Antiviral Activity of Ribavirin against Tilapia tilapinevirus in Fish Cells

The outbreak of the novel Tilapia tilapinevirus or Tilapia lake virus (TiLV) is having a severe economic impact on global tilapia aquaculture. Effective treatments and vaccines for TiLV are lacking. In this study, we demonstrated the antiviral activity of ribavirin against TiLV in E-11 cells. Our findings revealed that at concentrations above 100 μg/mL, ribavirin efficiently attenuates the cytopathic effect of the TiLV infection in fish cells. When administered in a dose-dependent manner, ribavirin significantly improved cell survival compared to the untreated control cells. Further investigation revealed that the cells exposed to ribavirin and TiLV had a lower viral load (p < 0.05) than the untreated cells. However, at concentrations above 1000 μg/mL, ribavirin led to cell toxicity. Taken together, our results demonstrate the efficacy of this antiviral drug against TiLV and could be a useful tool for future research on the pathogenesis and replication mechanism of TiLV as well as other piscine viruses.

RIG-I-induced innate antiviral immunity protects mice from lethal SARS-CoV-2 infection

The SARS-CoV-2 pandemic has underscored the need for rapidly employable prophylactic and antiviral treatments against emerging viruses. Nucleic acid agonists of the innate immune system can be administered to activate an effective antiviral program for prophylaxis in exposed populations, a measure of particular relevance for SARS-CoV-2 infection due to its efficient evasion of the host antiviral response. In this study, we utilize the K18-hACE2 mouse model of COVID-19 to examine whether prophylactic activation of the antiviral receptor RIG-I protects mice from SARS-CoV-2 infection. Systemic treatment of mice with a specific RIG-I ligand one to seven days prior to infection with a lethal dose of SARS-CoV-2 improved their survival of by up to 50 %. Improved survival was associated with lower viral load in oropharyngeal swabs and in the lungs and brain of RIG-I-treated mice. Moreover, despite antiviral protection, the surviving mice that were treated with RIG-I ligand developed adaptive SARS-CoV-2-specific immunity. These results reveal that prophylactic RIG-I activation by synthetic RNA oligonucleotides is a promising strategy to convey short-term, unspecific antiviral protection against SARS-CoV-2 infection and may be a suitable broad-spectrum approach to constraining the spread of newly emerging viruses until virus-specific therapies and vaccines become available.

Transmissibility of COVID-19 among Vaccinated Individuals: A Rapid Literature Review

Objectives: This is an update of a previous report that examined literature published up to March 11th, 2021. Sixteen additional studies have been included in this update. The objective of this report is to identify comparative observational studies and randomized controlled trials (RCTs) evaluating the efficacy and effectiveness of COVID-19 vaccination in reducing forward transmission from vaccinated people, and studies examining the biological plausibility of vaccination-induced transmission reduction. Method: A search of databases, MEDLINE, Embase, L-OVE and the Cochrane Central Register of Controlled Trials was conducted to identify RCTs or comparative observational studies evaluating the efficacy and effectiveness of COVID-19 vaccination in the prevention of transmission, asymptomatic infections and transmissibility of COVID-19 among vaccinated persons. An additional search of grey literature was conducted. This search is current to May 4th, 2021. Results: In this update, 16 additional studies, including 9 human and 7 animal studies, were included. Therefore, this review examines a total of 33 included studies: 21 human studies and 12 preclinical animal studies. Evidence from two large household surveillance studies from the UK suggests that a single or full dose of AstraZeneca (AZ) and Pfizer-BioNtech (PfBnT) vaccines may prevent household transmission of COVID-19 after 14 days of vaccination by up to 54%. The AZ vaccine trials in the general population suggest that an initial low dose followed by a standard dose may provide up to 59% protection against asymptomatic or unknown infection, although efficacy against these outcomes was not demonstrated following two standard doses. PfBnT vaccine observational studies in the general population suggest up to 90% effectiveness against asymptomatic infection after seven or more days of full dose vaccination. Up to 75% effectiveness against asymptomatic infection was reported after full-dose in healthcare workers. Across RCTs examining asymptomatic infection in the general population, one dose of Moderna was shown to provide an efficacy of 61.4% against asymptomatic infection 21 days after the first dose; in another trial, the J&J vaccine had an efficacy of 74% 28 days after the first dose. Lastly, seven of eight studies found significantly increased cycle threshold, suggestive of lower viral load, in PfBnT or AZ vaccinated individuals compared with those who were unvaccinated. Conclusion: The AZ and PfBnT vaccines may prevent household transmission of COVID-19 after 14 days of vaccination. More studies have found the vaccines to significantly reduce the risk of asymptomatic infection and significantly increase cycle threshold, suggestive of lower viral load. Further research is needed to evaluate post-vaccination infectivity and transmission of both the wild type COVID-19 virus and the variants of concern from other jurisdictions.

Elevated mucosal antibody responses against SARS-CoV-2 are correlated with lower viral load and faster decrease in systemic COVID-19 symptoms

ABSTRACTMucosal antibodies play a key role in protection against SARS-CoV-2 exposure, but their role during primary infection is not well understood. We assessed mucosal antibody responses during primary infection with SARS-CoV-2 and examined their relationship with viral load and clinical symptoms. Elevated mucosal IgM was associated with lower viral load. RBD and viral spike protein-specific mucosal antibodies were correlated with decreases in systemic symptoms, while older age was associated with an increase in respiratory symptoms. Up to 42% of household contacts developed SARS-CoV-2-specific mucosal antibodies, including children, indicating high transmission rates within households in which children might play an important role.

Tinjauan Azitromisin Pada Penyakit Virus Korona 2019 (COVID-19)

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by SARS-CoV-2. The World Health Organization has declared this disease a pandemic, where the scale of the spread of the disease occurs globally throughout the world. Currently, there is no validated pharmacological treatment for COVID-19 disease, and is still in the clinical trial stage. Azithromycin in conjunction with hydroxychloroquine or chloroquine has been proposed as a treatment that can improve the prognosis of COVID-19. This review aims to describe the mechanism of action and effectiveness of azithromycin in the treatment of COVID-19 patients. The review of the article literature was carried out through internet searches by accessing the database from google scholar, PubMed, and science direct sites. The inclusion criteria in this review are articles using azithromycin in clinical trials and COVID-19 therapy which were published from December 2019 to October 2020. Azithromycin is a macrolide antibacterial and is based on studies having antiviral and immunomodulatory effects. The use of azithromycin can lower viral load when added to hydroxychloroquine in COVID-19 patients based on small-scale clinical studies. Azithromycin used with hydroxychloroquine or chloroquine has shown good results, although it raises concerns about the risk of increased side effects of prolonged QT interval so that monitoring of the heart is needed and proven in a larger number of COVID-19 patients. The decision to use azithromycin must take into account the potential benefits and risks, evaluating the possibility of the drug being more effective than the risks to the patient.

Global Absence and Targeting of Protective Immune States in Severe COVID-19.

While SARS-CoV-2 infection has pleiotropic and systemic effects in some patients, many others experience milder symptoms. We sought a holistic understanding of the severe/mild distinction in COVID-19 pathology, and its origins. We performed a wholeblood preserving single-cell analysis protocol to integrate contributions from all major cell types including neutrophils, monocytes, platelets, lymphocytes and the contents of serum. Patients with mild COVID-19 disease display a coordinated pattern of interferonstimulated gene (ISG) expression across every cell population and these cells are systemically absent in patients with severe disease. Severe COVID-19 patients also paradoxically produce very high anti-SARS-CoV-2 antibody titers and have lower viral load as compared to mild disease. Examination of the serum from severe patients demonstrates that they uniquely produce antibodies with multiple patterns of specificity against interferon-stimulated cells and that those antibodies functionally block the production of the mild disease-associated ISG-expressing cells. Overzealous and autodirected antibody responses pit the immune system against itself in many COVID-19 patients and this defines targets for immunotherapies to allow immune systems to provide viral defense.

Pooled Saliva Specimens for SARS-CoV-2 Testing

We evaluated saliva (SAL) specimens for SARS-CoV-2 RT-PCR testing by comparison of 459 prospectively paired nasopharyngeal (NP) or mid-turbinate (MT) swabs from 449 individuals with the aim of using saliva for asymptomatic screening. Samples were collected in a drive-through car line for symptomatic individuals (N=380) and in the emergency department (ED) (N=69). The percent positive and negative agreement of saliva compared to nasopharyngeal swab were 81.1% (95% CI: 65.8% – 90.5%) and 99.8% (95% CI: 98.7% – 100%), respectively. The sensitivity increased to 90.0% (95% CI: 74.4% – 96.5%) when considering only samples with moderate to high viral load (Cycle threshold (Ct) for the NP <=34). Pools of five saliva specimens were also evaluated on three platforms: bioMérieux NucliSENS easyMAG with ABI 7500Fast (CDC assay), Hologic Panther Fusion, and Roche COBAS 6800. The median loss of signal upon pooling was 2-4 Ct values across the platforms. The sensitivity of detecting a positive specimen in a pool compared with testing individually was 100%, 93%, and 95% for CDC 2019-nCoV Real-Time RT-PCR, Panther Fusion® SARS-CoV-2 assay, and cobas® SARS-CoV-2 test respectively, with decreased sample detection trending with lower viral load. We conclude that although pooled saliva testing, as collected in this study, is not quite as sensitive as NP/MT testing, saliva testing is adequate to detect individuals with higher viral loads in an asymptomatic screening program, does not require swabs or viral transport media for collection, and may help to improve voluntary screening compliance for those individuals averse to various forms of nasal collections.

685. Comparison of Singleplex qPCR and the Luminex MAGPIX Platform for the Detection of Viral Pathogens

Background Various respiratory molecular assays are available, each with different characteristics and advantages that make them uniquely valuable. The objective of this study was to compare rates of viral detection using singleplex and multiplex platforms in a research setting. Methods A prospective viral surveillance study was conducted in Davidson County, TN. Infants under one year who presented with fever and/or respiratory symptoms were enrolled from the outpatient, emergency department and inpatient settings. Nasal swabs were collected and tested for influenza A (FluA), influenza B (FluB), human metapneumovirus (MPV), respiratory syncytial virus A and B (RSVA and RSVB), human adenovirus (AdV), parainfluenza 1, 2, 3, and 4 (PIV1-4) and SARS-2-CoV by both singleplex qPCR and the Luminex NxTAG Respiratory Pathogen and NxTAG CoV Extended panels. The rhinovirus/enterovirus, human bocavirus, Chlamydophila pneumoniae, Mycoplasma pneumoniae and coronavirus HKU1, NL63, 229E and OC43 results from the Luminex panel were excluded because singleplex qPCR was not performed on those targets. For singleplex qPCR results, cycle threshold (Ct) values were used as a surrogate for viral load, with a higher Ct value indicating a lower viral load. Results A total of 112 nasal specimens were tested by both singleplex qPCR and Luminex, of which 65 were positive for at least one virus by either platform and 56 had a virus detected on both platforms (Figure 1). Seven specimens were positive by singleplex qPCR only and two were positive by Luminex only (Figure 1). The targets positive by singleplex qPCR only included FluB, RSVA, AdV and PIV2 and those positive by Luminex only included FluA H1N1 and RSVB (Figure 2). Specimens that were positive only on the singleplex assay had a higher average Ct value than those that were positive on both assays, indicating a lower viral load (Figure 3). Figure 1 Figure 2 Figure 3 Conclusion The multiplex assay identified 89% of the total viruses detected while singleplex qPCR identified 97% of the total viruses detected. Lower viral loads may contribute to false negative results on the multiplex platforms. Future studies with larger sample sizes are needed in order validate our findings. Disclosures Erin Yepsen, BS, Sanofi Pasteur (Grant/Research Support, Research Grant or Support) Zaid Haddadin, MD, CDC (Grant/Research Support, Research Grant or Support)Quidel Corporation (Grant/Research Support, Research Grant or Support)sanofi pasteur (Grant/Research Support, Research Grant or Support) Danielle A. Rankin, MPH, CIC, Sanofi Pasteur (Grant/Research Support, Research Grant or Support) Natasha B. Halasa, MD, MPH, Genentech (Other Financial or Material Support, I receive an honorarium for lectures - it’s a education grant, supported by genetech)Karius (Consultant)Moderna (Consultant)Quidel (Grant/Research Support, Research Grant or Support)Sanofi (Grant/Research Support, Research Grant or Support)

Association of Viral Load With Disease Severity in Outpatient Children With Respiratory Syncytial Virus Infection

Background There are scarce data on whether viral load affects the severity of respiratory syncytial virus (RSV) disease in outpatient children. Methods We analyzed the association between viral load and disease severity among children who participated in a prospective cohort study of respiratory infections. The children were examined and nasal swabs for the detection of RSV were obtained during each respiratory illness. Quantification of RSV load was based on the cycle threshold (Ct) value. For the primary analysis, the children were divided into 2 groups: higher (Ct &lt; 27) and lower viral load (Ct ≥ 27). Results Among 201 episodes of RSV infection, children with higher viral load had significantly longer median durations of rhinitis (8 vs 6 days; P = .0008), cough (8 vs 6 days; P = .034), fever (2 vs 1 days; P = .018), and any symptom (10 vs 8 days; P = .024) than those with lower viral load. There were statistically significant negative correlations between the Ct values and durations of all measured symptoms. Conclusions Our findings support the concept that viral load drives the severity of RSV disease in children. Reducing the viral load by RSV antivirals might provide substantial benefits to outpatient children.