Tick-borne viruses (TBVs) include the highly pathogenic viruses associated with infectious diseases in both humans and animals. The global public health concern of TBVs is closely related to geographic distribution of ticks. In Africa, a variety of TBVs have been reported by detections from ticks and high seroprevalence in humans and domestic animals. In this study, we aimed to detect TBVs from ticks in Kenya by targeting viral genes of Orthoflavivirus, Bandavirus and Orthonairovirus. Ticks were collected from cattle, camels, sheep and goats in Isiolo, Narok and Baringo counties, and viral RNA detections were attempted by RT-PCR. There were no positive samples for Orthoflavivirus and Bandavirus. On the other hand, 10 samples tested positive for Orthonairovirus by RT-PCR, were identified from Rhipicephalus appendiculatus tick pools. Five pools were indicated as novel Orthonairovirus species, marigat tick orthonairovirus (MTOV). Interestingly, other 5 samples were considered to be Bole tick virus 4 (BLTV4) and BLTV4-related virus, marigat tick flavivirus (MTFV), belonging to unclassified genus within family Flaviviridae, but not Orthonairovirus. Our findings add to the knowledge of genetic diversity and geographic distribution of tick-borne viruses including novel Orthonairovirus MTOV, unclassified Flavivirus BLTV4 and MTFV in Kenya, and will provide useful clues for further epidemiological surveys.

BACKGROUND:Zika virus (ZIKV) is a mosquito-borne flavivirus mainly transmitted by Aedes aegypti and Aedes albopictus. While well-studied in the Americas, data from Southeast Asia, especially Myanmar, remain limited. This study assessed ZIKV infection among dengue-suspected patients in Yangon, Myanmar, from 2017 to 2019. METHODS:This was a cross-sectional retrospective study that collected serum samples from 1162 clinically dengue-suspected patients. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to detect ZIKV RNA and serological assays were used to identify ZIKV-specific immunoglobulin M (IgM), IgG and neutralizing antibodies. The age, gender, clinical manifestations and coinfections with dengue virus (DENV) were determined. RESULTS:Of the 1162 samples, 23 (2.0%) were positive for ZIKV by RT-qPCR. Among these, nine samples showed coinfection with DENV: four with DENV-1, two with DENV-3 and three with DENV-4. Of the 111 (9.6%) samples that tested positive for ZIKV IgM, 11 (9.9%) had neutralizing antibodies against ZIKV, with 9 (8.1%) confirmed as ZIKV positive and 2 (1.8%) classified as probable cases. CONCLUSIONS:Our study reported that 32 cases (2.8%) were confirmed as ZIKV infections by molecular and serological detection. The findings underscore the need for improved surveillance, diagnostic accuracy and public health interventions to mitigate the impact of ZIKV.

Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne pathogen listed as a World Health Organization priority virus, posing a serious public health threat. However, reliable serological assays remain limited, particularly for early IgM detection. In this study, we developed a safe and efficient indirect enzyme-linked immunosorbent assay (wv-ELISA) using β-propiolactone (BPL)-inactivated whole SFTSV virions as antigen and compared its performance with a recombinant nucleoprotein-based ELISA (rNP-ELISA). High-purity, structurally intact virions were prepared by large-scale SFTSV culture followed by polyethylene glycol precipitation and sucrose density gradient ultracentrifugation, then inactivated with 0.03% BPL to ensure biosafety while preserving antigenicity. Using serum samples from confirmed SFTSV patients and healthy volunteers, the IgM sensitivity of wv-ELISA and rNP-ELISA was 100% and 91.9%, respectively, with 100% specificity in both, when compared with the rNP-capture ELISA. While both assays performed comparably for IgG detection, the whole-virus ELISA exhibited superior sensitivity for IgM detection. Moreover, antibody titers measured by wv-ELISA showed significant negative correlations with viral RNA copy numbers and positive correlations with neutralizing antibody titers. Notably, IgG titers determined by wv-ELISA correlated more strongly with neutralizing activity than those measured by rNP-ELISA, likely reflecting the presence of native viral glycoproteins in the whole-virus antigen. Overall, this study establishes a safe, BPL-inactivated whole-virus ELISA system that offers high sensitivity and specificity for both IgM and IgG detection, providing a valuable tool for SFTSV serodiagnosis and immune evaluation.

H. pylori (Hp) is highly causative agent of chronic gastritis, gastric cancer and human death worldwide. To address the challenge of H. pylori infection, numerous immunological assays have been developed for its diagnosis and management. However, the limited availability of these assays in certain laboratories, coupled with their high cost, inconsistent specificity, and sensitivity, has hampered their widespread adoption, particularly in developing countries where H. pylori infection is prevalent. Therefore, this study aimed to develop and validate a competitive enzyme-linked immunosorbent assay (cELISA) assay for detecting H. pylori infections by targeting the Protective Surface Antigen (PSA) and Cytotoxic-Associated Gene Pathogenesis Island (Cag11) proteins in H. pylori stool antigen sample. In the current study, the optimal conditions including the dilution of anti-rPSA D15 and anti-rCag11 antibodies at 1:1000, coating antigens (rPSA D15 and rCag11) at a concentration of 1 μg/well, the dilution of HRP-labelled antibody at 1:5000 and H. pylori stool antigen dilution at 1:1000 with a 1hour incubation and color development time of 30 minutes for cELISA were determined using an ELISA checkerboard titration assay. Based on the optimized conditions, novel rPSA D15-cELISA and rCag11-cELISA assays with a respective optimum cut-off value of 20.80% PI and 24.16% PI were developed. According to the receiver operating characteristic (ROC) curve analysis on the diagnostic performance of the newly developed rPSA D15-cELISA and rCag11-cELISA assays using 60 clinical H. pylori stool samples, the rPSA D15-cELISA test assay established an optimum cut-off point of 20.80% with sensitivity and specificity of 90% (95% confidence of interval (CI) 74.38-96.54), Area under the curve (AUC) of 0.9556 (95% CI = 0.896-1.000) and P value <0.0001. Similarly, the rCag11-cELISA assay revealed optimum cut-off value of 24.16% with sensitivity of 93.33% (95% CI 78.68-98.82), specificity of 90% (95% CI 74.38-96.54), AUC of 0.986 (95% CI = 0.967-1.000) and P <0.0001. Furthermore, the reproducibility assay coefficients of variation (CV) of the newly developed rPSA D15-cELISA and rCag11-cELISA assay were less than 10%, indicating that the two cELISA assays exhibits excellent reproducibility and reliability. To validate their clinical diagnostic application, the comparative study results of rPSA D15-cELISA and rCag11-cELISA showed a high agreement (k = 0.766 and 0.799) with the commercially available H. pylori antigen test immunochromatographic kit and more accurate than the reference kit by detecting stool antigen of H. pylori strain, indicating it is promising for clinical testing. In conclusion, these results indicated that the newly developed rPSA D15-cELISA and rCag11-cELISA H. pylori stool antigen test assays were a potential reliable and a clinically useful assay for rapid, specifically, sensitively and accurately diagnosis and large-scale epidemiological investigation of H. pylori infection.

BACKGROUND:Chikungunya virus (CHIKV), transmitted by Aedes mosquitoes, causes significant morbidity characterized by acute febrile illness to chronic and permanent disability in some patients. Despite its potential for severe long-term effects, surveillance for CHIKV remains limited, especially in dengue-endemic region like Sri Lanka. To address the gap in surveillance, this study aimed to determine the prevalence of CHIKV among patients suspected of dengue fever during the 2017-2019 DENV outbreak in Sri Lanka. METHODS:Serum samples were collected from 295 patients at Kandy National Hospital and 300 patients at Negombo Hospitals, presenting with dengue-like symptoms such as fever, rash, and arthralgia. We performed quantitative real-time RT-PCR (RT-qPCR) to detect the CHIKV genome and conducted serological tests for anti-CHIKV IgM and IgG antibodies on all samples. Serology-positive samples were further validated with neutralization assays to confirm CHIKV-specific antibodies. RESULTS:The prevalence of recent CHIKV infection (IgM or RT-qPCR positive) was 2.4 % and 7.0 %, while past CHIKV infection (IgG-positive) was 16.3 % and 12.3 % with neutralizing antibody (NAb) in Kandy and Negombo Hospitals, respectively. All IgG-positive samples exhibited NAb with titers of 10 or higher. The NAb geometric mean titer in the Kandy and Negombo areas does not show a significant difference. In the Kandy area, the majority of CHIKV infections occurred in young adults aged 13-24 years, accounting for 57.1 % of recent infections and 52.1 % of past infections. CONCLUSION:CHIKV circulates alongside DENV outbreaks, with a higher prevalence of recent infections in Negombo compared to Kandy, while past infections are more common in Kandy than in Negombo. Neutralization assays confirmed the presence of CHIKV-specific antibodies, emphasizing the need for enhanced surveillance for proper patient care and management. These findings underscore the importance of public health interventions, including surveillance programs and vaccine development, to mitigate the burden of CHIKV in Sri Lanka.

BackgroundArboviruses like Yellow Fever Virus (YFV), Dengue Virus (DENV), Chikungunya Virus (CHIKV), and West Nile Virus (WNV) frequently cause outbreaks in sub-Saharan Africa. Identifying risk factors in children can improve diagnosis, treatment, and prevention strategies. This study identified factors associated with seropositivity to YFV, DENV, CHIKV and WNV among children in Teso South Sub-County, Western Kenya.MethodsThis survey involved 656 children aged 1-12 years, enrolled at two health facilities. Socio-demographic, environmental, behavioral, and medical information was collected via a questionnaire. Serological screening for antibodies to YFV, DENV, CHIKV, and WNV was performed using Indirect Enzyme-Linked Immunosorbent Assays. The collected data was summarized using descriptive statistics. Factors associated with seroprevalence were examined using multinomial logistic regression.ResultsOverall, 27.7% of children were seropositive for at least one arbovirus: 15.7% for DENV, 9.6% for WNV, 5.6% for CHIKV, and 4.4% for YFV. Factors associated with any arbovirus were: female gender, age 6-9 and 9-12 years, non-parent primary caregiver, and use of unknown bed nets brand (p < 0.05). YFV seropositivity was not associated with any of the risk factors, while DENV was associated with female gender and age 6-9 years (p < 0.05). CHIKV was associated with use of insect repellents and not using any mosquito bed nets. WNV seropositivity was significantly higher in all children aged above 3 years, those who lived in town/urban areas, use of olyset, supanet and unknown bed nets and in those who lived in houses roofed with tiles and iron sheets (p < 0.05).ConclusionArbovirus exposure among children is influenced by age, female gender, non-parental primary care giver, failure to use mosquito bed nets, type of bed net, use of insect repellents, and house roofing material. Interventions targeting housing improvements, education on bed net and mosquito repellent use, and environmental mosquito control can reduce infection risks in endemic areas.

The coronavirus disease 2019 (COVID-19) pandemic underscored the global need for reliable diagnostic tools with quick turnaround time for effective patient management and mitigation of virus spread. This study aimed to express severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid protein and produce monoclonal antibodies (mAbs) against the expressed protein. Following successful expression and purification of His-tagged SARS-CoV-2 N protein using a wheat germ cell-free protein expression system (WGCFS), BALB/c mice were immunized, and generated hybridomas screened for mAb production. Indirect and sandwich ELISA were used to screen the reactivity of the monoclonal antibody against both our recombinant antigen and commercial antigen. The mAbs were also assessed for their performance using RT-PCR confirmed positive samples with varying cycle threshold (CT) values and their specificity screened using virus isolates of other respiratory viruses. Our mAb demonstrated high reactivity against our recombinant antigen, commercial antigen, SARS-CoV-2 Beta and Omicron variants. There was no significant difference in the binding affinity of our mAb and commercial mAb against the study recombinant (p = 0.12) and commercial (p = 0.072) antigens. Our mAb detected SARS-CoV-2 from clinical samples with varying CT values and exhibited no cross-reactivity against other respiratory viruses. We successfully expressed SARS-CoV-2 N protein leveraging WGCFS in a resource-limited setting. Our mAb had a high binding affinity to the recombinant antigen, making it a suitable candidate for antigen detection kit development. Beyond diagnostics, the mAb holds potential for therapeutic applications as well as use in clinical and environmental surveillance platforms.

The dengue virus (DENV) and chikungunya virus (CHIKV) infection present with similar symptoms and are transmitted by Aedes mosquitoes. Until now, there have been no reported cases of DENV and CHIKV being detected in mosquitoes in Nepal. This study identified circulating arboviruses from mosquitoes collected in the capital city Kathmandu, and Dhading, Bhaktapur, and Lalitpur districts of Central Nepal in 2023. Of 105 Aedes pooled samples, 16 (15.2%) were positive for DENV, and six (5.7%) were positive for CHIKV by quantitative real-time polymerase chain reaction. DENV-2 was the most common serotype (11.4%), aligning with recent outbreaks in Nepal in 2023, followed by DENV-3 and DENV-4 (1.9% each). To the best of our knowledge, our study is the first report to detect DENV and CHIKV in Aedes mosquitoes circulating in Nepal. This study highlights the need for mosquito surveillance to prevent future outbreaks of mosquito-borne diseases in Nepal.

Introduction: Rift Valley fever virus (RVFV) belonging to the Phenuiviridae family is responsible for a zoonotic disease called Rift Valley fever (RVF). Currently, RVFV has spread from Africa to Asia, and due to its ability to cause high mortality rates, it has significantly impacted human health and economic development in many societies. Highly specific and sensitive systems for sero-diagnosis of RVFV infection are needed for clinical use. Method: BALB/c mice were immunized with recombinant RVFV nucleocapsid (rRVFV-N) protein and the spleen cells fused with SP2/0 myeloma cells to create hybridoma cell lines. The secreted monoclonal antibodies (MAbs) were purified and characterized. Enzyme-linked immunosorbent assay (ELISA) systems for the detection of IgG and IgM using the new MAbs were established and evaluated. Serum samples from 96 volunteers and 93 patients of suspected RVF from Kenya were tested compared with the ELISA systems based on inactivated viruses and the rabbit polyclonal antibody. Result: Three monoclonal antibodies against rRVFV-N protein were established. The performance of the MAb-based sandwich IgG ELISA and the IgM capture ELISA perfectly matched the ELISA systems using the inactivated virus or the polyclonal antibody. Conclusions: Recombinant RVFV-N protein-specific MAbs were developed and they offer useful tools for RVFV studies. The MAb-based ELISA systems for detecting IgG and IgM offer safe and useful options for diagnosing RVFV infections in humans.

Severe fever with thrombocytopenia syndrome (SFTS) is a potentially fatal tick-borne zoonosis caused by SFTS virus (SFTSV). In addition to tick bites, animal-to-human transmission of SFTSV has been reported, but little is known about feline SFTSV infection. In this study, we analyzed data on 187 cats with suspected SFTS to identify biomarkers for SFTS diagnosis and clinical outcome. Body weight, red and white blood cell and platelet counts, and serum aspartate aminotransferase and total bilirubin levels were useful for SFTS diagnosis, whereas alanine aminotransferase, aspartate aminotransferase and serum SFTSV RNA levels were associated with clinical outcome. We developed a scoring model to predict SFTSV infection. In addition, we performed a phylogenetic analysis to reveal the relationship between disease severity and viral strain. This study provides comprehensive information on feline SFTS and could contribute to the protection of cat owners, community members, and veterinarians from the risk of cat-transmitted SFTSV infection.

Background: Chikungunya virus (CHIKV) is an alphavirus (genus Alphavirus, family Togaviridae) that is primarily transmitted to humans by Aedes mosquitoes, and can be transmitted from mother to child. Little is known about CHIKV transmission in Vietnam, where dengue is endemic and Aedes mosquitoes are abundant. This study aimed to determine the prevalence and characteristics of vertical CHIKV infection in a birth cohort, and seroprevalence of anti-CHIKV antibodies with or without confirmation by neutralization tests among women bearing children in Vietnam. Methods: We collected umbilical cord blood plasma samples from each newly delivered baby in Nha Trang, Central Vietnam, between July 2017 and September 2018. Samples were subjected to molecular assay (quantitative real-time RT-PCR) and serological tests (anti-CHIKV IgM capture and IgG indirect enzymelinked immunosorbent assay, and neutralization tests). Results: Of the 2012 tested cord blood samples from newly delivered babies, the CHIKV viral genome was detected in 6 (0.3%) samples by RT-PCR, whereas, 15 samples (0.7%) were anti-CHIKV-IgM positive. Overall, 18 (0.9%, 95% CI: 0.6-1.5) samples, including three positives for both CHIKV IgM and viral genome on RTPCR, were regarded as vertical transmission of CHIKV infection. Of the 2012 cord blood samples, 10 (0.5%, 95% CI: 0.2-0.9) were positive for both anti-CHIKV IgM and IgG. Twenty-nine (1.4%, 95% CI: 1.0-2.1) were seropositive for anti-CHIKV IgG while 26 (1.3%, 95% CI: 0.8-1.9) of them were also positive for neutralizing antibodies, and regarded as seropositive with neutralization against CHIKV infection. Conclusion: This is the first report of a possible CHIKV maternal-neonatal infection in a birth cohort in Vietnam. The findings indicate that follow-up and a differential diagnosis of CHIKV infection in pregnant women are needed to clarify the potential for CHIKV vertical transmission and its impact in the newborn. (c) 2024 The Author(s). Published by Elsevier Ltd on behalf of King Saud Bin Abdulaziz University for Health Sciences. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/ 4.0/).

Chikungunya virus (CHIKV) infection is a re-emerging arboviral disease with no approved vaccine, although numerous options are in development. Before vaccine implementation, disease burden, affected age group, and hospitalization rate information should be documented. In 2019, a sizeable outbreak of the East Central South African genotype of CHIKV occurred in Myanmar, and during this period, a cross-sectional study was conducted in two regions, Mandalay and Yangon, to examine the molecular and seropositivity rate of the CHIKV infection. The participants (1124) included dengue-suspected pediatric patients, blood donors, and healthy volunteers, who were assessed using molecular assays (quantitative real-time RT-PCR), serological tests (anti-CHIKV IgM capture and IgG indirect enzyme-linked immunosorbent assays), and neutralization tests. The tests confirmed the following positivity rates: 11.3% (127/1124) for the molecular assay, 12.4% (139/1124) for the anti-CHIKV IgM Ab, 44.5% (500/1124) for the anti-CHIKV IgG Ab, and 46.3% (520/1124) for the CHIKV neutralizing Ab. The highest rate for the molecular test occurred with the dengue-suspected pediatric patients. The seroprevalence rate through natural infection was higher in the healthy volunteers and blood donors than that in the pediatric patients. The results of this study will help stakeholders determine the criteria for choosing appropriate recipients when a CHIKV vaccine is introduced in Myanmar.

Myanmar is an endemic country for arboviruses, and outbreaks occur frequently. A cross-sectional analytical study was conducted during the peak season of the chikungunya virus (CHIKV) outbreak in 2019. A total of 201 patients with acute febrile illness who were admitted to the 550-bedded Mandalay Children Hospital in Myanmar were enrolled in the study, and virus isolation, serological tests, and molecular tests for the dengue virus (DENV) and CHIKV were performed for all samples. Out of 201 patients, 71 (35.3%) were only DENV-infected, 30 (14.9%) were only CHIKV-infected and 59 (29.4%) were coinfected with DENV and CHIKV. The viremia levels of the DENV- and CHIKV- mono-infected groups were significantly higher than those of the group coinfected with DENV and CHIKV. Genotype I of DENV-1, genotypes I and III of DENV-3, genotype I of DENV-4 and the East/Central/South African genotype of CHIKV were co-circulating during the study period. Two novel epistatic mutations of CHIKV (E1:K211E and E2:V264A) were noted. This study highlighted that there were many coinfection cases during the outbreak and that the co-circulation of both viruses in DENV-endemic regions warrants effective monitoring of these emerging pathogens via comprehensive surveillance to facilitate the implementation of effective control measures.

In 2017, Sri Lanka experienced its largest dengue epidemic and reported severe and unusual presentations of dengue with high morbidity. This outbreak was associated with the reemergence of dengue virus-2 (DENV-2), with the responsible strain identified as a variant of the previously circulating DENV-2 cosmopolitan genotype. In this study, we characterized the DENV-2 cosmopolitan genotype from patients during this epidemic. Also, we identified host factors that contributed to the severity of dengue infection in patients infected with this particular virus. Ninety-one acute serum samples from patients at the National Hospital in Kandy were randomly selected. Of these, 40.2% and 48.9% were positive for dengue IgM and IgG, respectively. NS1 antigen levels were significantly higher in primary infections. The severe dengue (SD) and dengue with warning signs (DWWS) groups exhibited significantly higher viral genome and infectivity titers than the dengue without warning signs (DWoWS) group. The highest viremia level was observed in SD patients. As for host cytokine response, interferon α (IFN-α) levels were significantly higher in the DWoWS group than in the DWWS and SD groups, whereas interleukin (IL)-12p40 and tumor necrosis factor α (TNF-α) levels in SD patients were significantly higher than in the other two groups. The TNF-α, IL-4, and monocyte chemoattractant protein-1 concentrations were positively correlated with NS1 antigen levels. From whole-genome analysis, NS4 had the highest frequency of amino acid variants, followed by the E gene. Our study suggests that viremia levels and immune responses contributed to SD outcomes, and these findings may help in identifying an effective therapeutic strategy against SD infection.

Arboviruses are responsible for epidemics and are emerging and re-emerging in sub-Saharan Africa. However, the risk factors for arboviral diseases are poorly described in Kenyan children. Knowledge of risk factors can facilitate earlier diagnosis and better treatment and implementation of effective prevention in children.This study determined risk factors for seropositivity to Yellow fever (YFV), Dengue (DENV), Chikungunya (CHIKV) and West Nile (WNV) viruses among children at two facilities in Teso Sub-County in Western Kenya.In a hospital-based cross-sectional survey, the risk factors for seropositivity to the arboviruses were assessed. Eligible children aged 1 to 12 (n = 656) who visited Alupe Sub County Hospital and KEMRI Alupe Clinic in Teso Sub County were recruited. Socio-demographic, environmental, behavioural and medical information was collected using a questionnaire. Blood drawn from these children was screened for antibodies to YFV, DENV, CHIKV and WNV using Indirect Enzyme-Linked Immunosorbent Assays. Descriptive statistics were used to summarise seroprevalence, socio-demographic, clinical and environmental variables. Binomial logistic regression described the relationship between the risk factors and arbovirus seropositivity.Seropositivity to at least one arbovirus was found in 27.7%, with 15.7% being positive for DENV, 9.6% for WNV, 5.6% for CHIKV and 4.4% for YFV.The factors that significantly increased the risk to at least one of the arboviruses were: age 6-9 years (by 18%, p =0.006) compared to those 1-3 years, school attendance (by 66%, p =0.000) compared to none, the primary caregiver being “Other” (by 17%, p=0.026) and not the parent, the use of Olyset (by 7%, p =0.039), or an unknown mosquito net (by 26%, p =0.020) compared to Permanet.The risk of yellow fever seropositivity was increased where vegetation was close to the house (by 5%, p =0.042) compared to where vegetation was far. The risk was decreased by the use of an unknown bed net (by 4%, p=0.046) compared to Permanet and having a past history of rash (by 6%, p=0.018).For Dengue Fever, females were at an increased risk (by 8%, p =0.002) compared to males and having water bodies near the house (7%, p =0.030).The risk of chikungunya was increased by school attendance (by 25%, p =0.021) compared to not, the use of mosquito repellents (by 10%, p =0.006) compared to no interventions and having had a rash in the past (by 6%, p =0.043). The risk was decreased by roofing with iron sheets (by 3%, p =0.048) compared to grass-thatching. WNV seropositivity risk was higher in those aged 3-6 years (by 8%, p =0.004) and 6-9 years (by 15%, p =0.004) than in those aged 1-3 years. It was increased in those attending school (by 37%, p =0.006) compared to those not, and those using Olyset (by 11%, p =0.000) or an unknown bed net (by 30%, p =0.001) compared to Permanet. The risk was lower by between 25% and 33% ( p <0.003) in those in pre-school, in lower and upper primary compared to those not in school. These factors are amenable to interventions that can be implemented to prevent and reduce arbovirus infections in children in endemic areas in Kenya.Author Summary Yellow fever, Dengue, Chikungunya and West Nile are viruses (Arboviruses) transmitted to humans by mosquitoes. These infections are common in Sub-Saharan Africa and often affect children. However, the risk factors associated with arboviral infections are not well described, and yet, knowledge of these predisposing factors in children is essential for early diagnosis, correct treatment, and prevention. We carried out this study to determine the factors associated with these infections. We recruited 656 children aged between 1-12 years who sought health services at Alupe Sub-County Hospital and KEMRI Alupe Clinic in Teso Sub-County, Western Kenya. We used a structured questionnaire to collect data on sociodemographic, behavioural, environmental, and clinical factors. We then drew blood from these children and screened it for the four arboviruses. Out of 656 participants, 182 (27.7%) were seropositive for at least one of the four arboviruses, 29 (4.4%) for Yellow Fever, 102 (15.7%) for Dengue, 36 (5.6%) for Chikungunya and 62 (9.6%) for West Nile virus. We established that gender, age, school attendance, the primary caregiver, design of the house, type of mosquito nets used, skin rashes and other mosquito control methods all influence the risk of seropositivity. These behavioural, environmental, sociodemographic and clinical factors that influence arbovirus seropositivity are amenable to interventions that can be implemented within the community to reduce the risk and prevalence of arboviruses in children in endemic areas in Kenya.### Competing Interest StatementThe authors have declared no competing interest.### Funding StatementThis work was supported by the Department of Virology, Nagasaki University Institute of Tropical Medicine, Nagasaki, Japan and Kenya Medical Research Institute, Nairobi, Kenya.### Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:Kenyatta National Hospital-University of Nairobi Ethics and Research Committee P.O Box 19676-00202 Nairobi Email: uonknh_erc@uonbi.ac.ke Telephone: 0799-495829 / 0799-495830I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.YesRequests for data requests can be made to: The Director Kenya Medical Research Institute (KEMRI). Email: director{at}kemri.go.ke

In search of a mouse model for use in evaluating dengue vaccines, we assessed A129 mice that lacked IFN-α/β receptors, rendering them susceptible to dengue virus (DENV) infection. To our knowledge, no reports have evaluated dengue vaccine efficiency using A129 mice. A129 mice were given a single intraperitoneal (IP) or subcutaneous (SC) injection of the vaccine, Dengvaxia. After 14 days of immunization via the IP or SC injection of Dengvaxia, the A129 mice exhibited notably elevated levels of anti-DENV immunoglobulin G and neutralizing antibodies (NAb) targeting all four DENV serotypes, with DENV-4 displaying the highest NAb levels. After challenge with DENV-2, Dengvaxia and mock-immunized mice survived, while only the mock group exhibited signs of morbidity. Viral genome levels in the serum and tissues (excluding the brain) were considerably lower in the immunized mice compared to those in the mock group. The SC administration of Dengvaxia resulted in lower viremia levels than IP administration did. Therefore, given that A129 mice manifest dengue-related morbidity, including viremia in the serum and other tissues, these mice represent a valuable model for investigating novel dengue vaccines and antiviral drugs and for exploring dengue pathogenesis.

Negeviruses that infect insects are recently identified virus species that are phylogenetically related to several plant viruses. They exhibit a unique virion structure, an elliptical core with a short projection. Negeviruses encode two structural proteins, a glycoprotein that forms a short projection, and an envelope protein that forms an elliptical core. The glycoprotein has been reported only in the negeviruses' genes, and not in phylogenetically related plant viruses' genes. In this report, we first describe the three-dimensional electron cryo-microscopy (cryo-EM) structure of Tanay virus (TANAV), one of the nege-like viruses. TANAV particle demonstrates a periodical envelope structure consisting of three layers surrounding the centred viral RNA. The elliptical core dynamically changes its shape under acidic and even low detergent conditions to form bullet-like or tubular shapes. The further cryo-EM studies on these transformed TANAV particles reveal their overall structural rearrangement. These findings suggest putative geometries of TANAV and its transformation in the life cycle, and the potential importance of the short projection for enabling cell entry to the insect hosts.

Background: Zika Virus (ZIKV) is a re-emerging, arthropod-borne flavivirus transmitted byAedes mosquitoes (Ae. aegypti and Ae. albopictus). The coexistence of dengue virus (DENV) and ZIKV concurrently has been associated with a wide array of neurological complications, which may influence the clinical outcomes of infections. Sri Lanka witnessed a severe dengue epidemic in 2017, characterized by extraordinary and severe disease manifestations with considerable morbidity. Therefore, this study assessed the potential occurrence of ZIKV infection during DENV outbreak in Sri Lanka from 2017 to 2019, which could bear substantial implications for public health.Methods: Five hundred ninety-five serum samples were procured from individuals suspected of dengue and admitted to Kandy National Hospital between 2017 and 2018 and the Negombo District General Hospital be-tween 2018 and 2019. These samples underwent quantitative real-time RT-PCR (qRT-PCR) to identify the presence of the ZIKV gene, while enzyme-linked immunosorbent assay was employed to detect ZIKV-specific IgM and IgG antibodies. Focus reduction neutralization tests were subsequently conducted to confirm ZIKV infection.Results: Among the 595 serum samples, 6 (1.0%) tested positive for ZIKV using qRT-PCR. Anti-ZIKV IgM and IgG were identified in 18.0% and 38.6% patients. Sixty-six (11.0%) samples demonstrated the presence of anti-ZIKV IgM and IgG. Within ZIKV IgM-positive samples, 2.2% exhibited neutralizing antibodies against ZIKV. Through the implementation of qRT-PCR, ZIKV IgM detection, and neutralization testing, 2% and 3.7% cases of ZIKV infections were confirmed in the Kandy and Negombo regions, respectively.Conclusion: This study is the inaugural endeavor to substantiate the existence of ZIKV infection in Sri Lanka utilizing molecular and serological analysis. The findings of this investigation imply that ZIKV was circulating throughout the 2017-2019 DENV outbreak. These results underscore the necessity for improved preparedness for future outbreaks, fortifying governmental policies on public health, and establishing effective early warning systems regarding the emergence of these viruses.& COPY; 2023 The Author(s). Published by Elsevier Ltd on behalf of King Saud Bin Abdulaziz University for Health Sciences. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/ 4.0/).

Several Zika virus (ZIKV) seroprevalence studies have been conducted in Africa, Asia, Oceania, the Americas, and the Caribbean. However, studies on ZIKV seroprevalence are limited in Malaysia though several studies have shown that the disease is endemic in the Malaysian state of Sabah. To evaluate the seroprevalence of ZIKV infection, 818 serum samples were collected from febrile patients and healthy blood donors from the Kudat and Kota Kinabalu districts in Sabah from 2017 to 2018. They were screened for ZIKV infection by IgM and IgG ELISA, and positive ZIKV IgM samples were subjected to a 90% neutralization test for confirmation. Twenty-four (6% [95% CI 4 to 8]) confirmed and two (0.5% [95% CI 0.13 to 1.8]) probable ZIKV infections were detected among 400 febrile illness patients. Of 418 healthy blood donor samples, six (1.4% [95% CI 0.65 to 3]) were determined as confirmed ZIKV infections and six (1.4% [95% CI 0.65 to 3]) indicated probable ZIKV infection. This is the first study on the seroprevalence of ZIKV infections among patients and healthy blood donors in Sabah. Compared with previous studies in Malaysia, this study shows that the incidence of ZIKV infection has increased. It also suggests that a sero-surveillance system is essential to determine the circulation of ZIKV in Sabah, Malaysia.