Attenuation of neurovirulence of chikungunya virus by a single amino acid mutation in viral E2 envelope protein.

BACKGROUND: Chikungunya virus (CHIKV) has reemerged as a major public health concern, causing chikungunya fever with increasing cases and neurological complications. METHODS: In the present study, we investigated a low-passage human isolate of the East/ Central/South African (ECSA) lineage of CHIKV strain LK(EH)CH6708, which exhibited a mix of small and large viral plaques. The small and large plaque variants were isolated and designated as CHIKV-SP and CHIKV-BP, respectively. CHIKV-SP and CHIKV-BP were characterized in vitro and in vivo to compare their virus production and virulence. Additionally, whole viral genome analysis and reverse genetics were employed to identify genomic virulence factors. RESULTS: CHIKV-SP demonstrated lower virus production in mammalian cells and attenuated virulence in a murine model. On the other hand, CHIKV-BP induced higher pro-inflammatory cytokine levels, compromised the integrity of the blood-brain barrier, and led to astrocyte infection in mouse brains. Furthermore, the CHIKV-SP variant had limited transmission potential in Aedes albopictus mosquitoes, likely due to restricted dissemination. Whole viral genome analysis revealed multiple genetic mutations in the CHIKV-SP variant, including a Glycine (G) to Arginine (R) mutation at position 55 in the viral E2 glycoprotein. Reverse genetics experiments confirmed that the E2-G55R mutation alone was sufficient to reduce virus production in vitro and virulence in mice. CONCLUSIONS: These findings highlight the attenuating effects of the E2-G55R mutation on CHIKV pathogenicity and neurovirulence and emphasize the importance of monitoring this mutation in natural infections.

Antiviral Activity of Catechin against Dengue Virus Infection.

Dengue virus (DENV) is the cause of dengue fever, infecting 390 million people worldwide per year. It is transmitted to humans through the bites of mosquitoes and could potentially develop severe symptoms. In spite of the rising social and economic impact inflicted by the disease on the global population, a conspicuous lack of efficacious therapeutics against DENV still persists. In this study, catechin, a natural polyphenol compound, was evaluated as a DENV infection inhibitor in vitro. Through time-course studies, catechin was shown to inhibit a post-entry stage of the DENV replication cycle. Further investigation revealed its role in affecting viral protein translation. Catechin inhibited the replication of all four DENV serotypes and chikungunya virus (CHIKV). Together, these results demonstrate the ability of catechin to inhibit DENV replication, hinting at its potential to be used as a starting scaffold for further development of antivirals against DENV infection.

Relation of Blood Arsenic Concentration with Effect and Safety of Arsenic-Containing Qinghuang Powder () in Patients with Myelodysplastic Syndrome.

OBJECTIVE: To investigate the relation of blood arsenic concentration (BAC) with clinical effect and safety of arsenic-containing Qinghuang Powder (, QHP) in patients with myelodysplastic syndrome (MDS). METHODS: Totally 163 patients with MDS were orally treated with QHP for 2 courses of treatment, 3 months as 1 course. The BACs of patients were detected by atomic fluorescence spectrophotometry at 1, 3, and 6 months during the treatment, and the effective rate, hematological improvement and safety in patients after treatment with QHP were analyzed. RESULTS: After 2 courses of treatment, the total effective rate was 89.6% (146/163), with 31.3% (51/163) of hematological improvement and 58.3% (95/163) of stable disease. The hemoglobin increased from 73.48 ± 19.30 g/L to 80.39 ± 26.56 g/L (P<0.05), the absolute neutrophil count increased from 0.81 ± 0.48 × 109/L to 1.08 ± 0.62 × 109/L (P<0.05), and no significant changes were observed in platelet counts (P>0.05). Among 46 patients previously depended on blood transfusion, 28.3% (13/46) completely got rid of blood transfusion and 21.7% (10/46) reduced the volume of blood transfusion by more than 50% after treatment. The BACs were significantly increased in patients treated for 1 month with 32.17 ± 18.04 µ g/L (P<0.05), 3 months with 33.56 ± 15.28 µ g/L (P<0.05), and 6 months with 36.78 ± 11.92 µ g/L (P<0.05), respectively, as compared with those before treatment (4.08 ± 2.11 µ g/L). There were no significant differences of BACs among the patients treated for 1, 3 and 6 months (P>0.05). The adverse reactions of digestive tract during the treatment were mild abdominal pain and diarrhea in 14 cases (8.6%), and no patients discontinued the treatment. The BACs of patients with gastrointestinal adverse reactions were significantly lower than those without gastrointestinal adverse reactions (22.39 ± 10.38 vs. 37.89 ± 11.84, µ g/L, P<0.05). The BACs of patients with clinical effect were significantly higher than those failed to treatment (40.41 ± 11.69 vs. 23.84 ± 12.03, µ g/L, P<0.05). CONCLUSION: QHP was effective and safe in the treatment of patients with MDS and the effect was associated with BACs of patients.

Paeoniflorin Promotes Angiogenesis in A Vascular Insufficiency Model of Zebrafish in vivo and in Human Umbilical Vein Endothelial Cells in vitro.

OBJECTIVE: To investigate the pro-angiogenic effects of paeoniflorin (PF) in a vascular insufficiency model of zebrafish and in human umbilical vein endothelial cells (HUVECs). METHODS: In vivo, the pro-angiogenic effects of PF were tested in a vascular insufficiency model in the Tg(fli-1:EGFP)y1 transgenic zebrafish. The 24 h post fertilization (hpf) embryos were pretreated with vascular endothelial growth factor (VEGF) receptor tyrosine kinase inhibitor II (VRI) for 3 h to establish the vascular insufficiency model and then post-treated with PF for 24 h. The formation of intersegmental vessels (ISVs) was observed with a fluorescence microscope. The mRNA expression of fms-like tyrosine kinase-1 (flt-1), kinase insert domain receptor (kdr), kinase insert domain receptor like (kdrl) and von Willebrand factor (vWF) were analyzed by real-time polymerase chain reaction (PCR). In vitro, the pro-angiogenic effects of PF were observed in HUVECs in which cell proliferation, migration and tube formation were assessed. RESULTS: PF (6.25-100 µmol/L) could rescue VRI-induced blood vessel loss in zebrafish and PF (25-100 µmol/L), thereby restoring the mRNA expressions of flt-1, kdr, kdrl and vWF, which were down-regulated by VRI treatment. In addition, PF (0.001-0.03 µmol/L) could promote the proliferation of HUVECs while PF stimulated HUVECs migration at 1.0-10 µmol/L and tube formation at 0.3 µmol/L. CONCLUSION: PF could promote angiogenesis in a vascular insufficiency model of zebrafish in vivo and in HUVECs in vitro.

Optimization and Standardization of the Immunodeficient Mouse Model for Assessing Fat Grafting Outcomes.

BACKGROUND: Animal models are often used to assess interventions that might improve fat grafting outcomes; however, there is great variability in the models. The authors sought to determine the predictive value of the immunocompromised mouse model for fat grafting so that experiments could be standardized and optimized. METHODS: Human lipoaspirate injections at different volumes and time points were assessed in a nude mouse model and compared with control injections of nonviable fat. Volume retention and explant histologic score were compared. In a separate study, interanimal reproducibility was determined by implanting a highly consistent hydrogel and measuring variability in volume retention. RESULTS: Injection volume significantly affects adipose resorption kinetics at 6 and 12 weeks. Masson trichrome staining revealed that macrophages were unable to infiltrate large (1 ml) grafts, and oil cysts were not absorbed by 18 weeks, which interfered with interpretation of volume retention data. Nonviable tissue was resorbed when grafts were 0.3 ml, and quantification of graft histologic viability correlated well with graft retention at all study time points. Interanimal variability was measured to be 8.44 percent of the mean retention volume for small graft volumes. CONCLUSIONS: Human fat graft retention in the immunodeficient mouse correlates with graft viability in small, 0.3-ml-volume grafts. However, centralized oil cysts in nonviable 1.0-ml grafts were not resorbed by 18 weeks and thus volume measurements were confounded and not significantly different from viable samples. In addition, tissue injury scores increased in initially healthy fat grafts at 18 weeks, possibly because of a delayed immune reaction.