Seeing Biomolecular Condensates Through the Lens of Viruses

Phase separation of viral biopolymers is a key factor in the formation of cytoplasmic viral inclusions, known as sites of virus replication and assembly. This review describes the mechanisms and factors that affect phase separation in viral replication and identifies potential areas for future research. Drawing inspiration from studies on cellular RNA-rich condensates, we compare the hierarchical coassembly of ribosomal RNAs and proteins in the nucleolus to the coordinated coassembly of viral RNAs and proteins taking place within viral factories in viruses containing segmented RNA genomes. We highlight the common characteristics of biomolecular condensates in viral replication and how this new understanding is reshaping our views of virus assembly mechanisms. Such studies have the potential to uncover unexplored antiviral strategies targeting these phase-separated states.

Possibilities of using mussels (Mytilus galloprovincialis) to predict rotavirus contamination in Albania

Introduction

Rotaviruses are non-enveloped viruses that each consist of 11 double-stranded RNA molecules. These viruses are able to persist in the environment, and therefore play a fundamental role in the epidemiology of gastroenteritis and severe diarrhoea in children worldwide. While mussels have been primarily used as indicators of chemical pollution, they can also be used to monitor viral contamination. The purpose of this study was to demonstrate that the Mytilus galloprovincialis mussel can also be used to detect microbial contamination, owing to its tendency to naturally concentrate viruses and other pathogens.

Material and Methods

A total of 102 Mytilus galloprovincialis mussel samples from Albania were collected over a three-year period: 37 samples off the Cape of Stillo in 2015, 39 samples from Butrinti Lake in 2019 and 26 samples from Butrinti Lake in 2021.

Results

The presence of rotavirus in the Cape of Stillo samples in 2015 was noted in 47% of samples from site 1, 33% from site 2, and 52% from site 3. In Butrinti Lake the percentage of infected individuals in 2019 was 33% from site 1, 41% from site 2, and 33% from site 3, whereas in 2021, it was 50% from site 1, 19% from site 2, and 0% from site 3. In total the percentage of infected individuals off the Cape of Stillo in 2015 was 44%, in Butrinti Lake in 2019 it was 36%, and in Butrinti Lake in 2021 it was 23 %.

Conclusion

These results indicate the presence of rotavirus in the shellfish specimens tested, and further analysis is needed to assess the potential health risks associated with consuming these shellfish. This study also indicates that mussels can be used in marine virological surveillance programmes.

Evaluation of Activity of Zinc Oxide Nanoparticles on Human Rotavirus and Multi-Drug Resistant Acinetobacter Baumannii

BACKGROUND

Rotaviruses are the cause of acute gastroenteritis and severe diarrheal diseases in children worldwide. Children under the age of five are more susceptible to rotavirus infections. Due to such as the lack of effective drugs and supportive therapy only, the development of new antiviral agents against rotaviruses is required. Multi-drug-resistant Acinetobacter baumannii is also one of the most challenging Gram-negative bacteria to control and treat due to its antibiotic resistance, particularly in intensive care units.

OBJECTIVE

This study aimed to investigate the activity of zinc oxide nanoparticles against human rotavirus and multi-drug resistant Acinetobacter baumannii.

METHODS

The standard 50% tissue culture infectious dose method and the real-time polymerase chain reaction assay were used to investigate the effects of zinc oxide nanoparticles on rotaviruses. The well diffusion and the minimum inhibitory concentration method were used to assess the antibacterial activity of zinc oxide nanoparticles against Acinetobacter baumannii.

RESULTS

300 μg/ml of zinc oxide nanoparticles demonstrated the highest anti-rotavirus effects, resulting in a 3.16 logarithmic decrease in virus infectious titer, and a four-unit increase in the cycle threshold value of the real-time polymerase chain reaction assay compared to the untreated control (P value <0.001 and P value = 0.005, respectively). The diameter of the inhibition zone of zinc oxide nanoparticles solution against Acinetobacter baumannii was 17 mm. The minimum inhibitory concentration results of the zinc oxide nanoparticles solution against Acinetobacter baumannii was 1.56 mg/ml.

CONCLUSION

Our findings showed that zinc oxide nanoparticles could be considered a promising antimicrobial compound.

The Efficacy of Probiotics as Antiviral Agents for the Treatment of Rotavirus Gastrointestinal Infections in Children: An Updated Overview of Literature

Enteric viruses, including the rotavirus, norovirus, and adenoviruses, are the most common cause of acute gastroenteritis. The rotavirus disease is especially prevalent among children, and studies over the past decade have revealed complex interactions between rotaviruses and the gut microbiota. One way to treat and prevent dysbiosis is the use of probiotics as an antiviral agent. This review focuses on the latest scientific evidence on the antiviral properties of probiotics against rotavirus gastroenteric infections in children. A total of 19 studies exhibited a statistically significant antiviral effect of probiotics. The main probiotics that were effective were Saccharomyces cerevisiae var. boulardii, Lacticaseibacillus rhamnosus GG, and various multi-strain probiotics. The underlying mechanism of the probiotics against rotavirus gastroenteric infections in children included immune enhancement and modulation of intestinal microbiota leading to shortening of diarrhoea. However, several clinical studies also found no significant difference in the probiotic group compared to the placebo group even though well-known strains were used, thus showing the importance of correct dosage, duration of treatment, quality of probiotics and the possible influence of other factors, such as the production process of probiotics and the influence of immunisation on the effect of probiotics. Therefore, more robust, well-designed clinical studies addressing all factors are warranted.

Effect of rotavirus genetic diversity on vaccine impact

Group A rotaviruses (RVAs) are the leading cause of gastroenteritis, causing 0.2 million deaths and several million hospitalisations globally each year. Four rotavirus vaccines (Rotarix^TM , RotaTeq^TM , Rotavac^® and ROTASIIL^® ) have been pre-qualified by the World Health Organization (WHO), but the two newly pre-qualified vaccines (Rotavac^® and ROTASIIL^® ) are currently only in use in Palestine and India, respectively. In 2009, WHO strongly proposed that rotavirus vaccines be included in the routine vaccination schedule of all countries around the world. By the end of 2019, a total of 108 countries had administered rotavirus vaccines, and 10 countries have currently been approved by Gavi for the introduction of rotavirus vaccine in the near future. With 39% of global coverage, rotavirus vaccines have had a substantial effect on diarrhoeal morbidity and mortality in different geographical areas, although efficacy appears to be higher in high income settings. Due to the segmented RNA genome, the pattern of RVA genotypes in the human population is evolving through interspecies transmission and/or reassortment events for which the vaccine might be less effective in the future. However, despite the relative increase in some particular genotypes after rotavirus vaccine use, the overall efficacy of rotavirus mass vaccination worldwide has not been affected. Some of the challenges to improve the effect of current rotavirus vaccines can be solved in the future by new rotavirus vaccines and by vaccines currently in progress.

Poult Enteritis and Mortality Syndrome in Turkey Poults: Causes, Diagnosis and Preventive Measures

Simple Summary

The poult enteritis and mortality syndrome (PEMS) causes severe economic losses in turkeys. Several agents were described to be associated with the PEMS; however, a specific etiological agent(s) has not been identified. The diagnosis of PEMS is still a huge challenge for several reasons: (1) no specific clinical signs or pathognomonic lesions, (2) isolation of some enteric viruses still difficult, (3) the pathogenicity of several enteric viruses in turkeys is not fully understood, (4) PEMS is an interaction between several known and might be unknown agents and (5) opportunistic microorganisms also have a role in the pathogenesis of PEMS. Both electron microscopy and molecular techniques can be used for diagnosis of PEMS and might help to discover unknown causes. Until now, no specific vaccines against enteric viruses associated with PEMS. However, biosecurity, maintaining a healthy gut and strengthening the immune system of turkey poults using probiotics, prebiotics and/or phytogenic substances are crucial factors to prevent and/or reduce losses of PEMS in turkeys. This review is a call for scientists to perform further research to investigate the real cause(s) of PEMS and to develop a preventive strategy against it.

Abstract

Poult enteritis and mortality syndrome (PEMS) is one of the most significant problem affecting turkeys and continues to cause severe economic losses worldwide. Although the specific causes of PEMS remains unknown, this syndrome might involve an interaction between several causative agents such as enteropathogenic viruses (coronaviruses, rotavirus, astroviruses and adenoviruses) and bacteria and protozoa. Non-infectious causes such as feed and management are also interconnected factors. However, it is difficult to determine the specific cause of enteric disorders under field conditions. Additionally, similarities of clinical signs and lesions hamper the accurate diagnosis. The purpose of the present review is to discuss in detail the main viral possible causative agents of PEMS and challenges in diagnosis and control.

Emerging and Neglected Viruses of Zoonotic Importance in Croatia

Several arboviruses have emerged in Croatia in recent years. Tick-borne encephalitis is endemic in continental counties; however, new natural micro-foci have been detected. Two autochthonous dengue cases were reported in 2010. West Nile virus emerged in 2012, followed by emergence of Usutu virus in 2013. Although high seroprevalence rates of Toscana virus have been detected among residents of Croatian littoral, the virus remains neglected, with only a few clinical cases of neuroinvasive infections reported. Lymphocytic choriomeningitis virus is a neglected neuroinvasive rodent-borne virus. So far, there are no reports on human clinical cases; however, the seroprevalence studies indicate the virus presence in the Croatian mainland. Puumala and Dobrava hantaviruses are widely distributing rodent-borne viruses with sporadic and epidemic occurrence. Hepatitis E virus is an emerging food-borne virus in Croatia. After the emergence in 2012, cases were regularly recorded. Seropositivity varies greatly by region and population group. Rotaviruses represent a significant healthcare burden since rotavirus vaccination is not included in the Croatian national immunization program. Additionally, rotaviruses are widely distributed in the Croatian ecosystem. A novel coronavirus, SARS-CoV-2, emerged in February 2020 and spread rapidly throughout the country. This review focuses on emerging and neglected viruses of zoonotic importance detected in Croatia.

Induction of Cell Death in the Human Acute Lymphoblastic Leukemia Cell Line Reh by Infection with Rotavirus Isolate Wt1-5

Cancer is a major health problem that poses a great challenge to health care systems worldwide. Tools for cancer treatment have rapidly advanced in recent years, resulting in therapeutic strategies which are alternative and complementary to conventional treatment. To identify the cell surface receptors used by a tumor cell-adapted rotavirus and the cell death markers induced by its infection, we use Wt1-5, a rotavirus isolate recently adapted to tumor cells, to infect the human acute lymphoblastic leukemia cell line, Reh. The expression of cell surface receptors used by Wt1-5 was determined using flow cytometry and an antibody blocking assay to test for their implication in virus infection. Viral antigens and cell death markers induced by rotavirus infection were followed by flow cytometric analysis. The present study showed that rotavirus Wt1-5 was able to use cell surface proteins such as heat shock proteins (HSPs) 90, 70, 60 and 40, Hsc70, PDI and integrin β3. Rotavirus Wt1-5 induced cytotoxic effects including changes in cell membrane permeability, alteration of mitochondrial membrane potential, DNA fragmentation and activation of cell death signaling. Wt1-5 deserves to be further studied as a candidate oncolytic agent due to its ability to induce apoptosis in lymphoblastic leukemia-derived cells.

In situ hybridization detection and subtyping of rotaviruses in swine samples

Rotavirus groups A, B, and C (RVA, RVB, and RVC, respectively) have been the most prevalent and pathogenic in pigs. To date, immunohistochemistry is only available for RVA because of the lack of commercial antibodies for RVB and RVC. We developed a novel in situ hybridization RNA-based chromogenic technique (ISH-RNA) to detect and subtype RVA, RVB, and RVC. We evaluated 33 samples that were reverse-transcription PCR positive for RVA, RVB, and/or RVC. ISH-RNA was able to detect as few as 10³ RV RNA copies/mL. The new ISH-RNA test can be useful for routine investigation of rotavirus enteritis in order to guide strategies for control of the infection in pigs, but a full validation study needs to be completed. Pathogenesis studies may be conducted using ISH-RNA based on the identification of replicating virus.

Gastroduodenal Perforation and Ulcer Associated With Rotavirus and Norovirus Infections in Japanese Children: A Case Report and Comprehensive Literature Review

Race, young age, male gender, severe dehydration, metabolic acidosis, drowsiness/unconsciousness and shock are associated with gastroduodenal perforation/ulcer (GDPU) in childhood rotaviruses and noroviruses gastroenteritis. Awareness of the risk of GDPU prevents lethal outcome in these common infections among young children.

Background. There is no literature review on gastroduodenal perforation or ulcer (GDPU) with rotavirus (RV) and norovirus (NoV) gastroenteritis.

Methods. Pediatric cases of GDPU or upper gastrointestinal bleeding with RV and NoV gastroenteritis were searched from September 1974 until October 2015 using PubMed, Google for English, other-language-publications, and Ichushi (http://www.jamas.or.jp) for Japanese-language publications. All reports confirming GDPU or upper gastrointestinal bleeding with RV and NoV gastroenteritis were eligible for inclusion in the study. In addition, clinical characteristics were reviewed.

Results. A boy with duodenal ulcer (DU) and NoV gastroenteritis was described. There were 32 GDPU cases (23 RVs and 9 NoVs cases), including our case; with the exception of 1 case, all were Japanese. Mean age, male/female ratio, and symptoms' duration before admission were 21.6 months, 2.2, and 4.0 days, respectively. Vomiting was the most common symptom, followed by diarrhea, lethargy, fever, abdominal distension, and convulsion. Dehydration, hematemesis, melena, drowsiness or unconsciousness, shock, metabolic acidosis, leukocytosis, anemia, positive C-reactive protein, high blood urea nitrogen, and hyponatremia commonly occurred. Helicobacter pylori was a minor cause of GDPU. Duodenal (DP) or gastric perforation (GP) developed in 14 cases (10 DP/RVs, 1 GP/RV, and 3 DP/NoVs). Duodenal ulcer or gastric ulcer (GU) developed in 18 cases (10 DU/RVs, 4 DU/NoVs, 1 GU/RV, 1 GU + DU/NoV, and 2 upper gastrointestinal bleeding/RVs). The predominant perforation or ulcer site was in the duodenum. With the exception of 2 deaths from DU, all cases recovered.

Conclusions. Race, young age, male, severe dehydration, metabolic acidosis, drowsiness and unconsciousness, and shock may be potential risk factors of GDPU associated with RV and NoV gastroenteritis. Limitation of this descriptive study warrants further investigations to determine the risk factors in these infections that could be associated with GDPU.

Emerging OP354-Like P[8] Rotaviruses Have Rapidly Dispersed from Asia to Other Continents

The majority of human group A rotaviruses possess the P[8] VP4 genotype. Recently, a genetically distinct subtype of the P[8] genotype, also known as OP354-like P[8] or lineage P[8]-4, emerged in several countries. However, it is unclear for how long the OP354-like P[8] gene has been circulating in humans and how it has spread. In a global collaborative effort 98 (near-)complete OP354-like P[8] VP4 sequences were obtained and used for phylogeographic analysis to determine the viral migration patterns. During the sampling period, 1988-2012, we found that South and East Asia acted as a source from which strains with the OP354-like P[8] gene were seeded to Africa, Europe, and North America. The time to the most recent common ancestor (TMRCA) of all OP354-like P[8] genes was estimated at 1987. However, most OP354-like P[8] strains were found in three main clusters with TMRCAs estimated between 1996 and 2001. The VP7 gene segment of OP354-like P[8] strains showed evidence of frequent reassortment, even in localized epidemics, suggesting that OP354-like P[8] genes behave in a similar manner on the evolutionary level as other P[8] subtypes. The results of this study suggest that OP354-like P[8] strains have been able to disperse globally in a relatively short time period. This, in combination with a relatively large genetic distance to other P[8] subtypes, might result in a lower vaccine effectiveness, underscoring the need for a continued surveillance of OP354-like P[8] strains, especially in countries where rotavirus vaccination programs are in place.

[Rotavirus and other viruses causing acute childhood gastroenteritis]

Acute gastroenteritis is one of the most common diseases, affecting children worldwide. Viruses are recognized as a major cause of this disease, particularly in children. Since the Norwalk virus was identified as a cause of gastroenteritis, the number of viral agents associated with diarrheal disease in humans has progressively increased. Rotavirus is the most common cause of severe diarrhea in children under 5 years of age. Human astroviruses, caliciviruses and enteric adenovirus are also important etiologic agents of acute gastroenteritis. Other viruses such as toroviruses, coronaviruses, picobirnaviruses, Aichi virus and human bocavirus are increasingly being identified as causative agents of diarrhea. Vaccination against rotavirus could prevent cases of severe diarrhea and reduce the mortality attributable to this disease.

Viruses causing gastroenteritis

Acute gastroenteritis is one of the most common diseases in humans worldwide. Viruses are recognized as important causes of this disease, particularly in children. Since the Norwalk virus was identified as a cause of gastroenteritis, the number of viral agents associated with diarrheal disease in humans has steadily increased. Rotavirus is the most common cause of severe diarrhea in children under 5 years of age. Astrovirus, calicivirus and enteric adenovirus are also important etiologic agents of acute gastroenteritis. Other viruses, such as toroviruses, coronaviruses, picobirnaviruses and pestiviruses, are increasingly being identified as causative agents of diarrhea. In recent years, the availability of diagnostic tests, mainly immunoassays or molecular biology techniques, has increased our understanding of this group of viruses. The future development of a safe and highly effective vaccine against rotavirus could prevent, at least, cases of severe diarrhea and reduce mortality from this disease.

Molecular determinants of rotavirus virulence: localization of a potential virulence site in a murine rotavirus VP4

The molecular basis of pathogenesis in vivo for a virulent mouse rotavirus (MRV) and a less virulent bovine rotavirus (BRV) were compared under in vitro and in vivo conditions. Obvious differences in the mobility of several genomic RNA segments were observed in one-dimensional gels. Under in vitro conditions, partial proteolytic peptide mapping identified differences between the two outer capsid proteins of these virus and no difference in inner capsid protein was observed. Since it has been observed by us and others that the gene coding for VP4 protein plays a significant role in determining virulence, the variability observed in the present study between the 84 k proteins (VP4) provided a basis for further investigations in order to locate a potential virulence determinant. A comparison of the carboxypeptidase digests of the MRV- and BRV-VP4 revealed an area of variability between amino acids 307 and 407, which may represent a site of virulence determinant. Under in vivo conditions the virulence of both parenteral BRV and MRV isolates and their corresponding reassortants (with replaced gene 4) were studied in murine and bovine hosts. Like their parents, BRV and MRV isolates, reassortants obtained by replacement of gene 4 in BRV with MRV gene 4 indicated that the dose of the virus isolate used and the clinical outcome in vivo was determined by gene segment 4. The implications of these findings to elucidate the molecular basis of pathogenesis of rotaviruses are discussed.

Studies on the survival of aerosolized bovine rotavirus (UK) and a murine rotavirus

The effect of relative humidity (RH) and temperature on the survival of airborne bovine rotavirus UK isolate (BRV-UK) and a murine rotavirus (MRV) was studied. In any one experiment, the virus under test was suspended in tryptose phosphate broth (TPB) supplemented with uranine (physical tracer) and an antifoam, was aerosolized using a Collison nebulizer into the rotating drum with the RH at either low (30 +/- 5%), medium (50 + 5%) or high (80 +/- 5%) level at 20 +/- 1 degrees C. Following a 15-min period of viral aerosol stabilization, sequential samples of drum air were collected using an All-Glass Impinger (AGI) for 24 h post-aerosolization. Both of the rotavirus isolates were found to survive best at medium RH level and high RH was found least favorable for the survival of these aerosolized rotaviruses. The survival pattern of aerosolized MRV was found to be the best when compared with survival pattern of all animal and human rotavirus isolates studies performed under aerosolized conditions in our laboratory. The findings of these experiments confirm and extend our previous reports on the survival of other animal and human aerosolized rotaviruses and emphasize the fact that air may be one of the vehicles for their dissemination and could explain why it is difficult to control nosocomial outbreaks of rotavirus gastroenteritis and to keep animal colonies rotavirus-free.

Viral diarrhea of young animals: a review

A brief presentation is given of the enteric viral infections of young animals. The general characteristics of rotaviruses, coronaviruses and parvoviruses are reported, and the different aspects of the diseases associated with these viruses are discussed. Certain suggestions are made regarding the prevention of these diseases.