Mosquito-borne arboviral diseases such as dengue and chikungunya have continuously been a major global public health concern. Introducing the intracellular bacterial endosymbiont Wolbachia into mosquito populations has been proven to reduce dengue virus transmission, and its broader efficacy against other arboviruses has also been investigated. Several Wolbachia strains have been successfully propagated in insect cell lines, highlighting the utility of in vitro systems for studying microbial-host interactions under controlled conditions. This study investigated the initial establishment and replication kinetics of a flea-derived Wolbachia strain (wCfe), which was originally isolated from Malaysian Ctenocephalides felis and maintained in the Ixodes scapularis tick-derived cell line (IDE8), and then transferred into an Aedes albopictus-derived cell line (C6/36). The wCfe strain was semi-purified from IDE8 cultures and inoculated into C6/36 cells in 24-well plates. Replication dynamics were monitored by quantitative real-time PCR targeting the Wolbachia pipientis 16S rRNA gene. Following infection, a lag phase was observed at day 0 to 5 days post-infection (d.p.i.), followed by exponential growth from 6 d.p.i. after which Wolbachia levels remained relatively stable until the end of the observation period at 12 d.p.i. Overall, a 25.30-fold increase in Wolbachia density was detected relative to 0 d.p.i. Across replicates, the estimated generation time of wCfe in C6/36 cells ranged from 1.7 to 2.5 days. These results demonstrate successful initial establishment and replication of the flea-derived Wolbachia strain in the Aedes mosquito cell line. However, longer-term in vivo studies will be necessary to determine the persistence of wCfe infection in C6/36 cells and within the mosquito host.

The aim of this study was to investigate the antiviral property of Eurycoma longifolia Jack (EL) against dengue virus. A propriety standardized extract of Eurycoma longifolia Jack (Physta®) was tested for anti-viral activity after viral adsorption in Vero cell line. Viral yield was measured by qRT-PCR in four serotypes of dengue virus. The antiviral activity was further investigated in an in vivo AG129 mouse model for dengue inhibitory candidates. 100 mg/kg EL extract was fed twice daily and challenged with a lethal dose of (~1x105 PFU per mouse) of DENV-2 over a period of six days. Antiviral activity with IC50 of 33.84, 33.55, 58.35 and 119 μg/ml for DENV-1, DENV-2, DENV-3 and DENV-4 serotypes respectively was observed. The selectivity index (SI) values determined as the ratio of cytotoxic concentration (CC50) to inhibitory concentration (IC50) was the lowest for DENV-2 at 28.9. The dengue virus (DENV) replication measured by qRT-PCR showed a reduction of 100% for DENV-1, DENV-2, DENV-3 and 80% for DENV-4 at day 2 of exposure. In the in vivo AG129 mouse model, a lower weight reduction, 30% lower viral load and 12% higher platelet in the extract group compared to the control was observed at day 6. The extract of E. longifolia has potential anti-dengue properties with improving trends in platelet counts. E. longifolia supplementation is potentially a two-pronged approach in treating dengue fever.