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AIDS. 1997 Dec;11(15):1815-22.

Field evaluation of alternative testing strategies for diagnosis and differentiation of HIV-1 and HIV-2 infections in an HIV-1 and HIV-2-prevalent area.

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  • 1Swedish Institute for Infectious Disease Control, Stockholm, Sweden.

Abstract

OBJECTIVE:

To identify cost-efficient alternative antibody testing strategies for screening, confirmation and discrimination of HIV-1 and HIV-2 infections, including rapid simple tests (RST) as well as enzyme-linked immunosorbent assays (ELISA), in a HIV-1 and HIV-2-prevalent area.

DESIGN:

Evaluation and comparison of anti-HIV-1/2 assays, adhering to the World Health Organization recommendations for alternative confirmatory strategies, using banked and prospectively collected specimens in Guinea-Bissau.

METHODS:

A total of 1110 consecutive sera from Bissau were included in the first phase, of which 198 (17.8%) were HIV-seropositive: 52 (4.7%) HIV-1, 120 (10.8%) HIV-2, and 26 (2.3%) HIV-1/HIV-2 dually reactive. In addition, 95 selected HIV-positive specimens were included for study of sensitivity and cross-reactivity between HIV-1 and HIV-2. Western blot was used as a gold standard for confirming the reactivity of the specimens. All specimens were screened by two assays. Enzygnost ELISA and Capillus RST. Samples reactive by any of the screening assays were further tested by assays chosen for confirmation: UBI ELISA, Innotest ELISA Recombigen RST, Multispot RST and Immunocomb RST. The confirmatory RST as well as Wellcozyme Recombinant HIV-1 ELISA, PEPTI-LAV and INNO-LIA were also used to study differentiation between HIV-1 and HIV-2.

RESULTS:

The sensitivities of all assays were 100%. The specificities of the screening assays at initial and repeated testing were 98.0 and 99.7%, respectively, for Enzygnost and 99.8 and 99.9%, respectively, for Capillus. The various combinations of two or three assays showed specificities of 99.2-100%. Several possible combinations of assays were identified where a specificity of 100% and good differentiation between HIV-1 and HIV-2 was achieved. Significant differences in the capacity to discriminate were noted; Immunocomb and PEPTI-LAV had the lowest number of dual-reactive results. A follow-up study of 1501 consecutive samples tested with the strategy chosen for routine use showed a sensitivity and specificity comparable to ELISA and Western blot.

CONCLUSION:

High sensitivities and specificities were obtained with various combinations of assays including RST as well as ELISA, and these procedures are well suited for field use in Africa. Serodiagnostic strategies for HIV can be based on RST alone and differentiation between HIV-1 and HIV-2 can be achieved as part of these strategies. Large differences in the capacity of individual assays to discriminate between HIV-1 and HIV-2 were observed.

PIP:

Western blot (WB) is the most widely used serological confirmatory test of ELISA and rapid simple tests (RST) to detect infection with HIV. WB tests, however, are expensive, time-consuming, and have technical disadvantages. The authors therefore conducted a study to identify cost-efficient alternative strategies for HIV-antibody screening, confirmation, and discrimination of HIV-1 and HIV-2 infections in a HIV-1 and HIV-2 prevalent area. 1110 consecutively collected blood sera from Guinea-Bissau were included in the first phase of the study, of which 198 (17.8%) were known to be HIV-seropositive; 52 with HIV-1, 120 with HIV-2, and 26 being HIV-1/HIV-2 dually reactive. 95 selected HIV-positive specimens were included for study of sensitivity and cross-reactivity between HIV-1 and HIV-2, with WB used to confirm specimen reactivity. All specimens were screened by Enzygnost ELISA and Capillus RST, with reactive samples further tested by the following assays for confirmation: UBI ELISA, Innotest ELISA, Recombigen RST, Multispot RST, and Immunocomb RST. The confirmatory RST, Wellcozyme Recombinant HIV-1 ELISA, PEPTI-LAV, and INNO-LIA were also used to study differentiation between HIV-1 and HIV-2. All assays were 100% sensitive. The specificities of the screening assays at initial and repeated testing were 98.0% and 99.7%, respectively, for Enzygnost and 99.8% and 99.9%, respectively, for Capillus. Various combinations of 2-3 assays yielded specificities of 99.2-100%. Screening with Enzygnost ELISA and confirmation and differentiation between HIV-1 and HIV-2 with Capillus RST and Multispot RST was adopted for routine use at Guinea-Bissau's National Public Health Laboratory. A field trial of the approach conducted in 1996 involving 1501 sera found a sensitivity and specificity comparable to ELISA and WB.

PMID:
9412699
[PubMed - indexed for MEDLINE]
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