ORIGINAL RESEARCH article
Front. Microbiol.
Sec. Virology
Detection and genomic characterization of West Nile virus lineage 2 in captive harbor seals in Southern Italy
- CD
Claudio De Martinis 1
- LC
Lorena Cardillo 1
- MG
Marta Giovanetti 2
- AP
Alessia Pucciarelli 1
- GP
Gerardo Picazio 1
- MV
Maurizio Viscardi 1
- LC
Loredana Cozzolino 1
- SC
Sara Cavaliere 1
- AN
Alessia Napolitano 1
- ML
Maria Lella 1
- MD
Maria Dimatteo 1
- PS
Pasquale Silvestre 3
- ED
Evaristo Di Napoli 4
- ND
Nicola D'Alessio 1
- ED
Esterina De Carlo 1
- GG
GIORGIO GALIERO 1
- GI
Giuseppe Iovane 1
- OP
Orlando Paciello 1
- GF
Giovanna Fusco 1
1. Experimental Zooprophylactic Institute of Southern Italy (IZSM), Portici, Italy
2. Universita Campus Bio-Medico di Roma, Rome, Italy
3. Azienda Sanitaria Locale Napoli 2 Nord, Pozzuoli, Italy
4. Universita degli Studi di Napoli Federico II, Naples, Italy
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Abstract
West Nile virus (WNV) is a mosquito-borne flavivirus maintained in bird-mosquito cycles, with occasional spillover events causing neuroinvasive disease in humans and animals. This study describes two fatal cases of West Nile virus (WNV) lineage 2 infection in captive harbor seals housed in a zoological park in southern Italy, together with genomic characterization and phylogenetic analysis of the detected strains. Harbour seals were tested by multiplex real-time RT-PCR for the simultaneous detection of lineage 1 and 2. Next, selected extracts were analyzed by droplet digital PCR (dd-PCR). Next-generation sequencing was performed and phylogenetically analyzed. A CDC light trap was used for targeted mosquito collection near the fence of the dead harbor seals and female mosquitoes were screened for WNV. Histopathology was also carried out in one seal. WNV lineage 2 RNA was detected in central nervous system tissues of both seals and in female Culex pipiens pool collected. Near-complete genomes clustered with contemporary southern Italian strains and was consistent with local circulation. These findings document WNV lineage 2 infection associated with fatal neurological disease in harbor seals, expanding the knowledge of host range of infection of this virus, also supported by in-situ entomological and genomic evidence. Altogether, this study highlights the value of integrated One Health surveillance approach in zoological parks
Summary
Keywords
Fatal cases, Genetic characterization, Harbor seals, lineage 2, West Nile virus
Received
14 July 2026
Accepted
03 August 2026
Copyright
© 2026 De Martinis, Cardillo, Giovanetti, Pucciarelli, Picazio, Viscardi, Cozzolino, Cavaliere, Napolitano, Lella, Dimatteo, Silvestre, Di Napoli, D'Alessio, De Carlo, GALIERO, Iovane, Paciello and Fusco. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Lorena Cardillo
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