Rotaviruses

Epidemiological surveillance of astrovirus, norovirus, rotavirus, and enterovirus in sewage (2022-2023) in Giza, Egypt

The majority of people with enterically transmitted viruses excrete significant amounts of the virus in their feces for several days or weeks. Therefore, viruses causing diarrhea could be detected in the feces of infected persons and wastewater. In this study, the presence of human astrovirus (AstV), norovirus (NoV), rotavirus (RV), and enterovirus (EntV) was analyzed by real-time RT-PCR in raw sewage (n = 96), treated sewage (n = 96) and diarrheal stool samples (n = 200). Overall, 92.7% (89/96) of raw sewage samples and 48% (46/96) of treated sewage tested positive for at least one virus. The highest detection rates of the four viruses in raw sewage were observed in the winter season. Overall, the mean concentration of the four viruses was 7.3 log10 in raw and 4.8 log10 in treated wastewater, for a total removal of 34% of viral loads. In clinical samples, the most commonly detected virus was EntV followed by RV, NoV, and AstV. The mean concentrations of the four viruses in clinical samples ranged between 2.5 × 101 and 9.86 × 107 GC/g. The results presented here demonstrated that the environmental surveillance of entric viruses in sewage is a useful tool for the study of their transmission dynamics in humans and their molecular epidemiology.

Isolation and identification of BRV G6P[1] strain in Heilongjiang province, Northeast China

Bovine rotavirus (BRV) is the main cause of acute gastroenteritis in calves, resulting in significant economic losses to the cattle industry worldwide. Additionally, BRV has multiple genotypes, which could enable cross-species transmission, thereby posing a significant risk to public health. However, there is a problem of multiple genotypes coexisting in BRV, and the cross-protection effect between different genotypes of rotavirus strains is not effective enough. Therefore, mastering clinical epidemic genotypes and using epidemic genotype strains for vaccine preparation is an effective means of preventing and controlling BRV. In this study, BRV strain DQ2020 in MA104 cells was identified by transmission electron microscopy (TEM), reverse transcription polymerase chain reaction (RT-PCR), and colloidal gold immunochromatographic test strips. The whole genome of BRV strain DQ2020 was sequenced and pathogenicity in suckling mice was assessed. The results showed that after 10 passages in MA104 cells, BRV strain DQ2020 induced cytopathic effects. Wheel-shaped virus particles (diameter, ~80 nm) were observed by TEM. A target band of 382 bp was detected by RT-PCR, a positive band was detected with the colloidal gold immunochromatographic test strips, and significant green fluorescence was observed by indirect immunofluorescence (IFA). The highest median tissue culture infectious dose of strain DQ2020 after 9 passages in MA104 cells was 10-4.81 viral particles/0.1 mL. Based on phylogenetic analysis of 11 gene fragments, the genotype of BRV strain DQ2020 was G6-P[1]-I2-R2-C2-M2-A11-N2-T6-E2-H3, confirming transmission of the G6-P[1] genotype in Chinese cattle herds. Further analysis showed that the isolated strain was a reassortant of bovine (VP7, VP6, NSP3, and NSP5), human (VP4, VP1, VP2, VP3, NSP2, and NSP4), and ovine (NSP1) rotaviruses. BRV strain DQ2020 caused damage to the intestinal villi of suckling mice and diarrhea, confirming pathogenicity. In summary, this study identified a reassortant strain of bovine, human, and ovine rotavirus that is pathogenic to lactating mice, and conducted whole genome sequence analysis, providing valuable insights for the genetic evolution of the virus and the development of vaccines.

A randomized, double-blind, placebo-controlled phase I clinical trial of rotavirus inactivated vaccine (Vero cell) in a healthy adult population aged 18-49 years to assess safety and preliminary observation of immunogenicity

We conducted a phase I, randomized, double-blind, placebo-controlled trial including healthy adults in Sui County, Henan Province, China. Ninety-six adults were randomly assigned to one of three groups (high-dose, medium-dose, and low-dose) at a 3:1 ratio to receive one vaccine dose or placebo. Adverse events up to 28 days after each dose and serious adverse events up to 6 months after all doses were reported. Geometric mean titers and seroconversion rates were measured for anti-rotavirus neutralizing antibodies using microneutralization tests. The rates of total adverse events in the placebo group, low-dose group, medium-dose group, and high-dose group were 29.17 % (12.62 %-51.09 %), 12.50 % (2.66 %-32.36 %), 50.00 % (29.12 %-70.88 %), and 41.67 % (22.11 %-63.36 %), respectively, with no significant difference in the experimental groups compared with the placebo group. The results of the neutralizing antibody assay showed that in the adult group, the neutralizing antibody geometric mean titer at 28 days after full immunization in the low-dose group was 583.01 (95 % confidence interval [CI]: 447.12-760.20), that in the medium-dose group was 899.34 (95 % CI: 601.73-1344.14), and that in the high-dose group was 1055.24 (95 % CI: 876.28-1270.75). The GMT of serum-specific IgG at 28 days after full immunization in the low-dose group was 3444.26 (95 % CI: 2292.35-5175.02), that in the medium-dose group was 6888.55 (95 % CI: 4426.67-10719.6), and that in the high-dose group was 7511.99 (95 % CI: 3988.27-14149.0). The GMT of serum-specific IgA at 28 days after full immunization in the low-dose group was 2332.14 (95 % CI: 1538.82-3534.45), that in the medium-dose group was 4800.98 (95 % CI: 2986.64-7717.50), and that in the high-dose group was 3204.30 (95 % CI: 2175.66-4719.27). In terms of safety, adverse events were mainly Grades 1 and 2, indicating that the safety of the vaccine is within the acceptable range in the healthy adult population. Considering the GMT and positive transfer rate of neutralizing antibodies for the main immunogenicity endpoints in the experimental groups, it was initially observed that the high-dose group had higher levels of neutralizing antibodies than the medium- and low-dose groups in adults aged 18-49 years. This novel inactivated rotavirus vaccine was generally well-tolerated in adults, and the vaccine was immunogenic in adults (ClinicalTrials.gov number, NCT04626856).

Microbial health risks associated with rotavirus and enteric bacteria in River Ala in Akure, Nigeria

AIM

This study was carried out to determine the microbial health risks associated with a surface water commonly used for bathing, drinking, domestic and irrigational activities in Akure, Nigeria.

METHODS AND RESULTS

Water samples were collected from the river from March to June, 2018. The load of enteric bacteria, somatic coliphages and rotavirus in the water samples were determined using culture-based methods and molecular technique. The physicochemical characteristics of the water samples were determined using standard methods. The risks of rotavirus, Salmonella and Shigella infections resulting from ingestion of the water from the river were estimated using dose-response model. Redundancy analysis revealed that the levels of E. coli and Salmonella were highly associated with salinity and turbidity. The risks of infection associated with rotavirus (3.3 × 10^-3 ) was higher than those associated with Salmonella (1.3 × 10^-4 ) and Shigella (1.3 × 10^-3 ), and were all above the WHO acceptable risk limit (10^-4 ).

CONCLUSION

Accidental or intentional ingestion of water from the river may pose potential risks of gastrointestinal illness to humans.

SIGNIFICANCE AND IMPACT OF STUDY

Quantitative microbial risk assessment is essential in establishing adequate water management practices that must be strictly followed in order to protect human health.

Etiology of diarrheal disease among children under 5 years in Egypt: a high incidence of human bocavirus

BACKGROUND

Human bocavirus (HBoV) is globally distributed and associated with respiratory and enteric infections. Limited data are available about the incidence of HBoV in Egyptian children. We aimed to investigate the association of HBoV genotypes in children with diarrheal disease and also to determine the possibility of HBoV co-infections with other human enteric pathogens.

METHODS

A total of 102 stool samples were collected from children under five years old with diarrhea. Samples were analyzed for the presence of HBoV by real-time PCR. HBoV positive samples were tested for adenovirus (AdV), rotavirus (RoV), parasitic helminths, and enteric protozoa.

RESULTS

HBoV was detected in 58% of examined cases. HBoV-3 was the most prevalent genotype observed (44%; 45 of 102), followed by HBoV-2/4 (33%; 34 of 102) and HBoV-1 (30%; 31 of 102). Although the incidence of HBoV was higher in males (66.6%; 34 of 51) than females (49%; 25 of 51), the analysis showed no significant difference for HBoV between genders. The average HBoV concentrations were 5.3 × 10⁴ GC/g in males and 1.03 × 10⁵ GC/g in females. Among the HBoV-positive samples, the single infection of HBoV was 52.5% (31/59), while the co-infections with multiple viruses were found in 1.7% (1/59) for HBoV and AdV, 33.9% (20/59) for HBoV and RoV, and 11.9% (7/59) for HBoV, and RoV and AdV. No co-infection with parasitic helminths or enteric protozoa was found.

CONCLUSIONS

The single infection of HBoV in some children suffering from acute gastroenteritis indicated that HBoV could be the main etiologic agent of the disease. The study highlights the high incidence of HBoVs genotypes with remarkable multiple co-infections in the pre-school children in Egypt.

Structural basis of glycan interaction in gastroenteric viral pathogens

A critical event in the life cycle of a virus is its initial attachment to host cells. This involves recognition by the viruses of specific receptors on the cell surface, including glycans. Viruses typically exhibit strain-dependent variations in recognizing specific glycan receptors, a feature that contributes significantly to cell tropism, host specificity, host adaptation and interspecies transmission. Examples include influenza viruses, noroviruses, rotaviruses, and parvoviruses. Both rotaviruses and noroviruses are well known gastroenteric pathogens that are of significant global health concern. While rotaviruses, in the family Reoviridae, are the major causative agents of life-threatening diarrhea in children, noroviruses, which belong to the Caliciviridae family, cause epidemic and sporadic cases of acute gastroenteritis across all age groups. Both exhibit enormous genotypic and serotypic diversity. Consistent with this diversity each exhibits strain-dependent variations in the types of glycans they recognize for cell attachment. This chapter reviews the current status of the structural biology of such strain-dependent glycan specificities in these two families of viruses.

Genetic diversity of porcine group A rotavirus strains in the UK

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This is the first study of rotavirus genotypes circulating in UK pigs.

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Rotavirus transmission between pigs and humans is not thought to be common in the UK.

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Human rotavirus genotype P[8] found in a UK pig.

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The uncommon rotavirus genotype P[32] is widespread in UK pig herds.

Rotavirus is endemic in pig farms where it causes a loss in production. This study is the first to characterise porcine rotavirus circulating in UK pigs. Samples from diarrheic pigs with rotavirus enteritis obtained between 2010 and 2012 were genotyped in order to determine the diversity of group A rotavirus (GARV) in UK pigs. A wide range of rotavirus genotypes were identified in UK pigs: six G types (VP7); G2, G3, G4, G5, G9 and G11 and six P types (VP4); P[6], P[7], P[8], P[13], P[23], and P[32]. With the exception of a single P[8] isolate, there was less than 95% nucleotide identity between sequences from this study and any available rotavirus sequences.

The G9 and P[6] genotypes are capable of infecting both humans and pigs, but showed no species cross-over within the UK as they were shown to be genetically distinct, which suggested zoonotic transmission is rare within the UK. We identified the P[8] genotype in one isolate, this genotype is almost exclusively found in humans. The P[8] was linked to a human Irish rotavirus isolate in the same year. The discovery of human genotype P[8] rotavirus in a UK pig confirms this common human genotype can infect pigs and also highlights the necessity of surveillance of porcine rotavirus genotypes to safeguard human as well as porcine health.

The unpredictable diversity of co-circulating rotavirus types in Europe and the possible impact of universal mass vaccination programmes on rotavirus genotype incidence

This article reviews the incidence of group A rotavirus (RV) types isolated from children with acute gastroenteritis (AGE) in European countries during the last 5-10 years, with the aim of establishing an overview of RV diversity before the introduction of universal mass vaccination (UMV) programmes against RV disease in most European countries. Consistent with findings from previous surveys, a high degree of diversity of co-circulating RV types exists in different locations of Europe, and over different RV seasons. Whilst RV UMV can potentially change the diversity of co-circulating genotypes, there are at present insufficient data for Europe to come to firm conclusions. Even in countries outside Europe, with several years of RV surveillance following the introduction of RV UMV (Brazil, Australia, USA), it is not clear whether changes observed in the diversity of particular RV types are due to natural fluctuations or immunological pressure exerted by RV UMVs. Consequently, it will be very difficult for European countries that have RV UMVs to conclude whether incidence changes of RV types in children with AGE are driven by immune pressures from vaccination or simply reflect natural temporal and spatial fluctuations. Whilst the monitoring of co-circulating RV strains should be continued, it should be acknowledged that the licensed monovalent and pentavalent RV vaccines are similarly effective in developed countries and that levels of RV type-specific neutralising antibodies after RV vaccination are only partially correlated with the degree of protection achieved; therefore, the significance of RV diversity for RV vaccination may be less important than is often assumed.

Cell attachment protein VP8* of a human rotavirus specifically interacts with A-type histo-blood group antigen

As with many other viruses, the initial cell attachment of rotaviruses, major causative agent of infantile gastroenteritis, is mediated by interactions with specific cellular glycans^1–4. The distally located VP8* domain of the rotavirus spike protein VP4⁵ mediates such interactions. The existing paradigm is that ‘sialidase-sensitive’ animal rotavirus strains bind to glycans with terminal sialic acid (Sia), whereas ‘sialidase-insensitive’ human rotavirus (HR) strains bind to glycans with internal Sia such as GM1³. Although the involvement of Sia in the animal strains is firmly supported by crystallographic studies^1,3,6,7, it is not yet known how VP8* of HRs interacts with Sia and whether their cell attachment necessarily involves sialoglycans. We found that VP8* of a HR strain specifically recognizes A-type histo-blood group antigen (HBGA) using a glycan array screen comprised of 511 glycans, and that virus infectivity in HT-29 cells is abrogated by anti-Atype antibodies as well as significantly enhanced in CHO cells genetically modified to express the A-type HBGA, providing a novel paradigm for initial cell attachment of HR. HBGAs are genetically determined glycoconjugates present in mucosal secretions, epithelial and on red blood cells⁸, and are recognized as susceptibility and cell attachment factors for gastric pathogens like H. pylori⁹ and noroviruses¹⁰. Our crystallographic studies show that the A-type HBGA binds to the HR VP8* at the same location as the Sia in the VP8* of animal rotavirus, and suggest how subtle changes within the same structural framework allow for such receptor switching. These results raise the possibility that host susceptibility to specific HR strains and pathogenesis are influenced by genetically controlled expression of different HBGAs among the world’s population.