High pathogenic avian influenza A(H5) viruses of clade 2.3.4.4b in Europe-Why trends of virus evolution are more difficult to predict.

Since 2016, A(H5Nx) high pathogenic avian influenza (HPAI) virus of clade 2.3.4.4b has become one of the most serious global threats not only to wild and domestic birds, but also to public health. In recent years, important changes in the ecology, epidemiology, and evolution of this virus have been reported, with an unprecedented global diffusion and variety of affected birds and mammalian species. After the two consecutive and devastating epidemic waves in Europe in 2020-2021 and 2021-2022, with the second one recognized as one of the largest epidemics recorded so far, this clade has begun to circulate endemically in European wild bird populations. This study used the complete genomes of 1,956 European HPAI A(H5Nx) viruses to investigate the virus evolution during this varying epidemiological outline. We investigated the spatiotemporal patterns of A(H5Nx) virus diffusion to/from and within Europe during the 2020-2021 and 2021-2022 epidemic waves, providing evidence of ongoing changes in transmission dynamics and disease epidemiology. We demonstrated the high genetic diversity of the circulating viruses, which have undergone frequent reassortment events, providing for the first time a complete overview and a proposed nomenclature of the multiple genotypes circulating in Europe in 2020-2022. We described the emergence of a new genotype with gull adapted genes, which offered the virus the opportunity to occupy new ecological niches, driving the disease endemicity in the European wild bird population. The high propensity of the virus for reassortment, its jumps to a progressively wider number of host species, including mammals, and the rapid acquisition of adaptive mutations make the trend of virus evolution and spread difficult to predict in this unfailing evolving scenario.

Whole genome sequencing and phylogenetic characterisation of rabies virus strains from Moldova and north-eastern Romania.

BACKGROUND: Rabies is the oldest fatal zoonotic disease recognised as a neglected tropical disease and is caused by an RNA virus belonging to the genus Lyssavirus, family Rhabdoviridae. METHODOLOGY/PRINCIPAL FINDINGS: A deep molecular analysis was conducted on full-length nucleoprotein (N) gene and whole genome sequences of rabies virus from 37 animal brain samples collected between 2012 and 2017 to study the circulation of rabies virus (RABV) variants. The overall aim was to better understand their distribution in Moldova and north-eastern Romania. Both Sanger and high throughput sequencing on Ion Torrent and Illumina platforms were performed. Phylogenetic analysis of the RABV sequences from both Moldova and Romania revealed that all the samples (irrespective of the year of isolation and the species) belonged to a single phylogenetic group: north-eastern Europe (NEE), clustering into three assigned lineages: RO#5, RO#6 and RO#7. CONCLUSIONS/SIGNIFICANCE: High throughput sequencing of RABV samples from domestic and wild animals was performed for the first time for both countries, providing new insights into virus evolution and epidemiology in this less studied region, expanding our understanding of the disease.

A Deep-Sequencing Workflow for the Fast and Efficient Generation of High-Quality African Swine Fever Virus Whole-Genome Sequences.

African swine fever (ASF) is a severe disease of suids caused by African swine fever virus (ASFV). Its dsDNA genome (170-194 kbp) is scattered with homopolymers and repeats as well as inverted-terminal-repeats (ITR), which hamper whole-genome sequencing. To date, only a few genome sequences have been published and only for some are data on sequence quality available enabling in-depth investigations. Especially in Europe and Asia, where ASFV has continuously spread since its introduction into Georgia in 2007, a very low genetic variability of the circulating ASFV-strains was reported. Therefore, only whole-genome sequences can serve as a basis for detailed virus comparisons. Here, we report an effective workflow, combining target enrichment, Illumina and Nanopore sequencing for ASFV whole-genome sequencing. Following this approach, we generated an improved high-quality ASFV Georgia 2007/1 whole-genome sequence leading to the correction of 71 sequencing errors and the addition of 956 and 231 bp at the respective ITRs. This genome, derived from the primary outbreak in 2007, can now serve as a reference for future whole-genome analyses of related ASFV strains and molecular approaches. Using both workflow and the reference genome, we generated the first ASFV-whole-genome sequence from Moldova, expanding the sequence knowledge from Eastern Europe.