West Nile Virus (WNV) and Tick-Borne Encephalitis Virus (TBEV) are RNA viruses belonging to the Flavivirus family. They are endemic vector-borne pathogens: WNV is transmitted mainly by mosquitoes, while TBEV is transmitted by ticks. Their circulation cycle involves several animal reservoirs, including birds, sheep and horses, whereas human-to-human transmission is considered rare.
Both viruses show a seasonal pattern, with a peak in circulation during the spring and summer months, corresponding to the period of greatest vector activity. In recent years, factors such as climate change, globalisation and the progressive expansion of habitats favourable to mosquitoes and ticks have contributed to the increased spread of these infections. In Friuli Venezia Giulia, since 2020, WNV and TBEV have shown a significant increase in circulation, with particular attention, in the case of TBEV, to the presence of hyper-endemic foci in some mountain areas of the region.
The epidemiological data collected in recent years outline a still-evolving situation, characterised by a growing incidence and increased exposure of the regional population to the risk of infection. Friuli Venezia Giulia therefore represents an area of particular interest for monitoring and studying the spread of these viruses.
An integrated arbovirus surveillance system is currently active in the region, carried out by the Hygiene and Preventive Medicine services of ASUGI. This activity makes it possible to detect the presence or absence of viral infection, but does not include systematic genomic characterisation of the circulating strains. As a result, the available information on the genetic variability of the viruses and their evolution remains limited.
This is the context for the project “West Nile Virus and TBE Virus: Next-generation sequencing for the monitoring of variants in FVG – Vir Watch FVG”, which aims to integrate the existing surveillance system through the use of next-generation sequencing technologies, including Next Generation Sequencing and Illumina platforms.
The objective is to monitor in greater depth the genetic variants of WNV and TBEV circulating in Friuli Venezia Giulia, in order to understand viral evolution, track their spread across the region and contribute to strengthening prevention and control strategies to protect public health.
OBJECTIVE
The data generated within the project will be used, first of all, to identify mutations present in the viral genome and to characterise the circulating variants of West Nile Virus and Tick-Borne Encephalitis Virus. The information obtained will also make it possible to reconstruct viral phylogeny, providing a representation of the evolution of the strains present in the region and of their genetic relationships.
Subsequent analyses will aim to identify which regions of the genome and which proteins are most prone to mutation, as well as those that are more highly conserved. Knowledge of conserved regions is of particular interest, as it may contribute to the identification of potential therapeutic and preventive targets.
In the case of West Nile Virus, this information may provide a useful basis for future studies aimed at the development of vaccines or the optimisation of existing veterinary vaccines. With regard to Tick-Borne Encephalitis Virus, for which a vaccine is already in use in Friuli Venezia Giulia, the preliminary data obtained through the project may help to further assess its suitability in relation to the circulating strains and support possible updating or optimisation strategies.
Overall, the project will make it possible to acquire more in-depth knowledge of the viral population present in the region, providing useful information to anticipate virus circulation in the following seasons of greatest vector activity. The results may therefore contribute to strengthening local strategies for surveillance, prevention and containment of infection in humans.
