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|Year : 2014 | Volume
| Issue : 3 | Page : 344--345
False positive human immunodeficiency virus antibody test in chronic hepatitis B patient
SU Munshi, A Anwar, S Tabassum
Department of Virology, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh
S U Munshi
Department of Virology, Bangabandhu Sheikh Mujib Medical University, Dhaka
|How to cite this article:|
Munshi S U, Anwar A, Tabassum S. False positive human immunodeficiency virus antibody test in chronic hepatitis B patient.Indian J Med Microbiol 2014;32:344-345
|How to cite this URL:|
Munshi S U, Anwar A, Tabassum S. False positive human immunodeficiency virus antibody test in chronic hepatitis B patient. Indian J Med Microbiol [serial online] 2014 [cited 2019 Oct 18 ];32:344-345
Available from: http://www.ijmm.org/text.asp?2014/32/3/344/136599
Detection of specific antibodies against human immunodeficiency virus (HIV) is the primary means of routine laboratory diagnosis of HIV infection. Rapid tests or enzyme linked immunosorbent assays (ELISA) are the basic serological methods used to screen anti-HIV antibodies. In addition to these tests, new "4 th -generation" HIV tests either in ELISA or chemiluminescent microparticle-based immunoassay (CMIA) format are introduced to detect both HIV p24 antigen and antibody in a single immunoassay to shorten the diagnostic window.  Currently, these assays are widely used for routine laboratory diagnosis of HIV in numerous laboratories throughout the world. As the specificity of these screening tests is limited, western blot (WB) or line immunoblot assay (LIA) test is used as a confirmatory test for all anti-HIV reactive serum in the screening test. Recently, "4 th -generation" CMIA HIV test has been introduced in Bangladesh for routine diagnosis of HIV infection. According to existing published literatures; this is the first report of false anti-HIV positive test result in a chronic hepatitis B virus (HBV) patient. The aim of our report is to describe a case of false positive HIV test result detected by CMIA and discuss how other laboratory tests may help to diagnose such cases correctly.
Patient was a 63-year-old male, admitted in a Private Hospital in Dhaka City, Bangladesh for elective coronary angiogram (CAG). He had the complaints of shortness of breath, mild chest pain and fatigue, which was relieved by taking rest. Electrocardiography and echocardiography with colour Doppler report revealed some abnormalities and exercise tolerance test was also positive. He was advised to undergo CAG and was asked to take some routine investigations. On investigations, the patient was found non-diabetic, mildly anaemic (8.1 g/dl) and positive for both hepatitis B surface antigen (HBsAg) and anti-HIV antibody. On further testing his other HBV markers i.e. hepatitis B e antigen (HBeAg), anti-HBc immunoglobulin M (IgM), anti-HBsAg and HBV-deoxyribonucleic acid were found to be negative except anti-HBc (total) and anti-HBeAg, which indicates that this patient was in asymptomatic chronic HBV carrier stage. As the patient was positive for HIV antibody, he was referred to the HIV referral centre for confirmation and further management. The LIA (INNO-LIA™ HIV I/II Score/Innogenetics, Belgium) was performed at the Department as HIV confirmatory test and was non-reactive against all the HIV antigens used in this assay. Particle Agglutination Test (Capillus, HIV-1/HIV-2) and a rapid immunochromatographic test (ICT) (Uni-gold; Trinity Biotech, Ireland) were also negative. On history, the patient denied use of intravenous drug or any high-risk sexual behaviour and had no history of receiving any blood or blood products. His wife and two sons were negative for anti-HIV antibody. On checking the previous reports of the patient, it was observed that the HIV antibody test was performed at a private hospital with a 4 th generation CMIA (Abbott Architect, ci 8200). As per the assay protocol developed by the manufacturers, the assay result is presented as ratios of specimen signals to the cut-off values (S/CO), where an S/CO ratio ≥ 1.00 is considered reactive. As S/CO of that sample under study was 6.2, it was reported as positive for HIV antibody. Similar type of false positive HIV antibody test results in 4 th generation of CMIA using architect HIV Ag/Ab Combo has been reported previously in diagnosis of HIV where they have suggested using the S/CO of 6.6 to avoid such discrepancy.  Though these assays have been shown to reduce the HIV window period by 4-5 days compared with 3 rd -generation HIV-Ab detection assays,  discrepant results have been published on their specificities in population groups with low HIV prevalence.  Since some chronic infections may cause false positive HIV results, to rule out such cause, the patient was tested for antibody against hepatitis C virus (SD BIOLINE HCV Rapid, Korea), Filaria (Filariasis immunoglobulin G/IgM Combo Rapid Test, CTK Biotech, Inc., San Diego, CA), Toxoplasma gondii, Rubella virus, Cytomegalovirus, Herpes Simplex Virus-1 and 2 (HSV-1 and 2) (Toxo/Rubella/CMV/HSV1/2 IgM antibodies Combo Rapid Test; Abon Biopharma, P.R. China) and tested for antigen of visceral leishmaniasis (Kalazar Detect™ Test, InBios International, Inc., Seattle, WA.) M. Tuberculosis (SD BIOLINE, TB Ag MPT64 Rapid, Korea) by ICT method. The serum was tested for rheumatoid arthritis (RA) factor by latex agglutination tests (Prestige Diagnostics, United Kingdom) to check whether the patient was suffering from RA. All tests were negative. The only findings that related to the false positivity of the HIV test result could be that the patient was suffering from chronic HBV infection. There are reports of false positive result after HBV vaccination  or treatment with hepatitis B immune globulin;  therefore it may be assumed that false positivity of this case under study may be due to chronic HBV infection.
It is suggested that, laboratories in low prevalent countries like Bangladesh using 4 th generation CMIA should interpret their result cautiously. In addition, this types of discrepant result reemphasis the need of confirming HIV positive test result by WB or LIA.
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