scholarly journals Effects of Guangzhou seasonal climate change on the development of Aedes albopictus and its susceptibility to DENV-2

2021 ◽  
Author(s):  
Xueli Zheng ◽  
Shanshan Wu ◽  
Yulan He ◽  
Yong Wei ◽  
Peiyang Fan ◽  
...  
Keyword(s):  
Viral Load ◽  
Dengue Virus ◽  
Real Time ◽  
Oral Feeding ◽  
Viral Rna ◽  
Hatching Rate ◽  
Field Environment ◽  
Different Seasons ◽  
Simulated Field ◽  
Rna Levels

The susceptibility of Asian tiger mosquitoes to DENV-2 in different seasons was observed in simulated field environments as a reference to design dengue fever control strategies in Guangzhou. The life table experiments of mosquitoes in four seasons were carried out in the field. The susceptibility of Ae. albopictus to dengue virus was observed in both environments in Guangzhou in summer and winter. Ae. albopictus was infected with dengue virus by oral feeding. On day 7 and 14 after infection, the viral load in the head, ovary, and midgut of the mosquito was detected using real-time fluorescent quantitative PCR. Immune-associated gene expression in infected mosquitoes was performed using quantitative real-time reverse transcriptase PCR. The hatching rate and pupation rate of Ae. albopictus larvae in different seasons differed significantly. The winter hatching rate of larvae was lower than that in summer, and the incubation time was longer than in summer. In the winter field environment, Ae. albopictus still underwent basic growth and development processes. Mosquitoes in the simulated field environment were more susceptible to DENV-2 than those in the simulated laboratory environment. In the midgut, viral RNA levels on day 7 in summer were higher than those on day 7 in winter (F = 14.459, P = 0.01); ovarian viral RNA levels on day 7 in summer were higher than those on day 7 in winter (F = 8.656, P < 0.001), but there was no significant difference in the viral load at other time points (P > 0.05). Dicer-2 mRNA expression on day 7 in winter was 4.071 times than that on day 7 in summer: the viral load and Dicer-2 expression correlated moderately. Ae. albopictus could still develop and transmit dengue virus in winter in Guangzhou. Mosquitoes under simulated field conditions were more susceptible to DENV-2 than those under simulated laboratory conditions.

scholarly journals Persistence of SARS-CoV-2 Viral RNA in Nasopharyngeal Swabs after Death: An Observational Study

2021 ◽  
Vol 9 (4) ◽  
pp. 800
Author(s):  
Francesca Servadei ◽  
Silvestro Mauriello ◽  
Manuel Scimeca ◽  
Bartolo Caggiano ◽  
Marco Ciotti ◽  
...  
Keyword(s):  
Viral Load ◽  
Observational Study ◽  
Real Time ◽  
Real Time Pcr ◽  
Pcr Detection ◽  
Viral Rna ◽  
Clinical Documentation ◽  
Post Mortem ◽  
Medical Assistance ◽  
Time Points

The aim of this study was to investigate the persistence of SARS-CoV-2 in post-mortem swabs of subjects who died from SARS-CoV-2 infection. The presence of the virus was evaluated post-mortem from airways of 27 SARS-CoV-2 positive patients at three different time points (T1 2 h; T2 12 h; T3 24 h) by real-time PCR. Detection of antibodies to SARS-CoV-2 was performed by Maglumi 2019-nCoV IgM/IgG chemiluminescence assay. SARS-CoV-2 viral RNA was still detectable in 70.3% of cases within 2 h after death and in 66,6% of cases up to 24 h after death. Our data showed an increase of the viral load in 78,6% of positive individuals 24 h post-mortem (T3) in comparison to that evaluated 2 h after death (T1). Noteworthy, we detected a positive T3 post-mortem swab (24 h after death) from 4 subjects who were negative at T1 (2 h after death). The results of our study may have an important value in the management of deceased subjects not only with a suspected or confirmed diagnosis of SARS-CoV-2, but also for unspecified causes and in the absence of clinical documentation or medical assistance.

scholarly journals SARS-CoV-2 viral RNA levels are not “viral load”

2021 ◽  
Author(s):  
Yannis Michalakis ◽  
Mircea T. Sofonea ◽  
Samuel Alizon ◽  
Ignacio G. Bravo
Keyword(s):  
Viral Load ◽  
Viral Rna ◽  
Rna Levels

scholarly journals Detection of Dengue Virus RNA in Patients after Primary or Secondary Dengue Infection by Using the TaqMan Automated Amplification System

1999 ◽  
Vol 37 (8) ◽  
pp. 2543-2547 ◽  
Author(s):  
Thomas Laue ◽  
Petra Emmerich ◽  
Herbert Schmitz
Keyword(s):  
Viral Load ◽  
Dengue Virus ◽  
Dengue Infection ◽  
Immunoglobulin M ◽  
Viral Rna ◽  
Serum Samples ◽  
Igg Antibody ◽  
Igm Antibodies ◽  
Virus Rna ◽  
Virus Serotype

In consecutive serum samples from 25 tourists with acute dengue fever, virus-specific RNA was detected by using fully automated TaqMan reverse transcriptase PCR. For this amplification technique new primers and special fluorochrome-labeled probes had to be synthesized. During amplification the increasing amount of viral DNA could simultaneously be measured in the tightly sealed tubes. Dengue virus RNA was found in almost all patients (17 of 18), if the samples had been taken soon after the onset of symptoms and before anti-dengue virus antibody had been produced. RNA was detectable in only one of five persons who had anti-dengue virus immunoglobulin M (IgM) antibodies but not yet IgG antibodies. In 30 late samples with both IgG and IgM antibodies viral RNA was no longer demonstrable. In two early samples from two frequent travelers obtained 1 and 2 days after the onset of symptoms significant IgG antibody titers were present but there were no anti-dengue virus IgM antibodies. In these samples a viral load of >5 × 106 dengue virus RNA copies (dengue types 1 and 2) was detectable. These findings of a high viral load in the presence of anti-dengue virus IgG antibody are suggestive of a secondary dengue virus infection. In the 20 tourists (17 plus 1 plus 2) in whom viral RNA was found, the dengue virus serotype could be related to the area where the infection had taken place. Most of our patients came from southeast Asia and most frequently had dengue virus type 1 infections (8 of 20).

scholarly journals Prior Dengue Virus Infection Is Associated With Increased Viral Load in Patients Infected With Dengue but Not Zika Virus

2019 ◽  
Vol 6 (7) ◽  
Author(s):  
Gilberto A Santiago ◽  
Tyler M Sharp ◽  
Eli Rosenberg ◽  
Iris I Sosa Cardona ◽  
Luisa Alvarado ◽  
...  
Keyword(s):  
Viral Load ◽  
Virus Infection ◽  
Dengue Virus ◽  
Zika Virus ◽  
Denv Infection ◽  
T Test ◽  
Viral Rna ◽  
Zikv Infection ◽  
Dengue Virus Infection

Abstract To evaluate potential enhancement of Zika virus (ZIKV) infection among patients with prior dengue virus (DENV) infection, we compared loads of viral RNA among patients infected with ZIKV (n = 1070), DENV-2 (n = 312), or DENV-3 (n = 260). Compared to patients without prior DENV infection, patients with prior DENV infection had significantly higher mean loads of viral RNA if infected with DENV-2 (10.6 vs 11.6 log10 GCE/mL, respectively; t test, P &lt; .0001) or DENV-3 (10.3 vs 10.9 log10 GCE/mL; P &lt; .0001), but not ZIKV (4.7 vs 4.7 log10 GCE/mL; P = .959). These findings provide evidence against in vivo enhancement of ZIKV by anti-DENV antibodies.

Detection of SARS-CoV-2 RNA in nasopharyngeal swabs from COVID-19 patients and asymptomatic cases of infection by real-time and digital PCR

2020 ◽  
Vol 65 (12) ◽  
pp. 785-792
Author(s):  
V. A. Ternovoi ◽  
R. Yu. Lutkovsky ◽  
E. P. Ponomareva ◽  
A. V. Gladysheva ◽  
E. V. Chub ◽  
...  
Keyword(s):  
Viral Load ◽  
Real Time ◽  
Real Time Pcr ◽  
Clinical Symptoms ◽  
False Negative ◽  
Digital Pcr ◽  
Viral Rna ◽  
Laboratory Research ◽  
Low Concentration ◽  
Negative Results

In this work we tested two reagent kits developed by us for detecting SARS-CoV-2 RNA using a fragment of the ORF1ab gene in digital PCR and real-time PCR formats. Data were obtained on the detection of SARS-CoV-2 virus RNA in nasopharyngeal swabs of patients with COVID-19 and asymptomatic carriers. The developed reagent kits provided 100% sensitivity and a detection limit of 103 GE / ml for qPCR, and at least 200 copies / ml of viral RNA when performing digital PCR. These methods were tested using a panel of 1,328 samples collected from patients with suspected COVID-19 at the beginning of 2020 in the Russian Federation. It has been shown that dPCR is more sensitive and can be used to analyze samples with low viral load, including those from patients without clinical symptoms. dPCR significantly improves the accuracy of laboratory research and significantly reduces the number of false negative results in the diagnosis of SARS-CoV-2. Determination of the concentration of SARS-CoV-2 RNA in patients with different clinical course of the disease showed that the concentration of viral RNA can sharply decrease in the first days of the disease. A low concentration of viral RNA in samples from patients is also characteristic of asymptomatic disease. Digital PCR provides a higher detection rate for asymptomatic cases, which is approximately 75% of those infected, as opposed to 45% for real-time PCR. The results obtained on the use of the digital PCR method for detecting SARS-CoV-2 RNA showed that this method is especially suitable for detecting RNA in case of its low concentration in contacts, as well as for monitoring changes in viral load in convalescent patients.

scholarly journals Persistence of SARS-CoV-2 Viral RNA in Nasopharyngeal Swabs after Death: An Observational Study

2021 ◽  
Author(s):  
Francesca Servadei ◽  
Silvestro Mauriello ◽  
Manuel Scimeca ◽  
Bartolo Caggiano ◽  
Marco Ciotti ◽  
...  
Keyword(s):  
Viral Load ◽  
Observational Study ◽  
Real Time ◽  
Real Time Pcr ◽  
Pcr Detection ◽  
Viral Rna ◽  
Clinical Documentation ◽  
Post Mortem ◽  
Medical Assistance ◽  
Time Points

Background: The aim of this study was to investigate the persistence of SARS-CoV-2 in post-mortem swabs of subjects who died from SARS-CoV-2 infection. Methods: The presence of the virus was evaluated post-mortem from airways of 27 SARS-CoV-2 positive patients at three different time points (T1 2 hours; T2 12 hours &ndash; T3 24 hours) by real-time PCR. Detection of antibodies to SARS-CoV-2 was performed by Maglumi 2019-nCoV IgM/IgG chemiluminescence assay. Results: SARS-CoV-2 viral RNA was still detectable in 70,3% of cases within 2 hours after death and in 66,6% of cases up to 24 hours after death. Our data showed an increase of the viral load in 78,6% of positive individuals 24 hours post-mortem (T3) in comparison to that evaluated 2 hours after death (T1). Noteworthy, we detected a positive T3 post-mortem swab (24 hours after death) from 4 subjects who were negative at T1 (2 hours after death). Conclusion: The results of our study may have an important value in the management of deceased subjects not only with a suspected or confirmed diagnosis of SARS-CoV-2, but also for unspecified causes and in the absence of clinical documentation or medical assistance.

scholarly journals Viral Dynamics and Real-Time RT-PCR Ct Values Correlation with Disease Severity in COVID-19

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1091
Author(s):  
Ali A. Rabaan ◽  
Raghavendra Tirupathi ◽  
Anupam A Sule ◽  
Jehad Aldali ◽  
Abbas Al Mutair ◽  
...  
Keyword(s):  
Viral Load ◽  
Real Time ◽  
Disease Severity ◽  
False Negative ◽  
Influential Factors ◽  
Confirmatory Test ◽  
Acid Extraction ◽  
Rt Pcr ◽  
Viral Kinetics ◽  
Ct Value

Real-time RT-PCR is considered the gold standard confirmatory test for coronavirus disease 2019 (COVID-19). However, many scientists disagree, and it is essential to understand that several factors and variables can cause a false-negative test. In this context, cycle threshold (Ct) values are being utilized to diagnose or predict SARS-CoV-2 infection. This practice has a significant clinical utility as Ct values can be correlated with the viral load. In addition, Ct values have a strong correlation with multiple haematological and biochemical markers. However, it is essential to consider that Ct values might be affected by pre-analytic, analytic, and post-analytical variables such as collection technique, specimen type, sampling time, viral kinetics, transport and storage conditions, nucleic acid extraction, viral RNA load, primer designing, real-time PCR efficiency, and Ct value determination method. Therefore, understanding the interpretation of Ct values and other influential factors could play a crucial role in interpreting viral load and disease severity. In several clinical studies consisting of small or large sample sizes, several discrepancies exist regarding a significant positive correlation between the Ct value and disease severity in COVID-19. In this context, a revised review of the literature has been conducted to fill the knowledge gaps regarding the correlations between Ct values and severity/fatality rates of patients with COVID-19. Various databases such as PubMed, Science Direct, Medline, Scopus, and Google Scholar were searched up to April 2021 by using keywords including “RT-PCR or viral load”, “SARS-CoV-2 and RT-PCR”, “Ct value and viral load”, “Ct value or COVID-19”. Research articles were extracted and selected independently by the authors and included in the present review based on their relevance to the study. The current narrative review explores the correlation of Ct values with mortality, disease progression, severity, and infectivity. We also discuss the factors that can affect these values, such as collection technique, type of swab, sampling method, etc.

scholarly journals Assessment of Near-Real-Time Satellite Precipitation Products from GSMaP in Monitoring Rainfall Variations over Taiwan

2021 ◽  
Vol 13 (2) ◽  
pp. 202
Author(s):  
Wan-Ru Huang ◽  
Pin-Yi Liu ◽  
Jie Hsu ◽  
Xiuzhen Li ◽  
Liping Deng
Keyword(s):  
Real Time ◽  
Complex Terrain ◽  
Daily Rainfall ◽  
Rainfall Estimation ◽  
Rainfall Events ◽  
Satellite Precipitation ◽  
Different Seasons ◽  
Daily Scale ◽  
Rainfall Variations ◽  
Southwestern Taiwan

This study assessed four near-real-time satellite precipitation products (NRT SPPs) of Global Satellite Mapping of Precipitation (GSMaP)—NRT v6 (hereafter NRT6), NRT v7 (hereafter NRT7), Gauge-NRT v6 (hereafter GNRT6), and Gauge-NRT v7 (hereafter GNRT7)— in representing the daily and monthly rainfall variations over Taiwan, an island with complex terrain. The GNRT products are the gauge-adjusted version of NRT products. Evaluations for warm (May–October) and cold months (November–April) were conducted from May 2017 to April 2020. By using observations from more than 400 surface gauges in Taiwan as a reference, our evaluations showed that GNRT products had a greater error than NRT products in underestimating the monthly mean rainfall, especially during the warm months. Among SPPs, NRT7 performed best in quantitative monthly mean rainfall estimation; however, when examining the daily scale, GNRT6 and GNRT7 were superior, particularly for monitoring stronger (i.e., more intense) rainfall events during warm and cold months, respectively. Spatially, the major improvement from NRT6 to GNRT6 (from NRT7 to GNRT7) in monitoring stronger rainfall events over southwestern Taiwan was revealed during warm (cold) months. From NRT6 to NRT7, the improvement in daily rainfall estimation primarily occurred over southwestern and northwestern Taiwan during the warm and cold months, respectively. Possible explanations for the differences between the ability of SPPs are attributed to the algorithms used in SPPs. These findings highlight that different NRT SPPs of GSMaP should be used for studying or monitoring the rainfall variations over Taiwan for different purposes (e.g., warning of floods in different seasons, studying monthly or daily precipitation features in different seasons, etc.).

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