Neutralization assay for human group C rotaviruses using a reverse passive hemagglutination test for endpoint determination

Evolution of rotavirus C in humans and several domestic animal species

Rotavirus C (RVC) causes enteric disease in multiple species, including humans, swine, bovines, and canines. To date, the evolutionary relationships of RVC populations circulating in different host species are poorly understood, owing to the low availability of genetic sequence data. To address this gap, we sequenced 45 RVC complete genomes from swine samples collected in the United States and Mexico. A phylogenetic analysis of each genome segment indicates that RVC populations have been evolving independently in human, swine, canine, and bovine hosts for at least the last century, with inter-species transmission events occurring deep in the phylogenetic tree, and none in the last 100 years. Bovine and canine RVC populations clustered together nine of the 11 gene segments, indicating a shared common ancestor centuries ago. The evolutionary relationships of RVC in humans and swine were more complex, due to the extensive genetic diversity and multiple RVC clades identified in pigs, which were not structured geographically. Topological differences between trees inferred for different genome segments occurred frequently, including at nodes deep in the tree, indicating that RVC's evolutionary history includes multiple reassortment events that occurred a long time ago. Overall, we find that RVC is evolving within host-defined lineages, but the evolutionary history of RVC is more complex than previously recognized due to the high genetic diversity of RVC in swine, with a common ancestor dating back centuries. Pigs may act as a reservoir host for RVC, and a source of the lineages identified in other species, including humans, but additional sequencing is needed to understand the full diversity of this understudied pathogen across multiple host species.

Genetic heterogeneity in the VP7 of group C rotaviruses

Evidence for a possible zoonotic role of group C rotaviruses (GCRVs) has been recently provided. To gain information on the genetic relationships between human and animal GCRVs, we sequenced the VP7 gene of 10 porcine strains detected during a large surveillance study from different outbreaks of gastroenteritis in piglets. Four GCRV strains were genetically related to the prototype GCRV porcine Cowden strain. A completely new VP7 genotype included 4 strains (344/04-7-like) that shared 92.5% to 97.0% aa identity to each other, but <83% to human GCRVs and <79% to other porcine and bovine GCRVs. A unique 4-aa insertion (SSSV or SSTI), within a variable region at the carboxy-terminus of VP7, represented a distinctive feature for these 4 unique strains. An additional strain, 134/04-18, was clearly different from all human and animal GCRVs (<85% aa identity) and likely accounts for a distinct VP7 genotype. The VP7 of a unique strain, 42/05-21, shared similar ranges of aa sequence identities with porcine and human strains (88.0-90.7% to porcine GCRVs and 85.2-88.2% to human GCRVs). Plotting the VP7 gene of strain 42/05-21 against the VP7 of human and porcine strains revealed discontinuous evolution rates throughout the VP7 molecule, suggesting different mutational pressure or a remote intragenic recombination event. These findings provide the need for future epidemiological surveys and warrant studies to investigate the pathogenic potential of these novel GCRVs in pigs.

Detection and molecular characterization of human group C rotaviruses in Okayama Prefecture, Japan, between 1986 and 2005

A survey of human group C rotaviruses (CHRVs) was conducted in Okayama Prefecture, Japan, over a period of 19 years between 1986 and 2005. The presence of CHRVs was screened by enzyme-linked immunosorbent assay using CHRV-specific monoclonal antibodies and confirmed by reverse transcription-PCR. Of the 3,722 fecal specimens from sporadic cases of gastroenteritis, 44 specimens (1.2%) were positive for CHRV. The CHRV isolates were detected periodically but continuously, and the rates of positivity changed from one rotavirus season to the next. Moreover, the isolates were mainly detected in April and May, and the mean age of the patients infected with CHRV was 5.27 years. The genome electropherotypes (E types) of the isolates were classified into three patterns, and the dominant pattern changed from year to year. Nucleotide sequences of the VP7 and VP4 genes of 16 strains, which were representatives of 70 isolates from sporadic cases and outbreaks, were determined and analyzed. Although the VP7 and VP4 genes of the strains were closely related to each other, a phylogenetic analysis suggested that each of the VP7 and VP4 genes of the strains were grouped into three genetic lineages. Moreover, the strains could be divided into five types based on the combination of the E type and the genetic lineages of the VP7 and VP4 genes. These results indicate that CHRVs generally exist in Okayama Prefecture and that CHRVs with various genomic backgrounds prevailed in a limited area.

Detection and characterization of human group C rotavirus in the pediatric population of Barcelona, Spain

BACKGROUND

The role of group C rotavirus as a cause of childhood diarrhea is not well defined.

OBJECTIVES

To determine the prevalence of human group C rotavirus in stools of children in Barcelona, Spain, and to describe the genetic diversity of the rotavirus capsid proteins - VP6, VP7 and VP4 - in these samples.

STUDY DESIGN

Stool specimens were assayed for rotavirus C RNA by an RT-PCR/southern-blot technique that included controls to indicate the presence of inhibitors of RT-PCR in the samples.

RESULTS

Human rotavirus C was detected in 3 of 467 samples. One hundred and forty-five (31%) of these samples showed the presence of inhibitors of the RT-PCR assay. Thus, the corrected estimation for detection of group C rotavirus in Barcelona was of 1%. The entire VP4, VP6 and VP7 sequences were determined for all three isolates, revealing the relatedness of two of them to strains circulating in Europe, while the third was very close to sub-Saharan African strains.

CONCLUSION

The low rate of detection of group C rotavirus suggests that it is not an emerging pathogen in children in our region.

Detection and characterization of human group C rotaviruses in Bangladesh

Group C rotaviruses were detected by reverse transcription-PCR in 14 (2.3%) of 611 group A rotavirus-negative stool specimens from the patients admitted to the International Centre for Diarrhoeal Disease Research, Bangladesh hospital, Dhaka, Bangladesh, during July to December 2003. The low rate of detection suggested that infection with group C rotaviruses was an uncommon cause of hospitalization due to gastroenteritis. In addition, coinfections with pathogenic enteric bacteria were frequently observed in group C rotavirus-infected patients. Nucleotide sequence comparison of the VP4, VP6, and VP7 genes revealed that the Bangladeshi group C rotaviruses were most similar to Nigerian group C rotavirus strains. Phylogenetic analysis suggested that all human group C rotaviruses, including the strains isolated in our study, clustered in a monophyletic branch, which was distantly related to the branch comprised of animal group C rotaviruses.

Seroepidemiology of human group C rotavirus in Japan based on a blocking enzyme-linked immunosorbent assay

A novel blocking enzyme-linked immunosorbent assay (BL-ELISA) was developed for detection of antibodies to human group C rotavirus (CHRV). The specificity of the BL-ELISA was confirmed by using animal sera hyperimmunized to group A and group C rotaviruses and paired sera from five patients with acute CHRV gastroenteritis. Furthermore, there was concordance between the BL-ELISA and a neutralization assay for CHRV in 226 (95%) of 238 samples. By using the BL-ELISA, we determined the seroprevalence of CHRV in 704 serum samples obtained from nine different age groups of inhabitants of Okayama Prefecture, Japan, in 1992, 1994, and 1996. As a result, 211 sera (30%) were found to be positive for CHRV antibodies. The seroprevalence gradually increased with age and reached 52.7% in the oldest individuals. A further analysis of the youngest age group suggested that CHRVs predominantly prevail in persons older than 3 years of age in Japan. When comparing the three sampling years, a larger percentage of antibody-positive sera was detected in 1994 than in either 1992 or 1996 in individuals between 6 and 15 years of age, reflecting the occurrence of a CHRV outbreak among children during the winter of 1992 to 1993 that was previously documented. These results indicate that CHRV infections may occur more frequently in spite of the relatively low detection rate of the virus.