Revisiting the genetic diversity of classical swine fever virus: A proposal for new genotyping and subgenotyping schemes of classification

Classical swine fever (CSF) is a highly contagious febrile viral disease caused by CSF virus (CSFV), and it is considered one of the most important infectious diseases that affect domestic pigs and wild boar. Previous molecular epidemiology studies have revealed that the diversity of CSFV comprises three main genotypes and different subgenotypes defined using a reliable cut-off to accurately classify CSFV at genotype and subgenotype levels. However, a growing number of CSFV both complete genome and full E2 gene sequences have been submitted to GenBank (more than 500 sequences are currently available, revised on December 1, 2017). Therefore, the aim of this study was to revisit the taxonomy of CSFV at genotype and subgenotype levels, to unify nomenclature and to provide an update to the classification of CSFV. We propose here a new genotyping scheme with five well-defined CSFV genotypes (CSFV Genotypes 1–5) and 14 subgenotypes (seven for each of the CSFV Genotype 1 and CSFV Genotype 2). The findings showed in this study are relevant for molecular epidemiology approaches and will help to better understand the genetic diversity and spreading of CSFV at a global scale. The update in the classification of CSFV will allow the scientific community to establish more accurately the links among different outbreaks of the disease.