MMWR Weekly, May 10, 2002 / 51(18);395-6
Centers for Disease Control and Prevention

The Public Health Service has become aware of a potential shortage of supplemental test kits used for confirmatory testing of human immunodeficiency virus (HIV) antibodies in specimens obtained from either patients or blood and plasma donors. On April 17, 2002, Calypte Biomedical Corporation (Alameda, California) announced the company might stop manufacturing the Cambridge Biotech HIV-1 Western blot kit. The distributor, bioMérieux, Inc. (Durham, North Carolina), immediately notified customers that it no longer would be able to distribute the Cambridge Biotech HIV-1 Western blot kit.

The Cambridge kit is one of two HIV-1 Western blot (WB) kits licensed by the Food and Drug Administration (FDA) for supplemental testing of serum, plasma, and dried whole-blood spot specimens obtained for medical diagnosis or blood and plasma donor screening. The other WB test used for these purposes is the Genetic Systems Western blot kit made by BioRad Laboratories, Inc. (Hercules, California). A third, OraSure^® HIV-1 Western blot kit made by OraSure Technologies, Inc. (Bethlehem, Pennsylvania) and distributed by bioMérieux, Inc., is approved for supplemental testing of oral fluid samples found reactive for antibodies to HIV-1 in screening tests performed on oral fluids. However, use of oral fluid specimens is not approved for screening and supplemental testing of blood and plasma donors.

The algorithm for HIV testing in the United States begins with an initial screening enzyme immunoassay (EIA). If reactive, the EIA is repeated in duplicate on the same specimen. If repeatedly reactive, the specimen is tested with a more specific supplemental test to validate the true-positive EIA results and to prevent notification based on false-positive results that might occur during the screening tests. Supplemental tests include the WB test or the indirect immunofluorescence assay (IFA). This algorithm is used with serum, plasma, dried whole-blood spots, and oral fluid specimens (1--9).

Some laboratories are experiencing delays in obtaining WB supplemental test kits, and the potential exists for future delays in supplemental testing. Persons being tested for HIV might need to be counseled that they might experience delays in receiving their HIV test results.

If the Cambridge Biotech HIV-1 Western blot kit is unavailable, three options exist for supplemental testing to detect HIV antibodies using manufactured test kits approved by FDA:

1. Supplemental testing can be performed on serum, plasma, and dried whole-blood spots using the Genetic Systems Western blot kit. Information about the availability of the test kit is available by telephone, 800-224-6723, or at http://www.biorad.com.
2. Supplemental testing can be performed on serum, plasma, and dried whole-blood spots using the Fluorognost^™ HIV-1 IFA kit made by Sanochemia (Vienna, Austria) and distributed by Home Access Health (Hoffman Estates, Illinois). Information about the availability of this product is available by telephone, 203-227-6880, or at http://www.fluorognost.com. Sanochemia provides a self-taught course on performing the HIV-1 IFA and a proficiency panel free of charge.
3. Patient (but not blood or plasma donor) screening for antibodies to HIV can be performed on an oral fluid specimen collected with the OraSure^® HIV-1 oral fluid collection device made by OraSure Technologies, Inc. using an approved EIA test kit (Oral Fluid Vironostika HIV-1 MicroElisa) manufactured by bioMérieux, Inc. Repeatedly EIA reactive oral fluid samples can be tested further with the supplemental OraSure^® HIV-1 Western blot kit. Information about the availability of the OraSure^® HIV-1 collection device is available by telephone, 800-869-3538, or at http://www.orasure.com. Information about the availability of the oral fluid EIA and WB kits can be obtained from bioMérieux, Inc., telephone 800-682-2666.

The period during which kits might be in short supply is uncertain. CDC and FDA have contacted all the companies listed above about increasing production to ensure that sufficient quantities of supplemental test kits will be available for patient and donor screening. CDC is collaborating with FDA and other private and public health partners about the evaluation of alternative strategies for HIV diagnostic testing in case shortages of supplemental test kits continue. Laboratories experiencing difficulty obtaining manufactured kits for supplemental testing can contact CDC, telephone 404-639-4581.

References

1. CDC. Interpretation and use of the Western blot assay for serodiagnosis of human immunodeficiency virus type 1 infections. MMWR July 21, 1989 / 38(S-7);1-7.
2. Serological diagnosis of human immunodeficiency virus infection by Western blot testing. The Consortium for Retrovirus Serology Standardization. JAMA 1988 Aug 5;260(5):674-9.
3. Dodd RY, Fang CT. The western immunoblot procedure for HIV antibodies and its interpretation. Arch Pathol Lab Med 1990 Mar;114(3):240-5.
4. Sullivan PT, Mucke H, Kadey SD, Fang CT, Williams AE. Evaluation of an indirect immunofluoresence assay for confirmation of human immunodeficiency virus type 1 antibody in U.S. blood donor sera. J Clin Micro 1992;30:2509--10.
5. Iltis JP, Patel NM, Lee SR, Barmat SL, Wallen WC. Comparative evaluation of an immunofluorescent antibody test, enzyme immunoassay, and western blot for the detection of HIV-1 antibody. Intervirology 1990;31(2-4):122-8.
6. Stramer SL, Sapan CV, Henderson SE, et al. Commercial HIV-immunofluorescence assay (IFA) in confirmatory algorithms for HIV-1/2 EIA. Meeting of the International Society of Blood Transfusion, Amsterdam, The Netherlands, 1994
7. Gallo D, George JR, Fitchen JH, Goldstein AS, Hindahl MS. Evaluation of a system using oral mucosal transudate for HIV-1 antibody screening and confirmatory testing. JAMA 1997 Jan 15;277(3):254-8.
8. Cordeiro ML, Turpin CS, McAdams SA. A comparative study of saliva and OraSure oral fluid. Ann N Y Acad Sci 1993 Sep 20;694:330-1.
9. Granade TC, Phillips SK, Parekh B, et al. Detection of antibodies to human immunodeficiency virus type 1 in oral fluids: a large-scale evaluation of immunoassay performance. Clin Diag Lab Immunol 1998;5:171--5.

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