Novel highly divergent sapoviruses detected by metagenomics analysis in straw-colored fruit bats in Cameroon

Marc Van Ranst,Jelle Matthijnssens,Mark Zeller,Nádia Conceição-Neto,Elisabeth Heylen,Stephen Mbigha Ghogomu,Claude Kwe Yinda,Piet Maes

doi:10.1038/emi.2017.20

Abstract

Sapoviruses (SaVs) belong to the Sapovirus genus, in the family Caliciviridae. They have been associated with gastroenteritis in humans and in pigs but not in other animals. In addition, some strains from pigs, chimpanzees and rodents show close sequence identity with human SaVs thereby suggesting the possibility of interspecies transmissions. Bats are known to be a major reservoir of zoonotic viruses, however, very little is known about the genetic diversity of SaVs in bats. To explore the genetic diversity of bat SaVs, fecal samples of Eidolon helvum and Epomophorus gambianus were treated according to the NetoVIR protocol and sequenced by Illumina technology. Nearly complete genome sequences of six highly divergent SaVs and one partial SaV (only VP1 region) were identified in Eidolon helvum and based on sequence identities and phylogenetic analysis, they potentially represent two novel genogroups, only distantly related to known SaVs. Furthermore, comparing these sequences with currently used screening primers and probes indicated that the novel SaVs would not be detected in routine epidemiological screening studies in humans in case an interspecies transmission would occur. Therefore, we designed and validated new primers that can detect both human and bat SaVs. In this study, we identified multiple novel bat SaVs, however, further epidemiological studies in humans are needed to unravel their potential role in gastroenteritis.

Highlights

Sapovirus (SaV) particles were first detected in human diarrheic stool samples in 1976 in the United Kingdom using electron microscopy.[1]Shortly thereafter they were recognized as a new gastroenteritis pathogen as reviewed by Oka and colleagues.[2]
SaV genome contains two open reading frames (ORFs): ORF1 encodes for a large polyprotein containing the nonstructural proteins (helicase, VPg, protease, RNA-dependent-RNA-polymerase (RdRp)) followed by the major capsid protein, VP1; ORF2 is predicted to encode for the minor structural protein VP2.5 a third ORF has been found in some human[6,7,8,9,10,11] and bat[12] SaV strains, a known function is yet to be assigned
We describe the nearly complete sequences of six highly divergent SaVs and one partial SaV obtained from the fecal samples of straw-colored fruit bats (Eidolon helvum) in Cameroon

Summary

Introduction

Sapovirus (SaV) particles were first detected in human diarrheic stool samples in 1976 in the United Kingdom using electron microscopy.[1]. Thereafter they were recognized as a new gastroenteritis pathogen as reviewed by Oka and colleagues.[2] Initially these viruses were known as 'typical human caliciviruses' or 'Sapporo-like' viruses. SaV genome contains two open reading frames (ORFs): ORF1 encodes for a large polyprotein containing the nonstructural proteins (helicase, VPg, protease, RNA-dependent-RNA-polymerase (RdRp)) followed by the major capsid protein, VP1; ORF2 is predicted to encode for the minor structural protein VP2.5 a third ORF has been found in some human[6,7,8,9,10,11] and bat[12] SaV strains, a known function is yet to be assigned.

Methods

Results

Conclusion