Emerging themes in rotavirus cell entry, genome organization, transcription and replication

Unravelling aggregation propensity of rotavirus A VP6 expressed as E. coli inclusion bodies through in silico prediction

The inner capsid protein of rotavirus, VP6, emerges as a promising candidate for next-generation vaccines against rotaviruses owing to its abundance in virion particles and high conservation. However, the formation of inclusion bodies during prokaryotic VP6 expression poses a significant hurdle to rotavirus research and applications. Here, we employed experimental and computational approaches to investigate inclusion body formation and aggregation-prone regions (APRs). Heterologous recombinant VP6 expression in Escherichia coli BL21(DE3) cells resulted in inclusion body formation, confirmed by transmission electron microscopy revealing amorphous aggregates. Thioflavin T assay demonstrated incubation temperature-dependent aggregation of VP6 inclusion bodies. Computational predictions of APRs in rotavirus A VP6 protein were performed using sequence-based tools (TANGO, AGGRESCAN, Zyggregator, Waltz, FoldAmyloid, ANuPP, Camsol intrinsic) and structure-based tools (SolubiS, CamSol structurally corrected, Aggrescan3D). A total of 24 consensus APRs were identified, with 21 of them being surface-exposed in VP6. All identified APRs display a predominance of hydrophobic amino acids, ranging from 33 to 100%. Computational identification of these APRs corroborates our experimental observation of VP6 inclusion body or aggregate formation. Characterization of VP6's aggregation propensity facilitates understanding of its behaviour during prokaryotic expression and opens avenues for protein engineering of soluble variants, advancing research on rotavirus VP6 in pathology, therapy, and diagnostics.

Single domain antibodies from camelids in the treatment of microbial infections

Infectious diseases continue to pose significant global health challenges. In addition to the enduring burdens of ailments like malaria and HIV, the emergence of nosocomial outbreaks driven by antibiotic-resistant pathogens underscores the ongoing threats. Furthermore, recent infectious disease crises, exemplified by the Ebola and SARS-CoV-2 outbreaks, have intensified the pursuit of more effective and efficient diagnostic and therapeutic solutions. Among the promising options, antibodies have garnered significant attention due to their favorable structural characteristics and versatile applications. Notably, nanobodies (Nbs), the smallest functional single-domain antibodies of heavy-chain only antibodies produced by camelids, exhibit remarkable capabilities in stable antigen binding. They offer unique advantages such as ease of expression and modification and enhanced stability, as well as improved hydrophilicity compared to conventional antibody fragments (antigen-binding fragments (Fab) or single-chain variable fragments (scFv)) that can aggregate due to their low solubility. Nanobodies directly target antigen epitopes or can be engineered into multivalent Nbs and Nb-fusion proteins, expanding their therapeutic potential. This review is dedicated to charting the progress in Nb research, particularly those derived from camelids, and highlighting their diverse applications in treating infectious diseases, spanning both human and animal contexts.

Cryo-EM structure of rotavirus B NSP2 reveals its unique tertiary architecture

Rotavirus (RV) NSP2 is a multifunctional RNA chaperone that exhibits numerous activities that are essential for replication and viral genome packaging. We performed an in silico analysis that highlighted a distant relationship of NSP2 from rotavirus B (RVB) to proteins from other human RVs. We solved a cryo-electron microscopy structure of RVB NSP2 that shows structural differences with corresponding proteins from other human RVs. Based on the structure, we identified amino acid residues that are involved in RNA interactions. Anisotropy titration experiments showed that these residues are important for nucleic acid binding. We also identified structural motifs that are conserved in all RV species. Collectively, our data complete the structural characterization of rotaviral NSP2 protein and demonstrate its structural diversity among RV species.IMPORTANCERotavirus B (RVB), also known as adult diarrhea rotavirus, has caused epidemics of severe diarrhea in China, India, and Bangladesh. Thousands of people are infected in a single RVB epidemic. However, information on this group of rotaviruses remains limited. As NSP2 is an essential protein in the viral life cycle, including its role in the formation of replication factories, it may be a target for future antiviral strategy against viruses with similar mechanisms.

Equine Rotavirus A under the One Health Lens: Potential Impacts on Public Health

Group A rotaviruses are a well-known cause of viral gastroenteritis in infants and children, as well as in many mammalian species and birds, affecting them at a young age. This group of viruses has a double-stranded, segmented RNA genome with high genetic diversity linked to point mutations, recombination, and, importantly, reassortment. While initial molecular investigations undertaken in the 1900s suggested host range restriction among group A rotaviruses based on the fact that different gene segments were distributed among different animal species, recent molecular surveillance and genome constellation genotyping studies conducted by the Rotavirus Classification Working Group (RCWG) have shown that animal rotaviruses serve as a source of diversification of human rotavirus A, highlighting their zoonotic potential. Rotaviruses occurring in various animal species have been linked with contributing genetic material to human rotaviruses, including horses, with the most recent identification of equine-like G3 rotavirus A infecting children. The goal of this article is to review relevant information related to rotavirus structure/genomic organization, epidemiology (with a focus on human and equine rotavirus A), evolution, inter-species transmission, and the potential zoonotic role of equine and other animal rotaviruses. Diagnostics, surveillance and the current status of human and livestock vaccines against RVA are also reviewed.

Aspirin inhibits rotavirus replication and alters rat gut microbial composition

BACKGROUND

Aspirin is widely used to treat various clinical symptoms. Evidence suggests that aspirin has antiviral properties, but little is known about its specific effect against rotavirus.

METHODS

MA104, Caco-2, and CV-1 cells were infected with rotavirus, and aspirin was added after 12 h. Viral mRNA and titer levels were measured by qRT-PCR and immunofluorescence assays. For in vivo validation, forty specific-pathogen-free SD rats were randomly divided into oral aspirin (ASP) groups and control (NC) groups. 16 S rRNA gene sequencing was performed to identify gut microbiota. After 6 months of continuous ASP/NC administration, the rats were infected with rotavirus. Fecal samples were collected over a 30-day time course, and viral levels were quantified. Proinflammatory cytokines/chemokine levels were measured by ELISA.

RESULTS

Aspirin inhibited rotavirus infection in cell lines and in rats. The effects of aspirin on viral replication were associated with the alteration of gut microbiota composition by aspirin, including increased abundance of Firmicutes and decreased abundance of Bacteroidetes after aspirin treatment. Mechanistically, aspirin reduced IL-2 and IL-10 levels, and increased IRF-1 and COX-2 levels. Aspirin blocked rotavirus replication in vitro and in vivo, which might be related to effects on IRF-1, COX-2, chemokines, and gut microbial composition.

CONCLUSION

These results indicate that long-term oral aspirin administration reduces rotavirus infection. Intestinal virus infection may be suppressed in elderly patients who take aspirin for a long time. The change of their Gut microbiota may lead to functional disorder of the intestinal tract, which may provide some reference for clinical adjuvant probiotics treatment.

Rotavirus Particle Disassembly and Assembly In Vivo and In Vitro

Rotaviruses (RVs) are non-enveloped multilayered dsRNA viruses that are major etiologic agents of diarrheal disease in humans and in the young in a large number of animal species. The viral particle is composed of three different protein layers that enclose the segmented dsRNA genome and the transcriptional complexes. Each layer defines a unique subparticle that is associated with a different phase of the replication cycle. Thus, while single- and double-layered particles are associated with the intracellular processes of selective packaging, genome replication, and transcription, the viral machinery necessary for entry is located in the third layer. This modular nature of its particle allows rotaviruses to control its replication cycle by the disassembly and assembly of its structural proteins. In this review, we examine the significant advances in structural, molecular, and cellular RV biology that have contributed during the last few years to illuminating the intricate details of the RV particle disassembly and assembly processes.

Detection and genetic diversity of porcine rotavirus A, B and C in eastern Australian piggeries

Rotaviruses (RV) have a high prevalence in piggeries worldwide and are one of the major pathogens causing severe diarrhoea in young pigs. RV species A, B, and C have been linked to piglet diarrhoea in Australian pig herds, but their genetic diversity has not been studied in detail. Based on sequencing of the structural viral protein 7 (VP7) RVA G genotypes G3, G4 and G5, and RVC types G1, G3, G5, and G6 have been identified in Australian piggeries in previous studies. Although occurrence of RVB was reported in Australia in 1988, no further genetic analysis has been conducted. To improve health management decisions in Australian pig herds, more information on RV prevalence and genetic diversity is needed. Here, 243 enteric samples collected from 20 pig farms within Eastern Australia were analysed for the presence of RV in different age groups using a novel PCR-based multiplex assay (Pork MultiPath™ enteric panel). RVA, RVB, and RVC were detected in 10, 14, and 14 farms, respectively. Further sequencing of VP7 in selected RV-positive samples revealed G genotypes G2, G5, G9 (RVA), G6, G8, G14, G16, G20 (RVB), and G1, G3, G5, G6 (RVC) present. RVA was only detected in young (<10 weeks old) pigs whereas RVB and RVC were also detected in older animals (>11 weeks old). Interestingly, RVB and RVC G-type occurrence differed between age groups. In conclusion, this study provides new insights on the prevalence and diversity of different RV species in pig herds of Eastern Australia whilst demonstrating the ability of the Pork MultiPath™ technology to accurately differentiate between these RV species.

New Possibilities of Preventive Immunization for Rotavirus Infection in Russian Federation. Overview of the Innovative Rotavirus Vaccine Profile

This article is devoted to the issue of rotavirus infection in pediatric population and demonstrates worldwide prevalence of rotavirus among the causes of viral gastroenteritis and its persistent leadership among the causes of fatal diarrhea in children of the first 5 years of life. Specific prevention of rotavirus infection has been actively carried out around the world since 2005. Nowadays, we have adequate experience in the use of various rotavirus vaccines bolstered by their implementation in immunisation schedules for infants. The authors provide data on the efficacy and safety of rotavirus vaccines licensed and used in Russian Federation, involving the results of studies on safety, immunological and clinical efficacy of one of the pentavalent rotavirus vaccines.

Current Update on Rotavirus in-Silico Multiepitope Vaccine Design

Rotavirus gastroenteritis is one of the leading causes of pediatric morbidity and mortality worldwide in infants and under-five populations. The World Health Organization (WHO) recommended global incorporation of the rotavirus vaccine in national immunization programs to alleviate the burden of the disease. Implementation of the rotavirus vaccination in certain regions of the world brought about a significant and consistent reduction of rotavirus-associated hospitalizations. However, the efficacy of licensed vaccines remains suboptimal in low-income countries where the incidences of rotavirus gastroenteritis continue to happen unabated. The problem of low efficacy of currently licensed oral rotavirus vaccines in low-income countries necessitates continuous exploration, design, and development of new rotavirus vaccines. Traditional vaccine development is a complex, expensive, labor-intensive, and time-consuming process. Reverse vaccinology essentially utilizes the genome and proteome information on pathogens and has opened new avenues for in-silico multiepitope vaccine design for a plethora of pathogens, promising time reduction in the complete vaccine development pipeline by complementing the traditional vaccinology approach. A substantial number of reviews on licensed rotavirus vaccines and those under evaluation are already available in the literature. However, a collective account of rotavirus in-silico vaccines is lacking in the literature, and such an account may further fuel the interest of researchers to use reverse vaccinology to expedite the vaccine development process. Therefore, the main focus of this review is to summarize the research endeavors undertaken for the design and development of rotavirus vaccines by the reverse vaccinology approach utilizing the tools of immunoinformatics.

Rotavirus RNA chaperone mediates global transcriptome-wide increase in RNA backbone flexibility

Due to genome segmentation, rotaviruses must co-package eleven distinct genomic RNAs. The packaging is mediated by virus-encoded RNA chaperones, such as the rotavirus NSP2 protein. While the activities of distinct RNA chaperones are well studied on smaller RNAs, little is known about their global effect on the entire viral transcriptome. Here, we used Selective 2'-hydroxyl Acylation Analyzed by Primer Extension and Mutational Profiling (SHAPE-MaP) to examine the secondary structure of the rotavirus transcriptome in the presence of increasing amounts of NSP2. SHAPE-MaP data reveals that despite the well-documented helix-unwinding activity of NSP2 in vitro, its incubation with cognate rotavirus transcripts does not induce a significant change in the SHAPE reactivities. However, a quantitative analysis of mutation rates measured by mutational profiling reveals a global 5-fold rate increase in the presence of NSP2. We demonstrate that the normalization procedure used in deriving SHAPE reactivities from mutation rates can mask an important global effect of an RNA chaperone. Analysis of the mutation rates reveals a larger effect on stems rather than loops. Together, these data provide the first experimentally derived secondary structure model of the rotavirus transcriptome and reveal that NSP2 acts by globally increasing RNA backbone flexibility in a concentration-dependent manner.

Serological Humoral Immunity Following Natural Infection of Children with High Burden Gastrointestinal Viruses

Acute gastroenteritis (AGE) is a major cause of morbidity and mortality worldwide, resulting in an estimated 440,571 deaths of children under age 5 annually. Rotavirus, norovirus, and sapovirus are leading causes of childhood AGE. A successful rotavirus vaccine has reduced rotavirus hospitalizations by more than 50%. Using rotavirus as a guide, elucidating the determinants, breath, and duration of serological antibody immunity to AGE viruses, as well as host genetic factors that define susceptibility is essential for informing development of future vaccines and improving current vaccine candidates. Here, we summarize the current knowledge of disease burden and serological antibody immunity following natural infection to inform further vaccine development for these three high-burden viruses.

RNA Structures and Their Role in Selective Genome Packaging

To generate infectious viral particles, viruses must specifically select their genomic RNA from milieu that contains a complex mixture of cellular or non-genomic viral RNAs. In this review, we focus on the role of viral encoded RNA structures in genome packaging. We first discuss how packaging signals are constructed from local and long-range base pairings within viral genomes, as well as inter-molecular interactions between viral and host RNAs. Then, how genome packaging is regulated by the biophysical properties of RNA. Finally, we examine the impact of RNA packaging signals on viral evolution.

Secretors of HBGA and Susceptibility to Norovirus and Rotavirus Diarrhea

Histo-blood group antigen contains oligosaccharides that serve as receptors for norovirus (NoV) and rotavirus (RV). The receptors are only present on the surface of intestinal mucosal epithelial cells of secretors; therefore, secretors are susceptible to NoV and RV diarrhea and nonsecretors are resistant. The prevalence of secretors in different countries varies between 50% and 90%. Secretor rates evolved in response to environmental pressures such as infectious diseases.

Current and Future Antiviral Strategies to Tackle Gastrointestinal Viral Infections

Acute gastroenteritis caused by virus has a major impact on public health worldwide in terms of morbidity, mortality, and economic burden. The main culprits are rotaviruses, noroviruses, sapoviruses, astroviruses, and enteric adenoviruses. Currently, there are no antiviral drugs available for the prevention or treatment of viral gastroenteritis. Here, we describe the antivirals that were identified as having in vitro and/or in vivo activity against these viruses, originating from in silico design or library screening, natural sources or being repurposed drugs. We also highlight recent advances in model systems available for this (hard to cultivate) group of viruses, such as organoid technologies, and that will facilitate antiviral studies as well as fill some of current knowledge gaps that hamper the development of highly efficient therapies against gastroenteric viruses.

Rotavirus in Calves and Its Zoonotic Importance

Rotavirus is a major pathogen responsible for diarrheal disease in calves, resulting in loss of productivity and economy of farmers. However, various facets of diarrheal disease caused by rotavirus in calves in the world are inadequately understood, considering that diarrheal disease caused by rotavirus is a vital health problem in calves that interrupts production benefits with reduced weight gain and increased mortality, and its potential for zoonotic spread. The pathological changes made by rotavirus are almost exclusively limited to the small intestine that leads to diarrhea. It is environmentally distributed worldwide and was extensively studied. Reassortment is one of the important mechanisms for generating genetic diversity of rotaviruses and eventually for viral evolution. So, the primary strategy is to reduce the burden of rotavirus infections by practicing early colostrum's feeding in newborn calves, using vaccine, and improving livestock management. Rotaviruses have a wide host range, infecting many animal species as well as humans. As it was found that certain animal rotavirus strains had antigenic similarities to some human strains, this may be an indication for an animal to play a role as a source of rotavirus infection in humans. Groups A to C have been shown to infect both humans and animals. The most commonly detected strains in both human and animals are G2, G3, G4, and G9, P [6]. Therefore, this review was made to get overview epidemiology status and zoonotic importance of bovine rotavirus.

Alkaline phosphatase can promote the replication of Bombyx mori cypovirus 1 by interaction with its turret protein

Bombyx mori cypovirus 1 (BmCPV1) is a member of the Reoviridae family which is characterized by its single-layered capsid. Similar with other turreted viruses in the Reoviridae, transcription of BmCPV1 occurs inside the capsid, and the nascent mRNA is released to the turret which consists of five turret proteins (TPs) and located at the 5-fold axis of the outer capsid, then the capping enzyme TP will guanylate and methylate the nascent viral mRNA to produce a matured mRNA. However, during these processes, how the BmCPV1 draws other cellular proteins to facilitate its replication is still lesser-known. Here we used an ELISA to investigate the interaction between ALP and BmCPV1. A co-immunoprecipitation technique was employed to detect the interaction of ALP with the Methylase domain of TP. We further studied whether ALP affects the replication of BmCPV1 inside the cell, results show that reducing the expression of ALP through RNAi reduced the transcription level of the BmCPV1 VP1 gene, which was increased by overexpression of ALP. In summary, our data demonstrate an interaction between ALP and BmCPV1 and that ALP promoted the replication of BmCPV1, and support our hypothesis of the ALP is an RTPase to facilitate the capping process of BmCPV1.

Whole Genome Characterization and Evolutionary Analysis of G1P[8] Rotavirus A Strains during the Pre- and Post-Vaccine Periods in Mozambique (2012-2017)

Mozambique introduced the Rotarix^® vaccine (GSK Biologicals, Rixensart, Belgium) into the National Immunization Program in September 2015. Although G1P[8] was one of the most prevalent genotypes between 2012 and 2017 in Mozambique, no complete genomes had been sequenced to date. Here we report whole genome sequence analysis for 36 G1P[8] strains using an Illumina MiSeq platform. All strains exhibited a Wa-like genetic backbone (G1-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1). Phylogenetic analysis showed that most of the Mozambican strains clustered closely together in a conserved clade for the entire genome. No distinct clustering for pre- and post-vaccine strains were observed. These findings may suggest no selective pressure by the introduction of the Rotarix^® vaccine in 2015. Two strains (HJM1646 and HGM0544) showed varied clustering for the entire genome, suggesting reassortment, whereas a further strain obtained from a rural area (MAN0033) clustered separately for all gene segments. Bayesian analysis for the VP7 and VP4 encoding gene segments supported the phylogenetic analysis and indicated a possible introduction from India around 2011.7 and 2013.0 for the main Mozambican clade. Continued monitoring of rotavirus strains in the post-vaccine period is required to fully understand the impact of vaccine introduction on the diversity and evolution of rotavirus strains.

Antiviral activities of resveratrol against rotavirus in vitro and in vivo

BACKGROUND

Rotavirus (RV) is the primary causative agent for viral gastroenteritis among infants and young children worldwide. Currently, no clinically approved and effective antiviral drug for the treatment of RV infection is available.

PURPOSE

We investigated the potential anti-RV activity of resveratrol and underlying mechanisms by which resveratrol acted against RV.

METHODS

The anti-RV activity of resveratrol in vitro was evaluated using plaque reduction assays. The effects of resveratrol on yield of virion progeny, viral polyprotein expression and genomic RNA synthesis were respectively investigated using enzyme-linked immunosorbent assays, western blotting and qRT-PCR assays. Further, we also measured the antiviral effect of resveratrol by evaluation of antigen clearance and assessment of changes in proinflammatory cytokines/chemokines in RV-infected neonatal mouse model.

RESULTS

Our results indicated that 20 μM of resveratrol significantly inhibited RV replication in Caco-2 cell line by suppressing RV RNA synthesis, protein expression, viroplasm plaque formation, progeny virion production, and RV-induced cytopathy independent of the different strains and cell lines of RV that we used. Analysis of the effect of time post-addition of resveratrol indicated that its application inhibited early processes in the RV replication cycle. Further study of the underlying mechanism of anti-RV activity indicated that resveratrol inhibited RV replication by suppressing expression of heat-shock protein 90 (HSP90) mRNA and protein, and that the effect occurred in a dose-dependent manner. Overexpression of HSP90 was found to have attenuated the inhibitory effect of resveratrol on RV replication. Interestingly, the application of resveratrol were found to down-regulate the level of inhibition of RV-mediated MEK1/2 and ERK phosphorylation. Using a RV-infected suckling mice model, we found that application of resveratrol significantly lessened the severity of diarrhea, decreased viral titers, and relieved associated symptoms. Levels of mRNA expression of interleukin-2, interleukin-10, tumor necrosis factor-α, interferon-γ, macrophage inflammatory protein 1, and monocyte chemotactic protein-1 were all found to have been sharply reduced in intestinal tissue from mice which had been treated with resveratrol (10 or 20 mg/kg) after RV infection (p < 0.05).

CONCLUSION

These findings implied that resveratrol exhibits antiviral activity and could be a promising treatment for rotavirus infection.

Overview of the Development, Impacts, and Challenges of Live-Attenuated Oral Rotavirus Vaccines

Safety, efficacy, and cost-effectiveness are paramount to vaccine development. Following the isolation of rotavirus particles in 1969 and its evidence as an aetiology of severe dehydrating diarrhoea in infants and young children worldwide, the quest to find not only an acceptable and reliable but cost-effective vaccine has continued until now. Four live-attenuated oral rotavirus vaccines (LAORoVs) (Rotarix^®, RotaTeq^®, Rotavac^®, and RotaSIIL^®) have been developed and licensed to be used against all forms of rotavirus-associated infection. The efficacy of these vaccines is more obvious in the high-income countries (HIC) compared with the low- to middle-income countries (LMICs); however, the impact is far exceeding in the low-income countries (LICs). Despite the rotavirus vaccine efficacy and effectiveness, more than 90 countries (mostly Asia, America, and Europe) are yet to implement any of these vaccines. Implementation of these vaccines has continued to suffer a setback in these countries due to the vaccine cost, policy, discharging of strategic preventive measures, and infrastructures. This review reappraises the impacts and effectiveness of the current live-attenuated oral rotavirus vaccines from many representative countries of the globe. It examines the problems associated with the low efficacy of these vaccines and the way forward. Lastly, forefront efforts put forward to develop initial procedures for oral rotavirus vaccines were examined and re-connected to today vaccines.

Understanding the penetrance of intrinsic protein disorder in rotavirus proteome

Rotavirus is a major cause of severe acute gastroenteritis in the infants and young children. The past decade has evidenced the role of intrinsically disordered proteins/regions (IDPs)/(IDPRs) in viral and other diseases. In general, (IDPs)/(IDPRs) are considered as dynamic conformational ensembles that devoid of a specific 3D structure, being associated with various important biological phenomena. Viruses utilize IDPs/IDPRs to survive in harsh environments, to evade the host immune system, and to highjack and manipulate host cellular proteins. The role of IDPs/IDPRs in Rotavirus biology and pathogenicity are not assessed so far, therefore, we have designed this study to deeply look at the penetrance of intrinsic disorder in rotavirus proteome consisting 12 proteins encoded by 11 segments of viral genome. Also, for all human rotaviral proteins, we have deciphered molecular recognition features (MoRFs), which are disorder based binding sites in proteins. Our study shows the wide spread of intrinsic disorder in several rotavirus proteins, primarily the nonstructural proteins NSP3, NSP4, and NSP5 that are involved in viral replication, translation, viroplasm formation and/or maturation. This study may serve as a primer for understanding the role of IDPs/MoRFs in rotavirus biology, design of alternative therapeutic strategies, and development of disorder-based drugs.

The performance of biological and tertiary wastewater treatment procedures for rotaviruses A removal

Enteric viruses, generally found in sewage, are recognized as the main cause of waterborne and foodborne public health outbreaks. Among leading enteric viruses, the Rotavirus A (RVA) detection in wastewater appeared to be a novel approach to monitor the emergence of these viruses in some countries where the viral gastroenteritis surveillance is almost absent such as in Tunisia. The RVA detection and quantification in an industrial sewage purification plant of Charguia I (Tunis, Tunisia) were achieved to evaluate the performance of activated sludge procedures coupled to a macrofiltration monolamp ultraviolet irradiation type C (UV-C₂₅₄) disinfection reactor. This UV-C₂₅₄ system was preceded by a fiberglass cartridge filter system with an average porosity of 45 μm to clarify the water and thus increase its UV transmittance. A total of 140 composite sewage samples was collected from this line of treatment and analyzed for RVA detection. The detection and the viral load quantification of RVA were performed using real-time reverse transcription polymerase chain reaction (RT-PCR). The virological results showed in general that RVA were detected at high frequency of 98% (137/140). In fact, the RVA detection rates at the exit of the two studied wastewater treatment were about 100% at the exit of the activated sludge procedure. It means that all wastewater sampled at this last step of treatment was positive for RVA detection. On the other hand, 92.5% of the wastewater samples taken at the exit of the monolamp UV-C₂₅₄ reactor were positive for the RVA. However, the RVA quantification results expressed as viral load showed a significant reduction in the means of RVA viral loads at the exit of the biological activated sludge procedure and the tertiary UV-C₂₅₄ treatment, showing in general an improved treated wastewater virological quality. Therefore, the RVA load removal rates recorded at the two successive stages of treatment, the activated sludge and the UV-C₂₅₄ treatment, were around 85% and 73%, respectively, as compared to the one with 100% registered for the raw wastewater. In addition, good physical-chemical and bacteriological qualities of the treated sewage were found at the exit of the two considered wastewater treatment procedures. The present investigation represents the first Tunisian environmental report showing the good effectiveness and performance of the biological and the tertiary treatments for RVA removal. Therefore, an improved and an optimized tertiary disinfection treatment was needed since it could be a good means for getting better viral water quality and for minimizing the transmission and dissemination of human infectious viral diseases.

Development of a Colloidal Gold Immunochromatographic Strip Assay for Rapid Detection of Bovine Rotavirus

Bovine rotavirus (BRV) is one of main pathogens responsible for diarrhea, fever, and vomiting. In this study, we developed a colloidal gold immunochromatographic test strip for detecting BRV according to the principle of double-antibody sandwich. The monoclonal antibodies (mAbs) and polyclonal antibodies (pAbs) were prepared and purified. On the strip, the purified mAbs labeled with the colloidal gold were used as the detector, and the goat anti-mouse antibodies and purified pAbs were coated on the nitrocellulose membranes as the control line and the test line, respectively. We optimized different reaction conditions, including the amount of mAbs, the pH of colloidal gold solution, coating solution, blocking solution, sample pad treatment solution, antibody concentration in control line, and antibody concentration in detection line. In specificity assay, the strip had high specificity in detecting BRV. No cross-reaction was observed in detecting other viruses. The detection sensitivity of the strip was found to be 1 × 10³ TCID₅₀/0.1 mL. Two hundred twenty clinical samples were detected with the strip compared to reverse transcription-polymerase chain reaction. No false-negative or false-positive results were found, and the results obtained by the two methods were similar. In conclusion, we developed a novel immunochromatographic strip to rapidly detect BRV. The strip developed exhibited high sensitivity and specificity for BRV detection. It could be a rapid, convenient, and effective method for the rapid diagnosis of BRV infection in the fields.

Cryo-EM Reveals Architectural Diversity in Active Rotavirus Particles

Rotavirus is a well-studied RNA virus that causes severe gastroenteritis in children. During viral entry, the outer layer of the virion is shed, creating a double-layered particle (DLP) that is competent to perform viral transcription (i.e., mRNA synthesis) and launch infection. While inactive forms of rotavirus DLPs have been structurally characterized in detail, information about the transcriptionally-active DLP remains limited. Here, we used cryo-Electron Microscopy (cryo-EM) and 3D image reconstructions to compare the structures of internal protein components in transcriptionally-active versus inactive DLPs. Our findings showed that transcriptionally-active DLPs gained internal order as mRNA synthesis unfolded, while inactive DLPs remained dynamically disordered. Regions of viral protein/RNA constituents were analyzed across two different axes of symmetry to provide a more comprehensive view of moving components. Taken together, our results bring forth a new view of active DLPs, which may enable future pharmacological strategies aimed at obliterating rotavirus transcription as a therapeutic approach.

Emergence of G12P[6] rotavirus strains among hospitalised children with acute gastroenteritis in Belém, Northern Brazil, following introduction of a rotavirus vaccine

Species A rotavirus still remains a major cause of acute gastroenteritis in infants and young children. Globally, six genotypes (G1P[8], G2P[4], G3P[8], G4P[8], G9P[8] and G12P[8]) account for >90% of circulating strains; however, genotype G12 in combination with P[6] or P[9] has been detected at increasing rates. We sought to broaden our knowledge about the rotavirus strains circulating during the early post-vaccine-introduction period. Stool samples were obtained from children hospitalised for acute gastroenteritis in Belém, Northern Brazil, from May 2008 to May 2011 and examined by reverse transcription polymerase chain reaction and nucleotide sequencing. A total of 122 out of the original 1076 rotavirus strains were judged to be non-typeable in the first analysis and were therefore re-examined. G2P[4] was the most prevalent genotype (58.0%), followed by G1P[8] (16.9%), and G12P[6] (7.5%). G12P[6] strains were identified at similar rates during the first (2.5%) and second (3.9%) years, and the rate jumped to 15.6% in the third year. Analysis of VP7 sequences of the G12P[6] strains showed that they belonged to lineage III. In addition, co-circulating G12P[6] strains displaying long and short RNA patterns were found to belong to the Wa-like and DS-1-like constellation, respectively. Additional unusual circulating strains G12P[9] and G3P[9] were also identified. This hospital-based study showed a high prevalence of G12P[6] strains in the third year of surveillance. Our results highlight the need for continuous longitudinal monitoring of circulating rotavirus strains after introduction of rotavirus vaccines in Brazil and elsewhere.

Actin-Dependent Nonlytic Rotavirus Exit and Infectious Virus Morphogenetic Pathway in Nonpolarized Cells

During the late stages of rotavirus morphogenesis, the surface proteins VP4 and VP7 are assembled onto the previously structured double-layered virus particles to yield a triple-layered, mature infectious virus. The current model for the assembly of the outer capsid is that it occurs within the lumen of the endoplasmic reticulum. However, it has been shown that VP4 and infectious virus associate with lipid rafts, suggesting that the final assembly of the rotavirus spike protein VP4 involves a post-endoplasmic reticulum event. In this work, we found that the actin inhibitor jasplakinolide blocks the cell egress of rotavirus from nonpolarized MA104 cells at early times of infection, when there is still no evidence of cell lysis. These findings contrast with the traditional assumption that rotavirus is released from nonpolarized cells by a nonspecific mechanism when the cell integrity is lost. Inspection of the virus present in the extracellular medium by use of density flotation gradients revealed that a fraction of the released virus is associated with low-density membranous structures. Furthermore, the intracellular localization of VP4, its interaction with lipid rafts, and its targeting to the cell surface were shown to be prevented by jasplakinolide, implying a role for actin in these processes. Finally, the VP4 present at the plasma membrane was shown to be incorporated into the extracellular infectious virus, suggesting the existence of a novel pathway for the assembly of the rotavirus spike protein.IMPORTANCE Rotavirus is a major etiological agent of infantile acute severe diarrhea. It is a nonenveloped virus formed by three concentric layers of protein. The early stages of rotavirus replication, including cell attachment and entry, synthesis and translation of viral mRNAs, replication of the genomic double-stranded RNA (dsRNA), and the assembly of double-layered viral particles, have been studied widely. However, the mechanisms involved in the later stages of infection, i.e., viral particle maturation and cell exit, are less well characterized. It has been assumed historically that rotavirus exits nonpolarized cells following cell lysis. In this work, we show that the virus exits cells by a nonlytic, actin-dependent mechanism, and most importantly, we describe that VP4, the spike protein of the virus, is present on the cell surface and is incorporated into mature, infectious virus, indicating a novel pathway for the assembly of this protein.

MiR-525-3p mediates antiviral defense to rotavirus infection by targeting nonstructural protein 1

MicroRNAs (miRNAs) are short RNAs of approximately 22 nucleotides that post-transcriptionally regulate gene expression by controlling mRNA stability or translation. They play critical roles in intricate networks of host-pathogen interactions and innate immunity. Rotaviruses (RVs) are the leading cause of severe diarrhea among infants and young children worldwide. This study was undertaken to demonstrate the importance of cellular miRNAs during RV (human Wa RV or Rhesus RV) strains infection. Twenty-nine differentially regulated miRNAs were identified during RV infection, and miR-525-3p was downregulated and validated by quantitative real-time polymerase chain reaction (qRT-PCR). MiR-525-3p mimic inhibited RV replication in dose-dependent manner. Correspondingly, the miR-525-3p inhibitors enhanced RV replication. We confirmed that miR-525-3p was complementary to the 3' untranslated region (UTR) of nonstructural protein 1(NSP1) of RV (Wa or Rhesus) strains. Interestingly, miR-525-3p induced type I interferon (IFN) expression and proinflammatory cytokines during RV infection through IFN regulatory factor (IRF) 3/IRF7 and NF-κB activation, which can induce an antiviral state to further suppress RV infection. In addition, RV suppressed miR-525-3p expression to evade host innate immunity through the action of the RV protein NSP1. These results suggest that miR-525-3p has the potential to be used as an antiviral therapeutic against RV infection.

Genetic Susceptibility to Rotavirus Gastroenteritis and Vaccine Effectiveness in Taiwanese Children

The genetic susceptibility to and vaccine effectiveness against rotavirus gastroenteritis were different in distinct ethnic groups. The case-control study was aimed to evaluate the effectiveness of rotavirus vaccines and associations between the histo-blood group antigens and susceptibility to rotavirus infections in a Taiwanese population. Cases were children <18 years old who were hospitalized because of laboratory-confirmed rotavirus infection. Controls were healthy children matched to cases by age and gender. The secretor status and Lewis antigen and ABO types were determined by molecular methods. A total of 68 cases and 133 controls were included. Rotavirus immunization was recorded in 8 (12%) cases and 77 (58%) controls, indicating a vaccine effectiveness of 90.3% (95% confidence interval [CI], 78.1% - 95.7%). The secretor and Lewis-positive genotypes were independently associated with increased risk of rotavirus infections (matched odds ratio [mOR] 28.5, 95% CI 2.94-277, P = 0.003 and mOR 16.8, 95% CI 1.08-2601, P = 0.04, respectively). The distribution of ABO blood types did not differ significantly between cases and controls (P = 0.47). In conclusion, Taiwanese children with the secretor genotype and Lewis-positive genotype were at increased risk of moderate-to-severe rotavirus infections. The illness can be effectively prevented by immunization in this population.

Oral Administration of a Seed-based Bivalent Rotavirus Vaccine Containing VP6 and NSP4 Induces Specific Immune Responses in Mice

Rotavirus is the leading cause of severe diarrheal disease among newborns. Plant-based rotavirus vaccines have been developed in recent years and have been proven to be effective in animal models. In the present study, we report a bivalent vaccine candidate expressing rotavirus subunits VP6 and NSP4 fused with the adjuvant subunit B of E. coli heat-labile enterotoxin (LTB) in maize seeds. The RT-PCR and Western blot results showed that VP6 and LTB-NSP4 antigens were expressed and accumulated in maize seeds. The expression levels were as high as 0.35 and 0.20% of the total soluble protein for VP6 and LTB-NSP4, respectively. Oral administration of transgenic maize seeds successfully stimulated systemic and mucosal responses, with high titers of serum IgG and mucosal IgA antibodies, even after long-term storage. This study is the first to use maize seeds as efficient generators for the development of a bivalent vaccine against rotavirus.

Molecular epidemiology of Rotavirus causing diarrhea among children less than five years of age visiting national level children hospitals, Nepal

Background

Rotaviruses are the major cause of diarrhea among the infants and young children all over the world causing over 500,000 deaths and 2.4 million hospitalizations each year. In Nepal Rotavirus infection positivity rates ranges from 17.0 to 39.0% among children less than 5 years. However, little is known about the molecular genotypes of Rotavirus prevailing. The objective of this study was to estimate the burden of Rotavirus gastroenteritis and determine the genotypes of Rotavirus among children less than 5 years.

Methods

The cross sectional study was conducted from January to November 2014 among children less than 5 years old visiting Kanti Children’s Hospital and Tribhuvan University Teaching Hospital.

Rotavirus antigen detection was performed by Enzyme Linked Immunosorbent Assay (ELISA) using ProSpecT Rotavirus Microplate Assay. Among the Rotavirus antigen positive samples, 59 samples were used for Rotavirus RNA extraction. Multiplex PCR was performed to identify G type comprising G1-G4, G8-G10 and G12 and P type comprising P[4], P[6], P[8], P[9], P[10], and P[11].

Results

A total of 717 diarrheal stool samples were collected from patients ranging from 10 days to 59 months of age. Rotavirus antigen positive was found among (N = 164)22.9% of patients. The highest number of the diarrhea was seen in January. Molecular analysis of Rotavirus genotypes revealed that the predominant G-Type was G12 (36%) followed by G9 (31%), G1 (21%), G2 (8.6%). The predominant P- type was P6 (32.8%) followed by P8 (31%), P10 (14.8%), P4 (14.8%). A total of seven G/P type combinations were identified the most common being G12P [6] (35.8%), G1P [8] (15.1%), G9P [8] (15.1%).

Conclusion

Rotavirus diarrhea is, mostly affecting children from 7 to 24 months in Nepal, mostly occurring in winter. The circulating genotypes in the country are found to be primarily unusual genotypes and predominance of G12P[6]. It is recommended to conduct genotyping of Rotavirus on large samples before starting vaccination in the country.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-017-0858-0) contains supplementary material, which is available to authorized users.

Production and characterization of egg yolk antibody (IgY) against recombinant VP8-S2 antigen

Bovine Rotavirus and Bovine Coronavirus are the most important causes of diarrhea in newborn calves and in some other species such as pigs and sheep. VP8 subunit of rotavirus is the major determinant of the viral infectivity and neutralization. Spike glycoprotein of coronavirus is responsible for induction of neutralizing antibody response. Studies showed that immunoglobulin of egg yolk (IgY) from immunized hens has been identified to be a convenient source for specific antibodies for using in immunotherapy and immunodiagnostic to limit the infections. In this study, chimeric VP8-S2 gene was designed using by computational techniques. The chimeric VP8-S2 gene was cloned and sub-cloned into pGH and pET32a (+) vectors. Then, recombinant pET32a-VP8-S2 vector was transferred into E. coli BL21 CodonPlus (DE3). The expressed protein was purified by Ni-NTA chromatography column. Hens were immunized with the purified VP8-S2 protein three times. IgY was purified from egg yolks using polyethylene glycol precipitation method. Activity and specificity of anti-VP8-S2 IgY were detected by dot-blotting, Western-blotting and indirect ELISA. We obtained anti-VP8-S2 IgY by immunizing hens with the recombinant VP8-S2 protein. The anti-VP8-S2 IgY was showed to bind specifically to the chimeric VP8-S2 protein by dot-blotting, Western-blotting analyses and indirect ELISA. The result of this study indicated that such construction can be useful to investigate as candidates for development of detection methods for simultaneous diagnosis of both infections. Specific IgY against the recombinant VP8-S2 could be recommended as a candidate for passive immunization against bovine rotavirus and bovine coronavirus.

Antiviral Probiotics: A New Concept in Medical Sciences

In recent decades, probiotics have shown beneficial effects on animal and human health. Probiotics can protect the host against several health threats, including infectious diseases. Before 1995, researchers believed that the effect of probiotics was only on gut microbiota which can restore the gut flora and thus prevent pathogenic bacteria from triggering gastroenteritis. Recent studies have shown that the immunomodulatory activity is the most important mechanism of action of probiotics. From this information, researchers started to evaluate the effect of some immunobiotics, not only on pathogenic bacteria but also on viruses, including enteric and respiratory viruses. Several studies have confirmed the potential antiviral activity of some probiotics due to the immunomodulatory effect. These studies were conducted on humans (clinical trials) and in animal models. In this chapter, probiotics with antiviral effect against respiratory and enteric viruses will be presented and discussed, as well as their mechanisms of action.

The interaction of Rotavirus A pig/China/NMTL/2008/G9P[23] VP6 with cellular beta-actin is required for optimal RV replication and infectivity

VP6 forms the intermediate layer of the rotavirus (RV) capsid, and it plays important roles after RV penetration and uncoating. These functions rely on its ability to interact with host cell proteins. To gain further insights into the role of VP6 in porcine RV (PoRV) infection, a glutathione S-transferase pull-down assay was utilized to find unknown cellular factors that interact with VP6. In this study, beta-actin, tropomyosin 1, and 40S ribosomal protein S16 were identified as interaction partners of VP6 by mass spectrometry and co-immunoprecipitation. The interaction with beta-actin was further studied. By immunoelectron microscopy, we observed VP6 proteins that labeled with colloidal gold localized on the actin microfilaments at the early stage of PoRV infection, we also found VP6 distributed in the ribosome, mitochondria, endoplasmic reticulum and nucleus in the infected cells. Actin binding protein spin-down assays verified PoRV double-layered particles (DLPs) bound to F-actin in vitro, but didn't have actin polymerization enhancement activity. After a small interfering RNA (siACTB) was used to knock down beta-actin expression, PoRV VP6 expression and the infection rates of newly synthesized virions releasing into culture supernatants decreased dramatically. Our results confirm and extend previous reports indicating that the interaction between PoRV VP6 and beta-actin plays vital roles in the PoRV lifecycle.

Design and Construction of Chimeric VP8-S2 Antigen for Bovine Rotavirus and Bovine Coronavirus

PURPOSE

Bovine Rotavirus and Bovine Coronavirus are the most important causes of diarrhea in newborn calves and in some other species such as pigs and sheep. Rotavirus VP8 subunit is the major determinant of the viral infectivity and neutralization. Spike glycoprotein of coronavirus is responsible for induction of neutralizing antibody response.

METHODS

In the present study, several prediction programs were used to predict B and T-cells epitopes, secondary and tertiary structures, antigenicity ability and enzymatic degradation sites. Finally, a chimeric antigen was designed using computational techniques. The chimeric VP8-S2 antigen was constructed. It was cloned and sub-cloned into pGH and pET32a(+) expression vector. The recombinant pET32a(+)-VP8-S2 vector was transferred into E.oli BL21CodonPlus (DE3) as expression host. The recombinant VP8-S2 protein was purified by Ni-NTA chromatography column.

RESULTS

The results of colony PCR, enzyme digestion and sequencing showed that the VP8-S2 chimeric antigen has been successfully cloned and sub-cloned into pGH and pET32a(+).The results showed that E.coli was able to express VP8-S2 protein appropriately. This protein was expressed by induction of IPTG at concentration of 1mM and it was confirmed by Ni-NTA column, dot-blotting analysis and SDS-PAGE electrophoresis.

CONCLUSION

The results of this study showed that E.coli can be used as an appropriate host to produce the recombinant VP8-S2 protein. This recombinant protein may be suitable to investigate to produce immunoglobulin, recombinant vaccine and diagnostic kit in future studies after it passes biological activity tests in vivo in animal model and or other suitable procedure.

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.

A Non-Symmetric Reconstruction Technique for Transcriptionally-Active Viral Assemblies

The molecular mechanisms by which RNA viruses coordinate their transcriptional activities are not fully understood. For rotavirus, an important pediatric gastroenteric pathogen, transcription occurs within a double-layered particle that encloses the viral genome. To date, there remains very little structural information available for actively-transcribing rotavirus double-layered particles, which could provide new insights for antiviral development. To improve our vision of these viral assemblies, we developed a new combinatorial strategy that utilizes currently available high-resolution image processing tools. First, we employed a 3D classification routine that allowed us to sort transcriptionally-active rotavirus assemblies on the basis of their internal density. Next, we implemented an additional 3D refinement procedure using the most active class of DLPs. For comparison, the refined structures were computed in parallel by (1) enforcing icosahedral symmetry, and by (2) using no symmetry operators. Comparing the resulting structures, we were able to visualize the continuum that exists between viral capsid proteins and the viral RNA for the first time.

Genistein inhibits rotavirus replication and upregulates AQP4 expression in rotavirus-infected Caco-2 cells

Rotavirus (RV) is the primary cause of severe dehydrating gastroenteritis and acute diarrheal disease in infants and young children. Previous studies have revealed that genistein can inhibit the infectivity of enveloped or nonenveloped viruses. Although the biological properties of genistein are well studied, the mechanisms of action underlying their anti-rotavirus properties have not been fully elucidated. Here, we report that genistein significantly inhibits RV-Wa replication in vitro by repressing viral RNA transcripts, and possibly viral protein synthesis. Interestingly, we also found that aquaporin 4 (AQP4) mRNA and protein expression, which was downregulated in RV-infected Caco-2 cells, can be upregulated by genistein in a time- and dose-dependent manner. Further experiments confirmed that genistein triggers CREB phosphorylation through PKA activation and subsequently promotes AQP4 gene transcription. These findings suggest that the pathophysiological mechanism of RV infection involves decreased expression of AQP4 and that genistein may be a useful candidate for developing a new anti-RV strategy by inhibiting rotavirus replication and upregulating AQP4 expression via the cAMP/PKA/CREB signaling pathway. Further studies on the effect of genistein on RV-induced diarrhea are warranted.

Electron microscopic analysis of rotavirus assembly-replication intermediates

Rotaviruses (RVs) replicate their segmented, double-stranded RNA genomes in tandem with early virion assembly. In this study, we sought to gain insight into the ultrastructure of RV assembly-replication intermediates (RIs) using transmission electron microscopy (EM). Specifically, we examined a replicase-competent, subcellular fraction that contains all known RV RIs. Three never-before-seen complexes were visualized in this fraction. Using in vitro reconstitution, we showed that ~15-nm doughnut-shaped proteins in strings were nonstructural protein 2 (NSP2) bound to viral RNA transcripts. Moreover, using immunoaffinity-capture EM, we revealed that ~20-nm pebble-shaped complexes contain the viral RNA polymerase (VP1) and RNA capping enzyme (VP3). Finally, using a gel purification method, we demonstrated that ~30–70-nm electron-dense, particle-shaped complexes represent replicase-competent core RIs, containing VP1, VP3, and NSP2 as well as capsid proteins VP2 and VP6. The results of this study raise new questions about the interactions among viral proteins and RNA during the concerted assembly-replicase process.

Probing the sites of interactions of rotaviral proteins involved in replication

Replication and packaging of the rotavirus genome occur in cytoplasmic compartments called viroplasms, which form during virus infection. These processes are orchestrated by yet-to-be-understood complex networks of interactions involving nonstructural proteins (NSPs) 2, 5, and 6 and structural proteins (VPs) 1, 2, 3, and 6. The multifunctional enzyme NSP2, an octamer with RNA binding activity, is critical for viroplasm formation with its binding partner, NSP5, and for genome replication/packaging through its interactions with replicating RNA, the viral polymerase VP1, and the inner core protein VP2. Using isothermal calorimetry, biolayer interferometry, and peptide array screening, we examined the interactions between NSP2, VP1, VP2, NSP5, and NSP6. These studies provide the first evidence that NSP2 can directly bind to VP1, VP2, and NSP6, in addition to the previously known binding to NSP5. The interacting sites identified from reciprocal peptide arrays were found to be in close proximity to the RNA template entry and double-stranded RNA (dsRNA) exit tunnels of VP1 and near the catalytic cleft and RNA-binding grooves of NSP2; these sites are consistent with the proposed role of NSP2 in facilitating dsRNA synthesis by VP1. Peptide screening of VP2 identified NSP2-binding sites in the regions close to the intersubunit junctions, suggesting that NSP2 binding could be a regulatory mechanism for preventing the premature self-assembly of VP2. The binding sites on NSP2 for NSP6 were found to overlap that of VP1, and the NSP5-binding sites overlap those of VP2 and VP1, suggesting that interaction of these proteins with NSP2 is likely spatially and/or temporally regulated.

IMPORTANCE

Replication and packaging of the rotavirus genome occur in cytoplasmic compartments called viroplasms that form during virus infection and are orchestrated by complex networks of interactions involving nonstructural proteins (NSPs) and structural proteins (VPs). A multifunctional RNA-binding NSP2 octamer with nucleotidyl phosphatase activity is central to viroplasm formation and RNA replication. Here we provide the first evidence that NSP2 can directly bind to VP1, VP2, and NSP6, in addition to the previously known binding to NSP5. The interacting sites identified from peptide arrays are consistent with the proposed role of NSP2 in facilitating dsRNA synthesis by VP1 and also point to NSP2's possible role in preventing the premature self-assembly of VP2 cores. Our findings lead us to propose that the NSP2 octamer with multiple enzymatic activities is a principal regulator of viroplasm formation, recruitment of viral proteins into the viroplasms, and possibly genome replication.

Identification of novel Ghanaian G8P[6] human-bovine reassortant rotavirus strain by next generation sequencing

Group A rotaviruses (RVAs) are the most important etiological agent of acute gastroenteritis in children <5 years of age worldwide. The monovalent rotavirus vaccine Rotarix was introduced into the national Expanded Programme on Immunization (EPI) in Ghana in May 2012. However, there is a paucity of genetic and phylogenetic data on the complete genomes of human RVAs in circulation pre-vaccine introduction. The common bovine rotavirus VP7 genotype G8 has been sporadically detected in Ghanaian children, usually in combination with the VP4 genotype P[6]. To investigate the genomic constellations and phylogeny of RVA strains in circulation prior to vaccine introduction, the full genomes of two unusual G8P[6] strains, GH018-08 and GH019-08, detected during burden of disease surveillance, were characterized by Illumina MiSeq sequencing. The Ghanaian isolates, GH018-08 and GH019-08, exhibited the unusual, previously unreported genotype constellation G8-P[6]-I2-R2-C2-M2-A2-N2-T2-E2-H3. Phylogenetic analyses confirmed that 10 out of the 11 genes of GH018-08 and GH019-08 were identical/nearly identical, with significant variation detected only in their VP1 genes, and clearly established the occurrence of multiple independent interspecies transmission and reassortment events between co-circulating bovine/ovine/caprine rotaviruses and human DS-1-like RVA strains. These findings highlight the contribution of reassortment and interspecies transmission events to the high rotavirus diversity in this region of Africa, and justify the need for simultaneous monitoring of animal and human rotavirus strains.

Characterization and Transferring of Human Rotavirus Double-Layered Particles in MA104 Cells

BACKGROUND

Rotavirus (RV) is a major cause of gastroenteritis in infants and children and is one of the most severe public health problems. Rotaviruses outer layer contains two proteins including VP4 and VP7. These proteins are necessary for host-cell binding and penetration. TLP (triple layer virus particle) of RV is a complete infectious virion that binds to the target cells and internalized at the cytoplasm. The DLP (double layer virus particle) is a non-infectious particle that is formed through exclusion of the outer layer proteins including VP4 and VP7. These DLPs are the transcriptionally active forms of rotavirus.

OBJECTIVES

The aim of this study was to transfer DLP of RV into cytoplasm of MA104 cells by Lipofectamine and to analyze their replication.

MATERIALS AND METHODS

Initially, rotavirus was purified by CsCl discontinuous gradient and DLP was separated from TLP based on density differences. For confirmation, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of the proteins were conducted Then the purified DLP of RV was transferred into MA104 cells using Lipofectamine.

RESULTS

We attempt to avoid the attachment and entry of the rotavirus by using Lipofectamine to mediate the delivery of viral particles directly into the cytoplasm. DLP was endocytosed into the cytoplasm following treatment by Lipofectamine and then replicated in cytoplasm.

CONCLUSIONS

Therefore the non-infectious DLPs were became infectious if introduced into the cytoplasm of permissive and cancerous cells, without passing attachment and entry process.

Identification and genomic characterization of a novel fish reovirus, Hubei grass carp disease reovirus, isolated in 2009 in China

A novel fish reovirus, Hubei grass carp disease reovirus (HGDRV; formerly grass carp reovirus strain 104, GCRV104), was isolated from diseased grass carp in China in 2009 and the full genome sequence was determined. This reovirus was propagated in a grass carp kidney cell line with a typical cytopathic effect. The total size of the genome was 23 706 bp with a 51 mol% G+C content, and the 11 dsRNA segments encoded 12 proteins (two proteins encoded by segment 11). A nucleotide sequence similarity search using blastn found no significant matches except for segment 2, which partially matched that of the RNA-dependent RNA polymerase (RdRp) from several viruses in the genera Aquareovirus and Orthoreovirus of the family Reoviridae. At the amino acid level, seven segments (Seg-1 to Seg-6, and Seg-8) matched with species in the genera Aquareovirus (15-46 % identities) and Orthoreovirus (12-44 % identities), while for four segments (Seg-7, Seg-9, Seg-10 and Seg-11) no similarities in these genera were found. Conserved terminal sequences, 5'-GAAUU----UCAUC-3', were found in each HGDRV segment at the 5' and 3' ends, and the 5'-terminal nucleotides were different from any known species in the genus Aquareovirus. Phylogenetic analysis based on RdRp amino acid sequences from members of the family Reoviridae showed that HGDRV clustered with aquareoviruses prior to joining a branch common with orthoreoviruses. Based on these observations, we propose that HGDRV is a new species in the genus Aquareovirus that is distantly related to any known species within this genus.

Rotavirus mRNAS are released by transcript-specific channels in the double-layered viral capsid

Rotaviruses are the single most common cause of fatal and severe childhood diarrheal illness worldwide (>125 million cases annually). Rotavirus shares structural and functional features with many viruses, such as the presence of segmented double-stranded RNA genomes selectively and tightly packed with a conserved number of transcription complexes in icosahedral capsids. Nascent transcripts exit the capsid through 12 channels, but it is unknown whether these channels specialize in specific transcripts or simply act as general exit conduits; a detailed description of this process is needed for understanding viral replication and genomic organization. To this end, we developed a single molecule assay for capturing and identifying transcripts extruded from transcriptionally active viral particles. Our findings support a model in which each channel specializes in extruding transcripts of a specific segment that in turn is linked to a single transcription complex. Our approach can be extended to study other viruses and transcription systems.