Fig. 6

In Vivo evaluation of YT-DRI against respiratory viral infections. A Experimental design for HPIV3 infection. 6–8-week nude BALB/c mice were intranasally infected with 2 × 10⁶ PFU of HPIV3 per mouse and treated with PBS or YT-DRI (2 mg/kg) via intraperitoneal injection, administered once per day from Day 0 to Day 2. Mouse body weight was monitored daily for 4 days. B Body weight changes in HPIV3 infection. Graphical representation illustrating the body weight changes of mice in different groups over the course of the experiment. C and D Viral RNA copies, the infectious titers and the lung histopathology. At Day 3, animals were euthanized, lung tissues were collected, homogenized. Viral RNA level was measured with quantitative RT-qPCR and virion load was titered by TCID₅₀ assay (C). Histopathology of lung tissues was assessed through hematoxylin and eosin (H&E) staining (D). E Experimental design for RSV infection. 6–8-week nude BALB/c mice were intranasally challenged with 3 × 10⁶ PFU of RSV and treated with PBS or YT-DRI (2 mg/kg) via intraperitoneal injection. Treatment occurred once per day from Day 0 to Day 3. Daily monitoring of body weight was conducted for 5 days. F Body weight changes in RSV infection. Graphical representation illustrating the body weight changes of mice in different groups over the course of the experiment. G and H Viral RNA copies, the infectious titers and the lung histopathology in RSV infection. At Day 4, animals were euthanized, lung tissues were collected, homogenized, and supernatants were tested by quantitative RT-qPCR and TCID₅₀ (G). Histopathology of lung tissues was assessed through H&E staining (H). I Experimental design for WSN virus infection. 6–8-week BALB/c mice were intranasally challenged with 4,000 PFU of WSN virus and treated with PBS, Oseltamivir (20 mg/kg), or YT-DRI (2 mg/kg) via intraperitoneal injection. Treatment occurred once per day from Day 0 to Day 4. Daily monitoring of body weight and survival was conducted for 14 days or until body weights lost more than 25%. J Body Weight Changes in WSN Virus Infection. Graphical representation illustrating the body weight changes of mice in different groups over the course of the experiment. K Mouse survival was observed and recorded daily until 14 dpi. L and M In addition, another three groups of mice were administrated with the same methods except that these mice were sacrificed at Day 4 to determine the virus load via RT-qPCR (L) and the lung histopathology (M). All experiments were independently repeated at least twice with reproducible results. Statistical significance (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001 ) was determined by two-sided unpaired t-test for statistical significance and log-rank test for survival curves. Data are presented as means ± SEM