Reassortant human group C rotaviruses in Hungary

Multiple reassortment and interspecies transmission events contribute to the diversity of porcine-like human rotavirus C strains detected in South Korea

Globally, rotavirus C (RVC) causes diarrhoeal outbreaks, mainly in swine, with sporadic incidents in human, bovine, and canine populations. In this study, two human RVC strains, RVC/Human-wt/KOR/CAU13-1-77/2013 and RVC/Human-wt/KOR/CAU14-1-242/2014, were isolated in South Korea, and their complete genome sequences were compared with those of other human- and animal-origin RVC strains found worldwide. Genetic analysis revealed that these viruses have a G4-P[2]-I2-R2-C2-M3-A2-N2-T2-E2-H2 genotype constellation. Phylogenetic analysis indicated that these Korean RVC strains belong to the M3 lineage of the VP3 gene in human RVC from Japan and China and porcine RVC from Japan. These results suggest that RVC circulates in northeast Asia in both the human and porcine populations. These results also provide evidence of interspecies RVC reassortment events.

Human Group C Rotavirus VP8*s Recognize Type A Histo-Blood Group Antigens as Ligands

Group/species C rotaviruses (RVCs) have been identified as important pathogens of acute gastroenteritis (AGE) in children, family-based outbreaks, as well as animal infections. However, little is known regarding their host-specific interaction, infection, and pathogenesis. In this study, we performed serial studies to characterize the function and structural features of a human G4P[2] RVC VP8* that is responsible for the host receptor interaction. Glycan microarrays demonstrated that the human RVC VP8* recognizes type A histo-blood group antigens (HBGAs), which was confirmed by synthetic glycan-/saliva-based binding assays and hemagglutination of red blood cells, establishing a paradigm of RVC VP8*-glycan interactions. Furthermore, the high-resolution crystal structure of the human RVC VP8* was solved, showing a typical galectin-like structure consisting of two β-sheets but with significant differences from cogent proteins of group A rotaviruses (RVAs). The VP8* in complex with a type A trisaccharide displays a novel ligand binding site that consists of a particular set of amino acid residues of the C-D, G-H, and K-L loops. RVC VP8* interacts with type A HBGAs through a unique mechanism compared with that used by RVAs. Our findings shed light on the host-virus interaction and the coevolution of RVCs and will facilitate the development of specific antivirals and vaccines.IMPORTANCE Group/species C rotaviruses (RVCs), members of Reoviridae family, infect both humans and animals, but our knowledge about the host factors that control host susceptibility and specificity is rudimentary. In this work, we characterized the glycan binding specificity and structural basis of a human RVC that recognizes type A HBGAs. We found that human RVC VP8*, the rotavirus host ligand binding domain that shares only ∼15% homology with the VP8* domains of RVAs, recognizes type A HBGA at an as-yet-unknown glycan binding site through a mechanism distinct from that used by RVAs. Our new advancements provide insights into RVC-cell attachment, the critical step of virus infection, which will in turn help the development of control and prevention strategies against RVs.

Evaluation of the immunogenicity of a recombinant HSV-1 vector expressing human group C rotavirus VP6 protein

Group C Rotavirus (RVC) has been associated globally with sporadic outbreaks of gastroenteritis in children and adults. RVC also infects animals, and interspecies transmission has been reported as well as its zoonotic potential. Considering its genetic diversity and the absence of effective vaccines, it is important and necessary to develop new generation vaccines against RVC for both humans and animals. The aim of the present study was to develop and characterize an HSV-1-based amplicon vector expressing a human RVC-VP6 protein and evaluate the humoral immune response induced after immunizing BALB/c mice. Local fecal samples positive for RVC were used for isolation and sequencing of the vp6 gene, which phylogenetically belongs to the I2 genotype. We show here that cells infected with the HSV[VP6C] amplicon vector efficiently express the VP6 protein, and induced specific anti-RVC antibodies in mice immunized with HSV[VP6C], in a prime-boost schedule. This work highlights that amplicon vectors are an attractive platform for the generation of safe genetic immunogens against RVC, without the addition of external adjuvants.

Whole genome sequences of Japanese porcine species C rotaviruses reveal a high diversity of genotypes of individual genes and will contribute to a comprehensive, generally accepted classification system

Porcine rotavirus C (RVC) is distributed throughout the world and is thought to be a pathogenic agent of diarrhea in piglets. Although, the VP7, VP4, and VP6 gene sequences of Japanese porcine RVCs are currently available, there is no whole-genome sequence data of Japanese RVC. Furthermore, only one to three sequences are available for porcine RVC VP1-VP3 and NSP1-NSP3 genes. Therefore, we determined nearly full-length whole-genome sequences of nine Japanese porcine RVCs from seven piglets with diarrhea and two healthy pigs and compared them with published RVC sequences from a database. The VP7 genes of two Japanese RVCs from healthy pigs were highly divergent from other known RVC strains and were provisionally classified as G12 and G13 based on the 86% nucleotide identity cut-off value. Pairwise sequence identity calculations and phylogenetic analyses revealed that candidate novel genotypes of porcine Japanese RVC were identified in the NSP1, NSP2 and NSP3 encoding genes, respectively. Furthermore, VP3 of Japanese porcine RVCs was shown to be closely related to human RVCs, suggesting a gene reassortment event between porcine and human RVCs and past interspecies transmission. The present study demonstrated that porcine RVCs show greater genetic diversity among strains than human and bovine RVCs.

Analysis of the full genome of human group C rotaviruses reveals lineage diversification and reassortment

Group C rotaviruses (RVC) are enteric pathogens of humans and animals. Whole-genome sequences are available only for few RVCs, leaving gaps in our knowledge about their genetic diversity. We determined the full-length genome sequence of two human RVCs (PR2593/2004 and PR713/2012), detected in Italy from hospital-based surveillance for rotavirus infection in 2004 and 2012. In the 11 RNA genomic segments, the two Italian RVCs segregated within separate intra-genotypic lineages showed variation ranging from 1.9 % (VP6) to 15.9 % (VP3) at the nucleotide level. Comprehensive analysis of human RVC sequences available in the databases allowed us to reveal the existence of at least two major genome configurations, defined as type I and type II. Human RVCs of type I were all associated with the M3 VP3 genotype, including the Italian strain PR2593/2004. Conversely, human RVCs of type II were all associated with the M2 VP3 genotype, including the Italian strain PR713/2012. Reassortant RVC strains between these major genome configurations were identified. Although only a few full-genome sequences of human RVCs, mostly of Asian origin, are available, the analysis of human RVC sequences retrieved from the databases indicates that at least two intra-genotypic RVC lineages circulate in European countries. Gathering more sequence data is necessary to develop a standardized genotype and intra-genotypic lineage classification system useful for epidemiological investigations and avoiding confusion in the literature.

Genetic analysis of human rotavirus C: The appearance of Indian-Bangladeshi strain in Far East Asian countries

Rotaviruses C (RVCs) circulate worldwide as an enteric pathogen in both humans and animals. Most studies of their genetic diversity focus on the VP7 and VP4 genes, but the complete genomes of 18 human RVCs have been described in independent studies. The genetic background of the Far East Asian RVCs is different than other human RVCs that were found in India and Bangladesh. Recently, a RVC detected in 2010 in South Korea had genetic background similar to the Indian-Bangladeshi RVCs. This study was undertaken to determine the whole genome of eight Japanese RVCs detected in 2005-2012, and to compare them with other human and animal global RVCs to better understand the genetic background of contemporary Far East Asian RVC. By phylogenetic analysis, the human RVCs appeared to be distinct from animal RVCs. Among human RVCs, three lineage constellations had prolonged circulation. The genetic background of the Far East Asian RVC was distinguished from Indian-Bangladeshi RVC as reported earlier. However, we found one Japanese RVC in 2012 that carried the genetic background of Indian-Bangladeshi RVC, whereas the remaining seven Japanese RVCs carried the typical genetic background of Far East Asian RVC. This is the first report of the Indian-Bangladeshi RVC in Japan. With that observation and the reassortment event of human RVCs in Hungary, our study indicates that the RVCs are spreading from one region to another.

Complete Genome Sequence of Rotavirus Group C Isolated in South Korea

Rotavirus group C is the major etiological agent associated with acute gastroenteritis in all human age groups. Here, we report the complete genome sequence of human group C rotavirus (GpC-RV) isolated in South Korea.

Canine rotavirus C strain detected in Hungary shows marked genotype diversity

Species C rotaviruses (RVC) have been identified in humans and animals, including pigs, cows and ferrets. In dogs, RVC strains have been reported anecdotally on the basis of visualization of rotavirus-like virions by electron microscopy combined with specific electrophoretic migration patterns of the genomic RNA segments. However, no further molecular characterization of these viruses was performed. Here, we report the detection of a canine RVC in the stool of a dog with enteritis. Analysis of the complete viral genome uncovered distinctive genetic features of the identified RVC strain. The genes encoding VP7, VP4 and VP6 were distantly related to those of other RVC strains and were putatively classified as G10, P8 and I8, respectively. The new strain was named RVC/Dog-wt/HUN/KE174/2012/G10P[8]. Phylogenetic analyses revealed that canine RVC was most closely related to bovine RVC strains with the exception of the NSP4 gene, which clustered together with porcine RVC strains. These findings provide further evidence for the genetic diversity of RVC strains.