Sing-Sin Sam

Crimean–Congo haemorrhagic fever virus (CCHFV) is a widely distributed tick-borne arbovirus maintained in an enzootic cycle involving wild and domestic mammals and ixodid ticks, particularly Hyalomma. This systematic review synthesised 390 eligible publication-level reports published from 2015 through 31 August 2026, comprising 351 independent quantitative reports and 39 linked/nonadditive publications. The evidence tables contained 150 animal, 106 tick and 180 human records across 69 countries. Serology dominated animal investigations; among reports with species-specific raw counts, antibody positivity was highest in camels (72.9%; 3918/5377 across 23 reports), followed by red deer (41.4%) and cattle (25.1%). Among 106 tick reports, CCHFV-positive Hyalomma and Rhipicephalus were reported in 80 (75.5%) and 41 (38.7%), respectively. Human sensitivity analyses yielded median estimates of 3.8% for antibody positivity, 13.6% for direct/composite viral detection and 20.0% for case fatality. These summaries are descriptive rather than pooled prevalence estimates. Overall, the evidence supports livestock and tick surveillance as complementary components of One Health surveillance, while prospective temporal studies are needed to establish predictive early-warning performance.

The chikungunya virus (CHIKV) is an emerging alphavirus transmitted primarily by Aedes mosquitoes. This narrative review synthesised evidence from 56 mosquito-based records (34 field surveillance records and 22 laboratory vector competence records) published from January 2020 to June 2026. Aedes aegypti was the most frequently detected species, confirmed as CHIKV-positive in 22 of the 29 field studies that examined it, followed by Aedes albopictus (positive in nine of 12). Both species demonstrated consistent laboratory competence. Descriptive laboratory analysis showed mean infection, dissemination, and transmission values of approximately 76%, 77%, and 37% for Ae. aegypti, and 79%, 80%, and 47% for Ae. albopictus, respectively; these values are descriptive summaries across heterogeneous laboratory protocols and inconsistently reported genotypes. East/Central/South African–Indian Ocean Lineage of the chikungunya virus (ECSA-IOL) showed the highest mean transmission efficiency among genotype groups. In addition, CHIKV RNA was also detected in Culex quinquefasciatus, Psorophora spp., Wyeomyia spp., and other culicids in field studies, but laboratory evidence does not support these species as confirmed competent vectors. Other Aedes species, including Aedes vittatus, Aedes polynesiensis, Aedes koreicus, and Aedes japonicus, may have regional relevance but require further validation. Key evidence gaps include incomplete genotype reporting, limited virus isolation from positive mosquito pools, and inconsistent transmission metrics. Future preparedness for CHIKV emergence and spread requires integrated surveillance combining field detection, virus isolation, genomic sequencing, and standardised vector competence assays within an integrated surveillance framework.

Background: Chikungunya virus (CHIKV) is a mosquito-borne pathogen that imposes a substantial public health burden in tropical regions. After a decade of sporadic transmission, Malaysia experienced an alarming resurgence of CHIKV cases in 2019. This study investigated the reemergence of CHIKV in Malaysia following this prolonged period of sporadic transmission. Methods: An outbreak investigation was conducted in two phases across three hotspots in Perak, Malaysia (Kampung Baru Air Kuning, Bidor, and Sungkai) between October 2019 and February 2020. Blood samples were collected from 78 subjects and were tested by real-time reverse transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assays (ELISA). CHIKV was isolated and subjected to whole-genome sequencing. The resulting sequences were then analysed using phylogenetic, comparative sequence and selection pressure analyses. Results: A high CHIKV positivity rate of 69.2% (54/78) was observed in this study, with a 9.3% (5/54) rate of dengue virus (DENV) coinfection. Phylogenetic analysis revealed that the CHIKV isolates from this study belonged to the East/Central/South African-Indian Ocean Lineage (ECSA-IOL) genotype and clustered with recent outbreak isolates from Thailand, China, Myanmar, Bangladesh, Italy, Pakistan, and India during 2015–2019, rather than the Malaysia isolate from the previous 2009 outbreak. Malaysia 2019 and Thailand 2018 isolates shared relatively higher nucleotide similarity (99.78–99.89%). The reemerging CHIKV in Malaysia harboured E1-226 A, E1-K211E, and E2-V264A which enhance CHIKV fitness in Aedes aegypti , as well as nsP3-R524Opal that is associated with increased virulence. These mutations were consistent with globally circulating epidemic strains during 2015–2019, highlighting vector adaptation and disease severity. Conclusions: The reemerging ECSA-IOL strain in Malaysia was genetically distinct from the Malaysia 2009 outbreak strain but closely related to the globally circulating epidemic strains during 2015–2019. Collectively, it was likely introduced from neighbouring Thailand through cross-border transmission.

Background: Zika virus (ZIKV) infection is a public health concern and currently there is no specific therapeutic or approved vaccine. Resveratrol (RESV), a natural antiviral compound, has been shown to possess antiviral properties against ZIKV and other viral infections, but the mechanisms of action against ZIKV remain unknown. Objective: This study aimed to investigate the role of the high mobility group box 1 protein (HMGB1) in the underlying anti-ZIKV mechanisms of RESV. Methods: HMGB1 protein expression and ZIKV replication in both the RESV-treated wildtype (WT) and HMGB1-knockdown (shHMGB1) Huh7 cells were analyzed using ELISA, immunofluorescence assay, immunoblot assay, focus-forming assay and qRT-PCR. HMGB1’s role was explored by evaluating the changes in the type-1 interferon (IFN) response genes using the qRT-PCR and immunoblot assays. Results: The treatment of the ZIKV-infected WT Huh7 cells with RESV significantly reduced ZIKV titers by >90% (P < 0.001) at 48 and 72 hr pi in a dose-dependent manner and inhibited ZIKV-induced HMGB1 translocation (P < 0.001), resulting in nuclear HMGB1 accumulation. Compared to the WT Huh7 cells, shHMGB1 Huh7 cells without RESV treatment showed a significant increase in the infectious virus titers and RNA with a maximum rise of 74% (P < 0.001) and 65% (P < 0.01), respectively. RESV treatment of the ZIKV-infected WT Huh7 cells significantly increased the MxA (one of the classical interferon-stimulated genes, ISGs) and IFN-β levels (P < 0.05). The treatment of the infected shHMGB1 Huh7 cells with RESV showed a less effective antiviral response (P > 0.05) and did not cause changes in the expressions of MxA and IFN-β. Conclusion: RESV possesses therapeutic activity against ZIKV infection and the mechanism of action is mainly attributed to HMGB1 nuclear retention, which could upregulate the type-1 IFN and ISGs.

Introduction: Chikungunya fever is a mosquito-borne viral disease that usually presents with prominent arthralgia. An outbreak of chikungunya fever was reported in Tanjung Sepat, Malaysia in 2019. The outbreak was limited in size with a low number of cases being reported. The present study sought to determine the possible variables that could have affected the transmission of the infection. Methodology: A cross-sectional study involving 149 healthy adult volunteers from Tanjung Sepat was performed soon after the outbreak had subsided. All the participants donated blood samples and completed the questionnaires. Laboratory detection of anti-CHIKV IgM and IgG antibodies was performed using enzyme-linked immunoassays (ELISA). Risk factors associated with chikungunya seropositivity were determined using logistic regression. Results: The majority (72.5%, n = 108) of the study participants tested positive for CHIKV antibodies. Only 8.3% (n = 9) of the participants out of all the seropositive volunteers had an asymptomatic infection. Participants who resided with a febrile (p < 0.05, Exp(B) = 2.2, confidence interval [CI] 1.3-3.6) or a CHIKV-diagnosed person (p < 0.05, Exp(B) = 2.1, CI 1.2-3.6) in the same household were found likely to be tested positive for CHIKV antibodies. Conclusions: Findings from the study support that asymptomatic CHIKV infections and indoor transmission occurred during the outbreak. Hence, widespread community testing and indoor use of mosquito repellent are among the possible measures that can be implemented to reduce CHIKV transmission during an outbreak.

In the chronic phase of chikungunya virus (CHIKV) infection, excessive inflammation manifests as incapacitating joint pain and prolonged arthritis. Arthritis resulted from a large influx of infiltrating immune cells driven by pro-inflammatory cytokines and chemokines originating from the toll-like receptor (TLR)-mediated innate antiviral response. This study investigated fisetin’s ability to modulate TLR-mediated antiviral responses against CHIKV in Huh7 cells. The CHIKV inhibitory potential of fisetin was assessed by plaque-forming unit assay, virus yield reduction assay, and bright-field microscopy (cytopathic effect, immunofluorescence). Fisetin’s modulatory potential on TLR-mediated antiviral response was evaluated by immunofluorescence assay (expression of TLR proteins), qRT-PCR (mRNA level of antiviral genes), human cytokine array, and the immunoblotting of key transcription factors. The present study showed fisetin induced the expression of the antiviral genes at an early time-point by promoting the phosphorylation of IRF3 and IRF7. Fisetin reduced excessive inflammatory cytokine responses in CHIKV-infected Huh7 cells by impeding the over-phosphorylation of NF-κB. Fisetin also reduced CHIKV-induced cytopathic effects in CHIKV-infected Huh7 cells. Altogether, our study suggests that fisetin modulates TLR-mediated antiviral responses by affecting the CHIKV-induced inflammatory responses.

In the chronic phase of chikungunya virus (CHIKV) infection, excessive inflammation manifests as incapacitating joint pain and prolonged arthritis. Arthritis resulted from a large influx of infiltrating immune cells driven by pro-inflammatory cytokines and chemokines originating from the toll-like receptor (TLR)-mediated innate antiviral response. This study investigated fisetin's ability to modulate TLR-mediated antiviral responses against CHIKV in Huh7 cells. The CHIKV inhibitory potential of fisetin was assessed by plaque-forming unit assay, virus yield reduction assay, and bright-field microscopy (cytopathic effect, immunofluorescence). Fisetin’s modulatory potential on TLR-mediated antiviral response was evaluated by immunofluorescence assay (expression of TLR proteins), qRT-PCR (mRNA level of antiviral genes), human cytokine array, and immunoblotting of key transcription factors. The present study showed fisetin induced the expression of the antiviral genes at an early time-point by promoting the phosphorylation of IRF3 and IRF7. Fisetin reduced excessive inflammatory cytokine responses in CHIKV-infected Huh7 cells by impeding the over-phosphorylation of NF-κB. Fisetin also reduced CHIKV-induced cytopathic effects in CHIKV-infected Huh7 cells. Altogether, our study suggests that fisetin modulates TLR-mediated antiviral responses by affecting the CHIKV-induced inflammatory responses.

In the chronic phase of chikungunya virus (CHIKV) infection, excessive inflammation manifests as incapacitating joint pain and prolonged arthritis. Arthritis resulted from a large influx of infiltrating immune cells driven by pro-inflammatory cytokines and chemokines originating from the toll-like receptor (TLR)-mediated innate antiviral response. This study investigated fisetin's ability to modulate TLR-mediated antiviral responses against CHIKV in Huh7 cells. The CHIKV inhibitory potential of fisetin was assessed by plaque-forming unit assay, virus yield reduction assay, and bright-field microscopy (cytopathic effect, immunofluorescence). Fisetin’s modulatory potential on TLR-mediated antiviral response was evaluated by immunofluorescence assay (expression of TLR proteins), qRT-PCR (mRNA level of antiviral genes), human cytokine array, and immunoblotting of key transcription factors. The present study showed fisetin induced the expression of the antiviral genes at an early time-point by promoting the phosphorylation of IRF3 and IRF7. Fisetin reduced excessive inflammatory cytokine responses in CHIKV-infected Huh7 cells by impeding the over-phosphorylation of NF-κB. Fisetin also reduced CHIKV-induced cytopathic effects in CHIKV-infected Huh7 cells. Altogether, our study suggests that fisetin modulates TLR-mediated antiviral responses by affecting the CHIKV-induced inflammatory responses.

Getah virus is an emerging mosquito-borne animal pathogen. Four phylogenetic groups of GETV, Group I (GI), GII, GIII and GIV, were identified. However, only the GETV GIII was associated with disease epidemics suggesting possible virulence difference in this virus group. Here, we compared the genetic and in vitro phenotypic characteristics between the epidemic and non-epidemic GETV. Our complete coding genome sequence analyses revealed several amino acid substitutions unique to the GETV GIII and GIV groups, which were found mainly in the hypervariable domain of nsP3 and E2 proteins. Replication kinetics of the epidemic (GIII MI-110 and GIII 14-I-605) and non-epidemic GETV strains (prototype GI MM2021 and GIV B254) were compared in mammalian Vero cells and mosquito C6/36 and U4.4 cells. In all cells used, both epidemic GETV GIII MI-110 and GIII 14-I-605 strains showed replication rates and mean maximum titers at least 2.7-fold and 2.3-fold higher than those of GIV B254, respectively (Bonferroni posttest, p < 0.01). In Vero cells, the epidemic GETV strains caused more pronounced cytopathic effects in comparison to the GIV B254. Our findings suggest that higher virus replication competency that produces higher virus titers during infection may be the main determinant of virulence and epidemic potential of GETV.

Serum is commonly used as a specimen in immunoassays but the presence of heterophilic antibodies can potentially interfere with the test results. Previously, we have developed a microfluidic device called: 3D Stack for enzyme-linked immunosorbent assay (ELISA). However, its evaluation was limited to detection from a single protein solution. Here, we investigated the sensitivity of the 3D Stack in detecting a severe dengue biomarker—soluble CD163 (sCD163)—within the serum matrix. To determine potential interactions with serum matrix, a spike-and-recovery assay was performed, using 3D Stacks with and without surface modification by an EDC–NHS (N-ethyl-N′-(3-(dimethylamino)propyl)carbodiimide/N-hydroxysuccinimide) coupling. Without surface modification, a reduced analyte recovery in proportion to serum concentration was observed because of the Vroman effect, which resulted in competitive displacement of coated capture antibodies by serum proteins with stronger binding affinities. However, EDC–NHS coupling prevented antibody desorption and improved the sensitivity. Subsequent comparison of sCD163 detection using a 3D Stack with EDC–NHS coupling and conventional ELISA in dengue patients’ sera revealed a high correlation (R = 0.9298, p < 0.0001) between the two detection platforms. Bland–Altman analysis further revealed insignificant systematic error between the mean differences of the two methods. These data suggest the potentials of the 3D Stack for further development as a detection platform.