In situ observation of a buoys/moorings array and a model simulation were used to study the modulation of upper ocean thermal structure by Typhoon Kalmaegi in September 2014. The inertial period signals were significant after forcing of Kalmaegi, but they did not account for the net heat change. Removing the inertial period signals showed that the net thermal response biased to the right of Kalmaegi's track. Vertical mixing caused surface cooling with an inverted-cone structure and subsurface warming with a double-wing structure. Net upwelling converted the left wing of the subsurface warming to cooling, while net downwelling warmed the upper ocean in front and on both sides of the net upwelling zone. Horizontal advection was not as important as vertical mixing and vertical advection in modulating the thermal structure but contributed to the net outward advection of thermal anomaly in the mixed layer during the forced stage and also in the net along-track recovery of subsurface anomaly during the relaxation stage. In general, horizontal and vertical advection modulated thermal anomalies in the upper ocean across a broader horizontal range and into the deeper ocean compared with the effect of vertical mixing. Our results indicate the need to consider both mixing and advection (rather than only mixing) when studying the effects of tropical cyclones on local ocean heat uptake and global ocean heat transport.Plain Language Summary Tropical cyclones are strong natural phenomena occurring on the ocean. Tropical cyclones intensify ocean mixing and deepen surface mixed layer (defined as a layer with uniform temperature). In so doing, it creates cold anomaly at the surface and warm anomaly in the subsurface, which can be considered as a downward pump of warm water (heat pump effect). The subsurface warming cannot be directly recovered by air-sea surface interaction; it may stay in the ocean and contribute to global ocean heat transport and then influence the climate system. This work studied the upper ocean thermal response to a tropical cyclone (typhoon Kalmaegi) in September 2014. The results show that besides the surface cooling and subsurface warming, typhoon Kalmaegi also cools the subsurface by an upwelling process. Upwelling brings up cold water, and part of subsurface warming is modulated outside of the main response area and into the deeper ocean (cold suction effect). This work indicates that the upper ocean thermal response to a tropical cyclone is more complicated than only heat pump effect. Cold suction effect needs to be taken into consideration when estimating the tropical cyclones' contribution to global ocean heat budget.

Severe fever with thrombocytopenia syndrome (SFTS) virus (SFTSV) is an emerging tick-borne virus with high fatality and an expanding endemic. Currently, effective anti-SFTSV intervention remains unavailable. Favipiravir (T-705) was recently reported to show in vitro and in animal model antiviral efficacy against SFTSV. Here, we conducted a single-blind, randomized controlled trial to assess the efficacy and safety of T-705 in treating SFTS (Chinese Clinical Trial Registry website, number ChiCTR1900023350). From May to August 2018, laboratory-confirmed SFTS patients were recruited from a designated hospital and randomly assigned to receive oral T-705 in combination with supportive care or supportive care only. Fatal outcome occurred in 9.5% (7/74) of T-705 treated patients and 18.3% (13/71) of controls (odds ratio, 0.466, 95% CI, 0.174–1.247). Cox regression showed a significant reduction in case fatality rate (CFR) with an adjusted hazard ratio of 0.366 (95% CI, 0.142–0.944). Among the low-viral load subgroup (RT-PCR cycle threshold ≥26), T-705 treatment significantly reduced CFR from 11.5 to 1.6% (P = 0.029), while no between-arm difference was observed in the high-viral load subgroup (RT-PCR cycle threshold <26). The T-705-treated group showed shorter viral clearance, lower incidence of hemorrhagic signs, and faster recovery of laboratory abnormities compared with the controls. The in vitro and animal experiments demonstrated that the antiviral efficacies of T-705 were proportionally induced by SFTSV mutation rates, particularly from two transition mutation types. The mutation analyses on T-705-treated serum samples disclosed a partially consistent mutagenesis pattern as those of the in vitro or animal experiments in reducing the SFTSV viral loads, further supporting the anti-SFTSV effect of T-705, especially for the low-viral loads.

Since 2015, 69 countries and territories have reported evidence of vector-borne Zika virus (ZIKV) transmission. Currently, there are no effective licensed vaccines or drugs available for the treatment or prevention of ZIKV infection. We tested a series of compounds for their ability to inhibit ZIKV replication in cell culture. The compounds in T-705 (favipiravir) and T-1105 were found to have antiviral activity, suggesting that these compounds are promising candidates for further development as specific antiviral drugs against ZIKV.Electronic supplementary materialThe online version of this article (doi:10.1007/s00705-017-3436-8) contains supplementary material, which is available to authorized users.