Detection and characterization of group C rotavirus in Buenos Aires, Argentina, 1997-2003

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.

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.

Nucleotide Correlations Between Rotavirus C Isolates in Clinical Samples from Outbreaks and in Sewage Samples

Rotavirus C (RVC) is detected in both sporadic cases and outbreaks of gastroenteritis worldwide. However, the epidemic dynamics of RVC in populations remain poorly understood because the detection rate is low. In this study, raw sewage samples were collected from a wastewater treatment plant in Yokohama, Japan, over 5 years, in 12-month period from September to August, to identify the RVC strains in these samples and compare them with the RVC strains circulating in the population. RVC strains were detected in 15 of the 118 raw sewage samples collected between 2007 and 2012. The highest number of positive samples detected per period (seven) was in 2008-2009. A fragment (225 nucleotides) of the VP7 gene of RVC from 14 sewage samples was sequenced. The nucleotide sequences of 11 strains were completely consistent with those of clinical strains identified in Yokohama. A phylogenetic analysis showed that 13 strains from the sewage samples clustered with several Yokohama outbreak strains and were closely related to the clinical strains (except sewage-derived strain Y11-SW0805-C). Our study demonstrates a correlation between clinical and sewage strains of RVC based on a genetic analysis, and shows that monitoring environmental samples is an effective way to study the strains circulating in a population, including in asymptomatic or mildly symptomatic patients, even when these infections are not detected in clinical samples. This is the first report of the surveillance of RVC in sewage samples in Yokohama, Japan, for molecular epidemiological analysis.

Phylogenetic analysis of human group C rotavirus circulating in Brazil reveals a potential unique NSP4 genetic variant and high similarity with Asian strains

Group C rotaviruses (RVC) cause gastroenteritis in humans and animals worldwide, and the evidence for a possible zoonotic role has been recently provided. To gain information on the genetic diversity and relationships between human and animal RVC, we sequenced the VP4, VP7, and NSP4 genes of 12, 19, and 15 human strains, respectively, detected in São Paulo state during historical (1988 and 1993) and recent (2007 and 2008) Brazilian rotavirus surveillance. All RVC strains analyzed in the present study grouped into human genotype (G4-P[2]-E2), and did not show any evidence of animal ancestry. Phylogenetic analysis showed that RVC samples detected in 1988 and 1993 clustered together with strains from distinct continents, indicating that historical RVC strains circulating in São Paulo were closely related to those strains circulating worldwide. All three genes (VP7, VP4 and NSP4) of São Paulo RVC strains isolated in 2007-2008 exhibited close phylogenetic relationship with human RVC strains isolated in China and Japan, suggesting that they are genetically linked, and that a gene flow could be occurring between this Asian countries and Brazil. We identified two distinct clusters in the NSP4 phylogenetic tree. One cluster formed exclusively by human Brazilian strains detected in 1997 and 2003-2004 in Rio de Janeiro, Bahia, and Rio Grande do Sul states (Subgroup II) previously described in a different study, that displayed low sequence identities to other human strains formerly published, and to the Brazilian RVC strains (Subgroup I) characterized in the present study. These data suggests the circulation of two genetic profiles of the NSP4 gene in Brazil. High sequence diversity in NSP4 gene was previously reported in Asia, and additional diversity in NSP4 RVC strains spreading in the world should be expected. More in-depth molecular and epidemiological analysis of human RVC throughout the world will be needed to understand their diversity and clarify their evolution, as well as to develop classifications schemes.

Epidemiological and genetic analysis of human group C rotaviruses isolated from outbreaks of acute gastroenteritis in Yokohama, Japan, between 2006 and 2012

Group C rotavirus (GCRV) infection has been described in several parts of the world, predominantly as sporadic cases of acute gastroenteritis. Little is known about the yearly changes in the GCRV strains from diarrheal outbreaks. Stool samples collected from outbreaks of acute gastroenteritis in Yokohama, Japan, between 2006 and 2012 that were negative for norovirus, sapovirus, and group A rotavirus, were screened for GCRV using a reverse passive hemagglutination method. The GCRV strains were characterized by nucleotide sequence and phylogenetic analysis of their VP6, VP7, VP4, and NSP4 genes. Samples from nine of 735 outbreaks in Yokohama (1 %) contained GCRV, and eight of these outbreaks occurred in primary schools. The nucleotide sequences of the strains detected in this study were more closely related to Asian strains than to those from other regions of the world. The nucleotide sequences of the VP7 gene in these nine strains differed, and yearly changes were observed in the amino acid sequences of the VP4 genes. Phylogenetic trees constructed using the nucleotide sequences of the VP6, VP7, VP4, and NSP4 genes showed that sublineage S1 has divided into S1-1 and S1-2 in the VP4 gene only. Our results confirm that the prevalent strains of GCRV change yearly in Yokohama. This is the first study to demonstrate GCRV-associated gastroenteritis outbreaks in Yokohama, Japan.

Global seasonality of rotavirus disease

BACKGROUND

A substantial number of surveillance studies have documented rotavirus prevalence among children admitted for dehydrating diarrhea. We sought to establish global seasonal patterns of rotavirus disease before the introduction of widespread vaccination.

METHODS

We reviewed studies of rotavirus detection in children with diarrhea published since 1995. We assessed potential relationships between seasonal prevalence and locality by plotting the average monthly proportion of diarrhea cases positive for rotavirus according to geography, country development and latitude. We used linear regression to identify variables that were potentially associated with the seasonal intensity of rotavirus.

RESULTS

Among a total of 99 studies representing all 6 geographic regions of the world, patterns of year-round disease were more evident in low- and low-middle income countries compared with upper-middle and high-income countries where disease was more likely to be seasonal. The level of country development was a stronger predictor of strength of seasonality (P = 0.001) than geographic location or climate. However, the observation of distinctly different seasonal patterns of rotavirus disease in some countries with similar geographic location, climate and level of development indicate that a single unifying explanation for variation in seasonality of rotavirus disease is unlikely.

CONCLUSION

While no unifying explanation emerged for varying rotavirus seasonality globally, the country income level was somewhat more predictive of the likelihood of having seasonal disease than other factors. Future evaluation of the effect of rotavirus vaccination on seasonal patterns of disease in different settings may help understand factors that drive the global seasonality of rotavirus disease.

Monitoring of group C rotavirus in children with acute gastroenteritis in Brazil: an emergent epidemiological issue after rotavirus vaccine?

Group C rotavirus (GpCRV) has a worldwide distribution; however, its epidemiology and ecology are still unclear. Evidence for a possible zoonotic role has been postulated recently for Brazilian children strains. The aim of this study was to monitor GpCRV in children ≤15 years with acute gastroenteritis during the 2007-2010 national Brazilian rotavirus surveillance, and to undertake the molecular characterization of the major VP6 capsid protein. A total of 3,019 fecal samples were first screened for Group A rotavirus (GpARV). A total of 2,205 GpARV ELISA negative samples were tested further for the presence of GpCRV by SDS-PAGE, electronic microscopy, and RT-PCR for the VP6 gene. The genetic diversity of GpCRV was carried out by sequencing the VP6 gene. GpARV and GpCRV infections were detected in 24.6% (742/3,019) and 0.3% (8/3,019), respectively. The GpCRV detection rate increased from 0.2% (1/422) in 2007 to 1% (7/708) in 2008, and GpCRV cases were not detected in 2009 and 2010. The phylogenetic analysis indicated that the strains belonged to the human lineage, and showed a genetic relationship with the GpCRV strain from Japan isolated in 2009. None of the study sequences was related closely to animal GpCRV strains. This study provides further evidence that GpCRV is a minor cause of acute childhood gastroenteritis in Brazil, and does not suggest that GpCRV may assume epidemiological importance in the future, even after the introduction of a GpARV vaccine. In addition, the molecular analyses of the GpCRV samples in this study do not support the zoonotic hypothesis.