Single Virus Research Articles

Dengue Fever: Etiology, Diagnosis, Prevention and Treatment

Dengue fever (break-bone fever) is a viral disease transmitted by Aedes mosquitoes. It is caused by the Dengue virus, which is a single positive-stranded RNA virus belonging to the Flaviviridae family. Dengue fever is prevalent in tropical and subtropical areas and is a significant public health concern in many countries, including`g Nigeria. The disease is characterized by symptoms such as high fever, headache, body aches, nausea, vomiting, swollen glands, and rash. In severe cases, dengue fever can lead to complications such as bleeding, organ impairment, and dengue shock syndrome. Diagnosing dengue fever can be challenging, especially in areas where it is endemic. In endemic locations, diagnosis is often made clinically based on the patient's reported symptoms and a physical examination. Tourniquet testing, which involves applying a blood pressure cuff and counting any petechial hemorrhages, can help in the diagnosis. Laboratory methods, including full blood count, cell culture, nucleic acid identification (PCR), and serology, can be used to confirm the diagnosis. Preventing dengue fever involves controlling the mosquito vector and protecting oneself from mosquito bites. Measures such as eliminating mosquito breeding sites, using insect repellents, wearing protective clothing, and using bed nets can help prevent mosquito bites. Vaccination against dengue is also available, with the Dengvaxia vaccine being used in some countries. There is no specific antiviral treatment for dengue fever. Management focuses on supportive care, maintaining a healthy fluid balance, and relieving symptoms such as fever and pain. Severe cases may require hospitalization and intensive medical care. In Nigeria, dengue fever is often misdiagnosed or overlooked due to similarities with other febrile illnesses like malaria. This can lead to underreporting and inadequate management of dengue cases. Increasing awareness among healthcare professionals and the general population is crucial for early detection and appropriate management of dengue fever in Nigeria. In conclusion dengue fever is a viral disease transmitted by mosquitoes, primarily Aedes species. It is a significant global health concern, including in Nigeria. Early diagnosis, prevention measures, and supportive care are essential in managing dengue fever and reducing its impact on public health. This review is aimed at discussing the current issues of Dengue fever with focus on Nigeria.

A new compact adenine base editor generated through deletion of HNH and REC2 domain of SpCas9

BackgroundAdenine base editors (ABEs) are promising therapeutic gene editing tools that can efficiently convert targeted A•T to G•C base pairs in the genome. However, the large size of commonly used ABEs based on SpCas9 hinders its delivery in vivo using certain vectors such as adeno-associated virus (AAV) during preclinical applications. Despite a number of approaches having previously been attempted to overcome that challenge, including split Cas9-derived and numerous domain-deleted versions of editors, whether base editor (BE) and prime editor (PE) systems can also allow deletion of those domains remains to be proven. In this study, we present a new small ABE (sABE) with significantly reduced size.ResultsWe discovered that ABE8e can tolerate large single deletions in the REC2 (Δ174-296) and HNH (Δ786-855) domains of SpCas9, and these deletions can be stacked together to create a new sABE. The sABE showed higher precision than the original ABE8e, with proximally shifted protospacer adjacent motif (PAM) editing windows (A3- A15), and comparable editing efficiencies to 8e-SaCas9-KKH. The sABE system efficiently generated A-G mutations at disease-relevant loci (T1214C in GAA and A494G in MFN2) in HEK293T cells and several canonical Pcsk9 splice sites in N2a cells. Moreover, the sABE enabled in vivo delivery in a single adeno-associated virus (AAV) vector with slight efficiency. Furthermore, we also successfully edited the genome of mouse embryos by microinjecting mRNA and sgRNA of sABE system into zygotes.ConclusionsWe have developed a substantially smaller sABE system that expands the targeting scope and offers higher precision of genome editing. Our findings suggest that the sABE system holds great therapeutic potential in preclinical applications.

Genome editing of pseudorabies virus in the CRISPR/Cas9 era: a mini-review.

Pseudorabies virus (PRV) is an important swine virus that has a significant impact on the global swine industry. PRV is a member of the herpesvirus family, specifically the alphaherpesvirus subfamily, and has been extensively utilized as a prototype herpesvirus. Notably, recent studies have reported that PRV sporadically spills over into humans. The PRV genome is approximately 150 kb in size and is difficult to manipulate at the genomic level. The development of clustered regularly interspaced short palindromic repeat-associated protein (CRISPR/Cas9) technology has revolutionized PRV genome editing. CRISPR/Cas9 has been widely used in the construction of reporter viruses, knock-out/knock-in of genes of interest, single virus tracking and antiviral strategies. Most importantly, for vaccine development, virulence gene knockout PRV vaccine candidates can be obtained within 2 weeks using CRISPR/Cas9. In this mini-review, we provide a concise overview of the application of CRISPR/Cas9 in PRV research and mainly share our experience with methods for efficiently editing the PRV genome. Through this review, we hope to give researchers better insight into the genome editing of pseudorabies virus.

Discovery of deaminase functions by structure-based protein clustering

The elucidation of protein function and its exploitation in bioengineering have greatly advanced the life sciences. Protein mining efforts generally rely on amino acid sequences rather than protein structures. We describe here the use of AlphaFold2 to predict and subsequently cluster an entire protein family based on predicted structure similarities. We selected deaminase proteins to analyze and identified many previously unknown properties. We were surprised to find that most proteins in the DddA-like clade were not double-stranded DNA deaminases. We engineered the smallest single-strand-specific cytidine deaminase, enabling efficient cytosine base editor (CBE) to be packaged into a single adeno-associated virus (AAV). Importantly, we profiled a deaminase from this clade that edits robustly in soybean plants, which previously was inaccessible to CBEs. These discovered deaminases, based on AI-assisted structural predictions, greatly expand the utility of base editors for therapeutic and agricultural applications.

An allosteric inhibitor of sirtuin 2 deacetylase activity exhibits broad-spectrum antiviral activity.

Most drugs used to treat viral disease target a virus-coded product. They inhibit a single virus or virus family, and the pathogen can readily evolve resistance. Host-targeted antivirals can overcome these limitations. The broad-spectrum activity achieved by host targeting can be especially useful in combating emerging viruses and for treatment of diseases caused by multiple viral pathogens, such as opportunistic agents in immunosuppressed patients. We have developed a family of compounds that modulate sirtuin 2, an NAD+-dependent deacylase, and now report the properties of a member of that family, FLS-359. Biochemical and x-ray structural studies show that the drug binds to sirtuin 2 and allosterically inhibits its deacetylase activity. FLS-359 inhibits the growth of RNA and DNA viruses, including members of the coronavirus, orthomyxovirus, flavivirus, hepadnavirus, and herpesvirus families. FLS-359 acts at multiple levels to antagonize cytomegalovirus replication in fibroblasts, causing modest reductions in viral RNAs and DNA, together with a much greater reduction in infectious progeny, and it exhibits antiviral activity in humanized mouse models of infection. Our results highlight the potential of sirtuin 2 inhibitors as broad-spectrum antivirals and set the stage for further understanding of how host epigenetic mechanisms impact the growth and spread of viral pathogens.

Analyzing immune responses to varied mRNA and protein vaccine sequences

In response to the COVID-19 pandemic, different types of vaccines, such as inactive, live-attenuated, messenger RNA (mRNA), and protein subunit, have been developed against SARS-CoV-2. This has unintentionally created a unique scenario where heterologous prime-boost vaccination against a single virus has been administered to a large human population. Here, we aimed to analyze whether the immunization order of vaccine types influences the efficacy of heterologous prime-boost vaccination, especially mRNA and protein-based vaccines. We developed a new mRNA vaccine encoding the hemagglutinin (HA) glycoprotein of the influenza virus using the 3′-UTR and 5′-UTR of muscle cells (mRNA-HA) and tested its efficacy by heterologous immunization with an HA protein vaccine (protein-HA). The results demonstrated higher IgG2a levels and hemagglutination inhibition titers in the mRNA-HA priming/protein-HA boosting (R-P) regimen than those induced by reverse immunization (protein-HA priming/mRNA-HA boosting, P-R). After the viral challenge, the R-P group showed lower virus loads and less inflammation in the lungs than the P-R group did. Transcriptome analysis revealed that the heterologous prime-boost groups had differentially activated immune response pathways, according to the order of immunization. In summary, our results demonstrate that the sequence of vaccination is critical to direct desired immune responses. This study demonstrates the potential of a heterologous vaccination strategy using mRNA and protein vaccine platforms against viral infection.

Allele-specific gene-editing approach for vision loss restoration in RHO-associated retinitis pigmentosa.

Mutant RHO is the most frequent genetic cause of autosomal dominant retinitis pigmentosa (adRP). Here, we developed an allele-specific gene-editing therapeutic drug to selectively target the human T17M RHO mutant allele while leaving the wild-type RHO allele intact for the first time. We identified a Staphylococcus aureus Cas9 (SaCas9) guide RNA that was highly active and specific to the human T17M RHO allele. In vitro experiments using HEK293T cells and patient-specific induced pluripotent stem cells (iPSCs) demonstrated active nuclease activity and high specificity. Subretinal delivery of a single adeno-associated virus serotype 2/8 packaging SaCas9 and single guide RNA (sgRNA) to the retinas of the RHO humanized mice showed that this therapeutic drug targeted the mutant allele selectively, thereby downregulating the mutant RHO mRNA expression. Administration of this therapeutic drug resulted in a long-term (up to 11 months after treatment) improvement of retinal function and preservation of photoreceptors in the heterozygous mutant humanized mice. Our study demonstrated a dose-dependent therapeutic effect in vivo. Unwanted off-target effects were not observed at the whole-genome sequencing level. Our study provides strong support for the further development of this effective therapeutic drug to treat RHO-T17M-associated adRP, also offers a generalizable framework for developing gene-editing medicine. Furthermore, our success in restoring the vision loss in the suffering RHO humanized mice verifies the feasibility of allele-specific CRISPR/Cas9-based medicines for other autosomal dominant inherited retinal dystrophies.

Preparing for the next viral threat with broad-spectrum antivirals.

There is a large global unmet need for the development of countermeasures to combat hundreds of viruses known to cause human disease and for the establishment of a therapeutic portfolio for future pandemic preparedness. Most approved antiviral therapeutics target proteins encoded by a single virus, providing a narrow spectrum of coverage. This, combined with the slow pace and high cost of drug development, limits the scalability of this direct-acting antiviral (DAA) approach. Here, we summarize progress and challenges in the development of broad-spectrum antivirals that target either viral elements (proteins, genome structures, and lipid envelopes) or cellular proviral factors co-opted by multiple viruses via newly discovered compounds or repurposing of approved drugs. These strategies offer new means for developing therapeutics against both existing and emerging viral threats that complement DAAs.

AAV-vectored base editor trans-splicing delivers dystrophin repair

AAV-vectored base editor trans-splicing delivers dystrophin repair

Viral Coinfection of Children Hospitalized with Severe Acute Respiratory Infections during COVID-19 Pandemic.

This study was conducted between March 2020 and December 2021. All children admitted to the ICU with a diagnosis of SARI and who were tested by polymerase chain reaction on nasopharyngeal swabs for SARS-CoV-2 and other common respiratory viral pathogens were included in the study. The result of the viral panel identified 446 children, with one infected with a single virus and 160 co-infected with two or more viruses. This study employed descriptive analyses, where a total of twenty-two coinfections among SARI-causing viruses were identified. Thus, the five most frequent coinfections that were selected for the study are: hRV/SARS-CoV-2 (17.91%), hRV/RSV (14.18%), RSV/SARS-CoV-2 (12.69%), hRV/BoV (10.45%), and hRV/AdV (8.21%). The most significant age group was 38.1%, representing patients aged between 24 and 59 months (61 individuals). Patients older than 59 months represented a total of 27.5%, comprising forty-four patients. The use of oxygen therapy was statistically significant in coinfections with Bocavirus, other CoVs, Metapneumovirus, and RSV. Coinfections with SARS-CoV-2 and the other different coinfections presented a similar time of use of oxygen therapy with a value of (p > 0.05). In the year 2020, hRV/BoV was more frequent in relation to other types of coinfections, representing a total of 35.1%. The year 2021 presented a divergent profile, with hRV/SARS-CoV-2 coinfection being the most frequent (30.8%), followed by hRV/RSV (28.2%). Additionally, 25.6% and 15.4% represented coinfections between RSV/SARS-CoV-2 and hRV/AdV, respectively. We saw that two of the patients coinfected with hRV/SARS-CoV-2 died, representing 9.52% of all deaths in the study. In addition, both hRV/hBoV and hRV/RSV had death records for each case, representing 8.33% and 6.67% of all deaths, respectively. Coinfections with respiratory viruses, such as RSV and hBoV, can increase the severity of the disease in children with SARI who are admitted to the ICU, and children infected with SARS-CoV-2 have their clinical condition worsened when they have comorbidities.

Reciprocal enhancement of SARS-CoV-2 and influenza virus replication in human pluripotent stem cell-derived lung organoids

ABSTRACT Patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A virus (FLUAV) coinfections were associated with severe respiratory failure and more deaths. Here, we developed a model for studying SARS-CoV-2 and FLUAV coinfection using human pluripotent stem cell-induced alveolar type II organoids (hiAT2). hiAT2 organoids were susceptible to infection by both viruses and had features of severe lung damage. A single virus markedly enhanced the susceptibility to other virus infections. SARS-CoV-2 delta variants upregulated α-2-3-linked sialic acid, while FLUAV upregulated angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). Moreover, coinfection by SARS-CoV-2 and FLUAV caused hyperactivation of proinflammatory and immune-related signaling pathways and cellular damage compared to a respective single virus in hiAT2 organoids. This study provides insight into molecular mechanisms underlying enhanced infectivity and severity in patients with co-infection of SARS-CoV-2 and FLUAV, which may aid in the development of therapeutics for such co-infection cases.

A Comparative Study of Acute Gastroenteritis Symptoms in Single- versus Multiple-Virus Infections.

Many different enteric viruses can cause acute gastroenteritis in humans worldwide. While a single virus can indeed cause disease, multiple-virus infections are commonly reported. However, data regarding a comparison between single- and multiple-virus infections upon clinical manifestations of acute gastroenteritis are relatively limited. In this study, a total of 2383 fecal specimens were collected from children with acute gastroenteritis during June 2014-July 2017 in a pediatric clinic in Japan and tested for 11 viruses by multiplex RT-PCR. At least 1 virus was found in 1706 (71.6%) specimens and norovirus GII was the most frequent agent, followed by rotavirus A and other viruses. Multiple-virus infections were identified in 565 cases (33.1%). While major clinical symptoms were found to be significantly different in some single- vs. multiple-virus infections, the disease severity was statistically non-significant. Our study highlights the burden of multiple-virus infections for acute gastroenteritis and the clinical features of patients with multiple-virus infections.

Virological profile of upper respiratory tract infections in children under 5 years of age- a cross sectional study in a tertiary care hospital in North India

Objective: To study the virological profile of URI among children under 5 years of age. Since, it is very difficult to distinguish between various viral etiologies solely on the basis of symptoms, this study was attempted to generate evidence that majority of URI are caused due to viral illness and no antibiotics should be prescribed in the management of the same. Methods: This observational study was conducted over a period of one year (June 2021–May 2022) in a tertiary care teaching hospital in New Delhi. A total of 180 children between the age of 0–5 years with symptoms of URI were included. Nasopharyngeal swabs were taken and processed for detection of viruses using multiplex RT PCR. Results: Presence of viruses were detected in 136 (75.6%) samples. A single virus was identified in 113 samples, whereas 21 were found to harbour two viruses and 2 were carrying three viruses. The most common virus isolated was Human Rhinovirus (HRV- 55.8%) followed by Respiratory Syncytial Virus (RSV- 23.5%). In samples showing coinfection with two viruses, most common was Human Corona Virus (HCoV)- NL63, 229E, OC43, HKU1. None of the patients were given antibiotics. None of the patients required any hospital admission for severe respiratory illness. Conclusions: Viruses are a major cause of URI in children under five years of age, with the most prevalent organisms being HRV and RSV. Antibiotic prescriptions in URI are not warranted.

Natural Oncolysis of Enterovirus 71 in Antitumor Therapy of Colorectal Cancer.

Colorectal cancer (CRC) is an intestinal malignant tumor with high morbidity and mortality worldwide. Inoperability or resistanance to radiation and chemotherapy occur in the conventional treatments against CRC. Oncolytic viruses (OVs) are one kind of virus that selectively infects and lyses cancer cells, which is considered to be a new anticancer therapy with biological and immune-based approaches. Enterovirus 71 (EV71), belonging to the enterovirus genus in the family Picornaviridae, is a single positive-stranded RNA virus. EV71 is transmitted in a fetal-oral route and infects gastrointestinal tract in infants. Here, EV71 is exploited to be a novel oncolytic virus in colorectal cancer. It is revealed that EV71 infection can selectively cause colorectal cancer cells cytotoxicity but not primary intestinal epithelial cells. Consistently, EV71 injection significantly inhibits tumor growth in nude mice xenografted colorectal cancer cells. In detail, EV71 infects colorectal cancer cells to repress the expression of Ki67 and B-cell leukemia 2 (Bcl-2) leading to the inhibition of cell proliferation, while activating the cleavage of poly-adenosine diphosphatase-ribose polymerase and Caspase-3 protein resulting in the promotion of cell apoptosis. The findings demonstrate the oncolytic feature of EV71 in CRC treatment and may provide a potential clue for clinical anticancer therapy.

A comprehensive overview on the transmission, pathogenesis, diagnosis, treatment, and prevention of SARS-CoV-2.

Severe acute respiratory syndrome coronavirus (SARS-CoV) is a single positive-strand RNA virus that is responsible for the current pandemic that the world has been facing since 2019. The primary route of transmission of SARS-CoV-2 is through respiratory tract transmission. However, other transmission routes such as fecal-oral, vertical transmission, and aerosol-eye also exist. In addition, it has been found that the pathogenesis of this virus involves the binding of the virus's S protein to its host cell surface receptor angiotensin-converting enzyme 2, which results in the subsequent membrane fusion that is required for SARS-CoV-2 to replicate and complete its entire life. The clinical symptoms of patients infected with SARS-CoV-2 can range from asymptomatic to severe. The most common symptoms seen include fever, dry cough, and fatigue. Once these symptoms are observed, a nucleic acid test is done using reverse transcription-polymerase chain reaction. This currently serves as the main confirmatory tool for COVID-19. Despite the fact that no cure has been found for SARS-CoV-2, prevention methods such as vaccines, specific facial mask, and social distancing have proven to be quite effective. It is imperative to have a complete understanding of the transmission and pathogenesis of this virus. To effectively develop new drugs as well as diagnostic tools, more knowledge about this virus would be needed.

Single SARS virus mutation as a possible cause of the prevalence of asymptomatic COVID-19 infection forms

To explain the prevalence of asymptomatic SARS-CoV-2 infection forms, a hypothesis on a single virus mutation that causes changes in two important factors such as virus infectiousness and pathogenicity is proposed. According to this hypothesis, susceptible and asymptomatic forms affect the rate of change in infectiousness and pathogenicity, thereby influencing the rate of infectivity and the onset of a disease and as a result, altering the ratio of asymptomatic forms to symptomatic cases. With a mathematical model, constructed based on this hypothesis and identified using data from the first wave of COVID-19 in Saint-Petersburg, a correlation between changes in microbiological parameters of the model and changes in a ratio of asymptomatic forms to symptomatic cases is verified. It is concluded that single virus mutation may affect the ratio.

Digital Detection of Single Virus Particles by Multi-Spot, Label-Free Imaging Biosensor on Anti-Reflective Glass.

Rapid detection of whole virus particles in biological or environmental samples represents an unmet need for the containment of infectious diseases. Here, an optical device enabling the enumeration of single virion particles binding on antibody or aptamers immobilized on a surface with anti-reflective coating is described. In this regime, nanoparticles adhering to the sensor surface provide localized contributions to the reflected field that become detectable because of their mixing with the interfering waves in the reflection direction. Thus, these settings are exploited to realize a scan-free, label-free, micro-array-type digital assay on a disposable cartridge, in which the virion counting takes place in wide field-of-view imaging. With this approachwe could quantify, by enumeration, different variants of SARS-CoV-2 virions interacting with antibodies and aptamers immobilized on different spots. For all tested variants, the aptamers showed larger affinity but lower specificity relative to the antibodies. It is found that the combination of different probes on the same surface enables increasing specificity of detection and dynamicrange.

Amplification-Free Detection of SARS-CoV-2 Down to Single Virus Level by Portable Carbon Nanotube Biosensors.

The rapid and sensitive detection of trace-level viruses in a simple and reliable way is of great importance for epidemic prevention and control. Here,a multi-functionalized floating gate carbon nanotube field effect transistor (FG-CNT FET) based biosensor is reported for the single virus level detection of SARS-CoV-2 virus antigen and RNA rapidly with a portable sensing platform. The aptamers functionalized sensors can detect SARS-CoV-2 antigens from unprocessed nasopharyngeal swab samples within 1 min. Meanwhile, enhanced by a multi-probe strategy, the FG-CNT FET-based biosensor can detect the long chain RNA directly without amplification down to single virus level within 1 min.Thedevice, constructed with packaged sensor chips and a portable sensing terminal, can distinguish 10 COVID-19 patients from 10 healthy individuals in clinical tests both by the RNAs and antigens by a combination detection strategy with an combined overall percent agreement (OPA) close to 100%.Theresults provide a general and simple method to enhance the sensitivity of FET-based biochemical sensors for the detection of nucleic acid molecules and demonstrate that the CNT FG FET biosensor is a versatile and reliable integrated platform for ultrasensitive multibiomarker detection without amplification and has great potential for point-of-care (POC) clinical tests.

Engineered CRISPR-OsCas12f1 and RhCas12f1 with robust activities and expanded target range for genome editing

The type V-F CRISPR-Cas12f system is a strong candidate for therapeutic applications due to the compact size of the Cas12f proteins. In this work, we identify six uncharacterized Cas12f1 proteins with nuclease activity in mammalian cells from assembled bacterial genomes. Among them, OsCas12f1 (433 aa) from Oscillibacter sp. and RhCas12f1 (415 aa) from Ruminiclostridium herbifermentans, which respectively target 5’ T-rich Protospacer Adjacent Motifs (PAMs) and 5’ C-rich PAMs, show the highest editing activity. Through protein and sgRNA engineering, we generate enhanced OsCas12f1 (enOsCas12f1) and enRhCas12f1 variants, with 5’-TTN and 5’-CCD (D = not C) PAMs respectively, exhibiting much higher editing efficiency and broader PAMs, compared with the engineered variant Un1Cas12f1 (Un1Cas12f1_ge4.1). Furthermore, by fusing the destabilized domain with enOsCas12f1, we generate inducible-enOsCas12f1 and demonstate its activity in vivo by single adeno-associated virus delivery. Finally, dead enOsCas12f1-based epigenetic editing and gene activation can also be achieved in mammalian cells. This study thus provides compact gene editing tools for basic research with remarkable promise for therapeutic applications.

Single SARS Virus Mutation as a Possible Cause of the Predominance of Asymptomatic COVID-19 Infection Forms

Single SARS Virus Mutation as a Possible Cause of the Predominance of Asymptomatic COVID-19 Infection Forms