Inhibition of nidovirus RTC activity by Zn²⁺ can be reversed by chelation.

(A) Schematic representation of the in vitro assays with isolated RTCs, which were initiated with [α-³²P]CTP, either in the absence (sample 1 and 2) or presence of 500 µM Zn²⁺. After a 30-min incubation at 30°C, both the untreated and Zn²⁺-treated samples were split into two aliquots, and 1 mM of the Zn²⁺ chelator MgEDTA was added to samples 2 and 4. All reactions were subsequently incubated for another 70 min before termination. (B) Analysis of RNA products synthesized in assays with EAV RTCs. Numbers above the lanes refer to the sample numbers described under (A). (C) In vitro activity assay with SARS-CoV RTCs.