HIV-1/2 differentiation in a South African public laboratory

Background

The human immunodeficiency virus type-2 (HIV-2) prevalence in South Africa (SA) is unknown, however, sporadic cases have been reported. Human immunodeficiency virus -1 and 2 differentiation is not part of most South African public laboratories’ testing algorithm. Human immunodeficiency virus -2 diagnosis using serology assays may be complicated by HIV-1 and HIV-2 antibody cross-reactivity.

Objectives

To determine the proportion of HIV-2 infections in specimens that tested HIV-1/2 positive at a public laboratory in Tshwane.

Method

A total of 480 specimens that were previously tested with fourth generation ELISA platforms (Modular E170 [Roche, Switzerland] and Architect i2000 [Abbott, Germany]) were randomly selected. Human immunodeficiency virus -1 and 2 antibody differentiation testing was carried out using the Multispot HIV-1/2 rapid assay (Bio-Rad Laboratories, USA). An in-house nested HIV-2 PCR assay targeting the 5′-long terminal repeats (5′-LTR) region was evaluated and used as a confirmatory test.

Results

The study tested 480 HIV-1/2 seropositive patients and their mean age was 36.7 years (range 3–82 years). Of the 480 patients, 292 (60.8%) were female, 182 (37.9%) were male and 6 (1.3%) were not specified. Human immunodeficiency virus differentiation results were as follows: 466 (97.1%) were positive for only HIV-1 antibodies, 11 (2.3%) [95%CI: (0.98%; 3.74%)] were positive for both HIV-1 and HIV-2 antibodies, 3 (0.6%) were negative for both antibodies and none were positive for only HIV-2 antibodies. Of the 11 specimens with both HIV-1 and HIV-2 antibodies, seven had sufficient volume for confirmatory testing and were all negative on the in-house HIV-2 PCR assay.

Conclusion

The multispot HIV-1/2 rapid assay demonstrated cross-reactivity between HIV-1 and HIV-2 antibodies. Human immunodeficiency virus -2 infections were not detected.

Analytical performances of simultaneous detection of HIV-1, HIV-2 and hepatitis C- specific antibodies and hepatitis B surface antigen (HBsAg) by multiplex immunochromatographic rapid test with serum samples: A cross-sectional study

BACKGROUND

The HIV/HCV/HBsAg Triplex consists in manually performed, visually interpreted, lateral flow, immunochromatographic rapid diagnostic test simultaneously detecting in 15min human immunodeficiency virus (HIV)-1 and HIV-2 and hepatitis C virus (HCV)- specific antibodies (Ab) (IgG and IgM) and hepatitis B virus (HBV) surface antigen (HBsAg) in serum, plasma and whole blood.

METHODS

A hospital-based cross-sectional study was conducted on a prospective panel of serum samples from adult inpatients included from routine analysis irrespectively of age and sex, including 250 sera positive for HIV-1-specific Ab, 250 for HCV-specific Ab, 250 for HBsAg and 250 sera negative for HIV- and HCV- Ab and HBsAg, and from 110 HIV-2-infected patients living in Ivory Coast, according to the results obtained by the reference chemiluminiscent microparticle immunoassay (CMIA) Abbott Architect i2000SR analyzer (Abbott Diagnostic, Chicago, IL, USA). Among HCV-seropositive sera, 187 were positive for HCV RNA (chronic infection), whereas 63 were negative (resolved infection), respectively. Serum samples were further tested blindly by HIV/HCV/HBsAg Triplex according to manufacturers' recommendations.

RESULTS

HIV/HCV/HBsAg Triplex showed very high sensitivity and specificity, as well as excellent concordance with CMIA Abbott results, as shown in the Table. Lower sensitivity was observed only in individuals who had cleared their HCV infection (presence of HCV-specific Ab in absence of HCV RNA). The mean lower limit of HBsAg detection was 2.38±0.63 IU/ml. Erythrocytes-spiked serum samples gave similar results than serum samples.

CONCLUSIONS

Advantages of HIV/HCV/HBsAg Triplex for HIV-1, HIV-2, HCV and HBV include the requirement for less overall specimen volume, fewer finger-sticks if capillary whole blood is used, cost savings through lower cost per virus tested, improved patient flow with results for multiple viruses available at the same time, overall service delivery efficiencies with less time required per infected patient; and patient benefits from fewer visits and lower cost associated with each clinic attendance. The screening of chronic HIV, HCV and HBV by multiplex HIV-1/HIV-2/HCV/HBsAg Triplex may improve the "cascade of screening" and quite possibly linkage-to-care with reduced cost.