Experience of the National HIV-AIDS Reference Center of Turkey, in the Transition to the New HIV Diagnostic Algorithm; Comparative Analysis of Line-Immunoassay Test and Bio-Rad Geenius™ HIV-1/2 Antibody Confirmatory Assay

Abstract

Shortly after the first detection of human immundeficiency virus (HIV) infection in USA in 1981, the number of cases have increased gradually from all around the world. Turkey's high capacity for tourism and the unique geographic location extending between Europe and Asia, provides convenience for the passage of individuals across the countries and sexually transmitted infections including HIV, as well. According to the official data of the Ministry of Health; there are 25809 HIV positive and 1958 AIDS cases as of November 30, 2020, after the epidemic started in 1985 in Turkey. Despite the decrease in the number of newly detected HIV cases as a result of serious measures taken for the transmission of infection worldwide, the increase in the number of cases still continues in our country. Shortening the reporting period and starting treatment as soon as possible in the diagnosis of infection is critical for the control of the epidemic. For this purpose, Centers for Disease Control and Prevention (CDC) published a new test algorithm in 2010, which suggested the use of the Geenius™ HIV ½ supplemental assay test instead of western blot tests, which have been used for many years to verify HIV screening test positivity. In this study, we aimed to report the experience of the National HIV-Acquiner Immundeficiency Syndrome(AIDS) and Viral Hepatitis Reference Laboratories of Turkey in the first year of transition to the new HIV algorithm and to evaluate the diagnostic performance of Geenius™ HIV ó and line immunassay (LIA) s. A total of 2090 anti-HIV positive patient sera sent to National HIV-AIDS and Viral Hepatitis Reference Laboratories of Turkey, Ankara for HIV confirmation were included in the study. All samples were retested with a fourth-generation enzyme linked immunosorbent assay (ELISA) test (VIDAS® HIV-1/2 Duo Ultra assay, BioMerieux, France) followed by the confirmatory tests; Geenius™ HIV 1/2 confirmatory assay (BioRad, Redmond, WA) and Line-immunoassay (INNO-LIA HIV ½ Score, Fujirebio, reverse transcriptase polymerase chain reaction (RT-PCR) (artus HI Virus-1 RT-PCR, Qiagen, Germany) test and in-house HIV-2 RNA and proviral DNA PCR. The sensitivity, specificity, and the agreement of the each assay were compared. Cohen's Kappa analysis was used for the evaluation of the agreement between the tests. According to the new algorithm which recommended Geenius™ test besides HIV-1 RNA test, 1707 (81.7%) HIV-1 positive samples were identified. Of these samples; 95.9% and 95.02% were identified as HIV-1 positive by GeeniusTM and INNO-LIA, respectively. However, 2.5% of the positive samples were negative with Geenius™ and 3.5% with INNO-LIA. One and a half percentage (1.5%) of these samples were detected with Geenius™ and 1.4% with INNO-LIA as indeterminant. When all the positive samples determined with ELISA were evaluated; it was detected that,1.3% were indeterminate by Geenius™ test and 2.4% by the INNO-LIA test. When the INNO-LIA test was regarded as the gold standard method; sensitivity, specificity, positive predictive and negative predictive values of the Geenius™ test were as follows; 99.7%, 96.1%, 98.9%, and 99.1%. The agreement between INNO-LIA and Geenius™ tests was found to be 98.95% (κ= 0.969; very good). When the Geenius™ and HIV-1 PCR tests were evaluated together for the confirmation; the sensitivities of Geenius™ and INNO-LIA tests were 99.8% and 98.3%, specificities were 89.8% and 85.3%, respectively. Slight positive bands were detected in the gp36 or gp140 bands, the HIV-2 specific envelope proteins, were detected in seven samples, However, the positivity disappeared after the dilution of the samples and it was accepted as false positivite reaction due to the absence of HIV-2 RNA and proviral DNA in these samples. In conclusion; we concluded that Geenius ™ and INNO-LIA tests have a perfect agreement in HIV diagnosis and due to the rapid and reliable results provided for the HIV test protocol, Geenius™ test can be used safely as an alternative to the immunoblot tests. HIV-1 RNA testing must be performed in all HIV confirmation centers in order to detect acute HIV cases in the fast and early period which are the main reason for the updates in HIV diagnosis.