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ObjectivesWe aimed to evaluate the relationships between climate variability, animal reservoirs and scrub typhus incidence in Southern China.MethodsWe obtained data on scrub typhus cases in Guangzhou every month from 2006 to 2014 from the Chinese communicable disease network. Time-series Poisson regression models and distributed lag nonlinear models (DLNM) were used to evaluate the relationship between risk factors and scrub typhus.ResultsWavelet analysis found the incidence of scrub typhus cycled with a period of approximately 8–12 months and long-term trends with a period of approximately 24–36 months. The DLNM model shows that relative humidity, rainfall, DTR, MEI and rodent density were associated with the incidence of scrub typhus.ConclusionsOur findings suggest that the incidence scrub typhus has two main temporal cycles. Determining the reason for this trend and how it can be used for disease control and prevention requires additional research. The transmission of scrub typhus is highly dependent on climate factors and rodent density, both of which should be considered in prevention and control strategies for scrub typhus.

BackgroundDengue virus (DENV) infection is the most prevalent arthropod-borne viral infection in tropical and subtropical regions worldwide. Guangzhou has the ideal environment for DENV transmission and DENV epidemics have been reported in this region for more than 30 years.MethodsInformation for DENV infection cases in Guangzhou from 2001 to 2010 were collected and analyzed. The DENV strains were cultured and isolated from patients’ sera. Viral RNA was extracted from cell culture supernatants. cDNA was synthesized by reverse transcription PCR. Phylogenetic trees of four DENV serotypes were constructed respectively.ResultsIn total, 2478 DENV infection cases were reported; 2143 of these (86.43%) occurred during 3 months of the year: August, September and October. Of these, 2398 were local cases (96.77%) and 80 were imported cases (3.23%). Among the imported cases, 69 (86.25%) were from Southeast Asian countries. From the 90 isolated strains, 66.67%, 3.33%, 14.44%, and 15.56% belonged to DENV serotypes 1, 2, 3, and 4, respectively. DENV-1 was predominant in most of the years, including during 2 outbreaks in 2002 and 2006; however, none of the strains or genotypes identified in this study were found to be predominant. Interestingly, DENV strains from different years had different origins. Moreover, the strains from each year belonged to different serotypes and/or genotypes.ConclusionsSoutheast Asia countries were found to be the possible source of DENV in Guangzhou. These findings suggest that there is increasing diversity in DENV strains in Guangzhou, which could increase the risk of DENV outbreaks in the near future.

During dengue virus (DENV) infection, the virus manipulates different cellular pathways to assure productive replication, including autophagy. However, it remains unclear how this autophagic process is regulated. Here, we have demonstrated a novel role for the microRNA miR-146a in negatively regulating the cellular autophagic pathway in DENV-infected A549 cells and THP-1 cells. Overexpression of miR-146a significantly blocked DENV2-induced autophagy, and LNA-mediated inhibition of miR-146a counteracted these effects. Moreover, co-overexpression of TRAF6, a target of miR-146a, significantly reversed the inhibitory effect of miR-146a on autophagy. Notably, treatment with recombinant IFN-β fully restored the autophagic activity in TRAF6-silenced cells. Furthermore, our data showed that, in DENV2-infected A549 cells, autophagy promoted a pro-inflammatory response to significantly increase TNF-α and IL-6 production. Taken together, our results define a novel role for miR-146a as a negative regulator of DENV-induced autophagy and identify TRAF6 as a key target of this microRNA in modulating the DENV-autophagy interaction.

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MicroRNA-125b (miR-125b) has been implicated in a variety of diseases as either repressors or promoters, and plays crucial roles in many cellular processes such as cell differentiation, proliferation and apoptosis. Age-related cataract has become one of the most serious problems facing the aging population in the world. The purpose of this study was to investigate the role of miR-125b in the development of age-related cataract. We demonstrated that miR-125b was downregulated in both age-related cataract tissue and lens epithelial cell apoptosis induced by UV irradiation. We also identified the impact of miR-125b on apoptosis in a lens epithelial cell line. In vitro, miR-125b regulates human lens epithelial cell apoptosis at least in part by directly targeting p53. In addition,an inverse relationship between miR-125b and p53 expression was seen in age-related cataract tissue. In conclusion,this study suggests that miR-125b might be closely involved in the pathogenesis of cataract, and has the potential to be a diagnostic biomarker or even a therapeutic modality for cataract.

BackgroundDengue viruses (DENs) are the wildest transmitted mosquito-borne pathogens throughout tropical and sub-tropical regions worldwide. Infection with DENs can cause severe flu-like illness and potentially fatal hemorrhagic fever. Although RNA interference triggered by long-length dsRNA was considered a potent antiviral pathway in the mosquito, only limited studies of the value of small interfering RNA (siRNA) have been conducted.ResultsA 21 nt siRNA targeting the membrane glycoprotein precursor gene of DEN-1 was synthesized and transfected into mosquito C6/36 cells followed by challenge with DEN. The stability of the siRNA in cells was monitored by flow cytometry. The antiviral effect of siRNA was evaluated by measurement of cell survival rate using the MTT method and viral RNA was quantitated with real-time RT-PCR. The presence of cells containing siRNA at 0.25, 1, 3, 5, 7 days after transfection were 66.0%, 52.1%, 32.0%, 13.5% and 8.9%, respectively. After 7 days incubation with DEN, there was reduced cytopathic effect, increased cell survival rate (76.9 ± 4.5% vs 23.6 ± 14.6%) and reduced viral RNA copies (Ct value 19.91 ± 0.63 vs 14.56 ± 0.39) detected in transfected C6/36 cells.ConclusionsOur data showed that synthetic siRNA against the DEN-1 membrane glycoprotein precursor gene effectively inhibited DEN-1 viral RNA replication and increased C6/36 cell survival rate. siRNA may offer a potential new strategy for prevention and treatment of DEN infection.