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Vagner Fonseca

Publications and source records attributed to Vagner Fonseca.

2 recordsLinked to original sources

Nanopore Sequencing for Chikungunya Virus: Principles and Application.

Nanopore sequencing is transforming viral genomics through real-time, portable, long-read analysis of RNA and DNA. Unlike traditional short-read platforms, it detects nucleotide sequences by measuring ionic current changes as nucleic acids pass through nanoscale pores, enabling direct single-molecule sequencing and base modification detection. Its simplicity, flexibility, and capacity for ultra-long reads make it ideal for resolving complex genomic regions, structural variants, and full viral genomes. These advantages have accelerated its use in pathogen surveillance and outbreak response, especially in resource-limited settings. For chikungunya virus (CHIKV), nanopore sequencing allows rapid, culture-independent recovery of complete genomes from clinical and vector samples, enabling real-time tracking of viral diversity, evolution, and spread. Experiences from Ebola, Zika, and COVID-19 have demonstrated the power of portable sequencing, now applied to CHIKV monitoring. Advances in tools such as Guppy, Dorado, Minimap2, and Medaka enhance read quality, consensus accuracy, and downstream analyses. Despite challenges in basecalling and error correction, robust quality control pipelines ensure reliable results. Ongoing improvements in chemistry, flow cell design, and machine learning will further enhance fidelity and throughput, establishing nanopore sequencing as a cornerstone of CHIKV genomic surveillance and epidemic preparedness.

Chikungunya virus

Global inequities in hepatitis B and C genomic surveillance revealed through an interactive data integration dashboard.

OBJECTIVES: To assess global disparities in hepatitis B virus (HBV) and hepatitis C virus (HCV) genomic surveillance and to develop an integrated platform that links genomic data with epidemiological burden. STUDY DESIGN: Retrospective observational analysis. METHODS: We reviewed existing viral genomic repositories to identify structural and analytical limitations. Subsequently, we integrated 10 996 HBV and 3533 HCV whole-genome sequences (WGS) from public databases with Global Burden of Disease (GBD) estimates to quantify inequities in genomic surveillance across countries and genotypes. Using these data, we developed the open-access Hepatitis Dashboard, incorporating >14 000 sequences from 141 countries with GBD metrics to evaluate representativeness and sequencing coverage relative to disease burden. RESULTS: Marked inequities in hepatitis genomic surveillance were identified. Despite increasing HBV- and HCV-associated mortality, virus sequence availability remains geographically and genotypically skewed-dominated by China and the United States, with substantial underrepresentation of HBV genotype E and HCV genotypes 5 and 8. Many high-endemic countries in Africa and the Western Pacific remain severely undersampled. We detected circulating antiviral drug-resistance mutations and developed a burden-adjusted sequencing coverage metric, revealing that several high-burden countries, including China, Nigeria and India, are among the least represented in global genomic datasets. Projections to 2030 indicate that neither HBV nor HCV are currently on track to meet WHO elimination targets. CONCLUSIONS: The Hepatitis Dashboard provides an integrated, continuously updated resource that links genomic and epidemiological data to quantify and visualise global surveillance gaps. This analysis highlights a critical disconnect between sequencing efforts and public health needs, which may limit the effectiveness of surveillance-informed strategies to support progress toward WHO 2030 elimination goals. By enabling burden-adjusted prioritisation and longitudinal tracking of genomic coverage, the platform supports evidence-based sampling strategies, equitable resource allocation, and monitoring of global progress toward hepatitis elimination.

Humans