The handling of SARS-CoV-2 needs to be carried out in BSL3 (Biosafety level 3) laboratories that is expensive and not always available. This has urged the need for solutions that would allow to work with SARS-CoV-2 material in lower biosafety level laboratories. Therefore a collaboration was established with virologists from Tartu University (Prof. Merits and Dr. Varjak). This project proposes two approaches to provide solutions for this important obstacle. First, we aim to develop a complementation system (trans-replicases) based on SARS-CoV-2. Second, we will create stable cell lines enabling packaging of viral replicase into virion-like particles. The new tools developed during this project will allow the studies assessing the effect of emerging mutations for virus replication. In addition, our systems will offer the possibilities to test neutralizing antibodies against SARS-CoV-2 as well as other COVID-19 drug candidates. Therefore, the development of novel tools will support the tight collaboration with hospitals to study the effect of antibodies from patients.