scholarly journals Estimation SARS-CoV-2 viability in time on experimental surfaces over

2021 ◽  
Author(s):  
MA Nikiforova ◽  
AE Siniavin ◽  
EV Shidlovskaya ◽  
NA Kuznetsova ◽  
VA Guschin
Keyword(s):  
Tissue Culture ◽  
Infectious Virus ◽  
Aluminum Foil ◽  
Infected Person ◽  
Rt Pcr ◽  
Ceramic Tiles ◽  
Model Surfaces ◽  
Experimental Surface ◽  
Metal Aluminum ◽  
Over Time

Infected SARS-CoV-2 virus occurs not only through contact with an infected person, but also through surfaces with wich the illnes has contacted. The problem of preserving an infectious virus over time capable of infecting remains actual. We evaluated the SARS-CoV-2 viability preservation on different model surfaces over time. Ceramic tiles, metal (aluminum foil), wood (chipboard), plastic and cloth (towel) were used as model materials. Assessment of the presence of SARS-CoV-2 RNA was carried out by quantitative RT-PCR. Viable virus was determined by tissue culture assay on 293T/ACE2 cells. It was found that the SARS-CoV-2 RNA was detected on all studied surfaces for 360 minutes, but a significant decrease RNA by 1 log10 copies/ml was detected after contact of the virus with cloth (towel). While the viability of the virus was completely lost after 120 minutes. Type of experimental surface significantly affects viability preservation.

scholarly journals SARS-CoV-2 viability in time on experimental surfaces

2021 ◽  
Author(s):  
Maria A. Nikiforova ◽  
Andrei E. Siniavin ◽  
Elena V. Shidlovskaya ◽  
Nadezhda A. Kuznetsova ◽  
Vladimir A. Gushchin
Keyword(s):  
Model Surfaces ◽  
Experimental Surface ◽  
Over Time

AbstractWe evaluated the SARS-CoV-2 viability preservation on different model surfaces over time. It was found that the SARS-CoV-2 RNA was detected on all studied surfaces for 360 minutes, while the viability of the virus was completely lost after 120 minutes. Type of experimental surface significantly affects viability preservation.

scholarly journals A New Multiplatform Model for Outpatient Prenatal and Postpartum Care in a Cohort of COVID-19-Affected Obstetric Patients

2021 ◽  
Vol 18 (10) ◽  
pp. 5144
Author(s):  
Mar Muñoz-Chápuli Gutiérrez ◽  
Ana Durán-Vila ◽  
Javier Ruiz-Labarta ◽  
Pilar Payá-Martínez ◽  
Pilar Pintado Recarte ◽  
...  
Keyword(s):  
Clinical Manifestations ◽  
Specific Treatment ◽  
Rt Pcr ◽  
Good Adherence ◽  
Major Morbidity ◽  
Reference Hospital ◽  
The Mean ◽  
Discharge From Hospital ◽  
Over Time

Spain was one of the epicenters of the first wave of the COVID-19 pandemic. We describe in this article the design and results of a new telephone-and-telematic multiplatform model of systematic prenatal and postpartum follow-up for COVID-19-affected women implemented in a tertiary reference hospital in Madrid. We included patients with RT-PCR-confirmed COVID-19 during pregnancy or delivery from 10 March 2020 to 15 December 2020. We had a total of 211 obstetric patients: 148 (70.1%) were tested at the onset of suspicious clinical manifestations and 62 (29.4%) were tested in the context of routine screening. Of all the patients, 60 women (28.4%) were asymptomatic and 97 (46%) presented mild symptoms. Fifty-one women (24.2%) were admitted to our hospital for specific treatment because of moderate or severe symptoms. We had no missed cases and a good adherence. The mean number of calls per patient was 2.3. We performed 55 in-person visits. We analyzed the complexity of our program over time, showing a two-wave-like pattern. One patient was identified as needing hospitalization and we did not record major morbidity. Telemedicine programs are a strong and reproducible tool to reach to pregnant population affected by COVID-19, to assess its symptoms and severity, and to record for pregnancy-related symptoms both in an outpatient regime and after discharge from hospital.

scholarly journals Isolation of Viable SARS-CoV-2 Virus from Feces of an Immunocompromised Patient Suggesting a Possible Fecal Mode of Transmission

2021 ◽  
Vol 10 (12) ◽  
pp. 2696
Author(s):  
Julie Dergham ◽  
Jeremy Delerce ◽  
Marielle Bedotto ◽  
Bernard La Scola ◽  
Valérie Moal
Keyword(s):  
Kidney Transplantation ◽  
Infectious Virus ◽  
Immunocompromised Patient ◽  
Kidney Transplant Recipient ◽  
Enteric Virus ◽  
Rt Pcr ◽  
Virus Particles ◽  
Severe Diarrhea ◽  
Mode Of Transmission ◽  
Compromised Patients

(1) Background: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) excretion in stools is well documented by RT-PCR, but evidences that stools contain infectious particles are scarce. (2) Methods: After observing a Corona Virus 2019 Disease (COVID-19) epidemic cluster associated with a ruptured sewage pipe, we search for such a viable SARS-CoV-2 particle in stool by inoculating 106 samples from 46 patients. (3) Results: We successfully obtained two isolates from a unique patient with kidney transplantation under immunosuppressive therapy who was admitted for severe diarrhea. (4) Conclusions: This report emphasizes that SARS-CoV-2 is an enteric virus, and infectious virus particles can be isolated from the stool of immune-compromised patients like, in our case, kidney transplant recipient. Immune-compromised patients are likely to have massive multiplication of the virus in the gastrointestinal tract and this report suggests possible fecal transmission of SARS-CoV-2.

scholarly journals Efficient trans-Encapsidation of Hepatitis C Virus RNAs into Infectious Virus-Like Particles

2008 ◽  
Vol 82 (14) ◽  
pp. 7034-7046 ◽  
Author(s):  
Eike Steinmann ◽  
Christiane Brohm ◽  
Stephanie Kallis ◽  
Ralf Bartenschlager ◽  
Thomas Pietschmann
Keyword(s):  
Tissue Culture ◽  
Hepatitis C Virus ◽  
Hepatitis C ◽  
High Efficiency ◽  
Infectious Virus ◽  
Buoyant Density ◽  
Target Cells ◽  
Packaging Cell Line ◽  
Virus Like Particles ◽  
Rna Elements

ABSTRACT Recently, complete replication of hepatitis C virus (HCV) in tissue culture was established using the JFH1 isolate. To analyze determinants of HCV genome packaging and virion assembly, we developed a system that supports particle production based on trans-packaging of subgenomic viral RNAs. Using JFH1 helper viruses, we show that subgenomic JFH1 replicons lacking the entire core to NS2 coding region are efficiently encapsidated into infectious virus-like particles. Similarly, chimeric helper viruses with heterologous structural proteins trans-package subgenomic JFH1 replicons. Like authentic cell culture-produced HCV (HCVcc) particles, these trans-complemented HCV particles (HCVTCP) penetrate target cells in a CD81 receptor-dependent fashion. Since HCVTCP production was limited by competition between the helper and subgenomic RNA and to avoid contamination of HCVTCP stocks with helper viruses, we created HCV packaging cells. These cells encapsidate various HCV replicons with high efficiency, reaching infectivity titers up to 106 tissue culture infectious doses 50 per milliliter. The produced particles display a buoyant density comparable to HCVcc particles and can be propagated in the packaging cell line but support only a single-round infection in naïve cells. Together, this work demonstrates that subgenomic HCV replicons are assembly competent, thus excluding cis-acting RNA elements in the core-to-NS2 genomic region essential for RNA packaging. The experimental system described here should be helpful to decipher the mechanisms of HCV assembly and to identify RNA elements and viral proteins involved in particle formation. Similar to other vector systems of plus-strand RNA viruses, HCVTCP may prove valuable for gene delivery or vaccination approaches.

scholarly journals Quantitative measurement of infectious virus in SARS-CoV-2 Alpha, Delta and Epsilon variants reveals higher infectivity (viral titer:RNA ratio) in clinical samples containing the Delta and Epsilon variants.

2021 ◽  
Author(s):  
Hannah W Despres ◽  
Margaret G Mills ◽  
David J Shirley ◽  
Madaline M Schmidt ◽  
Meei-Li Huang ◽  
...  
Keyword(s):  
Quantitative Measurement ◽  
Infectious Virus ◽  
Viral Rna ◽  
Clinical Samples ◽  
Rt Pcr ◽  
Genome Copy ◽  
Live Virus ◽  
High Degree ◽  
The Relationship ◽  
Rna Levels

ABSTRACT Background Novel SARS-CoV-2 Variants of Concern (VoC) pose a challenge to controlling the COVID-19 pandemic. Previous studies indicate that clinical samples collected from individuals infected with the Delta variant may contain higher levels of RNA than previous variants, but the relationship between viral RNA and infectious virus for individual variants is unknown. Methods We measured infectious viral titer (using a micro-focus forming assay) as well as total and subgenomic viral RNA levels (using RT-PCR) in a set of 165 clinical samples containing SARS-CoV-2 Alpha, Delta and Epsilon variants that were processed within two days of collection from the patient. Results We observed a high degree of variation in the relationship between viral titers and RNA levels. Despite the variability we observed for individual samples the overall infectivity differed among the three variants. Both Delta and Epsilon had significantly higher infectivity than Alpha, as measured by the number of infectious units per quantity of viral E gene RNA (6 and 4 times as much, p=0.0002 and 0.009 respectively) or subgenomic E RNA (11 and 7 times as much, p<0.0001 and 0.006 respectively). Conclusion In addition to higher viral RNA levels reported for the Delta variant, the infectivity (amount of replication competent virus per viral genome copy) may also be increased compared to Alpha. Measuring the relationship between live virus and viral RNA is an important step in assessing the infectivity of novel SARS-CoV-2 variants. An increase in the infectivity of the Delta variant may further explain increased spread and suggests a need for increased measures to prevent viral transmission.

scholarly journals Estimating the effectiveness of routine asymptomatic PCR testing at different frequencies for the detection of SARS-CoV-2 infections

2020 ◽  
Author(s):  
Joel Hellewell ◽  
Timothy W. Russell ◽  
Rupert Beale ◽  
Gavin Kelly ◽  
Catherine Houlihan ◽  
...  
Keyword(s):  
Vulnerable Populations ◽  
Research Unit ◽  
Asymptomatic Infection ◽  
Nasopharyngeal Swab ◽  
Rt Pcr ◽  
Symptomatic Infection ◽  
Testing Frequency ◽  
Peak Sensitivity ◽  
Pcr Test ◽  
Over Time

AbstractBackgroundRoutine asymptomatic testing using RT-PCR of people who interact with vulnerable populations, such as medical staff in hospitals or care workers in care homes, has been employed to help prevent outbreaks among vulnerable populations. Although the peak sensitivity of RT-PCR can be high, the probability of detecting an infection will vary throughout the course of an infection. The effectiveness of routine asymptomatic testing will therefore depend on testing frequency and how PCR detection varies over time.MethodsWe fitted a Bayesian statistical model to a dataset of twice weekly PCR tests of UK healthcare workers performed by self-administered nasopharyngeal swab, regardless of symptoms. We jointly estimated times of infection and the probability of a positive PCR test over time following infection, we then compared asymptomatic testing strategies by calculating the probability that a symptomatic infection is detected before symptom onset and the probability that an asymptomatic infection is detected within 7 days of infection.FindingsWe estimated that the probability that the PCR test detected infection peaked at 77% (54 - 88%) 4 days after infection, decreasing to 50% (38 - 65%) by 10 days after infection. Our results suggest a substantially higher probability of detecting infections 1–3 days after infection than previously published estimates. We estimated that testing every other day would detect 57% (33-76%) of symptomatic cases prior to onset and 94% (75-99%) of asymptomatic cases within 7 days if test results were returned within a day.InterpretationOur results suggest that routine asymptomatic testing can enable detection of a high proportion of infected individuals early in their infection, provided that the testing is frequent and the time from testing to notification of results is sufficiently fast.FundingWellcome Trust, National Institute for Health Research (NIHR) Health Protection Research Unit, Medical Research Council (UKRI)

scholarly journals Quantification of Hepatitis A Virus in Shellfish by Competitive Reverse Transcription-PCR with Coextraction of Standard RNA

1999 ◽  
Vol 65 (1) ◽  
pp. 322-326 ◽  
Author(s):  
Charlotte Arnal ◽  
Virginie Ferre-Aubineau ◽  
Berangere Mignotte ◽  
Berthe Marie Imbert-Marcille ◽  
Sylviane Billaudel
Keyword(s):  
Tissue Culture ◽  
Reverse Transcription ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Internal Standard ◽  
Wild Type ◽  
Rt Pcr ◽  
Reverse Transcription Pcr ◽  
Reproducible Method ◽  
Dna Enzyme Immunoassay

ABSTRACT To quantify hepatitis A virus (HAV) in experimentally contaminated mussels, we developed an internal standard RNA with a 7-nucleotide deletion for competitive reverse transcription (RT)-PCR. Deposited directly into the sample, this standard was used both as extraction control and as quantification tool. After coextraction and competitive RT-PCR, standard and wild-type products were detected by differential hybridization with specific probes and a DNA enzyme immunoassay. The quantifiable range with this reproducible method was 104 to 107 copies of HAV/gram or 400 to 106 50% tissue culture infective doses/ml.

scholarly journals STUDIES ON THE PSITTACOSIS-LYMPHOGRANULOMA GROUP

1952 ◽  
Vol 96 (3) ◽  
pp. 233-246 ◽  
Author(s):  
Anthony J. Girardi ◽  
Emma G. Allen ◽  
M. Michael Sigel
Keyword(s):  
Tissue Culture ◽  
Infectious Virus ◽  
Virus Titer ◽  
Subsequent Development ◽  
Developmental Cycle ◽  
In Ovo ◽  
Virus Inoculation ◽  
Virus Adsorption ◽  
Infectious Form

The pattern of growth of meningopneumonitis virus in vitro seemed to be similar to that occurring in ovo and thus the initial stages of development, the adsorption and the latent periods, were investigated by the use of tissue culture procedures. The initial increment of infectivity in allantoic membrane suspensions following virus inoculation in ovo was due to prolonged adsorption of virus and not to immediate virus reproduction. The length of the adsorption period varied with the virus dilution employed. The reduction of virus titer in allantoic membrane suspensions subsequent to adsorption was due to a change of infectious virus to a non-infectious form and this seemed to be a part of the normal developmental cycle of the virus. The possible causes for both prolonged virus adsorption and for the subsequent development of a non-infectious form are discussed.

scholarly journals Measurement of the Infection and Dissemination of Bluetongue Virus in Culicoides Biting Midges Using a Semi-Quantitative RT-PCR Assay and Isolation of Infectious Virus

PLoS ONE ◽  
2013 ◽  
Vol 8 (8) ◽  
pp. e70800 ◽  
Author(s):  
Eva Veronesi ◽  
Frank Antony ◽  
Simon Gubbins ◽  
Nick Golding ◽  
Alison Blackwell ◽  
...  
Keyword(s):  
Bluetongue Virus ◽  
Infectious Virus ◽  
Rt Pcr ◽  
Pcr Assay ◽  
Biting Midges ◽  
Culicoides Biting Midges

Performance over Time of Adhesive Systems for Bonding Ceramic Tiles – A Detailed Case Study

2015 ◽  
Vol 3 ◽  
pp. 183-193
Author(s):  
V.P. de Freitas ◽  
H. Corvacho ◽  
M. Quintela ◽  
João M.P.Q. Delgado
Keyword(s):  
Experimental Research ◽  
Adhesive Bonding ◽  
Accelerated Ageing ◽  
Adhesive Systems ◽  
Ceramic Tiles ◽  
Detailed Case ◽  
Building Physics ◽  
Over Time

An efficient adhesive bonding of exterior ceramic tiles applied on façades is an obvious important factor to ensure the safety and the durability of the façade. The failure of adhesive bonding is a common issue with relevant technical and economic consequences.The aim of this work is to present an evaluation of the performance overtime of adhesives systems in bonded ceramic tiles on façades, based on extensive experimental research works carried out at the Laboratory of Building Physics (LFC).A detailed case study is presented which evaluate the performance of adhesives systems to be used on the façades of a building located near the sea. For this purpose, accelerated ageing tests are performed following two different ageing procedures, allowing the comparison of the performance over time of the systems under analysis).

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