Performances of fourth generation HIV antigen/antibody assays on filter paper for detection of early HIV infections

Abstract

BackgroundPoint-of-care testing and diagnosis of HIV acute infections play important roles in preventing transmission, but HIV rapid diagnosis tests have poor capacity to detect early infections. Filter paper can be used for capillary blood collection and HIV testing using 4th generation immunoassays. ObjectivesAntigen/antibody combined immunoassays were evaluated for their capacity to identify early HIV infections using filter paper in comparison with rapid test. Study designThirty nine serum samples collected from HIV seroconverters were spotted onto filter paper and tested by the Roche Elecsys® HIV Combi PT test and the DiaSorin Liaison XL Murex HIV Ab/Ag assay. ResultsFourth generation immunoassays identified 34 out of 39 HIV early infections using dried serum spot, whereas the Determine™ HIV-1/2 rapid test detected 24 out of 39 HIV positive serum (87.2% vs 61.5% respectively, p=0.009). p24 antigen was detected by the Liaison XL in 19 dried serum samples (48.7%). In the group characterized by a negative western blot, 7 out of 8 (87.5%) and 6 out of 8 (75.0%) samples were found positive for HIV using the Elecsys and the Liaison XL, respectively. None of these eight samples classified in this group of early acute infections were found positive by the rapid test. ConclusionFourth generation Ag/Ab immunoassays performed on dried serum spot had good performance for HIV testing during the early phases of HIV infection. This method may be useful to detect HIV early infections in hard-to-reach populations and individuals living in remote areas before rapid tests become positive.