Repurposing of approved antivirals against dengue virus serotypes: an in silico and in vitro mechanistic study

Dengue is an emerging, mosquito-borne viral disease of international public health concern. Dengue is endemic in more than 100 countries across the world. However, there are no clinically approved antivirals for its cure. Drug repurposing proves to be an efficient alternative to conventional drug discovery approaches in this regard, as approved drugs with an established safety profile are tested for new indications, which circumvents several time-consuming experiments. In the present study, eight approved RNA-dependent RNA polymerase inhibitors of Hepatitis C virus were virtually screened against the Dengue virus polymerase protein, and their antiviral activity was assessed in vitro. Schrödinger software was used for in silico screening, where the compounds were passed through several hierarchical filters. Among the eight compounds, dasabuvir was finally selected for in vitro cytotoxicity and antiviral screening. Cytotoxicity profiling of dasabuvir in Vero cells revealed changes in cellular morphology, cell aggregation, and detachment at 50 μM. Based on these results, four noncytotoxic concentrations of dasabuvir (0.1, 0.25, 0.5, and 1 µM) were selected for antiviral screening against DENV-2 under three experimental conditions: pre-infection, co-infection, and post-infection treatment, by plaque reduction assay. Viral plaques were reduced significantly (p < 0.05) in the co-infection and post-infection treatment regimens; however, no reduction was observed in the pretreatment group. This indicated a possible interference of dasabuvir with NS5 RdRp, as seen from in silico interaction studies, translating into a reduction in virus plaques. Such studies reiterate the usefulness of drug repurposing as a viable strategy in antiviral drug discovery. In this drug repurposing study, dasabuvir, a known anti-hepatitis C drug, was selected through virtual screening and assessed for its anti-dengue activity.

Genetic diversity of Dengue virus serotypes circulating among Aedes mosquitoes in selected regions of northeastern Nigeria

The flaviviruses are mosquito borne pathogens that continue to pose a considerable public health risk to animals and humans. The members of this group includes, Dengue virus (DENV), Yellow fever virus (YVF), Japanese encephalitis virus (JEV), West Nile virus (WEV) and Zika virus (ZKV). The DENV mosquito vector is endemic to tropical and subtropical climates, placing ∼40% of the world's population at direct risk of dengue infection. Currently, in Nigeria the status of DENV serotypes circulating among mosquito vectors is unknown. Our study was designed to identify and characterize the DENV serotypes circulating in Aedes mosquito populations collected in selected sites in Nigeria. The mosquitoes were collected and identified morphologically to species level using colored identification keys of Rueda. Generally, each species identified was tested in pools of 20 individuals of each Aedes species. RT-PCR and semi nested PCR were used to detect DENV serotypes in mosquitoes and characterized using Sanger sequencing methods. The results showed that DENV serotypes were detected in 58.54% (24/41) of the pools of Aedes mosquitoes from Mubi, Numan and Yola screened. All DENV1-4 serotypes were detected in Ae. aegypti. While DENV 1, 2 and 4 were detected in Ae. albopictus. And only DENV 2 was detected in Ae. galloisi with DENV4 serotype being reported for the first time in Nigeria. DENV2 (37.8%) was the most detected serotypes, while double and triple co-infections of serotypes were detected in 24.4% of the pools. Phylogenetic analysis revealed a strong evolutionary relatedness of DENV serotypes in our study with that of South and Southeast Asia, North America, and other African countries. This is the first reports on the natural DENV serotypes co-infection among Aedes species pools in Nigeria, which can create possible interaction with other flaviviruses causing animal and human diseases. In addition, our study postulates the possible linkage between DENV serotypes infection and human febrile flu-like disease burden being experienced by host communities in northeastern Nigeria.

Serotype and genotype diversity of dengue viruses circulating in India: a multi-centre retrospective study involving the Virus Research Diagnostic Laboratory Network in 2018

OBJECTIVES

A retrospective study was undertaken to investigate the circulating dengue virus (DENV) serotypes and genotypes in India in 2018.

METHODS

In total, 4963 samples referred to virus research diagnostic laboratories (n=21), the Indian Council of Medical Research-National Institute of Virology (ICMR-NIV) and ICMR-NIV field units (n=2) for diagnosis of dengue in 2018 were tested using a real-time reverse transcription polymerase chain reaction assay for the presence of DENV serotypes. Representative samples were sequenced for the envelope (E) gene.

RESULTS

Regional diversity was observed with regard to the dominant circulating serotypes. DENV-2 was found to be the most common serotype in many states. Thrombocytopenia, petechiae and malaise were associated with DENV-2 infection. Phylogenetic analyses of DENV E gene sequences revealed the circulation of genotypes I and V of DENV-1, two lineages of DENV-2 genotype IV, DENV-3 genotype III and DENV-4 genotype I.

CONCLUSIONS

This study found regional differences in the prevalence of circulating DENV serotypes in India, and provides baseline data for continuous molecular surveillance. Molecular surveillance may have implications for predicting large-scale outbreaks of dengue if regional shifts in the predominantly circulating serotypes and genotypes are detected during the early phase of the dengue season.

The burden of dengue, source reduction measures, and serotype patterns in Myanmar, 2011 to 2015-R2

Background

Myanmar is currently classified as a high burden dengue country in the Asian Pacific region. The Myanmar vector-borne diseases control (VBDC) program has collected data on dengue and source reduction measures since 1970, and there is a pressing need to collate, analyze, and interpret this information. The aim of this study was to describe the burden of hospital-based dengue disease, dengue control measures, and serotype patterns in Myanmar between 2011 and 2015.

Methods

This was a cross-sectional study using annual records from the Dengue Fever/Dengue Hemorrhagic Fever Prevention and Control Project in Myanmar.

Results

Between 2011 and 2015, there were a total of 89,832 cases and 393 deaths in hospitals, with 97% of cases being in children. In 2013 and 2015, there was an increased number of cases, respectively at 21,942 and 42,913, while during the other 3 years, numbers ranged from 4738 to 13,806. The distribution of dengue deaths each year mirrored the distribution of cases. Most cases (84%) occurred in the wet season and 54% occurred in the delta/lowlands. Case fatality rate (CFR) was highest in 2014 at 7 per 1000 dengue cases, while in the other years, it ranged from 3 to 5 per 1000 cases. High CFR per 1000 were also observed in infants < 1 year (CFR = 8), adults ≥ 15 years (CFR = 7), those with disease severity grade IV (CFR = 17), and those residing in hilly regions (CFR = 9). Implementation and coverage of dengue source reduction measures, including larval control, space spraying, and health education, all increased between 2012 and 2015, although there was low coverage of these interventions in households and schools and for water containers. In the 2013 outbreak, dengue virus serotype 1 predominated, while in the 2015 outbreak, serotypes 1, 2, and 4 were those mainly in circulation.

Conclusion

Dengue is a serious public health disease burden in Myanmar. More attention is needed to improve monitoring, recording, and reporting of cases, deaths, and vector control activities, and more investment is needed for programmatic research.

Impedimetric cell-based biosensor for real-time monitoring of cytopathic effects induced by dengue viruses

We describe an impedimetric cell-based biosensor constructed from poly-l-lysine (PLL)-modified screen-printed carbon electrode for real-time monitoring of dengue virus (DENV) infection of surface-immobilized baby hamster kidney (BHK-21) fibroblast cells. Cytopathic effects (CPE) induced by DENV-2 New Guinea C strain (including degenerative morphological changes, detachment, membrane degradation and death of host cells), were reflected by drastic decrease in impedance signal response detected as early as ~30 hours post-infection (hpi). In contrast, distinct CPE by conventional microscopy was evident only at ~72 hpi at the corresponding multiplicity of infection (MOI) of 10. A parameter that describes the kinetics of cytopathogenesis, CIT₅₀, which refers to the time taken for 50% reduction in impedance signal response, revealed an inverse linear relationship with virus titer and MOI. CIT₅₀ values were also delayed by 31.5 h for each order of magnitude decrease in MOI. Therefore, based on the analysis of CIT₅₀, the virus titer of a given sample can be determined from the measured impedance signal response. Furthermore, consistent impedance results were also obtained with clinical isolates of the four DENV serotypes verified by RT-PCR and cycle sequencing. This impedimetric cell-based biosensor represents a label-free and continuous approach for the dynamic measurement of cellular responses toward DENV infection, and for detecting the presence of infectious viral particles.

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Impedimetric cell-based biosensor detected negligible changes in cell morphology and adhesion caused by dengue virus infection.

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Dengue viral-induced cytopathic effects could be detected within ~30 hours post-infection.

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Virus titers may be estimated based on impedance signal responses.

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Advantages include non-invasive label-free measurement, reduced diagnosis time, and identification of infectious viruses.

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Potentially useful application for the analysis of clinical isolates.