Molecular Evolutionary Analyses of the RNA-Dependent RNA Polymerase (RdRp) Region and VP1 Gene in Sapovirus GI.1 and GI.2

Human sapovirus (HuSaV) is a significant cause of gastroenteritis. This study aims to analyze the evolutionary dynamics of the RNA-dependent RNA polymerase (<i>RdRp</i>) and capsid (<i>VP1</i>) genes of the HuSaV GI.1 and GI.2 genotypes between 1976 and 2020. Using bioinformatics tools such as the Bayesian phylogenetics software BEAST 2 package (v.2.7.6), we constructed time-scale evolutionary trees based on the gene sequences. Most of the recent common ancestors (MRCAs) of the <i>RdRp</i> region and <i>VP1</i> gene in the present HuSaV GI.1 diverged around 1930 and 1933, respectively. The trees of the HuSaV GI.1 <i>RdRp</i> region and <i>VP1</i> gene were divided into two clusters. Further, the MRCAs of the <i>RdRp</i> region and <i>VP1</i> gene in HuSaV GI.2 diverged in 1960 and 1943, respectively. The evolutionary rates were higher for <i>VP1</i> gene in HuSaV GI.1 than that in HuSaV GI.2, furthermore, were higher in GI.1 Cluster B than GI.1 Cluster A. In addition, a steep increase was observed in the time-scaled genome population size of the HuSaV GI.1 Cluster B. These results indicate that the HuSaV GI.1 Cluster B may be evolving more actively than other genotypes. The conformational B-cell epitopes were predicted with a higher probability in <i>RdRp</i> for GI.1 and in <i>VP1</i> for GI.2, respectively. These results suggest that the <i>RdRp</i> region and <i>VP1</i> gene in HuSaV GI.1 and GI.2 evolved uniquely. These findings suggest unique evolutionary patterns in the <i>RdRp</i> region and <i>VP1</i> gene of HuSaV GI.1 and GI.2, emphasizing the need for a 'One Health' approach to better understand and combat this pathogen.