Journal of Microbial Systematics and Biotechnology (2020) (2) (2): pp.1-11 ISSN (Online): 2685-4430 Copyright© 2019, Indonesian Culture Collection, LIPI 1 Received July 15, 2020 / Accepted August 25, 2020 / Published online December 31, 2020 DOI: 10.37604/jmsb.v2i1.42 Corresponding Author: afibriani@sith.itb.ac.id Development of a dimer-based screening system for dimerization inhibitor of HIV-1 protease I Dewa Agung Panji Dwipayana 1 , Yana Maolana Syah 2 , Reza Aditama 2 , Feraliana 1 , Azzania Fibriani* 1 1 Biology Department, School of Life Science and Technology, Bandung Institute of Technology (ITB), Ganesha street 10, 40132, Bandung, Jawa Barat-Indonesia 2 Chemistry Department, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology (ITB), Ganesha street 10, 40132, Bandung, Jawa Barat-Indonesia Dwipayana IDAP, Syah YM, Aditama R, Feraliana, Fibriani A. 2020. Development of a dimer-based screening system for dimerization inhibitor of HIV-1 protease. Journal of Microbial Systematics and Biotechnology 2(2),1-11 Abstract An in vitro dimer-based screening system (DBSS) for selecting new HIV-1 protease dimerization inhibitor candidates from natural compounds had been established. This system utilizes a fusion between HIV-1 protease and dimer binding domain of AraC protein (proteaseHIV1-AraCDBD) where fluorescence signal will be emitted in the presence of HIV- 1 protease inhibitor. However, this screening system had not been evaluated. Therefore, this study was aimed to evaluate it in recombinant Escherichia coli culture. The expression of proteaseHIV1-AraCDBD fusion gene was observed for 18 hours. Its crude lysate isolation was done once every 3 hours and analyzed using SDS PAGE. To test the DBSS, darunavir was used as positive control, and Nigella sativa extract (JH3) was used as the test compound. The results of SDS PAGE analysis on crude lysates presented a ~24.2 kDa band, which was the predicted size of the proteaseHIV1-AraCDBD fusion protein based on its amino acid sequence. The growth curve and protein expression profiles revealed that the 15 hours was the optimum culture age to be used in the screening system. Darunavir testing in DBSS showed an increase in fluorescence signal compared to the negative control. The same increase in fluorescence signal was also obtained from the JH3 compound test. In conclusion, DBSS could be used as an assay to screen for new HIV-1 protease inhibitors, and the JH3 compound demonstrated the ability to inhibit HIV-1 protease dimerization. Keywords: dimer based screening system, HIV, protease Introduction Today, HIV is still a global problem, especially in developing countries. In 2019, there were around 38 million people living with HIV, 1.7 million new infections, and 690 thousand AIDS-related deaths in the world (UNAIDS, 2020). Even with this urgency, the coverage of antiretroviral therapy (ART) is still low. For example, it only covers 17% of all adult HIV patients (aged 15 years and over) in Indonesia (UNAIDS, 2019). The antiretroviral therapy (ART) itself, both first-line and second-line therapies, are constrained by the high level of virus mutations that enables the virus to evolve resistance quickly (Cuevas et al. 2015). One of the drugs used in second-line therapy is darunavir,