a report by C a l y p t e B i o m e d i c a l C o r p o r a t i o n Calypte Biomedical Corporation has been involved in the pursuit of novel infectious disease diagnostics for over a decade. Not content with simply making Calypte versions of tests that are readily available from a variety of suppliers, Calypte’s focus is on developing, manufacturing and distributing tests that other companies do not or cannot, with a particular focus on HIV. Calypte may be best known as the only company to have developed and achieved US Food and Drug Administration (FDA) approval for a urine screening enzyme-linked immunosorbent assay (ELISA) for HIV-1 antibodies, as well as its corresponding Western Blot. The development of HIV antibody assays, which use non-blood samples, remains a passion of the company. It is currently launching three rapid tests for HIV-1/2 antibody, including a rapid urine test and a rapid oral fluid test. T h e C a s e f o r A l t e r n a t i v e S a m p l e s There is broad consensus that testing, coupled with counselling, is a fundamental and critical aspect to HIV control. With a few exceptions, such testing and counselling is voluntary, so the success of such efforts depends largely on the willingness of the public to participate; however, for a variety of reasons, the public may not participate in the numbers desired. Knowing, for example, that HIV testing is typically performed on blood samples, the public may opt out of testing – even if they know they may be at risk – due to fears of pain and safety, or for cultural reasons. The ability to perform HIV testing accurately and safely using both urine or oral fluid samples has been amply documented, as has the increase in voluntary testing rates when such alternatives are offered. T h e C a s e f o r R a p i d H I V A n t i b o d y T e s t i n g Rapid, point-of-care (POC) testing for HIV antibody is appropriate in a variety of settings. It has been widely noted that substantial numbers of people who participate in voluntary testing and counselling programmes and provide samples for testing, never return for their results. Whether this occurs due to fear of the outcome, inconvenience or other reasons, the result is that HIV-infected people remain undiagnosed and untreated. In the developing world where the HIV epidemic is most acute, rapid testing algorithms using multiple rapid tests in series or parallel have become commonplace. In addition to the benefit of immediate referral to treatment, rapid tests can be performed in the absence of properly equipped laboratories or skilled laboratorians. Aware™ Rapid HIV Antibody T e s t i n g w i t h A l t e r n a t e F l u i d s Calypte’s Aware rapid tests have been designed with the developing world in mind. Available only in selected markets, the tests have been designed to offer optimal accuracy, economy and patient appeal. The assay test strip is in a dipstick format that is more economical to manufacture and less expensive for disposal. Patients are familiar with the dipstick format from participating in routine urinalysis. By combining the proven benefits of alternate fluid sampling with the proven benefits of rapid testing, Calypte believes that it offers a broader range of rapid testing options than any other company. A w a r e T e s t s Three Aware tests have been developed: • Aware BSP for use with whole blood, serum,and plasma; • Aware OMT for use with oral mucosal transudate(oral fluid); and • Aware U for use with urine samplesAll three tests are sensitive to both HIV-1 and HIV-2. Calypte is a duly licensed manufacturer of HIV-2 rapid tests, so there is no risk that production will be interrupted in the future for reasons of HIV-2 patent infringement. Calypte Biomedical Corporation – Innovators in Infectious Disease Testing 1.B U S I N E S S B R I E F I N G : E U R O P E A N P H A R M A C O T H E R A P Y 2 0 06 Technology & Services Section 2. B U S I N E S S B R I E F I N G : E U R O P E A N P H A R M A C O T H E R A P Y 2 0 0 6Each of the three tests takes 20 minutes to perform, and include a true human immunoglobulin G (IgG) control line that verifies both that the test device is working properly and that the appropriate sample was introduced to the device. Each of the three tests is sold in kits of 25 or 50 tests and can be stored and shipped without refrigeration. Two of the Aware tests (BSP and OMT) require the use of a buffer solution and this is provided in excess. The kits include multiple buffer droppers so that multiple users can use the same test kit simultaneously. The rapid urine test requires no buffers or sample preparation – simply drop a dipstick into a tube containing urine. S p e c i a l i t y P r o d u c t s f o r H I V E p i d e m i o l o g y The use of widely available HIV antibody tests can provide useful information about HIV prevalence in a given population at a given point in time. However, one of the most vexing problems for HIV researchers has been the estimation of HIV incidence – the number of newly acquired infections. Clearly, two populations with identical prevalence at some point in time can have dramatically different incidence rates – one group may be experiencing a steady or declining rate of new infections while the other may be experiencing explosive growth. An understanding of HIV incidence trends is critical for many people engaged in HIV control efforts. Policy makers, financial and resource planners and programme managers all need to understand the nature and scope of the HIV epidemic in populations if they hope to intervene in a timely manner, plan for the future and determine which programmes are working and which are not. Past efforts to estimate HIV incidence have been based on assay ‘detuning’, whereby highly diluted samples are run on a commercially available HIV-1 enzyme immunoassay (EIA) test, with the expectation that only those sera associated with longestablished infections will have a high enough titre to yield a reactive result. This approach is prone to reproducibility problems and a sensitivity that is limited to a small range of HIV subtypes. The HIV-1 BED Incidence EIA is a microwell EIA test for use with serum or plasma samples previously determined to be reactive for HIV antibody. Originally developed by the US Centers for Disease Control (CDC), Calypte was licensed to commercialise the test in 2004. The assay is intended for surveillance purposes only, to estimate HIV-1 incidence in populations. Since it is not used in the diagnosis or treatment of individual patients, most countries permit the import and use of this product without official registration. The assay is based on the observation that following infection, the ratio of HIV-specific IgG:Total IgG ratio continues to rise. This EIA is quantitative and includes the standards needed to validate the assay. A calibrator is also provided that performs in the assay at the typical HIV-specific IgG:Total IgG ratio found 5.5 months postinfection and is used to provide a threshold cutoff for the classification of recent seroconversion. Samples with optical densities (ODs) below this threshold are presumptively considered ‘recent’ and must be repeated in triplicate. The reference in the product’s name to BED relates to the use of a unique branched multi-subtype gp41 peptide that incorporates the immunodominant regions from subtypes B, E and D. This confers upon the assay with equal sensitivity across types A–F. F u t u r e D e v e l o p m e n t s i n I n c i d e n c e T e s t i n g In collaboration with the US CDC, Calypte is developing an application that will permit the BED Incidence EIA to be used with dried blood spots (DBS) or dried serum spots (DSS) – a development that will expand the utility and convenience of the assay. Dried blood and serum samples are easy to collect and store and the blood spot application for BED would permit retrospective analysis of archived samples that have been collected in this manner. In addition, routine collection of such samples can be conveniently integrated into HIV screening programmes in such a way that blood spot samples associated with positive HIV antibody screening results can be set aside for subsequent incidence testing. The dried blood spot application for the HIV-1 BED Incidence EIA will entail the use of an accessory pack of controls and standards in DBS format, which is used along with the regular BED test kit. Commercial availability of the accessory pack is anticipated late in 2005. ■ http://www.touchbriefings.com/cdps/cditem.cfm?cid=5&nid=1890 |
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