Genetic and Biological Diversity of Porcine Sapeloviruses Prevailing in Zambia

Porcine sapelovirus (PSV) has been detected worldwide in pig populations. Although PSV causes various symptoms such as encephalomyelitis, diarrhea, and pneumonia in pigs, the economic impact of PSV infection remains to be determined. However, information on the distribution and genetic diversity of PSV is quite limited, particularly in Africa. In this study, we investigated the prevalence of PSV infection in Zambia and characterized the isolated PSVs genetically and biologically. We screened 147 fecal samples collected in 2018 and found that the prevalences of PSV infection in suckling pigs and fattening pigs were high (36.2% and 94.0%, respectively). Phylogenetic analyses revealed that the Zambian PSVs were divided into three different lineages (Lineages 1–3) in the clade consisting of Chinese strains. The Zambian PSVs belonging to Lineages 2 and 3 replicated more efficiently than those belonging to Lineage 1 in Vero E6 and BHK cells. Bioinformatic analyses revealed that genetic recombination events had occurred and the recombination breakpoints were located in the L and 2A genes. Our results indicated that at least two biologically distinct PSVs could be circulating in the Zambian pig population and that genetic recombination played a role in the evolution of PSVs.