Dissection of pleiotropic effects of variants in and adjacent to F8 exon 19 and rescue of mRNA splicing and protein function.

The pathogenic significance of nucleotide variants commonly relies on nucleotide position within the gene, with exonic changes generally attributed to quantitative or qualitative alteration of protein biosynthesis, secretion, activity, or clearance. However, these changes may exert pleiotropic effects on both protein biology and mRNA splicing due to the overlapping of the amino acid and splicing codes, thus shaping the disease phenotypes. Here, we focused on hemophilia A, in which the definition of F8 variants' causative role and association to bleeding phenotypes is crucial for proper classification, genetic counseling, and management of affected individuals. We extensively characterized a large panel of hemophilia A-causing variants (n = 30) within F8 exon 19 by combining and comparing in silico and recombinant expression analyses. We identified exonic variants with pleiotropic effects and dissected the altered protein features of all missense changes. Importantly, results from multiple prediction algorithms provided qualitative results, while recombinant assays allowed us to correctly infer the likely phenotype severity for 90% of variants. Molecular characterization of pathogenic variants was also instrumental for the development of tailored correction approaches to rescue splicing affecting variants or missense changes impairing protein folding. A single engineered U1snRNA rescued mRNA splicing of nine different variants and the use of a chaperone-like drug resulted in improved factor VIII protein secretion for four missense variants. Overall, dissection of the molecular mechanisms of a large panel of HA variants allowed precise classification of HA-affected individuals and favored the development of personalized therapeutic approaches.

Isolation and Molecular Evidence of Tunisian Sheep-like Pestivirus (Pestivirus N) in Persistently Infected Sheep in Northern Italy, 2023.

Over the last few decades, several pestiviruses have been discovered in ruminants, pigs, and, more recently, in non-ungulate hosts. Consequently, the nomenclature and taxonomy of pestiviruses have been updated. The Tunisian sheep-like pestivirus (TSV, Pestivirus N) is an additional ovine pestivirus genetically closely related to classical swine fever virus (CSFV). In this study, during a survey of pestivirus infections in ovine farms in the Lombardy region of Northern Italy, we identified and isolated a pestivirus strain from a sheep that was found to belong to Pestivirus N species based on its genomic nucleotide identity. The sheep itself and its lamb were found to be persistently infected. We performed molecular characterization and phylogenetic analysis of three viral genomic regions (a fragment of 5'-UTR, partial Npro, and the whole E2 region). In conclusion, these results confirmed circulating TSV in Northern Italy after notification in Sicily, Italy, and France. Correlation with Italian, Tunisian, and French strains showed that detection might have resulted from the trading of live animals between countries, which supports the need for health control measures.

Presence and Characterisation of Porcine Respirovirus 1 (PRV1) in Northern Italy.

Porcine Respirovirus 1 (PRV1) is an enveloped, single-stranded, negative-sense RNA virus belonging to the genus Respirovirus within the Paramyxoviridae family. Since its first detection in China in 2013, PRV1 has been identified in several American and European countries. Although its pathogenicity is uncertain, recent studies have suggested that it may play a role in the Porcine Respiratory Disease Complex (PRDC) because of its capacity to replicate in the upper and lower respiratory tracts. This study aimed to determine the spread of PRV1 in Northern Italy and the phylogeny of the isolates. Therefore, PRV1 was investigated using real-time RT-PCR in 902 samples collected from September 2022 to September 2023 from pigs with respiratory symptoms in North Italy. Fourteen (1.55%) samples tested as PRV1-positive. The full-length fusion (F) gene, which codifies for a major surface protein, was amplified and used for phylogenetic analysis to help carry out molecular epidemiological studies on this virus. In addition, swine influenza virus (SIV) and porcine reproductive and respiratory syndrome virus (PRRSV) infections were detected in most of the PRV1-positive samples. In conclusion, we report the detection of PRV1 in Italy and discuss its potential role as a co-factor in causing the Porcine Respiratory Disease Complex.