of blood screening at Roche Molecular Diagnostics, the

business area of Roche responsible for developing the test. "At the same time,

we were able to introduce next-generation features that automate the

extraction, amplification, and detection steps. We feel strongly," continued

Thayer, "that the full automation of our system and the ability of our test to

detect other Japanese Encephalitis virus group members offers blood banks an

essential advantage in a world where the spread of infectious agents can be

accelerated by travel. As the world leader in the international molecular

blood screening market, we remain committed to driving innovation and

providing our customers with the most comprehensive and reliable tools for

ensuring the safety of their blood supplies."

To further improve the blood screening process, Roche introduced "generic

extraction" as a feature of its TaqScreen West Nile virus test. Generic

extraction isolates the genetic material (nucleic acids called DNA or RNA) of

any infectious agent, viral or bacterial, present in a sample of donated blood

before a test for a specific infectious agent, such as West Nile virus, is

performed. Capturing this broader range of genetic material in the extraction

process makes it possible to "multiplex" tests, that is, to perform several

screening tests simultaneously on the same sample of blood.

"Three features distinguish Roche's West Nile Virus test," explained James

Gallarda, director of blood screening development at Roche Molecular

Diagnostics. "First, its broader coverage, made possible by the detailed

genetic research our scientists conducted up front to understand the Japanese

Encephalitis group of viruses. Second, total automation, an important feature

for blood banks working hard to ensure the safest possible blood supplies. And

third," continued Gallarda, "generic extraction, which adds further value by

allowing us to respond more quickly should our customers need to screen for

other emerging pathogens."

Clinical trials of Roche's TaqScreen West Nile Virus test are scheduled to

begin in the United States and Canada on or before July 1. The trials are

designed primarily to demonstrate the test's clinical performance for

detecting West Nile virus. Roche also expects the clinical trials and other

non-clinical studies to provide additional data about the test's performance

in detecting other members of the Japanese Encephalitis virus group.

West Nile virus and other members of the Japanese Encephalitis virus group

are more commonly found in Africa, West Asia, the Middle East, Central

America, South America, and Australia. West Nile virus was first observed in

the United States in 1999. In 2002, an epidemic of more than 4,100 West Nile

virus infections in the United States resulted in 277 deaths. In previous

years, before nucleic acid-based blood screening was available, the US also

experienced periodic epidemics of St. Louis Encephalitis virus, primarily in

the Gulf Coast and Mississippi valley regions of the country.

For most individuals, infection with these viruses causes no symptoms or

mild flu-like symptoms that resolve in several days without harm. But for

others, especially people over the age of 60 or those with compromised immune

systems, infection with these viruses can cause life-threatening medical

conditions, including encephalitis, meningitis or


Roche's patented polymerase chain reaction (PCR) technology, the world's

leading nucleic acid amplification technology, is an essential component of

Roche's blood screening assays and other diagnostic products. PCR allows

minute amounts of genetic material to be amplified into billions of copies

(that is, to detectable levels) in only a few hours. In addition to its

applications in nucleic acid fingerprinting and the diagnosis and monitoring

of disease, PCR enables detection of infectious agents in donated blood

earlier in the infection cycle, often before symptoms appear. Standard

immunoassay testing, in contrast, detects evidence of a body's immune response

(antibodies) later in the infection cycle, leaving an increased period of time

when infections can be missed.

To date, the majority of testing conducted to understand the spread of

West Nile virus in the United States has relied on Roche's PCR technology.

Several national and state-level public health agencies have used PCR-based

tools to better understand the epidemiology of West Nile virus in humans and

animals. Many healthcare providers and veterinary technicians rely on PCR-

based tests for diagnosing the disease.

Through its global licensing and scientific collaboration programs, Roche

has developed and encouraged the utility of PCR technology for a wide variety

of clinical and research applications.

Roche is a leading provider of nucleic acid-based diagnostic products

for the international blood bank market. Roche's PCR-based AmpliScreen

tests, which include assays for detecting HIV and Hepatitis C in donated

blood, have been approved for use in the US and abroad, and are also used in

other countries where product registration is not required. The company's

AmpliScreen assay for Hepatitis B is currently in clinical trials in the

United States. Roche's AmpliNAT system has been used exclusively by the

Japanese Red Cross since 1999 to screen Japan's entire blood supply. Roche's

AmpliNAT system is the first commercially available blood screening system

that can identify, in a single triplex reaction, whether or not a blood sample

is infected with HIV, hepatitis B or hepatitis C.

Source: Roche Diagnostics

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