CpG islands: Features and distribution in the genomes of porcine parvovirus

Porcine parvovirus disease is a reproductive disorder caused by the porcine parvovirus (PPV) in sows and is characterised by miscarriage, stillbirth and mummification in pregnant sows. Porcine parvovirus disease poses a significant threat to pork herds and seriously hinders healthy and sustainable development of the pig farming industry. Currently, there is no effective treatment for porcine parvovirus disease except for prevention and control measures. Based on genotype differences, PPV can be classified into at least eight subtypes, PPV1-PPV8. Epigenetic mechanisms, particularly cytosine methylation of cytosine-phosphate-guanine (CpG) dinucleotides, are proven to have a significant impact on the life cycle of various viruses. Therefore, we selected the PPV genome as the research object and analysed the number, distribution and length of CpG islands in the genome of strains PPV1-PPV8. PPV1-6 had AT rich genomes (GC content ≤50%), whereas PPV7 had a GC content >50%. PPV1, PPV4, PPV5 and PPV6 contained fewer CpG islands (1-5), PPV7 contained moderate CpG islands (6-11) and PPV2 and PPV3 contained more CpG islands (12-16). This study provides a foundation for exploring novel antiviral treatment strategies from an epigenetic perspective.