Understanding RSV Testing

Transcription

1 TECHNICAL BULLETIN Vol. 1 No. 1, September 2004 Understanding RSV Testing 1 RSV Facts 2 3 Synagis and Its Effects On RSV Testing Choosing a Rapid RSV Test BD Directigen RSV Technology: Two antibodies detect RSV nucleoprotein and fusion protein BD Directigen RSV Technology: Two-step lateral flow process enhanced by proprietary reagents BD Directigen EZ RSV: Optimal readability

2 1 RSV Facts l RSV is the number one cause of respiratory infection in infants and children, infecting virtually every child in the first few years of life. 1 l Worldwide, RSV contributes to the deaths of up to 1,000,000 infants and children under the age of five each year. 2 l In the U.S., RSV is associated with 11,000 deaths, 3 and 125,000 hospitalizations per year. 4 l Prevention of RSV among the high risk population is critically important. Monthly injections of Synagis is one of the most commonly used treatments to help prevent RSV infection in young children at high-risk of RSV. 4 The immunoprophylaxis treatment with Synagis reduces the incidence of RSV hospitalizations by 55%. 4 l RSV high-risk pediatric populations include children with: n prematurity n chronic lung disease n congenital heart disease and other congenital disorders n immunocompromised n various neuromuscular disorders n family history of asthma l Treatment for RSV is largely supportive, e.g. maintenance of hydration and oxygenation, as well as keeping the airways clear of mucus. l RSV infection confers only limited protective immunity. Thus, persons can be repeatedly infected and develop serious disease throughout their lifetime. 5 1 Epidemiology and Prevention of Pediatric Viral Respiratory Infections in Health- Care Institutions, Donald A Goldmann, Harvard Medical School, Emerging Infectious Disease Vol. 7 No.2, March-April Respiratory Syncytial Virus (RSV): Overview, Treatment, and Prevention Strategies, Mark J. Polak, MD Guidelines for Preventing Health-Care Associated Pneumonia, 2003, page 43 TECHNICAL BULLETIN

3 Synagis and Its Effects On RSV Testing 2 Synagis Antibody Synagis (palivizumab), manufactured by MedImmune, Inc., is a humanized monoclonal antibody targeted against RSV. Synagis is commonly prescribed during the RSV season to reduce hospitalizations from RSV infection in high-risk infants. Since the launch of Synagis in 1998, over 400,000 babies in the US have been treated with monthly injections of Synagis. 6 Illustration 1. Synagis antibody may compete for the same fusion protein epitope as other rapid RSV test antibodies.* BD uses a unique antibody that does not compete with the Synagis antibody for binding. The BD Directigen EZ RSV test was carefully developed to utilize an RSV monoclonal antibody that detects a unique RSV antigen epitope. The BD Directigen EZ RSV monoclonal antibody does not compete for the same RSV fusion protein epitope that is the target of both the Synagis antibody and other commercially available RSV assays (see illustration 1). The presence of Synagis has been demonstrated not to interfere with the results of the BD Directigen EZ RSV test.* BD Directigen EZ Antibody 6 * Data on file, BD Directigen RSV package insert. VOL. 1 NO. 1, SEPTEMBER 2004

4 3 Choosing a Rapid RSV Test There are several rapid RSV tests currently available utilizing two major technologies, enzyme immunoassay (EIA) and lateral flow. Each test offers a wide range of performance, specimen choices, and limitations for drug interference. Key factors that each lab should be aware of when choosing a rapid RSV test, include: l Test accuracy l Turn around time l Interference with commonly used medications, such as, Albuterol and Synagis l Choices of specimen type l Reliable supply BD Directigen RSV Built on enzyme immunoassay technology BD Directigen EZ RSV Built on rapid chromatographic immunoassay (lateral flow) technology BD Diagnostics provides two choices of RSV rapid tests BD Directigen RSV and BD Directigen EZ RSV. BD Directigen RSV BD Directigen EZ RSV Technology Positive Result Indicator Detection Antibody(s) Antigen(s) Detected Specimen Options Enzyme immunoassay (EIA) A purple triangle Two antibodies: anti-nucleoprotein and anti-fusion protein RSV nucleoprotein and fusion protein NP swab, NP wash, NP aspirate and tracheal aspirate Chromatographic immunoassay (lateral flow) A visable test line One antibody: anti-fusion protein antibody RSV fusion protein NP swab, NP wash, NP aspirate Transport Options 11 transport products 22 transport products Extraction Reagent External Controls Improves antigen exposure Sufficient liquid controls provided Improves antigen exposure and breaks down mucoid specimens with easy-to-read clear background Sufficient liquid controls provided Time to Results Number of Organisms Tested for Cross-Reactivity 15 minutes 15 minutes Common Medications Tested with No Interference Kit Configuration N/A 20 Tests (Cat. # ) 40 tests (Cat# ) 19 medications, including Synagis, Albuterol, Zanamavir, Amantadine, Rimantadine and Ribavirin 30 Tests (Cat. # ) TECHNICAL BULLETIN

5 BD Directigen RSV Technology: Two antibodies detect RSV nucleoprotein and fusion protein 4 Anti-Fusion Protein Antibody Anti-Nucleoprotein Antibody BD Directigen RSV is built on the unique EIA technology of using two antibodies (anti-fusion protein antibody and antinucleoprotein antibody) detecting both the RSV fusion protein and nucleoprotein antigens (see illustration 2). Other rapid lateral flow RSV kits detect only one antigen, the fusion protein. While detection of both antigens requires a few more steps, test sensitivity is optimized and the time-to-results remains the same. BD Directigen RSV features: l High overall accuracy, sensitivity of 97% and specificity of 97%* l Unique technology of two antibodies detecting two RSV antigens l A wide range of specimen types: NP swabs, NP washes, NP aspirates, and tracheal aspirates l Rapid time to results in 15 minutes l Room temperature storage Illustration 2. BD Directigen RSV utilizes the unique technology of two antibodies detecting both RSV nucleoprotein and fusion protein. * Data on file, BD Directigen RSV package insert. VOL. 1 NO. 1, SEPTEMBER 2004

6 5 BD Directigen EZ RSV Technology: Two-step lateral flow process enhanced by proprietary reagents BD Directigen EZ RSV utilizes a unique patented form of lateral flow technology, invented by BD. This technology enables a simpler workflow while providing maximum performance, easy readability and no interference from common drugs used to help prevent or treat RSV. BD Directigen EZ RSV utilizes a proprietary sample processing reagent specially developed to break down mucoid specimens to release more antigens (compare illustrations 3 and 4). Increased antigen release can allow for improved sensitivity. Other lateral flow RSV tests may lack the sample process step or may require mucoid samples to be sonicated prior to testing. Illustration 3. RSV Antigen release without sample processing. Illustration 4. RSV Antigen release after sample processing. TECHNICAL BULLETIN

7 BD Directigen EZ RSV: Optimal readability 6 BD Directigen EZ RSV is designed for easy readability. Variations in test line intensity are typically seen with chromatographic (lateral flow) immunoassays. The sample processing reagent in the BD Directigen EZ RSV test helps create a clear white background in the test result window. This allows for easier to read test lines. Optimized concentrations of antibodies and detector provide clearer test lines that are easier to read even with weak positive samples. BD Directigen EZ RSV features: l Easy-to-use workflow l High performance without compromising specimen types and transport choices l No interference with commonly used RSV drugs Synagis and Albuterol l Clear white background in test result window improving readability l Clearer test line intensity even with weak positive samples VOL. 1 NO. 1, SEPTEMBER 2004

8 Featured in this bulletin: PRODUCT CATALOG # BD Directigen RSV 20 test kit BD Directigen RSV 40 test kit BD Directigen EZ RSV 30 test kit BD Diagnostics 7 Loveton Circle Sparks, MD USA rue Aristide Bergès Le Pont de Claix, France Tel: Bristol Circle Oakville, Ontario Canada L6H 6R5 Tel: Tuas Avenue 2 Singapore Tel: Monte Pelvoux 111, 9th Floor Col. Lomas de Chapultepec México D.F. Tel: Rua Alexandre Dumas São Paulo, S.P. Brazil Tel: Akasaka DS Building 5-26 Akasaka 8-chome Minato-ku Tokyo, 107 Japan Tel: Synagis is a registered trademark of MedImmune Inc. BD, BD Logo and Directigen are trademarks of Becton, Dickinson and Company BD September 2004 Printed in the USA