Indirect Immunofluorescence assay, Particle Agglutination and ELISA for the detection of HIV type 1

Screening of blood and blood products for human immunodeficiency virus (HIV) is routinely performed using the enzyme-linked immunosorbent assay (ELISA), and the results confirmed by western blot (WB). In an effort to identify alternative techniques, two locally prepared test kits were evaluated to determine the performance in comparison to commercial kits. These diagnostic kits were indirect immunofluorescence assay (IFA) and particle agglutination (PA). Blood obtained from 400 patients seeking treatment for sexually transmitted infections (STI) at a special treatment clinic in Nairobi were tested for ant-HIV-1 antibody by ELISA, PA and IFA. Out of 160 samples that were HIV antibody positive by PA, 10 (6.3%) were HIV antibody negative by IFA. Out of 240 samples that were HIV antibody negative by PA, 1(0.4%) was HIV antibody positive by IFA. The IFA results agreed with those of PA with a consistency of 97.3% (389 out of 400). The sensitivity and specificity of IFA was 99.3% and 95.9% respectively. Out of 170 samples that were HIV antibody positive by ELISA, 22 (5.8%) were HIV antibody negative by IFA. The IFA results agreed with those of ELISA with a consistency of 93.8% (375 out of 400). The sensitivity and specificity of IFA was 98.0% and 91.2% respectively. This study demonstrates that PA can be used for epidemiological studies and as a screening test in resource poor settings.