Antiviral Activity of Benzavir-2 against Emerging Flaviviruses

Gwon, Yong-Dae; Strand, Mårten; Lindqvist, Richard; Nilsson, Emma; Saleeb, Michael; Elofsson, Mikael; Överby, Anna K.; Evander, Magnus

Flaviviruses share several common cellular factors in their infectious cycle that might specifically be targeted by benzavir-2 [1, 13, 44] . Our previous findings of the broad-spectrum antiviral activity for benzavir-2, inhibiting both DNA and RNA viruses, indicated that benzavir-2 could act on a host cell target(s). To elucidate where in the ZIKV infectious cycle this target(s) could be present, we performed a time-of-addition analysis. It revealed that benzavir-2 was most effective at the early time-points of the ZIKV infectious cycle and did not inhibit the binding or entry to the same extent. The most pronounced inhibition was found when benzavir-2 was present between 2 to 4 h after infection, which could indicate an effect on protein translation and protein maturation or early replication and assembly of replication vesicles in the ZIKV infectious cycle. Previously, we performed similar time-of-addition analysis of benzavir-2 on RVFV [19] . There, the most pronounced inhibition was also in the early time-points, more precise between 0 and 2 h after infection. This indicated that RVFV binding, endocytosis, primary transcription, or protein translation might be inhibited. The discrepancy of the timing of benzavir-2 activity between RVFV and ZIKV might be explained by the difference in kinetics between the two viruses. RVFV is known to have a more rapid infectious cycle compared to ZIKV, hence possibly utilizes the target(s) that benzavir-2 acts upon earlier [45, 46] . It also indicated that benzavir-2 was not interfering with general endocytosis and infection and might not inhibit membrane rearrangements needed in the ER for flavivirus replication as the negative stranded RNA virus RVFV does not share this feature [47] .