Evaluation of HIV Indeterminate Confirmatory Tests\' Results in Blood Donors in Northeast of Iran

Background and Aims: Human Immunodeficiency virus (HIV) is spreading rapidly among the people worldwide. Infection with this virus leads to immune suppression and finally acquired immune deficiency syndrome. Early HIV detection is dependent on antibody screening against virus by Enzyme Linked Immunosorbent Assay (ELISA). Some confirmatory tests such as Western Blot and Recombinant Immunobloting Assay (RIBA) are used to verify viral infection. Many of the confirmatory test results are indeterminate. The aim of this study was to compare the frequency and patterns of indeterminate results of confirmatory tests in two groups blood donors and patients with high risk behaviors in the northeast of Iran. Materials and methods: It is a cross-sectional study from October 2009 to March 2014, a total number of 1055 serum samples with previous positive HIV ElISA test history were tested in our laboratory, Some by RIBA and some by western blot method. Results: Most of the indeterminate results belonged to blood donors and Western Blot analysis. The most reacting band was P24 in both methods and groups. Conclusions: RIBA assay is more sensitive and reliable than western Blot but it’s necessary to use other supplementary tests with less indistinctive results. It’s necessary to pay attention to HIV glycoprotein reactivity in some methods too.