Distribution of Human Sapovirus Strain Genotypes over the last four Decades in Japan: a Global Perspective

Abstract

Sapovirus (SaV) infections are a public health problem because they cause acute gastroenteritis in humans of all ages both as outbreaks and in sporadic cases. However, publicly-available SaV sequence information, especially whole genome sequences for all the SaV genotypes, is still limited. Therefore, in this study, we determined the full/near-full-length genomic sequences of 138 SaVs from the 2001-2015 seasons in 13 prefectures across Japan. The GI genogroup was predominant (67%, n = 92), followed by GII (18%, n = 25), GIV (9%, n = 12), and GV (6%, n = 9). Within the GI genogroup, four different genotypes were identified, as follows: GI.1 (n=44), GI.2 (n=40), GI.3 (n=7), and GI.5 (n=1). We then compared these Japanese SaV sequences with a total of 3119 public human SaV sequences from 49 countries over the last 46 years. The results indicated that GI.1 and GI.2 have been the predominant genotypes in Japan as well as in other countries over at least four decades. Together with public SaV sequences, the 138 newly determined Japanese SaV sequences could facilitate a better understanding of the evolutionary patterns of SaV genotypes.