Abstract Background The human immunodeficiency virus (HIV) consists of three main genes (gag, pol, and env) encoding structural proteins and enzymes. HIV diagnostic tests use various methods, combining screening and confirmatory assays to differentiate antigen and antibody positivity, essential for clinical interpretation of the infection stage. Screening can be done using chemiluminescent (CL) assays and other widely recognized methods capable of detecting antigens and antibodies. Among the most well-known confirmatory tests are Western blot (WB) and Rapid Immunoblot, also called dual-path migration immunochromatography (DPP – Dual-path Platform). This study aimed to compare the Western blot and dual-path migration immunochromatography techniques for confirming HIV diagnosis. Methods Both methods (WB and DPP) were compared using 71 serum samples with known results from 4th generation CL (Abbott) and WB (BioRad) methods. Based on the CL and WB data, the selected samples were grouped as follows: group I (non-reactive CL and non-reactive WB), group II (reactive CL and non-reactive WB), group III (reactive CL and reactive WB), and group IV (reactive and non-reactive CL, and indeterminate WB). All samples were processed by the DPP method using the Geenius™ platform (BioRad) according to the manufacturer’s recommendations. Focusing exclusively on the identification of HIV-1 infection, the CL method detects the p24 target or antibodies anti-HIV-1, while the WB method could detect the gag targets: p17, p24, p55, pol: p31, p51, p66, and env: gp41, gp120, and gp160. The DPP method is designed to identify the targets p24, p31, gp160, and gp41. Divergent results were confirmed using the RT-qPCR molecular method. The clinical outcome for data was analyzed according to the guidelines of the Technical Manual for HIV Infection Diagnosis in Adults and Children from the Brazilian Ministry of Health. Statistical analysis was performed using general agreement analysis and Cohen’s kappa index in EP Evaluator software version 14.2. Results The analysis was conducted considering the clinical outcome (positive, negative, or indeterminate) for both analytical scenarios: CL + WB and CL + DPP. Among the 71 samples evaluated, group I (N=7), group II (N=13), group III (N=49), and group IV (N=2), only two samples from group IV showed divergence between the WB and DPP results. One of them showed reactive CL, indeterminate WB, positive DPP, and detectable viral load by RT-qPCR assay. The second sample showed non-reactive CL, indeterminate WB and negative DPP, presenting undetectable viral load by RT-qPCR. A concordance of 97% and kappa = 93.9% were obtained when the results from both groups: CL + WB and CL + DPP were compared. The only divergences found were in those samples mentioned above. Conclusions Although there was no 100% agreement between the targets, no clinically significant difference was found between the WB and DPP methodologies, both combined with CL. The WB method is considered the gold standard for confirmatory HIV diagnosis, but the DPP method stands out for presenting speed, accessibility, and ease of result documentation due to automated reading. Therefore, the DPP method represents an attractive alternative for laboratories facing high demand and limited resources.
Feres et al. (Wed,) studied this question.