Molecular Characterisation of the Romanian African Swine Fever Virus p72 and B602L Genetic Markers

Abstract

African swine fever (ASF) remains one of the most devastating transboundary diseases affecting domestic pigs and wild boars worldwide, making molecular epidemiology essential for understanding viral transmission and supporting disease control. This study aimed to characterise African swine fever virus (ASFV) isolates circulating in Romania through comparative analysis of the B646L (p72) gene and the B602L central variable region (CVR). Fifty-four ASFV-positive samples collected from domestic pigs and wild boars were confirmed by real-time PCR and subjected to molecular analysis. Following Sanger sequencing and sequence quality assessment, 32 reliable consensus sequences were retained for B602L and 33 for p72. Sequencing of the p72 gene demonstrated a very high degree of nucleotide conservation, confirming that all successfully sequenced isolates belonged to genotype II. In contrast, the B602L region exhibited limited intra-genotypic variability characterised by scattered single nucleotide polymorphisms and localised insertion/deletion events, providing additional molecular resolution compared to p72, although insufficient for fine-scale epidemiological tracking. No genetic segregation according to host species was observed for either genomic region, and sequences obtained from domestic pigs and wild boar were interspersed in the phylogenetic analyses, demonstrating a high degree of genetic similarity at the investigated loci. These findings highlight the complementary value of p72 and B602L for ASFV molecular characterisation, while also indicating that these partial genomic markers alone cannot resolve transmission pathways or epidemiological links between domestic and wild host populations.