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Patients with COVID-19 may be recurrence positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA after being cured and discharged from the hospital. The aim of this study was to explore independent influencing factors as markers for predicting positive SARS-CoV-2 RNA recurrence. The study included 601 COVID-19 patients who were cured and discharged from the Public and Health Clinic Centre of Chengdu from January 2020 to March 2021, and the recurrence positive of patients within 6 weeks after SARS-CoV-2 RNA turned negative was followed up. We used propensity score matching to eliminate the influence of confounding factors, and multivariate Logistic regression analysis was used to determine the independent influencing factors for positive SARS-CoV-2 RNA recurrence. Multivariate Logistic regression showed that the elevated serum potassium (odds ratio [OR] = 6.537, 95% confidence interval [CI]: 1.864-22.931, p = 0.003), elevated blood chlorine (OR = 1.169, 95% CI: 1.032-1.324, p = 0.014) and elevated CD3 + CD4 + count (OR = 1.003, 95% CI: 1.001-1.004, p < 0.001) were identified as independent risk factors for positive SARS-CoV-2 RNA recurrence (p < 0.05). The difference in virus shedding duration (OR = 1.049, 95% CI: 1.000-1.100, p = 0.05) was borderline statistically significant. For sensitivity analysis, we included virus shedding duration as a categorical variable in the model again and found that the OR value related to recurrence positively increased with delayed virus shedding duration, and the trend test showed a statistical difference (P trend = 0.03). Meanwhile, shortening of activated partial prothrombinase time (OR = 0.908, 95% CI: 0.824-1.000, p = 0.049) was identified as an independent protection factor for SARS-CoV-2 RNA recurrence positive. We have identified independent factors that affect the recurrence of SARS-CoV-2 RNA positive. It is recommended that doctors pay attention to these indicators when first admitted to the hospital., (© 2021 Wiley Periodicals LLC.)

Isolation guidelines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are largely derived from data collected prior to the emergence of the delta variant. We followed a cohort of ambulatory patients with postvaccination breakthrough SARS-CoV-2 infections with longitudinal collection of nasal swabs for SARS-CoV-2 viral load quantification, whole-genome sequencing, and viral culture. All delta variant infections in our cohort were symptomatic, compared with 64% of non-delta variant infections. Symptomatic delta variant breakthrough infections were characterized by higher initial viral load, longer duration of virologic shedding by PCR, greater likelihood of replication-competent virus at early stages of infection, and longer duration of culturable virus compared with non-delta variants. The duration of time since vaccination was also correlated with both duration of PCR positivity and duration of detection of replication-competent virus. Nonetheless, no individuals with symptomatic delta variant infections had replication-competent virus by day 10 after symptom onset or 24 hours after resolution of symptoms. These data support US CDC isolation guidelines as of November 2021, which recommend isolation for 10 days or until symptom resolution and reinforce the importance of prompt testing and isolation among symptomatic individuals with delta breakthrough infections. Additional data are needed to evaluate these relationships among asymptomatic and more severe delta variant breakthrough infections.

The SARS-CoV-2 Delta variant has spread rapidly worldwide. To provide data on its virological profile, we here report the first local transmission of Delta in mainland China. All 167 infections could be traced back to the first index case. Daily sequential PCR testing of quarantined individuals indicated that the viral loads of Delta infections, when they first become PCR-positive, were on average ~1000 times greater compared to lineage A/B infections during the first epidemic wave in China in early 2020, suggesting potentially faster viral replication and greater infectiousness of Delta during early infection. The estimated transmission bottleneck size of the Delta variant was generally narrow, with 1-3 virions in 29 donor-recipient transmission pairs. However, the transmission of minor iSNVs resulted in at least 3 of the 34 substitutions that were identified in the outbreak, highlighting the contribution of intra-host variants to population-level viral diversity during rapid spread., (© 2022. The Author(s).)

COVID-19 has restricted singing in communal worship. We sought to understand variations in droplet transmission and the impact of wearing face masks. Using rapid laser planar imaging, we measured droplets while participants exhaled, said 'hello' or 'snake', sang a note or 'Happy Birthday', with and without surgical face masks. We measured mean velocity magnitude (MVM), time averaged droplet number (TADN) and maximum droplet number (MDN). Multilevel regression models were used. In 20 participants, sound intensity was 71 dB for speaking and 85 dB for singing (p < 0.001). MVM was similar for all tasks with no clear hierarchy between vocal tasks or people and > 85% reduction wearing face masks. Droplet transmission varied widely, particularly for singing. Masks decreased TADN by 99% (p < 0.001) and MDN by 98% (p < 0.001) for singing and 86-97% for other tasks. Masks reduced variance by up to 48%. When wearing a mask, neither singing task transmitted more droplets than exhaling. In conclusion, wide variation exists for droplet production. This significantly reduced when wearing face masks. Singing during religious worship wearing a face mask appears as safe as exhaling or talking. This has implications for UK public health guidance during the COVID-19 pandemic., (© 2021. The Author(s).)

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infection worldwide, but reports of temporal changes in the risk of transmission among close contacts has been scarce. This study aimed to examine an association between the viral load trajectory and transmission risk to develop a better control strategy for the disease spread. We conducted a household-based prospective cohort study in Biliran Province, the Philippines, and enrolled 451 participants to observe the development of acute respiratory infection. Including the cases found at the health-care facility, we analyzed the data of viral loads with symptom records obtained from 172 followed participants who had household member positive for RSV with a rapid test during an RSV outbreak in 2018-2019. We developed a model estimating a temporal change in the viral shedding from the infection and evaluated transmission dynamics. We found that most transmission events occurred within approximately 7 days of the household exposure, including potential presymptomatic transmissions. The inferred risk of infection among those younger than 5 years was 3.5 times higher than that of those older than 5 years. This finding suggested that the initial week after the household exposure is particularly important for preventing RSV spread., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health.)

ABSTRACT The risk of secondary infection with SARS-CoV-2 and influenza A virus is becoming a practical problem that must be addressed as the flu season merges with the COVID-19 pandemic. As SARS-CoV-2 and influenza A virus have been found in patients, understanding the in vivo characteristics of the secondary infection between these two viruses is a high priority. Here, hACE2 transgenic mice were challenged with the H1N1 virus at a nonlethal dose during the convalescent stage on 7 and 14 days post SARS-CoV-2 infection, and importantly, subsequent H1N1 infection showed enhanced viral shedding and virus tissue distribution. Histopathological observation revealed an extensive pathological change in the lungs related to H1N1 infection in mice recovered from SARS-CoV-2 infection, with severe inflammation infiltration and bronchiole disruption. Moreover, upon H1N1 exposure on 7 and 14 dpi of SARS-CoV-2 infection, the lymphocyte population activated at a lower level with T cell suppressed in both PBMC and lung. These findings will be valuable for evaluating antiviral therapeutics and vaccines as well as guiding public health work.

The pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a global threat to human health and life. A useful pathological animal model accurately reflecting human pathology is needed to overcome the COVID-19 crisis. In the present study, COVID-19 cynomolgus monkey models including monkeys with underlying diseases causing severe pathogenicity such as metabolic disease and elderly monkeys were examined. Cynomolgus macaques with various clinical conditions were intranasally and/or intratracheally inoculated with SARS-CoV-2. Infection with SARS-CoV-2 was found in mucosal swab samples, and a higher level and longer period of viral RNA was detected in elderly monkeys than in young monkeys. Pneumonia was confirmed in all of the monkeys by computed tomography images. When monkeys were readministrated SARS-CoV-2 at 56 d or later after initial infection all of the animals showed inflammatory responses without virus detection in swab samples. Surprisingly, in elderly monkeys reinfection showed transient severe pneumonia with increased levels of various serum cytokines and chemokines compared with those in primary infection. The results of this study indicated that the COVID-19 cynomolgus monkey model reflects the pathophysiology of humans and would be useful for elucidating the pathophysiology and developing therapeutic agents and vaccines., Competing Interests: The authors declare no competing interest., (Copyright © 2021 the Author(s). Published by PNAS.)

This study investigated the infectivity of severe acute respiratory syndrome (SARS-CoV-2) in individuals who re-tested positive for SARS-CoV-2 RNA after recovering from their primary illness. We investigated 295 individuals with re-positive SARS-CoV-2 polymerase chain reaction (PCR) test results and 836 of their close contacts. We attempted virus isolation in individuals with re-positive SARS-CoV-2 PCR test results using cell culture and confirmed the presence of neutralizing antibodies using serological tests. Viral culture was negative in all 108 individuals with re-positive SARS-CoV-2 PCR test results in whom viral culture was performed. Three new cases of SARS-CoV-2 infection were identified among household contacts using PCR. Two of the three new cases had had contact with the index patient during their primary illness, and all three had antibody evidence of past infection. Thus, there was no laboratory evidence of viral shedding and no epidemiological evidence of transmission among individuals with re-positive SARS-CoV-2 PCR test results.

Whether subclinical shedding of canine parvovirus (CPV) by cats might contribute to the epidemiology of canine CPV infections, particularly in facilities housing both cats and dogs, requires clarification. Conflicting results are reported to date. Using conventional PCR (cPCR) to amplify the VP2 gene, shedding of the CPV variants (CPV-2a, 2b, 2c) by healthy cats in multi-cat environments was reportedly common in Europe but rare in Australia. The aim of this study was to determine whether low-level faecal CPV shedding occurs in multi-cat environments in Australia and Italy using a TaqMan real-time PCR to detect Carnivore protoparvovirus 1 (CPV and feline parvovirus, FPV) DNA, and minor-groove binder probe real-time PCR assay to differentiate FPV and CPV types and to characterize CPV variants. In total, 741 non-diarrhoeic faecal samples from shelters in Australia (n = 263) and from shelters or cat colonies in Italy (n = 478) were tested. Overall, Carnivore protoparvovirus 1 DNA was detected in 49 of 741 (6.61 %) samples. Differentiation was possible for 31 positive samples. FPV was most common among positive samples (28/31, 90.3 %). CPV was detected in 4/31 samples (12.9 %) including CPV-2a in one sample, CPV-2b in another and co-infections of FPV/CPV-2b and CPV-2a/CPV-2b in the remaining two samples. A high rate of subclinical FPV infection was detected in one shelter during an outbreak of feline panleukopenia, during which 21 of 22 asymptomatic cats (95.5 %) sampled were shedding FPV. Faecal shedding of CPV by cats in multi-cat environments is uncommon suggesting that domestic cats are not significant reservoirs of CPV., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: The dynamic alteration and comparative study of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA shedding pattern during treatment are limited. This study explores the potential risk factors influencing prolonged viral shedding in COVID-19., Methods: A total of 126 COVID-19 patients were enrolled in this retrospective longitudinal study. A multivariate logistic regression analysis was carried out to estimate the potential risk factors., Results: 38.1% (48/126) cases presented prolonged respiratory tract viral shedding, and 30 (23.8%) cases presented prolonged rectal swab viral shedding. Obesity (OR, 3.31; 95% CI, 1.08-10.09), positive rectal swab (OR, 3.43; 95% CI, 1.53-7.7), treatment by lopinavir/ritonavir with chloroquine phosphate (OR, 2.5; 95% CI, 1.04-6.03), the interval from onset to antiviral treatment more than 7 days (OR, 2.26; 95% CI, 1.04-4.93), lower CD4+ T cell (OR, 0.92; 95% CI, 0.86-0.99) and higher NK cells (OR, 1.11; 95% CI, 1.02-1.20) were significantly associated with prolonged respiratory tract viral shedding. CD3-CD56+ NK cells (OR, 0.87; 95% CI, 0.76-0.99) were related with prolonged fecal shedding., Conclusions: Obesity, delayed antiviral treatment, and positive SARS-CoV-2 for stool were independent risk factors for prolonged SARS-CoV-2 RNA shedding of the respiratory tract. A combination of LPV/r and abidol as the initial antiviral regimen was effective in shortening the duration of viral shedding compared with LPV/r combined with chloroquine phosphate. CD4+ T cell and NK cells were significantly associated with prolonged viral shedding, and further studies are to be warranted to determine the mechanism of immunomodulatory response in virus clearance., (© 2021 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals LLC.)

Inpatient coronavirus disease 2019 (COVID-19) cases present enormous costs to patients and health systems in the United States. Many hospitalized patients may continue testing COVID-19 positive even after the resolution of symptoms. Thus, a pressing concern for clinicians is the safety of discharging these asymptomatic patients if they have any remaining infectivity. This case report explores the viral viability in a patient with persistent COVID-19 over the course of a 2-month hospitalization. Positive nasopharyngeal swab samples were collected and isolated in the laboratory and analyzed by quantitative reverse-transcription polymerase chain reactions (qRT-PCR), and serology was tested for neutralizing antibodies throughout the hospitalization period. The patient experienced waning symptoms by hospital day 40 and had no viable virus growth by hospital day 41, suggesting no risk of infectivity, despite positive RT-PCR results which prolonged his hospital stay. Notably, this case showed infectivity for at least 24 days after disease onset, which is longer than the discontinuation of transmission-based precautions recommended by the Center for Disease Control and Prevention. Thus, our findings suggest that the timeline for discontinuing transmission-based precautions may need to be extended for patients with severe and prolonged COVID-19 disease. Additional large-scale studies are needed to draw definitive conclusions on the appropriate clinical management for these patients. ​., (© 2021 Wiley Periodicals LLC.)

Information regarding the infectivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in asymptomatic carriers is scarce. In order to determine the duration of infectivity and its correlation with reverse transcription-PCR (RT-PCR) results and time since initial positive PCR test in this population, we evaluated SARS-CoV-2 cell infectivity in nasopharyngeal samples longitudinally obtained from asymptomatic carriers who disembarked from a cruise ship during a COVID-19 outbreak. Of 166 nasopharyngeal samples collected from 39 asymptomatic carriers every 48 h until two consecutive negative PCR test results were obtained, SARS-CoV-2 was successfully isolated from 9 PCR-positive samples which were obtained from 7 persons (18%; 7/39). Viable viruses were isolated predominantly within 7 days after the initial positive PCR test, except for one person who shed viable virus until day 15. The median crossing point (Cp) value of RT-PCR of culture-positive samples was 24.6 (interquartile range [IQR], 20.4 to 25.8; range, 17.9 to 30.3), and Cp values were significantly associated with isolation of viable virus (odds ratio, 0.496; 95% confidence interval [CI], 0.329 to 0.747; P value, 0.001), which was consistent with existing data for symptomatic patients. Genome sequence analysis of SARS-CoV-2 samples consecutively obtained from a person who shed viable virus for 15 days identified the emergence of two novel single nucleotide variants (C8626T transition and C18452T transition) in the sample collected on day 15, with the latter corresponding to an amino acid substitution in nonstructural protein 14. The impact of these mutations on prolonged viable-virus shedding is unclear. These findings underscore the potential role of asymptomatic carriers in transmission. IMPORTANCE A growing number of studies suggest the potential role of asymptomatic SARS-CoV-2 carriers as a major driver of the COVID-19 pandemic; however, virological assessment of asymptomatic infection has largely been limited to reverse transcription-PCR (RT-PCR), which can be persistently positive without necessarily indicating the presence of viable virus (e.g., replication-competent virus). Here, we evaluated the infectivity of asymptomatic SARS-CoV-2 carriers by detecting SARS-CoV-2-induced cytopathic effects on Vero cells using longitudinally obtained nasopharyngeal samples from asymptomatic carriers. We show that asymptomatic carriers can shed viable virus until 7 days after the initial positive PCR test, with one outlier shedding until day 15. The crossing point (Cp) value of RT-PCR was the leading predictive factor for virus viability. These findings provide additional insights into the role of asymptomatic carriers as a source of transmission and highlight the importance of universal source control measures, along with isolation policy for asymptomatic carriers., (Copyright © 2021 Murata et al.)

The emergence of the novel coronavirus disease 2019 (COVID-19) presented the field of reproductive medicine with many challenges due to an absence of data to guide clinical decision-making and inform patient counseling and management in the early days of the pandemic. Epidemiological studies rapidly filled key gaps in our understanding of the susceptibility of reproductive-aged women to the virus, transmission dynamics during pregnancy and lactation, and the effect of infection during the prenatal, pregnancy, and postpartum periods. This data guided the development of clinical guidelines written by the American Society for Reproductive Medicine as patients and clinicians navigated reproductive decisions during a time of uncertainty. We present a review of epidemiologic studies published between March and December 2020 that have directly informed prenatal and fertility care during the COVID-19 pandemic. Despite a significant increase in our knowledge base over the past year, many questions remain about the impact of COVID-19 on conception, pregnancy, fetal development, and lactation. In the future, a commitment toward inclusion of pregnant persons and those attempting pregnancy in the design of observational and interventional trials is necessary to gain earlier insights about outcomes and assist providers and patients in making data-driven decisions., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The worldwide spread of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the associated infectious coronavirus disease (COVID-19) has posed a unique challenge to medical staff, patients and their families. Patients with cancer, particularly those with haematologic malignancies, have been identified to be at high risk to develop severe COVID-19. Since publication of our previous guideline on evidence-based management of COVID-19 in patients with cancer, research efforts have continued and new relevant data has come to light, maybe most importantly in the field of vaccination studies. Therefore, an update of our guideline on several clinically important topics is warranted. Here, we provide a concise update of evidence-based recommendations for rapid diagnostics, viral shedding, vaccination and therapy of COVID-19 in patients with cancer. This guideline update was prepared by the Infectious Diseases Working Party (AGIHO) of the German Society for Haematology and Medical Oncology by critically reviewing the currently available data on these topics applying evidence-based medicine criteria., Competing Interests: Conflict of Interest statement The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: N.G. reports receiving personal fees from MSD, Roche, Pfizer; grants from BMS, Karyopharm, outside the submitted work. SCM reports grants from University of Cologne (KoelnFortune), DMyKG, DZIF, personal fees from Octapharma, outside the submitted work. YK reports personal fees from GILEAD Sciences, grants, personal fees and other from MSD SHARP & DOHME, outside the submitted work. GB reports grants from The German Federal Ministry of Research and Education, The German Federal Ministry of Health, personal fees from Jazz Pharmaceuticals, MSD, NewConceptOncology, outside the submitted work. CL reports non-financial support from Jazz Pharmaceuticals, Neovii, outside the submitted work. MH reports personal fees from Amgen, Janssen, Celgene, Sanofi, Takeda, outside the submitted work. MBB is the PI of the COVACTA Trial at LMU. OAC is supported by the German Federal Ministry of Research and Education, is funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy - CECAD, EXC 2030 - 390661388 and has received research grants from Actelion, Amplyx, Astellas, Basilea, Cidara, Da Volterra, F2G, Gilead, Janssen, Medicines Company, Melinta, Merck/MSD, Octapharma, Pfizer, Scynexis, is a consultant to Actelion, Allecra, Amplyx, Astellas, Basilea, Biosys, Cidara, Da Volterra, Entasis, F2G, Gilead, IQVIA, Matinas, MedPace, Menarini, Merck/MSD, Mylan, Nabriva, Noxxon, Octapharma, Paratek, Pfizer, PSI, Roche Diagnostics, Scynexis, and Shionogi, and received lecture honoraria from Astellas, Basilea, Gilead, Grupo Biotoscana, Merck/MSD and Pfizer. PK has received non-financial scientific grants from Miltenyi Biotec GmbH, Bergisch Gladbach, Germany, and the Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, University of Cologne, Cologne, Germany, and received lecture honoraria from or has been advisor to Akademie für Infektionsmedizin e.V., Ambu GmbH, Astellas Pharma, Gilead Sciences GPR Academy Ruesselsheim, MSD Sharp & Dohme GmbH, Noxxon N.V., and University Hospital, LMU Munich, outside the submitted work. ES reports lecture honoraria from Gilead, outside the submitted work. M.v.L.T. reports personal fees from Celgene, Gilead, Chugai, Janssen, Novartis, Amgen, Takeda, BMS, Medac, Oncopeptides, Merck, CDDF, Pfizer, 4DPharma, Shionogi; grants from BMBF, Deutsche Jose Carreras Leukämie-Stiftung, IZKF Jena, DFG, Novartis, Gilead, Deutsche Krebshilfe, Celgene, outside the submitted work. RS, MR, MK, MS, HW, HHH, BW have nothing to disclose., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Genital cytomegalovirus (CMV) reactivation is common during the third trimester of pregnancy. We hypothesized that cervical CMV shedding may increase risk of spontaneous preterm birth (sPTB) through the release of inflammatory cytokines in the cervix. We conducted a nested case-control analysis to determine the relationship between CMV shedding and sPTB using data and samples from a prospective cohort study in western Kenya. Women who delivered between 28 + 0 and 33 + 6 weeks gestation were matched by gestational age at sample collection to controls who delivered ≥ 37 + 0 weeks. Levels of CMV DNA and interleukin (IL)-1 beta (β), IL-6, IL-8 and tumor necrosis factor (TNF)-α were measured in cervical swabs. We used conditional logistic regression to assess relationships between CMV shedding, cervical cytokine levels and sPTB. Among 86 cases and 86 matched controls, cervical CMV levels were not significantly associated with sPTB [odds ratio (OR) = 1·23, 95% confidence interval (CI) = 0·59-2·56], but were significantly associated with higher levels of cervical IL-6 (β = 0·15, 95% CI = 0·02-0·29) and TNF-α (β = 0·14, 95% CI = 0·01-0·27). In univariate analysis, higher odds of sPTB was associated with higher cervical IL-6 levels (OR = 1·54, 95% CI = 1·00-2·38), but not with other cervical cytokines. In this cohort of Kenyan women, we did not find a significant association between cervical CMV shedding and sPTB before 34 weeks., (© 2020 British Society for Immunology.)

To address the COVID-19 pandemic, there has been an unprecedented global effort to advance potent neutralizing mAbs against SARS-CoV-2 as therapeutics. However, historical efforts to advance antiviral monoclonal antibodies (mAbs) for the treatment of other respiratory infections have been met with categorical failures in the clinic. By investigating the mechanism by which SARS-CoV-2 and similar viruses spread within the lung, along with available biodistribution data for systemically injected mAb, we highlight the challenges faced by current antiviral mAbs for COVID-19. We summarize some of the leading mAbs currently in development, and present the evidence supporting inhaled delivery of antiviral mAb as an early intervention against COVID-19 that could prevent important pulmonary morbidities associated with the infection., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A key parameter in epidemiological modeling which characterizes the spread of an infectious disease is the generation time, or more generally the distribution of infectiousness as a function of time since infection. There is increasing evidence supporting a prolonged viral shedding window for COVID-19, but the transmissibility in this phase is unclear. Based on this, we develop a generalized Susceptible-Exposed-Infected-Resistant (SEIR) model including an additional compartment of chronically infected individuals who can stay infectious for a longer duration than the reported generation time, but with infectivity reduced to varying degrees. Using the incidence and fatality data from different countries, we first show that such an assumption also yields a plausible model in explaining the data observed prior to the easing of the lockdown measures (relaxation). We then test the predictive power of this model for different durations and levels of prolonged infectiousness using the incidence data after the introduction of relaxation in Switzerland, and compare it with a model without the chronically infected population to represent the models conventionally used. We show that in case of a gradual easing on the lockdown measures, the predictions of the model including the chronically infected population vary considerably from those obtained under a model in which prolonged infectiousness is not taken into account. Although the existence of a chronically infected population still remains largely hypothetical, we believe that our results provide tentative evidence to consider a chronically infected population as an alternative modeling approach to better interpret the transmission dynamics of COVID-19., Competing Interests: The authors have declared that no competing interests exist.

Oncolytic virotherapy is an emerging strategy that uses replication-competent viruses to kill tumor cells. We have reported the oncolytic effects of TG6002, a recombinant oncolytic vaccinia virus, in preclinical human xenograft models and canine tumor explants. To assess the safety, biodistribution and shedding of TG6002 administered by the intravenous route, we conducted a study in immune-competent healthy dogs. Three dogs each received a single intravenous injection of TG6002 at 10 5 PFU/kg, 10 6 PFU/kg or 10 7 PFU/kg, and one dog received three intravenous injections at 10 7 PFU/kg. The injections were well tolerated without any clinical, hematological or biochemical adverse events. Viral genomes were only detected in blood at the earliest sampling time point of one-hour post-injection at 10 7 PFU/kg. Post mortem analyses at day 35 allowed detection of viral DNA in the spleen of the dog which received three injections at 10 7 PFU/kg. Viral genomes were not detected in the urine, saliva or feces of any dogs. Seven days after the injections, a dose-dependent antibody mediated immune response was identified. In conclusion, intravenous administration of TG6002 shows a good safety profile, supporting the initiation of clinical trials in canine cancer patients as well as further development as a human cancer therapy.

To investigate the factors associated with the duration of severe acute respiratory syndrome coronavirus 2 RNA shedding in patients with coronavirus disease 2019 (COVID-19). A retrospective cohort of COVID-19 patients admitted to a designated hospital in Beijing was analyzed to study the factors affecting the duration of viral shedding. The median duration of viral shedding was 11 days (IQR, 8-14.3 days) as measured from illness onset. Univariate regression analysis showed that disease severity, corticosteroid therapy, fever (temperature>38.5°C), and time from onset to hospitalization were associated with prolonged duration of viral shedding (P < .05). Multivariate regression analysis showed that fever (temperature>38.5°C) (OR, 5.1, 95%CI: 1.5-18.1), corticosteroid therapy (OR, 6.3, 95%CI: 1.5-27.8), and time from onset to hospitalization (OR, 1.8, 95%CI: 1.19-2.7) were associated with increased odds of prolonged duration of viral shedding. Corticosteroid treatment, fever (temperature>38.5°C), and longer time from onset to hospitalization were associated with prolonged viral shedding in COVID-19 patients., (© 2020 Wiley Periodicals LLC.)

Background: Various factors may determine the duration of viral shedding (the time from infection to viral RNA-negative conversion or recovery) in COVID-19 patients. Understanding the average duration of recovery and its predictors is crucial in formulating preventive measures and optimizing treatment options. Therefore, evidence showing the duration of recovery from COVID-19 in different contexts and settings is necessary for tailoring appropriate treatment and prevention measures. This study aimed to investigate the average duration and the predictors of recovery from Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection among COVID-19 patients., Method: A hospital-based prospective cohort study was conducted at Eka Kotebe General Hospital, COVID-19 Isolation and Treatment Center from March 18 to June 27, 2020. The Center was the first hospital designated to manage COVID-19 cases in Ethiopia. The study participants were all COVID-19 adult patients who were admitted to the center during the study period. Follow up was done for the participants from the first date of diagnosis to the date of recovery (negative Real-time Reverse Transcriptase Polymerase Chain Reaction (rRT-PCT) test of throat swab)., Result: A total of 306 COVID-19 cases were followed up to observe the duration of viral clearance by rRT-PCR. Participants' mean age was 34 years (18-84 years) and 69% were male. The median duration of viral clearance from each participant's body was 19 days, but the range was wide: 2 to 71 days. Cough followed by headache was the leading sign of illness among the 67 symptomatic COVID-19 patients; and nearly half of those with comorbidities were known cancer and HIV/AIDS patients on clinical follow up. The median duration of recovery from COVID-19 was different for those with and without previous medical conditions or comorbidities. The rate of recovery from SARS-CoV-2 infection was 36% higher in males than in females (p = 0.043, CI: 1.01, 1.85). The rate of recovery was 93% higher in those with at least one comorbidity than in those without any comorbidity. The risk of delayed recovery was not influenced by blood type, BMI and presence of signs or symptoms. The findings showed that study participants without comorbidities recovered more quickly than those with at least one comorbidity. Therefore, isolation and treatment centers should be prepared to manage the delayed stay of patients having comorbidity., Competing Interests: NO authors have competing interests.

At present, the time-frame used for the quarantine of individuals with coronavirus disease 2019 (COVID-19) is the entire duration of symptoms plus 14 days after symptom recovery; however, no data have been reported specifically for healthcare workers (HCWs). In the study population of 142 HCWs with COVID-19, the mean time for viral clearance was 31.8 days. Asymptomatic subjects cleared the virus more quickly than symptomatic subjects (22 vs 34.2 days; P<0.0001). The presence of fever at the time of diagnosis was associated with a longer time to viral clearance (relative risk 11.45, 95% confidence interval 8.66-14.25; P<0.0001). These findings may have a significant impact on healthcare strategies for the future management of the COVID-19 pandemic., (Copyright © 2020 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.)

Background: RT-PCR on nasopharyngeal (NPS)/oropharyngeal swabs is the gold standard for diagnosis of SARS-CoV-2 infection and viral load monitoring. Oral fluid (OF) is an alternate clinical sample, easy and safer to collect and could be useful for COVID-19 diagnosis, monitoring viral load and shedding., Methods: Optimal assay conditions and analytical sensitivity were established for the commercial Simplexa™ COVID-19 Direct assay adapted to OF matrix. The assay was used to test 337 OF and NPS specimens collected in parallel from 164 hospitalized patients; 50 bronchoalveolar lavage (BAL) specimens from a subgroup of severe COVID-19 cases were also analysed., Results: Using Simplexa™ COVID-19 Direct on OF matrix, 100% analytical detection down to 1 TCID50/mL (corresponding to 4 × 10 3 copies (cp)/mL) was observed. No crossreaction with other viruses transmitted through the respiratory toute was observed. Parallel testing of 337 OF and NPS samples showed highly concordant results (κ = 0.831; 95 % CI = 0.771-0.891), and high correlation of Ct values (r = 0.921; p < 0.0001). High concordance and elevated correlation was observed also between OF and BAL. Prolonged viral RNA shedding was observed up to 100 days from symptoms onset (DSO), with 32% and 29% positivity observed in OF and NPS samples, respectively, collected between 60 and 100 DSO., Conclusions: Simplexa™ COVID-19 Direct assays on OF have high sensitivity and specificity to detect SARS-CoV-2 RNA and provide an alternative to NPS for diagnosis and monitoring SARS-CoV-2 shedding.

Acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first identified in Wuhan, China; and spread all over the world. Reverse-transcription polymerase chain reaction (RT-PCR) test for SARS-CoV-2 usually returns to negative in 20 days post-infection, but prolonged positivity has been reported up to 63 days. A case whose viral shedding lasted 60 days is reported from China. Herein we report a patient with a history of autologous stem cell transplantation (ASCT) for lymphoma whose RT-PCR test remained positive for SARS-CoV-2 for 74 days. The prolonged RT-PCR positivity, despite convalescent plasma infusion, may suggest that the given antibodies may be ineffective in terms of viral clearance. In patients with hematological malignancies or immunosuppression, such as ASCT, may lead to prolonged viral shedding, and strict isolation is warranted for long-term SARS-CoV-2 infection control., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Since the start of the COVID-19 pandemic, there have been many scientific reports regarding gastrointestinal manifestations. Several reports indicate the possibility of viral shedding via faeces and the possibility of faecal-oral transmission., Aims: To critically assess the clinical relevance of testing stool samples and anal swabs and provide an overview of the potential faecal-oral transmission of SARS-CoV-2., Methods: A systematic literature search with MeSH terms was performed, scrutinising the Embase database, Google scholar, MEDLINE database through PubMed and The Cochrane Library, including articles from December 2019 until July 7 2020. Data were subsequently analysed with descriptive statistics., Results: Ninety-five studies were included in the qualitative analysis. 934/2149 (43%) patients tested positive for SARS-CoV-2 in stool samples or anal swabs, with positive test results up to 70 days after symptom onset. A meta-analysis executed with studies of at least 10 patients revealed a pooled positive proportion of 51.8% (95% CI 43.8 - 59.7%). Positive faecal samples of 282/443 patients (64%) remained positive for SARS-CoV-2 for a mean of 12.5 days, up to 33 days maximum, after respiratory samples became negative for SARS-CoV-2. Viable SARS-CoV-2 was found in 6/17 (35%) patients in whom this was specifically investigated., Conclusions: Viral shedding of SARS-CoV-2 in stool samples occurs in a substantial proportion of patients, making faecal-oral transmission plausible. Furthermore, detection in stool samples or anal swabs can persist long after negative respiratory testing. Therefore, stool sample or anal swab testing should be (re)considered in relation to decisions for isolating or discharging a patient., (© 2020 The Authors. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd.)

Introduction: The novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is responsible for a worldwide pandemic. While the medical community understands the mode of viral transmission, less is known about how long viral shedding occurs once viral symptoms have resolved. Our objective was to determine how long the SARS-CoV-2 remains detectable following self-reporting of viral symptom resolution., Methods: This study was approved by the University of Wisconsin Institutional Review Board. A cohort of patients who were previously SARS-CoV-2 positive less than 28 days after self-reported symptom resolution were retested for proof of viral recovery by nasal swab reverse transcriptase polymerase chain reaction for SARS-CoV-2 RNA., Results: A total of 152 potential participants were screened, of which 5 declined, 54 were ineligible, and 93 were recruited; 86 of 93 completed testing. Eleven of 86 (13%) were still positive at a median of 19 days (range, 12-24 days) after symptom resolution. Positive participants were significantly older than negative participants (mean, 54 years; 95% confidence interval [CI], 44-63 vs 42 years; 95% CI, 38-46; P = .024). C T values were significantly, inversely associated with age (β = -.04; r 2 = 0.389; P = .04). The number of days since symptom recovery was not apparently different between positive and negative participants., Conclusion: We found evidence of persistent viral shedding in nasopharyngeal secretions more than 2 weeks after resolution of symptoms from confirmed COVID-19 infection. Persistent shedding was more common in older participants, and viral load was higher among older positive participants. These results underscore the necessity of testing COVID-19 convalescent plasma donors less than 28 days after symptom resolution., (© 2020 AABB.)

Since severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became a pandemic event in the world, it has not only caused huge economic losses, but also a serious threat to global public health. Many scientific questions about SARS-CoV-2 and Coronavirus disease (COVID-19) were raised and urgently need to be answered, including the susceptibility of animals to SARS-CoV-2 infection. Here we tested whether tree shrew, an emerging experimental animal domesticated from wild animal, is susceptible to SARS-CoV-2 infection. No clinical signs were observed in SARS-CoV-2 inoculated tree shrews during this experiment except the increasing body temperature particularly in female animals. Low levels of virus shedding and replication in tissues occurred in all three age groups. Notably, young tree shrews (6 months to 12 months) showed virus shedding at the earlier stage of infection than adult (2 years to 4 years) and old (5 years to 7 years) animals that had longer duration of virus shedding comparatively. Histopathological examine revealed that pulmonary abnormalities were the main changes but mild although slight lesions were also observed in other tissues. In summary, tree shrew is less susceptible to SARS-CoV-2 infection compared with the reported animal models and may not be a suitable animal for COVID-19 related researches. However, tree shrew may be a potential intermediate host of SARS-CoV-2 as an asymptomatic carrier.

The coronavirus disease 2019 (COVID-19) pandemic continues to pose a global threat to the human population. Identifying animal species susceptible to infection with the SARS-CoV-2/ HCoV-19 pathogen is essential for controlling the outbreak and for testing valid prophylactics or therapeutics based on animal model studies. Here, different aged Chinese tree shrews (adult group, 1 year old; old group, 5-6 years old), which are close relatives to primates, were infected with SARS-CoV-2. X-ray, viral shedding, laboratory, and histological analyses were performed on different days post-inoculation (dpi). Results showed that Chinese tree shrews could be infected by SARS-CoV-2. Lung infiltrates were visible in X-ray radiographs in most infected animals. Viral RNA was consistently detected in lung tissues from infected animals at 3, 5, and 7 dpi, along with alterations in related parameters from routine blood tests and serum biochemistry, including increased levels of aspartate aminotransferase (AST) and blood urea nitrogen (BUN). Histological analysis of lung tissues from animals at 3 dpi (adult group) and 7 dpi (old group) showed thickened alveolar septa and interstitial hemorrhage. Several differences were found between the two different aged groups in regard to viral shedding peak. Our results indicate that Chinese tree shrews have the potential to be used as animal models for SARS-CoV-2 infection.

Vaccines are urgently needed to combat the global coronavirus disease 2019 (COVID-19) pandemic, and testing of candidate vaccines in an appropriate non-human primate (NHP) model is a critical step in the process. Infection of African green monkeys (AGM) with a low passage human isolate of SARS-CoV-2 by aerosol or mucosal exposure resulted in mild clinical infection with a transient decrease in lung tidal volume. Imaging with human clinical-grade 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) co-registered with computed tomography (CT) revealed pulmonary lesions at 4 days post-infection (dpi) that resolved over time. Infectious virus was shed from both respiratory and gastrointestinal (GI) tracts in all animals in a biphasic manner, first between 2-7 dpi followed by a recrudescence at 14-21 dpi. Viral RNA (vRNA) was found throughout both respiratory and gastrointestinal systems at necropsy with higher levels of vRNA found within the GI tract tissues. All animals seroconverted simultaneously for IgM and IgG, which has also been documented in human COVID-19 cases. Young AGM represent an species to study mild/subclinical COVID-19 disease and with possible insights into live virus shedding. Future vaccine evaluation can be performed in AGM with correlates of efficacy being lung lesions by PET/CT, virus shedding, and tissue viral load., Competing Interests: The authors have declared that no competing interests exist.

The human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) trimer of gp120-gp41 heterodimers mediates virus entry into CD4-positive (CD4 + ) cells. Single-molecule fluorescence resonance energy transfer (smFRET) has revealed that native Env on the surface of viruses predominantly exists in a pretriggered conformation (state 1) that is preferentially recognized by many broadly neutralizing antibodies (bNAbs). Env is activated by binding receptor CD4, which drives transitions through a default intermediate conformation (state 2) into the three-CD4-bound open conformation (state 3). The application of smFRET to assess the conformational state of existing Env constructs and ligand complexes recently revealed that all current high-resolution structures correspond to downstream states 2 and 3. The structure of state 1, therefore, remains unknown. We sought to identify conditions whereby HIV-1 Env could be stabilized in the pretriggered state 1 for possible structural characterization. Shedding of gp120, known to severely complicate structural studies, can be prevented by using the uncleaved gp160 JR-FL precursor with alterations in the protease cleavage site (R508S/R511S) or by introducing a disulfide bridge between gp120 and gp41 designated "SOS" (A501C/T605C). smFRET demonstrated that both shedding-preventing modifications shifted the conformational landscape of Env downstream toward states 2 and 3. However, both membrane-bound Env proteins on the surface of intact viruses remained conformationally dynamic, responsive to state-stabilizing ligands, and able to be stabilized in state 1 by specific ligands such as the Bristol-Myers Squibb (BMS) entry inhibitors. The here-described identification of state 1-stabilizing conditions may enable structural characterization of the state 1 conformation of HIV-1 Env. IMPORTANCE The HIV-1 envelope glycoprotein (Env) opens in response to receptor CD4 binding from a pretriggered (state 1) conformation through a necessary intermediate to the three-CD4-bound conformation. The application of smFRET to test the conformational state of existing Env constructs and ligand complexes used for high-resolution structures recently revealed that they correspond to the downstream conformations. The structure of the pretriggered Env conformation, preferentially recognized by broadly neutralizing antibodies, remains unknown. Here, we identify experimental conditions that stabilize membrane-bound and shedding-resistant virus Env trimers in state 1, potentially facilitating structural characterization of this unknown conformational state., (Copyright © 2020 American Society for Microbiology.)

Severe acute respiratory syndrome coronavirus 2 viral load in the upper respiratory tract peaks around symptom onset and infectious virus persists for 10 days in mild-to-moderate coronavirus disease (n = 324 samples analysed). RT-PCR cycle threshold (Ct) values correlate strongly with cultivable virus. Probability of culturing virus declines to 8% in samples with Ct > 35 and to 6% 10 days after onset; it is similar in asymptomatic and symptomatic persons. Asymptomatic persons represent a source of transmissible virus.

Background: The COVID-19 pandemic caused by SARS-CoV-2 remains a significant issue for global health, economics and society. A wealth of data has been generated since its emergence in December 2019, and it is vital for clinicians to keep up with this data from across the world at a time of uncertainty and constantly evolving guidelines and clinical practice., Objectives: Here we provide an update for clinicians on the recent developments in the virology, diagnostics, clinical presentation, viral shedding, and treatment options for COVID-19 based on current literature., Sources: We considered published peer-reviewed papers and non-peer-reviewed pre-print manuscripts on COVID19 and related aspects with an emphasis on clinical management aspects., Content: We describe the virological characteristics of SARS-CoV-2 and the clinical course of COVID-19 with an emphasis on diagnostic challenges, duration of viral shedding, severity markers and current treatment options., Implications: The key challenge in managing COVID-19 remains patient density. However, accurate diagnosis as well as early identification and management of high-risk severe cases are important for many clinicians. For improved management of cases, there is a need to understand test probability of serology, qRT-PCR and radiological testing, and the efficacy of available treatment options that could be used in severe cases with a high risk of mortality., (Copyright © 2020 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

The clinical characteristics of patients with COVID-19 were analysed to determine the factors influencing the prognosis and virus shedding time to facilitate early detection of disease progression. Logistic regression analysis was used to explore the relationships among prognosis, clinical characteristics and laboratory indexes. The predictive value of this model was assessed with receiver operating characteristic curve analysis, calibration and internal validation. The viral shedding duration was calculated using the Kaplan-Meier method, and the prognostic factors were analysed by univariate log-rank analysis and the Cox proportional hazards model. A retrospective study was carried out with patients with COVID-19 in Tianjin, China. A total of 185 patients were included, 27 (14.59%) of whom were severely ill at the time of discharge and three (1.6%) of whom died. Our findings demonstrate that patients with an advanced age, diabetes, a low PaO2/FiO2 value and delayed treatment should be carefully monitored for disease progression to reduce the incidence of severe disease. Hypoproteinaemia and the fever duration warrant special attention. Timely interventions in symptomatic patients and a time from symptom onset to treatment <4 days can shorten the duration of viral shedding.

Objective: To determine the dynamic changes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in respiratory and fecal specimens in children with coronavirus disease 2019 (COVID-19)., Methods: From January 17, 2020 to February 23, 2020, three paediatric cases of COVID-19 were reported in Qingdao, Shandong Province, China. Epidemiological, clinical, laboratory, and radiological characteristics and treatment data were collected. Patients were followed up to March 10, 2020, and dynamic profiles of nucleic acid testing results in throat swabs and fecal specimens were closely monitored., Results: Clearance of SARS-CoV-2 in respiratory tract occurred within two weeks after abatement of fever, whereas viral RNA remained detectable in stools of pediatric patients for longer than 4 weeks. Two children had fecal SARS-CoV-2 undetectable 20 days after throat swabs showing negative, while that of another child lagged behind for 8 days., Conclusions: SARS-CoV-2 may exist in children's gastrointestinal tract for a longer time than respiratory system. Persistent shedding of SARS-CoV-2 in stools of infected children raises the possibility that the virus might be transmitted through contaminated fomites. Massive efforts should be made at all levels to prevent spreading of the infection among children after reopening of kindergartens and schools., Competing Interests: Declaration of Competing Interest None reported., (Copyright © 2020. Published by Elsevier B.V.)

Introduction: On the last three months the new SARS-COV-2 coronavirus has created a pandemic, rapidly spreading all around the world. The aim of the study is to investigate whether obesity impacts on COVID-19 morbidity., Methods: One hundred consecutive patients with COVID-19 pneumonia admitted in our Medical Unit were evaluated. Anthropometric parameters and past medical history were registered. Nasopharyngeal swab samples and biochemical analysis were obtained at admission and during hospital stay., Results: Patients with (OB, 29) and without obesity (N-OB, 71) were similar in age, gender and comorbidities, with the exception of hypertension that was more frequent in OB group. At admission, inflammatory markers were higher in OB than N-OB group. OB group showed a worse pulmonary clinical picture, with lower PaO2 (57 ± 15 vs. 68 ± 14 mmHg, p = 0.042), and SaO2 (88 ± 6 vs. 92 ± 5%, p = 0.049) at admission consequently requiring higher volumes of oxygen (Fi02: 38 ± 15 vs. 29 ± 19%, p = 0.047) and a longer period to achieve oxygen weaning (10 ± 6 vs. 15 ± 7 days, p = 0.03). OB group also had positive swabs for longer time (19 ± 8 vs. 13 ± 7, days, p = 0.002), and required longer hospital stay (21 ± 8 vs. 13 ± 8, days, p = 0.0008). Partial least square regression analysis showed that BMI, age and CRP at admission were related to longer length of hospital stay, and time for negative swab. On the contrary, in this cohort, obesity did not predict higher mortality., Conclusions: Subjects with obesity affected by COVID-19 require longer hospitalization, more intensive and longer oxygen treatment, and they may have longer SARS-COV-2 shedding., (Copyright © 2020 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.)

Astroviruses are a global cause of pediatric diarrhea, but they are largely understudied, and it is unclear how and where they replicate in the gut. Using an in vivo model, here we report that murine astrovirus preferentially infects actively secreting small intestinal goblet cells, specialized epithelial cells that maintain the mucus barrier. Consequently, virus infection alters mucus production, leading to an increase in mucus-associated bacteria and resistance to enteropathogenic E. coli colonization. These studies establish the main target cell type and region of the gut for productive murine astrovirus infection. They further define a mechanism by which an enteric virus can regulate the mucus barrier, induce functional changes to commensal microbial communities, and alter host susceptibility to pathogenic bacteria.

The occurrence of severe outbreaks of highly pathogenic avian influenza in Korea led to establishment of a national antigen bank for emergency preparedness. Here, we developed five vaccines for this bank (clade 2.3.2.1C, clade 2.3.4.4A, B, C, and D) by reverse genetics, inactivated them with formalin, and evaluated the protective efficacy and potency of serial dilutions against lethal homologous challenge in specific-pathogen-free chickens. After vaccination with one dose, each vaccine resulted in 100% survival, with no clinical symptoms, or lack of detectable virus shedding, and high levels of pre-challenge protective immunity (8.4-10.2 log 2 ). After vaccination with one-tenth of the full dose, protection was similar to that with the full dose. After vaccination with one-hundredth of the initial dose, survival was 20-80%, and all vaccines showed virus shedding. Four vaccines (excluding clade 2.3.2.1C) had satisfactory potency. In antibody-persistence tests, all vaccines maintained long-lasting protective immunity. Our results suggest that inactivated reverse-genetics vaccines genetically matched to outbreak viruses provide adequate protection after a single vaccination., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Background: The outbreak of severe acute respiratory syndrome β-coronavirus 2 (SARS-CoV-2) has the potential to become a long-lasting global health crisis. The number of people infected with the novel coronavirus has surpassed 22 million globally, resulting in over 700,000 deaths with more than 15 million people having recovered (https://covid19.who.int). Enormous efforts are underway for rapid vaccine and treatment developments. Amongst the many ways of tackling the novel coronavirus disease 2019 (COVID-19) pandemic, extracellular vesicles (EVs) are emerging., Summary: EVs are lipid bilayer-enclosed structures secreted from all types of cells, including those lining the respiratory tract. They have established roles in lung immunity and are involved in the pathogenesis of various lung diseases, including viral infection. In this review, we point out the roles and possible contribution of EVs in viral infections, as well as ongoing EV-based approaches for the treatment of COVID-19, including clinical trials. Key Messages: EVs share structural similarities to viruses and recent findings demonstrate that viruses exploit EVs for cellular exit and EVs exploit viral entry mechanisms for cargo delivery. Moreover, EV-virus interplay could be exploited for future antiviral drug and vaccine development. EV-based therapies, especially the mesenchymal stem cell-derived EVs, are being intensively studied for the treatment of COVID-19., (© 2020 The Author(s) Published by S. Karger AG, Basel.)

The risk of postnatal HIV transmission exists throughout the breastfeeding period. HIV shedding in breast milk beyond six months has not been studied extensively. The aim of this study was to determine prevalence and determinants of HIV shedding in breast milk during continued breastfeedingA cross-sectional study was nested in the PROMISE-PEP trial in Lusaka, Zambia to analyze breast milk samples collected from both breasts at week 38 post-partum (mid-way during continued breastfeeding). We measured concurrent HIV deoxyribonucleic acid (DNA) and HIV ribonucleic acid (RNA) as proxies for cell-associated HIV (CAV) and cell-free HIV (CFV) shedding in breast milk respectively. Participants' socio-demographic date, concurrent blood test results, sub clinical mastitis test results and contraceptive use data were available. Logistic regression models were used to identify determinants of HIV shedding in breast milk (detecting either CAV or CFV).The prevalence of HIV shedding in breast milk at 9 months post-partum was 79.4% (95%CI: 74.0 - 84.0). CAV only, CFV only and both CAV and CFV were detectable in 13.7%, 17.3% and 48.4% mothers, respectively. The odds of shedding HIV in breast milk decreased significantly with current use of combined oral contraceptives (AOR: 0.37; 95%CI: 0.17 - 0.83) and increased significantly with low CD4 count (AOR: 3.47; 95%CI: 1.23 - 9.80), unsuppressed plasma viral load (AOR: 6.27; 95%CI: 2.47 - 15.96) and severe sub-clinical mastitis (AOR: 12.56; 95%CI: 2.48 - 63.58).This study estimated that about 80% of HIV infected mothers not on ART shed HIV in breast milk during continued breastfeeding. Major factors driving this shedding were low CD4 count, unsuppressed plasma viral load and severe sub-clinical mastitis. The inverse relationship between breast milk HIV and use of combined oral contraceptives needs further clarification. Continued shedding of CAV may contribute to residual postnatal transmission of HIV in mothers on successful ART.

1. Infectious bursal disease virus (IBDV) causes immunosuppression in chickens, increasing their susceptibility to other infectious diseases and resulting in vaccination failure. Here, we investigated the immune-depressing effect of IBDV on H9N2 avian influenza viral infection in the broiler chickens. 2. For this purpose, chickens were divided into four groups. In group A, chickens were inoculated with IBDV at 21 days of age and H9N2 avian influenza virus (AIV) 5 days later. Groups B and C only received AIV at 26 days of age and IBDV at 21 days, respectively. The control group (D) were inoculated with normal saline at the same times. Tissue samples from different organs were collected on the days 1, 3, 6, 9, and 12 after H9N2 infection. 3. Macroscopic observation showed IBD lesions in groups A and C, including swollen bursa with the presence of gelatinous exudates, haemorrhages in the thigh muscle, edema, and nephritis. 4. Reverse Transcription-PCR was used to study H9N2 AIV dissemination, and qRT-PCR to determine viral genome copy number in different organs. A considerable titre of AIV was found in the trachea, lungs, cecal tonsils, spleens, and feces of infected chickens. The genome copy number of the virus in the trachea and lungs of group A was significantly higher than that in group B on the first day after inoculation. But in the other days post inoculation, RT-PCR did not detect the AIV genome in group A. Although there might have been some immunosuppression in group A, IBDV could interfere with AIV replication in the chickens of this group. 5. In conclusion, we propose that pre-exposure to IBDV at 3 weeks of age reduces the replication and shedding of H9N2 in broiler chicken.

Purpose: Manifestations of infection and the degree of influenza virus vary. We hypothesized that the nose/throat microbiota modifies the duration of influenza symptoms and viral shedding. Exploring these relationships may help identify additional methods for reducing influenza severity and transmission., Methods: Using a household transmission study in Nicaragua, we identified secondary cases of influenza virus infection, defined as contacts with detectable virus or a greater than 4-fold change in hemagglutinin inhibition antibody titer. We characterized the nose/throat microbiota of secondary cases before infection and explored whether the duration of symptoms and shedding differed by bacterial community characteristics., Results: Among 124 secondary cases of influenza, higher bacterial community diversity before infection was associated with longer shedding duration (Shannon acceleration factor [AF]: 1.61, 95% confidence interval [CI]: 1.24, 2.10) and earlier time to infection (Shannon AF: 0.72, 95% CI: 0.53, 0.97; Chao1 AF: 0.992, 95% CI: 0.986, 0.998). Neisseria and multiple other oligotypes were significantly associated with symptom and shedding durations and time to infection., Conclusions: The nose/throat microbiota before influenza virus infection was associated with influenza symptoms and shedding durations. Further studies are needed to determine if the nose/throat microbiota is a viable target for reducing influenza symptoms and transmission., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Chronic viruses such as herpes simplex virus 1 (HSV-1) evade the hosts' immune system by inducing the exhaustion of antiviral T cells. In the present study, we found that exhausted HSV-specific CD8 + T cells, with elevated expression of programmed death ligand-1 (PD-1) and lymphocyte activation gene-3 (LAG-3) receptors were frequent in symptomatic patients, with a history of numerous episodes of recurrent corneal herpetic disease, compared to asymptomatic patients who never had corneal herpetic disease. Subsequently, using a rabbit model of recurrent ocular herpes, we found that the combined blockade of PD-1 and LAG-3 pathways with antagonist antibodies significantly restored the function of tissue-resident antiviral CD8 + T RM cells in both the cornea and the trigeminal ganglia (TG). An increased number of functional tissue-resident HSV-specific CD8 + T RM cells in latently infected rabbits was associated with protection against recurrent herpes infection and disease. Compared to the PD-1 or LAG-3 blockade alone, the combined blockade of PD-1 and LAG-3 appeared to have a synergistic effect in generating frequent polyfunctional Ki-67 + , IFN-γ + , CD107 + , and CD8 + T cells. Moreover, using the human leukocyte antigen (HLA) transgenic rabbit model, we found that dual blockade of PD-1 and LAG-3 reinforced the effect of a multiepitope vaccine in boosting the frequency of HSV-1-specific CD8 + T RM cells and reducing disease severity. Thus, both the PD-1 and the LAG-3 exhaustion pathways play a fundamental role in ocular herpes T cell immunopathology and provide important immune checkpoint targets to combat ocular herpes. IMPORTANCE HSV-specific tissue-resident memory CD8 + T RM cells play a critical role in preventing virus reactivation from latently infected TG and subsequent virus shedding in tears that trigger the recurrent corneal herpetic disease. In this report, we determined how the dual blockade of PD-1 and LAG-3 immune checkpoints, combined with vaccination, improved the function of CD8 + T RM cells associated with a significant reduction in recurrent ocular herpes in HLA transgenic (Tg) rabbit model. The combined blockade of PD-1 and LAG-3 appeared to have a synergistic effect in generating frequent polyfunctional CD8 + T RM cells that infiltrated both the cornea and the TG. The preclinical findings using the established HLA Tg rabbit model of recurrent herpes highlight that blocking immune checkpoints combined with a T cell-based vaccine would provide an important strategy to combat recurrent ocular herpes in the clinic., (Copyright © 2019 American Society for Microbiology.)

Exposure to stress is one way in which social disadvantages during childhood may alter biological and psychological systems with long-term consequences. Family social and economic conditions are critical for early childhood development and exposure to difficult family conditions may have lasting physiological effects. However, there is little research linking early childhood conditions with physiological indicators of stress and system dysregulation in adolescence. In this study, we assess how family social and economic instability that occurred in early childhood (birth to age 5) is associated with immune system dysregulation in adolescence, as indicated by DNA shedding of the Epstein-Barr virus (EBV). We utilize a biomarker of EBV obtained through saliva, a non-invasive method of collecting immune-system biomarkers, in 674 adolescents 11-17 years old. Multivariable regression results indicated that experiences of moving into a new parent/caregiver household or moving in with a grandparent during early childhood was associated with an estimated 100% increase in EBV DNA shedding among prior EBV-infected adolescents. Other measures of early childhood family instability, total number of family structure changes and economic insecurity, were marginally significant. Contemporaneous family conditions were not associated with adolescents' EBV DNA shedding., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Reactivation of herpes simplex virus 2 (HSV-2) results in infection of epithelial cells at the neuro-epithelial junction and shedding of virus at the epithelial surface. Virus shedding can occur in either the presence or absence of clinical disease and is usually of short duration, although the shedding frequency varies among individuals. The basis for host control of virus shedding is not well understood, although adaptive immune mechanisms are thought to play a central role. To determine the importance of CD4 + T cells in control of HSV-2 shedding, this subset of immune cells was depleted from HSV-2-infected guinea pigs by injection of an anti-CD4 monoclonal antibody (MAb). Guinea pigs were treated with the depleting MAb after establishment of a latent infection, and vaginal swabs were taken daily to monitor shedding by quantitative PCR. The cumulative number of HSV-2 shedding days and the mean number of days virus was shed were significantly increased in CD4-depleted compared to control-treated animals. However, there was no difference in the incidence of recurrent disease between the two treatment groups. Serum antibody levels and the number of HSV-specific antibody-secreting cells in secondary lymphoid tissues were unaffected by depletion of CD4 + T cells; however, the frequency of functional HSV-specific, CD8 + gamma interferon-secreting cells was significantly decreased. Together, these results demonstrate an important role for CD4 + T lymphocytes in control of virus shedding that may be mediated in part by maintenance of HSV-specific CD8 + T cell populations. These results have important implications for development of therapeutic vaccines designed to control HSV-2 shedding. IMPORTANCE Sexual transmission of HSV-2 results from viral shedding following reactivation from latency. The immune cell populations and mechanisms that control HSV-2 shedding are not well understood. This study examined the role of CD4 + T cells in control of virus shedding using a guinea pig model of genital HSV-2 infection that recapitulates the shedding of virus experienced by humans. We found that the frequency of virus-shedding episodes, but not the incidence of clinical disease, was increased by depletion of CD4 + T cells. The HSV-specific antibody response was not diminished, but frequency of functional HSV-reactive CD8 + T cells was significantly diminished by CD4 depletion. These results confirm the role of cell-mediated immunity and highlight the importance of CD4 + T cells in controlling HSV shedding, suggesting that therapeutic vaccines designed to reduce transmission by controlling HSV shedding should include specific enhancement of HSV-specific CD4 + T cell responses., (Copyright © 2019 American Society for Microbiology.)

Porcine circovirus type 2 (PCV2), a highly prevalent, economically important swine pathogen is classified into different genotypes (PCV2a-f) based on phylogenetic analysis. Since the introduction of extensive vaccination programs, at least two major shifts have been observed in the prevalence of PCV2 genotypes. The first genotype shift from 2a towards 2b occurred around 2003, while in recent years, we are witnessing the second change in genotype prevalence from the predominant 2b towards 2d.In this study, a PCV2d-2 isolate was characterized as a potential challenge virus for the evaluation of PCV2 vaccine efficacy. Ten-week-old pigs carrying low to moderate levels of maternally derived antibodies to PCV2 were infected with the isolate by the nasal route. Over the next 4 weeks post-infection, the pigs were monitored for the presence of viremia, fecal virus excretion, and humoral immune responses. At the end of the post-infection observation period, samples were taken from the mediastinal and mesenteric lymph nodes of the animals and tested for viral load. The gradual depletion of maternally derived antibodies in the sera of piglets was demonstrated by ELISA and virus neutralization tests. Following experimental infection by PCV2d-2, specific IgM antibodies were first detected at 14 days post challenge (dpch), while IgG class antibodies were first detected at 21 dpch. Both viremia and virus shedding could be detected at 7 dpch, in 36 and 50% of the pigs, respectively. The proportion of shedders reached 100% by 14 dpch and remained at this level, while viremia was demonstrated in 86, 100, and 100% of the pigs at 14, 21, and 28 dpch, respectively. Both the mediastinal and mesenteric lymph nodes contained high levels of virus (7.6 and 8.5 log 10 copies/mg tissue, respectively).

The wide geographic spread of Eurasian Goose/Guangdong lineage highly pathogenic avian influenza (HPAI) clade 2.3.4.4 viruses by wild birds is of great concern. In December 2014, an H5N8 HPAI clade 2.3.4.4 Group A (2.3.4.4A) virus was introduced to North America. Long-distance migratory wild aquatic birds between East Asia and North America, such as Northern Pintail (Anas acuta), were strongly suspected of being a source of intercontinental transmission. In this study, we evaluated the pathogenicity, infectivity and transmissibility of an H5N8 HPAI clade 2.3.4.4A virus in Northern Pintails and compared the results to that of an H5N1 HPAI clade 2.3.2.1 virus. All of Northern Pintails infected with either H5N1 or H5N8 virus lacked clinical signs and mortality, but the H5N8 clade 2.3.4.4 virus was more efficient at replicating within and transmitting between Northern Pintails than the H5N1 clade 2.3.2.1 virus. The H5N8-infected birds shed high titre of viruses from oropharynx and cloaca, which in the field supported virus transmission and spread. This study highlights the role of wild waterfowl in the intercontinental spread of some HPAI viruses. Migratory aquatic birds should be carefully monitored for the early detection of H5 clade 2.3.4.4 and other HPAI viruses., (© 2018 Blackwell Verlag GmbH.)