ArticlePLoS neglected tropical diseases2018
Viridot: An automated virus plaque (immunofocus) counter for the measurement of serological neutralizing responses with application to dengue virus.
Article in PLoS neglected tropical diseases, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 75 papers.
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Who cites it
75 citing papers in PubMed.
- Rapid decline in vaccine-boosted neutralizing antibodies against SARS-CoV-2 Omicron variant.Cell reports. Medicine · 2022Trial
- Automated Counting of Chikungunya Virus-Formed Plaques.Methods in molecular biology (Clifton, N.J.) · 2027Article
- Immunological imprinting shapes the cross-reactive antibody responses to the KP.2 and LP.8.1 vaccine doses.Journal of virology · 2026Article
- Enhancing, controlling, and sterilizing dengue immunity and the development of broadly protective responses.medRxiv : the preprint server for health sciences · 2026Article
- A weakly supervised framework for automated biological assay assessment.Virus research · 2026Article
- Monocyte-eosinophil signaling axis promotes vaccine-mediated protection against SARS-CoV-2.PLoS pathogens · 2025Article
- Evolution of the PRNT: Merging tradition and innovation to set the gold standard in the era of automation.Human vaccines & immunotherapeutics · 2025Review
- mRNA-LNP Vaccines Encoding for Dengue Optimized prM/ENV Proteins Induce Protective Immunity without ADE.bioRxiv : the preprint server for biology · 2025Article
- PyPlaque is an open-source python package for phenotypic analysis of virus plaque assays.Scientific reports · 2025Article
- Protective envelope dimer epitope-like antibodies are elicited against dengue virus in children after infection and vaccination.Science translational medicine · 2025Article
- Multivalent administration of dengue E dimers on liposomes elicits type-specific neutralizing responses without immune interference.NPJ vaccines · 2025Article
- Stabilized dengue virus 2 envelope subunit vaccine redirects the neutralizing antibody response to all E-domains.Journal of virology · 2025Article
- Immune imprinting and vaccine interval determine antibody responses to monovalent XBB.1.5 COVID-19 vaccination.Communications medicine · 2025Article
- Altered baseline immunological state and impaired immune response to SARS-CoV-2 mRNA vaccination in lung transplant recipients.Cell reports. Medicine · 2025Article
- Development of an automated plaque-counting program for the quantification of the Chikungunya virus.Scientific reports · 2025Article
- Immunity to Non-Dengue Flaviviruses Impacts Dengue Virus Immunoglobulin G Enzyme-Linked Immunosorbent Assay Specificity in Cambodia.The Journal of infectious diseases · 2025Observational
- Dengue virus IgG and neutralizing antibody titers measured with standard and mature viruses are protective.Nature communications · 2025Article
- Development and Concordance of Binding and Neutralizing Assays to Determine SARS-CoV-2 Antibody Activity in Human Milk.Pathogens & immunity · 2025Article
- Influence of blood trace elements on immune responses and adverse symptoms subsequent to Sinopharm COVID-19 vaccination.Scientific reports · 2024Article
- Divergence of variant antibodies following SARS-CoV-2 booster vaccines in myeloma and impact of hybrid immunity.NPJ vaccines · 2024Article
15 more citing papers are in PubMed but not listed here.
Corrections and comments
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Authors and funding
13 authors.
Funding
Abstract
The gold-standard method for quantifying neutralizing antibody responses to many viruses, including dengue virus (DENV), is the plaque reduction neutralization test (PRNT, also called the immunofocus reduction neutralization test). The PRNT conducted on 96-well plates is high-throughput and requires a smaller volume of antiserum than on 6- or 24-well plates, but manual plaque counting is challenging and existing automated plaque counters are expensive or difficult to optimize. We have developed Viridot (Viridot package), a program for R with a user interface in shiny, that counts viral plaques of a variety of phenotypes, estimates neutralizing antibody titers, and performs other calculations of use to virologists. The Viridot plaque counter includes an automatic parameter identification mode (misses <10 plaques/well for 87% of diverse DENV strains [n = 1521]) and a mode that allows the user to fine-tune the parameters used for counting plaques. We compared standardized manual and Viridot plaque counting methods applied to the same wells by two analyses and found that Viridot plaque counts were as similar to the same analyst's manual count (Lin's concordance correlation coefficient, ρc = 0.99 [95% confidence interval: 0.99-1.00]) as manual counts between analysts (ρc = 0.99 [95% CI: 0.98-0.99]). The average ratio of neutralizing antibody titers based on manual counted plaques to Viridot counted plaques was 1.05 (95% CI: 0.98-1.14), similar to the average ratio of antibody titers based on manual plaque counts by the two analysts (1.06 [95% CI: 0.84-1.34]). Across diverse DENV and ZIKV strains (n = 14), manual and Viridot plaque counts were mostly consistent (range of ρc = 0.74 to 1.00) and the average ratio of antibody titers based on manual and Viridot counted plaques was close to 1 (0.94 [0.86-1.02]). Thus, Viridot can be used for plaque counting and neutralizing antibody titer estimation of diverse DENV strains and potentially other viruses on 96-well plates as well as for formalization of plaque-counting rules for standardization across experiments and analysts.
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