Genomic Characterization of Mosquito Isolates of Chikungunya Virus (Outbreak Strains 2022) Using Next-Generation Sequencing.

Background: A massive outbreak of dengue-like illness was reported from Pune district of Maharashtra, India during May-June 2022. Isolation and characterization of the etiological agent at genomic level for possible mutations that led to higher transmissibility is the topic of the study. Methods: Entomological investigations were carried out by ICMR-National Institute of Virology (Pune, India); Aedes aegypti mosquitoes were collected and processed for virus detection by molecular techniques. Positive mosquito pools were processed for virus isolation in cell culture. Sanger sequencing and whole-genome sequencing (WGS) using Oxford Nanopore Technology platform were used for genomic characterization. Results: Reverse transcriptase RT-PCR and qRT-PCR analysis detected chikungunya virus (CHIKV) in mosquito samples. Six CHIKV isolates were obtained. WGS revealed four nonsynonymous mutations in the structural polyprotein region, and five in the nonstructural polyprotein encoding region when compared with Yawat-2000 and Shivane-2016 strains. Sixty-four nucleotide changes in the nonstructural polyprotein region and 35 in the structural polyprotein region were detected. One isolate had an exclusive amino acid change, T1123I, in the nsP2 (protease) region. Conclusion: Abundant Ae. aegypti breeding and detection of CHIKV RNA in mosquitoes confirmed it as a chikungunya outbreak. Novel mutations detected in the epidemic strain warrants investigations to address their role in disease severity, transmission, and fitness.

Seroepidemiological survey on chikungunya in endemic zones for arboviruses in Brazil, 2019.

This study aimed to identify the seroprevalence of chikungunya and its associated factors in the city of Quixadá, Ceará, Brazil. We also aimed to identify the spatial distribution patterns of positive cases. A cross-sectional survey was conducted with a questionnaire about clinical symptoms, socioeconomic and demographic factors, and a 10 ml blood sample was collected and analysed by ELISA. For the bivariate analysis, we use the chi-square test, a prevalence ratio and its 95% confidence interval. A robust Poisson hierarchical regression was used to adjust for confounders. The Kernel density was performed for the spatial analysis. A total of 409 samples were analysed; of them, 70.7% were seropositive for previous exposure to chikungunya virus (CHIKV). High seropositivity for CHIKV was higher in female participants (75.5%; PR = 1.23; 95% CI: 1.06-1.43), those aged 31 years or more (74.3%; PR = 1.62; 95% CI: 1.04-2.52), and those with elementary education level (75.0%; PR = 1.30; 95% CI: 1.06-1.60). There were also high seroprevalence in those with less than a minimum wage per month (89.5%; PR = 1.59; 95% CI: 1.11-2.30), housewives (87.5%; PR = 1.64; 95% CI: 1.24-2.18) and unemployed (80.0%; PR = 1.50; 95% CI: 1.10-2.06). After adjusting for age, morning stiffness was the only chikungunya symptom that remained associated (PR = 1.20; 95% CI: 1.06-1.37; p < .001). There was an area of high density of cases in the downtown and two areas of medium density in nearby regions. Otherwise, the higher seroprevalence rates were in the peripherical neighbourhoods. There is a hyperendemicity of CHIKV in Quixadá, and most cases are spatially contiguous. The main associated clinical sign is morning stiffness, but other factors such as low income and spending a longer time at home were significantly associated with higher seroprevalence.

Engineering and evaluation of amyloid assemblies as a nanovaccine against the Chikungunya virus.

The design of nanoparticles exposing a high density of antigens constitutes a promising strategy to address safety concerns of conventional life-attenuated vaccines as well as to increase the immunogenicity of subunit vaccines. In this study, we developed a fully synthetic nanovaccine based on an amyloid peptide sequence with high self-assembling properties. The immunogenic epitope E2EP3 from the E2 glycoprotein of the Chikungunya virus was used to evaluate the potential of a 10-mer peptide derived from an endogenous amyloidogenic polypeptide as a novel vaccine platform. Chimeric peptides, comprising the peptide antigen attached to the amyloid core by a short flexible linker, were prepared by solid phase synthesis. As observed using atomic force microscopy, these polypeptides self-assembled into linear and unbranched fibrils with a diameter ranging from 6 to 8 nm. A quaternary conformation rich in cross-ß-sheets characterized these assemblies, as demonstrated by circular dichroism spectroscopy and thioflavin T fluorescence. ELISA assays and transmission electronic microscopy of immunogold labeled-fibrils revealed a high density of the Chikungunya virus E2 glycoprotein derived epitope exposed on the fibril surface. These amyloid fibrils were cytocompatible and were efficiently uptaken by macrophages. Mice immunization revealed a robust IgG response against the E2EP3 epitope, which was dependent on self-assembly and did not require co-injection of the Alhydrogel adjuvant. These results indicate that cross-ß-sheet amyloid assemblies constitute suitable synthetic self-adjuvanted assemblies to anchor antigenic determinants and to increase the immunogenicity of peptide epitopes.