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2.
Sci Rep ; 11(1): 20121, 2021 10 11.
Article in English | MEDLINE | ID: covidwho-1532138

ABSTRACT

The Brazilian strategy to overcome the spread of COVID-19 has been particularly criticized due to the lack of a national coordinating effort and an appropriate testing program. Here, a successful approach to control the spread of COVID-19 transmission is described by the engagement of public (university and governance) and private sectors (hospitals and oil companies) in Macaé, state of Rio de Janeiro, Brazil, a city known as the National Oil Capital. In 2020 between the 17th and 38th epidemiological week, over two percent of the 206,728 citizens were subjected to symptom analysis and RT-qPCR testing by the Federal University of Rio de Janeiro, with positive individuals being notified up to 48 h after swab collection. Geocodification and spatial cluster analysis were used to limit COVID-19 spreading in Macaé. Within the first semester after the outbreak of COVID-19 in Brazil, Macaé recorded 1.8% of fatalities associated with COVID-19 up to the 38th epidemiological week, which was at least five times lower than the state capital (10.6%). Overall, considering the successful experience of this joint effort of private and public engagement in Macaé, our data suggest that the development of a similar strategy countrywise could have contributed to a better control of the COVID-19 spread in Brazil. Quarantine decree by the local administration, comprehensive molecular testing coupled to scientific analysis of COVID-19 spreading, prevented the catastrophic consequences of the pandemic as seen in other populous cities within the state of Rio de Janeiro and elsewhere in Brazil.


Subject(s)
COVID-19 Nucleic Acid Testing/statistics & numerical data , COVID-19/epidemiology , Pandemics/statistics & numerical data , SARS-CoV-2/isolation & purification , Adolescent , Adult , Aged , Brazil/epidemiology , COVID-19/diagnosis , COVID-19/transmission , COVID-19/virology , Cities/epidemiology , Cities/statistics & numerical data , Female , Humans , Male , Middle Aged , RNA, Viral/isolation & purification , SARS-CoV-2/genetics , Young Adult
3.
J Infect Dis ; 224(8): 1287-1293, 2021 10 28.
Article in English | MEDLINE | ID: covidwho-1505875

ABSTRACT

BACKGROUND: Previous studies demonstrated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA can be detected for weeks after infection. The significance of this finding is unclear and, in most patients, does not represent active infection. Detection of subgenomic RNA has been proposed to represent productive infection and may be a useful marker for monitoring infectivity. METHODS: We used quantitative reverse-transcription polymerase chain reaction (RT-qPCR) to quantify total and subgenomic nucleocapsid (sgN) and envelope (sgE) transcripts in 185 SARS-CoV-2-positive nasopharyngeal swab samples collected on hospital admission and to relate to symptom duration. RESULTS: We find that all transcripts decline at the same rate; however, sgE becomes undetectable before other transcripts. The median duration of symptoms to a negative test is 14 days for sgE and 25 days for sgN. There is a linear decline in subgenomic compared to total RNA, suggesting that subgenomic transcript copy number is dependent on copy number of total transcripts. The mean difference between total and sgN is 16-fold and the mean difference between total and sgE is 137-fold. This relationship is constant over duration of symptoms, allowing prediction of subgenomic copy number from total copy number. CONCLUSIONS: Subgenomic RNA may be no more useful in determining infectivity than a copy number threshold determined for total RNA.


Subject(s)
COVID-19 Nucleic Acid Testing/methods , COVID-19/diagnosis , RNA, Viral/isolation & purification , SARS-CoV-2/isolation & purification , Viral Load , Aged , COVID-19/transmission , COVID-19/virology , COVID-19 Nucleic Acid Testing/standards , COVID-19 Nucleic Acid Testing/statistics & numerical data , Coronavirus Envelope Proteins/genetics , Coronavirus Nucleocapsid Proteins/genetics , Feasibility Studies , Female , Humans , Male , Middle Aged , Nasopharynx/pathology , Nasopharynx/virology , Phosphoproteins/genetics , Real-Time Polymerase Chain Reaction/statistics & numerical data , Reference Values , Retrospective Studies , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity
5.
J Infect Dis ; 224(8): 1325-1332, 2021 Oct 28.
Article in English | MEDLINE | ID: covidwho-1493826

ABSTRACT

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse-transcription polymerase chain reaction (RT-PCR) provides a highly variable cycle threshold (Ct) value that cannot distinguish viral infectivity. Subgenomic ribonucleic acid (sgRNA) has been used to monitor active replication. Given the importance of long RT-PCR positivity and the need for work reincorporation and discontinuing isolation, we studied the functionality of normalized viral loads (NVLs) for patient monitoring and sgRNA for viral infectivity detection. METHODS: The NVLs measured through the Nucleocapsid and RNA-dependent-RNA-polymerase genes and sgRNA RT-PCRs were performed in 2 consecutive swabs from 84 healthcare workers. RESULTS: The NVLs provided similar and accurate quantities of both genes of SARS-CoV-2 at 2 different timepoints of infection, overcoming Ct-value and swab collection variability. Among SARS-CoV-2-positive samples, 51.19% were sgRNA-positive in the 1st RT-PCR and 5.95% in the 2nd RT-PCR. All sgRNA-positive samples had >4 log10 RNA copies/1000 cells, whereas samples with ≤1 log10 NVLs were sgRNA-negative. Although NVLs were positive until 29 days after symptom onset, 84.1% of sgRNA-positive samples were from the first 7 days, which correlated with viral culture viability. Multivariate analyses showed that sgRNA, NVLs, and days of symptoms were significantly associated (P < .001). CONCLUSIONS: The NVLs and sgRNA are 2 rapid accessible techniques that could be easily implemented in routine hospital practice providing a useful proxy for viral infectivity and coronavirus disease 2019 patient follow-up.


Subject(s)
COVID-19/diagnosis , SARS-CoV-2/isolation & purification , Viral Load/standards , Adult , Aftercare/standards , COVID-19/therapy , COVID-19/transmission , COVID-19/virology , COVID-19 Nucleic Acid Testing/statistics & numerical data , Clinical Decision-Making/methods , Epidemiological Monitoring , Female , Health Personnel/statistics & numerical data , Humans , Male , Middle Aged , Nasopharynx/pathology , Nasopharynx/virology , RNA, Viral/isolation & purification , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity
6.
Emerg Microbes Infect ; 10(1): 2173-2182, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1493581

ABSTRACT

The continuing emergence of SARS-CoV-2 variants calls for regular assessment to identify differences in viral replication, shedding and associated disease. In this study, we compared African green monkeys infected intranasally with either the UK B.1.1.7 (Alpha) variant or its contemporary D614G progenitor. Both variants caused mild respiratory disease with no significant differences in clinical presentation. Significantly higher levels of viral RNA and infectious virus were found in upper and lower respiratory tract samples and tissues from B.1.1.7 infected animals. Interestingly, D614G infected animals showed significantly higher levels of viral RNA and infectious virus in rectal swabs and gastrointestinal tissues. Our results indicate that B.1.1.7 infection in African green monkeys is associated with increased respiratory replication and shedding but no disease enhancement similar to human B.1.1.7 cases.


Subject(s)
COVID-19/virology , Chlorocebus aethiops/virology , Respiratory System/virology , Virus Replication , Virus Shedding , Administration, Intranasal , Animals , COVID-19/epidemiology , Gastrointestinal Tract/virology , Host Specificity , Polymorphism, Single Nucleotide , RNA, Viral/isolation & purification , Random Allocation , Rectum/virology , United Kingdom/epidemiology , Vero Cells , Viral Load
7.
Sci Rep ; 11(1): 21385, 2021 11 01.
Article in English | MEDLINE | ID: covidwho-1493218

ABSTRACT

Shortages of reverse transcriptase (RT)-polymerase chain reaction (PCR) reagents and related equipment during the COVID-19 pandemic have demonstrated the need for alternative, high-throughput methods for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)-mass screening in clinical diagnostic laboratories. A robust, SARS-CoV-2 RT-loop-mediated isothermal amplification (RT-LAMP) assay with high-throughput and short turnaround times in a clinical laboratory setting was established and compared to two conventional RT-PCR protocols using 323 samples of individuals with suspected SARS-CoV-2 infection. Limit of detection (LoD) and reproducibility of the isolation-free SARS-CoV-2 RT-LAMP test were determined. An almost perfect agreement (Cohen's kappa > 0.8) between the novel test and two classical RT-PCR protocols with no systematic difference (McNemar's test, P > 0.05) was observed. Sensitivity and specificity were in the range of 89.5 to 100% and 96.2 to 100% dependent on the reaction condition and the RT-PCR method used as reference. The isolation-free RT-LAMP assay showed high reproducibility (Tt intra-run coefficient of variation [CV] = 0.4%, Tt inter-run CV = 2.1%) with a LoD of 95 SARS-CoV-2 genome copies per reaction. The established SARS-CoV-2 RT-LAMP assay is a flexible and efficient alternative to conventional RT-PCR protocols, suitable for SARS-CoV-2 mass screening using existing laboratory infrastructure in clinical diagnostic laboratories.


Subject(s)
COVID-19 Nucleic Acid Testing/methods , COVID-19/diagnosis , COVID-19/epidemiology , Molecular Diagnostic Techniques/methods , Nucleic Acid Amplification Techniques/methods , Pandemics , Reverse Transcriptase Polymerase Chain Reaction/methods , SARS-CoV-2/genetics , COVID-19/virology , Genome, Viral , Humans , Infection Control/methods , Limit of Detection , Mass Screening/methods , RNA, Viral/genetics , RNA, Viral/isolation & purification , RNA-Directed DNA Polymerase/genetics , Reproducibility of Results , Reverse Transcription/genetics , Sensitivity and Specificity
8.
Lancet Infect Dis ; 21(11): 1507-1517, 2021 11.
Article in English | MEDLINE | ID: covidwho-1492844

ABSTRACT

BACKGROUND: The more infectious SARS-CoV-2 lineage B.1.1.7 rapidly spread in Europe after December, 2020, and a concern that B.1.1.7 could cause more severe disease has been raised. Taking advantage of Denmark's high RT-PCR testing and whole genome sequencing capacities, we used national health register data to assess the risk of COVID-19 hospitalisation in individuals infected with B.1.1.7 compared with those with other SARS-CoV-2 lineages. METHODS: We did an observational cohort study of all SARS-CoV-2-positive cases confirmed by RT-PCR in Denmark, sampled between Jan 1 and March 24, 2021, with 14 days of follow-up for COVID-19 hospitalisation. Cases were identified in the national COVID-19 surveillance system database, which includes data from the Danish Microbiology Database (RT-PCR test results), the Danish COVID-19 Genome Consortium, the National Patient Registry, the Civil Registration System, as well as other nationwide registers. Among all cases, COVID-19 hospitalisation was defined as first admission lasting longer than 12 h within 14 days of a sample with a positive RT-PCR result. The study population and main analysis were restricted to the proportion of cases with viral genome data. We calculated the risk ratio (RR) of admission according to infection with B.1.1.7 versus other co-existing lineages with a Poisson regression model with robust SEs, adjusted a priori for sex, age, calendar time, region, and comorbidities. The contribution of each covariate to confounding of the crude RR was evaluated afterwards by a stepwise forward inclusion. FINDINGS: Between Jan 1 and March 24, 2021, 50 958 individuals with a positive SARS-CoV-2 test and at least 14 days of follow-up for hospitalisation were identified; 30 572 (60·0%) had genome data, of whom 10 544 (34·5%) were infected with B.1.1.7. 1944 (6·4%) individuals had a COVID-19 hospitalisation and of these, 571 (29·4%) had a B.1.1.7 infection and 1373 (70·6%) had an infection with other SARS-CoV-2 lineages. Although the overall number of hospitalisations decreased during the study period, the proportion of individuals infected with B.1.1.7 increased from 3·5% to 92·1% per week. B.1.1.7 was associated with a crude RR of hospital admission of 0·79 (95% CI 0·72-0·87; p<0·0001) and an adjusted RR of 1·42 (95% CI 1·25-1·60; p<0·0001). The adjusted RR was increased in all strata of age and calendar period-the two covariates with the largest contribution to confounding of the crude RR. INTERPRETATION: Infection with SARS-CoV-2 lineage B.1.1.7 was associated with an increased risk of hospitalisation compared with that of other lineages in an analysis adjusted for covariates. The overall effect on hospitalisations in Denmark was lessened due to a strict lockdown, but our findings could support hospital preparedness and modelling of the projected impact of the epidemic in countries with uncontrolled spread of B.1.1.7. FUNDING: None.


Subject(s)
COVID-19/epidemiology , Hospitalization/statistics & numerical data , SARS-CoV-2/isolation & purification , Adolescent , Adult , COVID-19/diagnosis , COVID-19/therapy , COVID-19/transmission , COVID-19 Nucleic Acid Testing/statistics & numerical data , Child , Child, Preschool , Cohort Studies , Comorbidity , Denmark/epidemiology , Female , Genome, Viral/genetics , Humans , Infant , Infant, Newborn , Male , Middle Aged , RNA, Viral/genetics , RNA, Viral/isolation & purification , Risk Assessment/statistics & numerical data , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , Whole Genome Sequencing/statistics & numerical data , Young Adult
10.
Nat Commun ; 12(1): 6032, 2021 10 15.
Article in English | MEDLINE | ID: covidwho-1469967

ABSTRACT

Vaccine breakthrough SARS-CoV-2 infection has been monitored in 3720 healthcare workers receiving 2 doses of BNT162b2. SARS-CoV-2 infection is detected in 33 subjects, with a 100-day cumulative incidence of 0.93%. Vaccine protection against acquisition of SARS-CoV-2 infection is 83% (95%CI: 58-93%) in the overall population and 93% (95%CI: 69-99%) in SARS-CoV-2-experienced subjects, when compared with a non-vaccinated control group from the same Institution, in which SARS-CoV-2 infection occurs in 20/346 subjects (100-day cumulative incidence: 5.78%). The infection is symptomatic in 16 (48%) vaccinated subjects vs 17 (85%) controls (p = 0.01). All analyzed patients, in whom the amount of viral RNA was sufficient for genome sequencing, results infected by the alpha variant. Antibody and T-cell responses are not reduced in subjects with breakthrough infection. Evidence of virus transmission, determined by contact tracing, is observed in two (6.1%) cases. This real-world data support the protective effect of BNT162b2 vaccine. A triple antigenic exposure, such as two-dose vaccine schedule in experienced subjects, may confer a higher protection.


Subject(s)
Asymptomatic Infections/epidemiology , COVID-19 Vaccines/administration & dosage , COVID-19/diagnosis , Health Personnel/statistics & numerical data , SARS-CoV-2/pathogenicity , Antibodies, Viral/blood , COVID-19/epidemiology , COVID-19/prevention & control , COVID-19/virology , COVID-19 Nucleic Acid Testing/statistics & numerical data , Case-Control Studies , Female , Humans , Immunization Schedule , Incidence , Male , Prospective Studies , RNA, Viral/genetics , RNA, Viral/isolation & purification , SARS-CoV-2/genetics , SARS-CoV-2/immunology , SARS-CoV-2/isolation & purification , Severity of Illness Index
12.
Sci Rep ; 11(1): 19579, 2021 10 01.
Article in English | MEDLINE | ID: covidwho-1447327

ABSTRACT

The increasing risk from viral outbreaks such as the ongoing COVID-19 pandemic exacerbates the need for rapid, affordable and sensitive methods for virus detection, identification and quantification; however, existing methods for detecting virus particles in biological samples usually depend on multistep protocols that take considerable time to yield a result. Here, we introduce a rapid fluorescence in situ hybridization (FISH) protocol capable of detecting influenza virus, avian infectious bronchitis virus and SARS-CoV-2 specifically and quantitatively in approximately 20 min, in virus cultures, combined nasal and throat swabs with added virus and likely patient samples without previous purification. This fast and facile workflow can be adapted both as a lab technique and a future diagnostic tool in enveloped viruses with an accessible genome.


Subject(s)
In Situ Hybridization, Fluorescence/methods , RNA, Viral/isolation & purification , Viruses/isolation & purification , Viruses/genetics
13.
Sci Rep ; 11(1): 19456, 2021 09 30.
Article in English | MEDLINE | ID: covidwho-1447320

ABSTRACT

Coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerges to scientific research and monitoring of wastewaters to predict the spread of the virus in the community. Our study investigated the COVID-19 disease in Bratislava, based on wastewater monitoring from September 2020 until March 2021. Samples were analyzed from two wastewater treatment plants of the city with reaching 0.6 million monitored inhabitants. Obtained results from the wastewater analysis suggest significant statistical dependence. High correlations between the number of viral particles in wastewater and the number of reported positive nasopharyngeal RT-qPCR tests of infected individuals with a time lag of 2 weeks/12 days (R2 = 83.78%/R2 = 52.65%) as well as with a reported number of death cases with a time lag of 4 weeks/27 days (R2 = 83.21%/R2 = 61.89%) was observed. The obtained results and subsequent mathematical modeling will serve in the future as an early warning system for the occurrence of a local site of infection and, at the same time, predict the load on the health system up to two weeks in advance.


Subject(s)
COVID-19/epidemiology , SARS-CoV-2/genetics , Waste Water/analysis , Waste Water/virology , COVID-19/mortality , Disease Outbreaks/prevention & control , Humans , Models, Theoretical , RNA, Viral/isolation & purification , Real-Time Polymerase Chain Reaction , Slovakia/epidemiology , Waste Water/chemistry , Wastewater-Based Epidemiological Monitoring , Water Purification
14.
PLoS One ; 16(9): e0258151, 2021.
Article in English | MEDLINE | ID: covidwho-1443858

ABSTRACT

BACKGROUND: Few studies have quantified aerosol concentrations of SARS-CoV-2 in hospitals and long-term care homes, and fewer still have examined samples for viability. This information is needed to clarify transmission risks beyond close contact. METHODS: We deployed particulate air samplers in rooms with COVID-19 positive patients in hospital ward and ICU rooms, rooms in long-term care homes experiencing outbreaks, and a correctional facility experiencing an outbreak. Samplers were placed between 2 and 3 meters from the patient. Aerosol (small liquid particles suspended in air) samples were collected onto gelatin filters by Ultrasonic Personal Air Samplers (UPAS) fitted with <2.5µm (micrometer) and <10 µm size-selective inlets operated for 16 hours (total 1.92m3), and with a Coriolis Biosampler over 10 minutes (total 1.5m3). Samples were assayed for viable SARS-CoV-2 virus and for the viral genome by multiplex PCR using the E and N protein target sequences. We validated the sampling methods by inoculating gelatin filters with viable vesicular stomatitis virus (VSV), and with three concentrations of viable SARS-CoV-2, operating personal samplers for 16hrs, and quantifying viable virus recovery by TCID50 assay. RESULTS: In total, 138 samples were collected from 99 rooms. RNA samples were positive in 9.1% (6/66) of samples obtained with the UPAS 2.5µm samplers, 13.5% (7/52) with the UPAS 10µm samplers, and 10.0% (2/20) samples obtained with the Coriolis samplers. Culturable virus was not recovered in any samples. Viral RNA was detected in 15.1% of the rooms sampled. There was no significant difference in viral RNA recovery between the different room locations or samplers. Method development experiments indicated minimal loss of SARS-CoV-2 viability via the personal air sampler operation.


Subject(s)
Aerosols/isolation & purification , Air Microbiology , COVID-19/virology , SARS-CoV-2/isolation & purification , Animals , COVID-19/epidemiology , COVID-19/transmission , Chlorocebus aethiops , Hospitals , Humans , Long-Term Care , RNA, Viral/isolation & purification , Vero Cells
15.
Nat Commun ; 12(1): 5705, 2021 09 29.
Article in English | MEDLINE | ID: covidwho-1442779

ABSTRACT

COVID-19 transmission rates are often linked to locally circulating strains of SARS-CoV-2. Here we describe 203 SARS-CoV-2 whole genome sequences analyzed from strains circulating in Rwanda from May 2020 to February 2021. In particular, we report a shift in variant distribution towards the emerging sub-lineage A.23.1 that is currently dominating. Furthermore, we report the detection of the first Rwandan cases of the B.1.1.7 and B.1.351 variants of concern among incoming travelers tested at Kigali International Airport. To assess the importance of viral introductions from neighboring countries and local transmission, we exploit available individual travel history metadata to inform spatio-temporal phylogeographic inference, enabling us to take into account infections from unsampled locations. We uncover an important role of neighboring countries in seeding introductions into Rwanda, including those from which no genomic sequences were available. Our results highlight the importance of systematic genomic surveillance and regional collaborations for a durable response towards combating COVID-19.


Subject(s)
COVID-19/virology , Genome, Viral/genetics , SARS-CoV-2/genetics , Travel-Related Illness , Adult , COVID-19/diagnosis , COVID-19/epidemiology , COVID-19/transmission , Epidemiological Monitoring , Female , Humans , Male , Phylogeny , Phylogeography , RNA, Viral/genetics , RNA, Viral/isolation & purification , Rwanda/epidemiology , SARS-CoV-2/isolation & purification , SARS-CoV-2/pathogenicity , Whole Genome Sequencing
16.
Nat Commun ; 12(1): 5653, 2021 09 27.
Article in English | MEDLINE | ID: covidwho-1440472

ABSTRACT

Among the currently available virus detection assays, those based on the programmable CRISPR-Cas enzymes have the advantage of rapid reporting and high sensitivity without the requirement of thermocyclers. Type III-A CRISPR-Cas system is a multi-component and multipronged immune effector, activated by viral RNA that previously has not been repurposed for disease detection owing in part to the complex enzyme reconstitution process and functionality. Here, we describe the construction and application of a virus detection method, based on an in vivo-reconstituted Type III-A CRISPR-Cas system. This system harnesses both RNA- and transcription-activated dual nucleic acid cleavage activities as well as internal signal amplification that allow virus detection with high sensitivity and at multiple settings. We demonstrate the use of the Type III-A system-based method in detection of SARS-CoV-2 that reached 2000 copies/µl sensitivity in amplification-free and 60 copies/µl sensitivity via isothermal amplification within 30 min and diagnosed SARS-CoV-2-infected patients in both settings. The high sensitivity, flexible reaction conditions, and the small molecular-driven amplification make the Type III-A system a potentially unique nucleic acid detection method with broad applications.


Subject(s)
COVID-19 Nucleic Acid Testing/methods , COVID-19/diagnosis , CRISPR-Cas Systems/genetics , SARS-CoV-2/isolation & purification , COVID-19/blood , COVID-19/virology , Humans , Limit of Detection , RNA, Viral/genetics , RNA, Viral/isolation & purification , SARS-CoV-2/genetics
18.
PLoS One ; 16(9): e0257563, 2021.
Article in English | MEDLINE | ID: covidwho-1416905

ABSTRACT

The COVID-19 pandemic caused by the SARS-CoV-2 is a serious health threat causing worldwide morbidity and mortality. Real-time reverse transcription PCR (RT-qPCR) is currently the standard for SARS-CoV-2 detection. Although various nucleic acid-based assays have been developed to aid the detection of SARS-CoV-2 from COVID-19 patient samples, the objective of this study was to develop a diagnostic test that can be completed in 30 minutes without having to isolate RNA from the samples. Here, we present an RNA amplification detection method performed using reverse transcription loop-mediated isothermal amplification (RT-LAMP) reactions to achieve specific, rapid (30 min), and sensitive (<100 copies) fluorescent detection in real-time of SARS-CoV-2 directly from patient nasopharyngeal swab (NP) samples. When compared to RT-qPCR, positive NP swab samples assayed by fluorescent RT-LAMP had 98% (n = 41/42) concordance and negative NP swab samples assayed by fluorescent RT-LAMP had 87% (n = 59/68) concordance for the same samples. Importantly, the fluorescent RT-LAMP results were obtained without purification of RNA from the NP swab samples in contrast to RT-qPCR. We also show that the fluorescent RT-LAMP assay can specifically detect live virus directly from cultures of both SARS-CoV-2 wild type (WA1/2020), and a SARS-CoV-2 B.1.1.7 (alpha) variant strain with equal sensitivity to RT-qPCR. RT-LAMP has several advantages over RT-qPCR including isothermal amplification, speed (<30 min), reduced costs, and similar sensitivity and specificity.


Subject(s)
COVID-19 Nucleic Acid Testing/methods , COVID-19/diagnosis , Diagnostic Tests, Routine/methods , Molecular Diagnostic Techniques/methods , Nucleic Acid Amplification Techniques/methods , Real-Time Polymerase Chain Reaction/methods , SARS-CoV-2/isolation & purification , Humans , RNA, Viral/isolation & purification , Sensitivity and Specificity
19.
PLoS One ; 16(9): e0257464, 2021.
Article in English | MEDLINE | ID: covidwho-1416902

ABSTRACT

Despite the development of effective vaccines against SARS-CoV-2, epidemiological control of the virus is still challenging due to slow vaccine rollouts, incomplete vaccine protection to current and emerging variants, and unwillingness to get vaccinated. Therefore, frequent testing of individuals to identify early SARS-CoV-2 infections, contact-tracing and isolation strategies remain crucial to mitigate viral spread. Here, we describe WHotLAMP, a rapid molecular test to detect SARS-CoV-2 in saliva. WHotLAMP is simple to use, highly sensitive (~4 viral particles per microliter of saliva) and specific, as well as inexpensive, making it ideal for frequent screening. Moreover, WHotLAMP does not require toxic chemicals or specialized equipment and thus can be performed in point-of-care settings, and may also be adapted for resource-limited environments or home use. While applied here to SARS-CoV-2, WHotLAMP can be modified to detect other pathogens, making it adaptable for other diagnostic assays, including for use in future outbreaks.


Subject(s)
COVID-19 Nucleic Acid Testing/methods , COVID-19/diagnosis , RNA, Viral/genetics , SARS-CoV-2/genetics , Saliva/virology , COVID-19/epidemiology , COVID-19/virology , COVID-19 Nucleic Acid Testing/instrumentation , Epidemics/prevention & control , Humans , Point-of-Care Systems/statistics & numerical data , RNA, Viral/isolation & purification , Reproducibility of Results , SARS-CoV-2/physiology , Sensitivity and Specificity
20.
Vet Res ; 52(1): 121, 2021 Sep 16.
Article in English | MEDLINE | ID: covidwho-1414142

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is causing a global crisis. It is still unresolved. Although many therapies and vaccines are being studied, they are still in their infancy. As this pandemic continues, rapid and accurate research for the development of therapies and vaccines is needed. Therefore, it is necessary to understand characteristics of diseases caused by SARS-CoV-2 through animal models. Syrian hamsters are known to be susceptible to SARS-CoV-2. They were intranasally inoculated with SARS-CoV-2. At 2, 4, 8, 12, and 16 days post-infection (dpi), these hamsters were euthanized, and tissues were collected for ultrastructural and microstructural examinations. Microscopic lesions were prominent in the upper and lower respiratory tracts from 2 and 4 dpi groups, respectively. The respiratory epithelium in the trachea, bronchiole, and alveolar showed pathological changes. Inflammatory cells including neutrophils, lymphocytes, macrophages, and eosinophils were infiltrated in/around tracheal lamina propria, pulmonary vessels, alveoli, and bronchiole. In pulmonary lesions, alveolar wall was thickened with infiltrated inflammatory cells, mainly neutrophils and macrophages. In the trachea, epithelial damages started from 2 dpi and recovered from 8 dpi, consistent with microscopic results, High levels of SARS-CoV-2 nucleoprotein were detected at 2 dpi and 4 dpi. In the lung, lesions were most severe at 8 dpi. Meanwhile, high levels of SARS-CoV-2 were detected at 4 dpi. Electron microscopic examinations revealed cellular changes in the trachea epithelium and alveolar epithelium such as vacuolation, sparse micro-organelle, and poor cellular margin. In the trachea epithelium, the number of cytoplasmic organelles was diminished, and small vesicles were prominent from 2 dpi. Some of these electron-lucent vesicles were filled with virion particles. From 8 dpi, the trachea epithelium started to recover. Because of shrunken nucleus and swollen cytoplasm, the N/C ratio of type 2 pneumocyte decreased at 8 and 12 dpi. From 8 dpi, lamellar bodies on type 2 pneumocyte cytoplasm were increasingly observed. Their number then decreased from 16 dpi. However, there was no significant change in type 1 pneumocyte. Viral vesicles were only observed in the cytoplasm of type 2 pneumocyte. In conclusion, ultra- and micro-structural changes presented in this study may provide useful information for SARS-CoV-2 studies in various fields.


Subject(s)
COVID-19/pathology , Respiratory System/pathology , SARS-CoV-2/pathogenicity , Animals , Cricetinae , Immunohistochemistry/veterinary , Male , Mesocricetus , Pilot Projects , RNA, Viral/chemistry , RNA, Viral/isolation & purification , Real-Time Polymerase Chain Reaction/veterinary , Respiratory System/chemistry , Respiratory System/ultrastructure , Respiratory System/virology , Time Factors , Trachea/pathology , Trachea/ultrastructure , Trachea/virology , Weight Loss
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