Development of an Isothermal Point-of-care Genetic Rapid Test for the Detection of the HLA-B*57:01 Allele, a Predictor for Hypersensitivity Reaction Caused by Abacavir, for Stratifying Patients for Antiretroviral Abacavir HIV Therapy

Abstract

Background: Abacavir is used in the treatment of HIV-infected patients. A hypersensitive reaction (HSR) occurs in about 5-8% of patients treated with Abacavir. The HLA-B*57:01 allele is a valuable predictor for HSR and its screening is mandatory prior to treatment with Abacavir. Objective: Current screening methods require considerable investments for equipment. In order to lower the required investments and enable physician practices to perform the screening in a point-of-care (PoC) setting, our objective was to develop a novel isothermal genetic rapid test that requires a minimal setup cost, does not require specific training and thus is suitable for a physician practice setting. Methods: We developed an isothermal recombinase polymerase amplification (RPA) for the specific amplification of the HLA-B*57:01 allele using allele-specific primers coupled to Biotin. Primers specific for human lactase gene, coupled to Digoxigenin, were used as an internal amplification control (IAC). Lateral flow dipstick provided rapid and accurate detection of HLA-B*57:01 allele and IAC via the respective antibodies sprayed on the strips surface. Results: The reference method identified the HLA-B*57:01 allele in the reference sample, in 2 out of 28 buccal swab samples and in 2 out of 13 blood samples. The initial isothermal RPA resulted in unspecific amplification of the HLA-B*57:01 allele. By further optimization steps the specific amplification of the allele and the detection on lateral flow dipstick was observed. The newly developed isothermal RPA was validated. Conclusion: The method developed fulfils the requirements for a genetically based PoC screening system for the HLA-B*57:01 variant, requiring a minimal investment for a heating block and a pipette.