Replication of plus-strand RNA viruses proceeds in cytoplasmic replication organelles (ROs), corresponding to remodeled intracellular membranes to which the viral replicase is attached. During the last funding period, we made important progress in identifying relevant viral and cellular factors in flavivirus (dengue virus, DENV; Zika virus, ZIKV) RO biogenesis and functionality. We identified endoplasmic reticulum (ER) proteins that are essential for flaviviral RO formation, replication and virus particle assembly and established a system supporting DENV RO biogenesis independent from viral replication. Moreover, we deciphered a hitherto unknown function of NS1 in DENV RO formation. Based on these data we established an integrated mathematical model of DENV replication at single-cell resolution and identified a sensitive step in the DENV replication cycle that turned out to be well suited for antiviral therapy.
In the light of the COVID-19 pandemic, we began to study RO biogenesis induced by SARS-CoV-2. By employing multiple imaging approaches, we determined cellular alterations induced by SARS-CoV-2 in infected cells and gained first knowledge on involved viral and host cell factors, revealing striking similarities to hepatitis C virus (HCV) RO formation.
Moreover, we were able to characterize the structure of the SARS-CoV-2 particle, including the structures and distributions of the spike proteins on intact virions.