JN.1 variants circulating in Italy from October 2023 to April 2024: genetic diversity and immune recognition

Abstract Background The continuous emergence of SARS-CoV-2 variants and subvariants poses significant public health challenges. The latest designated subvariant JN.1, with all its descendants, shows more than 30 mutations in the spike gene. JN.1 has raised concerns due to its genomic diversity and i...

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Main Authors: Emanuela Giombini, Ilaria Schiavoni, Luigina Ambrosio, Alessandra Lo Presti, Angela Di Martino, Stefano Fiore, Pasqualina Leone, Francesca Fortunato, Rosa Prato, Giorgio Fedele, Anna Teresa Palamara, Paola Stefanelli, the Italian Genomic Laboratory Network
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Language:English
Published: BMC 2025-02-01
Series:BMC Infectious Diseases
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Online Access:https://doi.org/10.1186/s12879-025-10685-0
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author Emanuela Giombini
Ilaria Schiavoni
Luigina Ambrosio
Alessandra Lo Presti
Angela Di Martino
Stefano Fiore
Pasqualina Leone
Francesca Fortunato
Rosa Prato
Giorgio Fedele
Anna Teresa Palamara
Paola Stefanelli
the Italian Genomic Laboratory Network
author_facet Emanuela Giombini
Ilaria Schiavoni
Luigina Ambrosio
Alessandra Lo Presti
Angela Di Martino
Stefano Fiore
Pasqualina Leone
Francesca Fortunato
Rosa Prato
Giorgio Fedele
Anna Teresa Palamara
Paola Stefanelli
the Italian Genomic Laboratory Network
author_sort Emanuela Giombini
collection DOAJ
description Abstract Background The continuous emergence of SARS-CoV-2 variants and subvariants poses significant public health challenges. The latest designated subvariant JN.1, with all its descendants, shows more than 30 mutations in the spike gene. JN.1 has raised concerns due to its genomic diversity and its potential to enhance transmissibility and immune evasion. This study aims to analyse the molecular characteristics of JN.1-related lineages (JN.1*) identified in Italy from October 2023 to April 2024 and to evaluate the neutralization activity against JN.1 of a subsample of sera from individuals vaccinated with XBB.1.5 mRNA. Methods The genomic diversity of the spike gene of 794 JN.1* strain was evaluated and phylogenetic analysis was conducted to compare the distance to XBB.1.5. Moreover, serum neutralization assays were performed on a subsample of 19 healthcare workers (HCWs) vaccinated with the monovalent XBB.1.5 mRNA booster to assess neutralizing capacity against JN.1. Results Sequence analysis displayed high spike variability between JN.1* and phylogenetic investigation confirmed a substantial differentiation between JN.1* and XBB.1.5 spike regions with 29 shared mutations, of which 17 were located within the RBD region. Pre-booster neutralization activity against JN.1 was observed in 42% of HCWs sera, increasing significantly post-booster, with all HCWs showing neutralization capacity three months after vaccination. A significant correlation was found between anti-trimeric Spike IgG levels and neutralizing titers against JN.1. Conclusions The study highlights the variability of JN.1* in Italy. Results on a subsample of sera from HCWs vaccinated with XBB.1.5 mRNA booster vaccine suggested enhanced neutralization activity against JN.1.
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spelling doaj-art-ff4ee79c8de54af8bdfc6d617e7d88bf2025-08-20T03:04:01ZengBMCBMC Infectious Diseases1471-23342025-02-0125111010.1186/s12879-025-10685-0JN.1 variants circulating in Italy from October 2023 to April 2024: genetic diversity and immune recognitionEmanuela Giombini0Ilaria Schiavoni1Luigina Ambrosio2Alessandra Lo Presti3Angela Di Martino4Stefano Fiore5Pasqualina Leone6Francesca Fortunato7Rosa Prato8Giorgio Fedele9Anna Teresa Palamara10Paola Stefanelli11the Italian Genomic Laboratory NetworkDepartment of Infectious Diseases, Istituto Superiore Di SanitàDepartment of Infectious Diseases, Istituto Superiore Di SanitàDepartment of Infectious Diseases, Istituto Superiore Di SanitàDepartment of Infectious Diseases, Istituto Superiore Di SanitàDepartment of Infectious Diseases, Istituto Superiore Di SanitàDepartment of Infectious Diseases, Istituto Superiore Di SanitàDepartment of Infectious Diseases, Istituto Superiore Di SanitàDepartment of Medical and Surgical Sciences, Hygiene Unit, Policlinico Foggia Hospital, University of FoggiaDepartment of Medical and Surgical Sciences, Hygiene Unit, Policlinico Foggia Hospital, University of FoggiaDepartment of Infectious Diseases, Istituto Superiore Di SanitàDepartment of Infectious Diseases, Istituto Superiore Di SanitàDepartment of Infectious Diseases, Istituto Superiore Di SanitàAbstract Background The continuous emergence of SARS-CoV-2 variants and subvariants poses significant public health challenges. The latest designated subvariant JN.1, with all its descendants, shows more than 30 mutations in the spike gene. JN.1 has raised concerns due to its genomic diversity and its potential to enhance transmissibility and immune evasion. This study aims to analyse the molecular characteristics of JN.1-related lineages (JN.1*) identified in Italy from October 2023 to April 2024 and to evaluate the neutralization activity against JN.1 of a subsample of sera from individuals vaccinated with XBB.1.5 mRNA. Methods The genomic diversity of the spike gene of 794 JN.1* strain was evaluated and phylogenetic analysis was conducted to compare the distance to XBB.1.5. Moreover, serum neutralization assays were performed on a subsample of 19 healthcare workers (HCWs) vaccinated with the monovalent XBB.1.5 mRNA booster to assess neutralizing capacity against JN.1. Results Sequence analysis displayed high spike variability between JN.1* and phylogenetic investigation confirmed a substantial differentiation between JN.1* and XBB.1.5 spike regions with 29 shared mutations, of which 17 were located within the RBD region. Pre-booster neutralization activity against JN.1 was observed in 42% of HCWs sera, increasing significantly post-booster, with all HCWs showing neutralization capacity three months after vaccination. A significant correlation was found between anti-trimeric Spike IgG levels and neutralizing titers against JN.1. Conclusions The study highlights the variability of JN.1* in Italy. Results on a subsample of sera from HCWs vaccinated with XBB.1.5 mRNA booster vaccine suggested enhanced neutralization activity against JN.1.https://doi.org/10.1186/s12879-025-10685-0SARS-CoV-2JN.1Genomic surveillancePhylogenetic analysisNeutralizing antibodies
spellingShingle Emanuela Giombini
Ilaria Schiavoni
Luigina Ambrosio
Alessandra Lo Presti
Angela Di Martino
Stefano Fiore
Pasqualina Leone
Francesca Fortunato
Rosa Prato
Giorgio Fedele
Anna Teresa Palamara
Paola Stefanelli
the Italian Genomic Laboratory Network
JN.1 variants circulating in Italy from October 2023 to April 2024: genetic diversity and immune recognition
BMC Infectious Diseases
SARS-CoV-2
JN.1
Genomic surveillance
Phylogenetic analysis
Neutralizing antibodies
title JN.1 variants circulating in Italy from October 2023 to April 2024: genetic diversity and immune recognition
title_full JN.1 variants circulating in Italy from October 2023 to April 2024: genetic diversity and immune recognition
title_fullStr JN.1 variants circulating in Italy from October 2023 to April 2024: genetic diversity and immune recognition
title_full_unstemmed JN.1 variants circulating in Italy from October 2023 to April 2024: genetic diversity and immune recognition
title_short JN.1 variants circulating in Italy from October 2023 to April 2024: genetic diversity and immune recognition
title_sort jn 1 variants circulating in italy from october 2023 to april 2024 genetic diversity and immune recognition
topic SARS-CoV-2
JN.1
Genomic surveillance
Phylogenetic analysis
Neutralizing antibodies
url https://doi.org/10.1186/s12879-025-10685-0
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