High‐throughput droplet‐based digital PCR (ddPCR) is a refinement of the conventional polymerase chain reaction (PCR) methods. In ddPCR, DNA/RNA is encapsulated stochastically inside the microdroplets as reaction chambers. A small percentage of the reaction chamber contains one or fewer copies of the DNA or RNA. After PCR amplification, concentrations are determined based on the proportion of nonfluorescent partitions through the Poisson distribution. Some of the main features of ddPCR include high sensitivity and specificity, absolute quantification without a standard curve, high reproducibility, good tolerance to PCR inhibitor, and high efficacy compared to conventional molecular methods. These advantages make ddPCR a valuable addition to the virologist's toolbox. The following review outlines the recent technological advances in ddPCR methods and their applications in viral identification.
the aim of the study is to provide insights into the use of the corpus-based approach in L2 classes. The study aimed at comparing the effects of the corpus-based approach with the effects of the traditional approach on learning collocations of near-synonymous pairs. The study was run on 2 groups of L2 learners. One group named experimental group studied with concordancing and the other group named the control group studied with the traditional approach. The participants in each group were similar in terms of their proficiency and collocation competence. During the study, the first group was taught through concordancing materials taken from BNC as the concordancing, whereas the control group was taught the collocations explicitly. The instruments used for data collection were a pretest, a posttest, a prewriting and a postwriting. Through running a t test and descriptive statistics, the results revealed a difference between the two approaches about their effect on the comprehension and production of collocations of synonyms. The study has some implications for L2 learning and teaching that are discussed in the last part of the study
Background. Coinfections have a potential role in increased morbidity and mortality rates during pandemics. Our investigation is aimed at evaluating the viral coinfection prevalence in COVID-19 patients. Methods. We systematically searched scientific databases, including Medline, Scopus, WOS, and Embase, from December 1, 2019, to December 30, 2020. Preprint servers such as medRxiv were also scanned to find other related preprint papers. All types of studies evaluating the viral coinfection prevalence in COVID-19 patients were considered. We applied the random effects model to pool all of the related studies. Results. Thirty-three studies including 10484 patients were identified. The viral coinfection estimated pooled prevalence was 12.58%; 95% CI: 7.31 to 18.96). Blood viruses (pooled prevalence: 12.48%; 95% CI: 8.57 to 16.93) had the most frequent viral coinfection, and respiratory viruses (pooled prevalence: 4.32%; 95% CI: 2.78 to 6.15) had less frequent viral coinfection. The herpesvirus pooled prevalence was 11.71% (95% CI: 3.02 to 24.80). Also, the maximum and minimum of viral coinfection pooled prevalence were in AMRO and EMRO with 15.63% (95% CI: 3.78 to 33.31) and 7.05% (95% CI: 3.84 to 11.07), respectively. Conclusion. The lowest rate of coinfection belonged to respiratory viruses. Blood-borne viruses had the highest coinfection rate. Our results provide important data about the prevalence of blood-borne viruses among COVID-19 patients which can be critical when it comes to their treatment procedure.
The SARS‐CoV‐2 virus has been rapidly spreading globally since December 2019, triggering a pandemic, soon after its emergence. While Iran was among the first countries confronted with rapid spread of virus in February 2020, no real‐time SARS‐CoV‐2 whole‐genome tracking in early phase of outbreak was performed in the country. To address this issue, we provided 50 whole‐genome sequences of viral isolates ascertained from different geographical locations in Iran during March–July 2020. The corresponding analysis on origins, transmission dynamics and genetic diversity of SARS‐CoV‐2 virus, represented at least two introductions of the virus into the country, constructing two major clusters defined as B.4 and B.1*. The first entry of the virus might have occurred around very late 2019/early 2020, as suggested by the time to the most recent common ancestor, followed by a rapid community transmission that led to dominancy of B.4 lineage in early epidemic till the end of June. Gradually, reduction in dominancy of B.4 occurred possibly as a result of other entries of the virus, followed by surge of B.1* lineages, as of mid‐May. Remarkably, variation tracking of the virus indicated the increase in frequency of D614G mutation, along with B.1* lineages, which showed continuity till October 2020. The increase in frequency of D614G mutation and B.1* lineages from mid‐May onwards predicts a rapid viral transmission that may push the country into a critical health situation followed by a considerable change in composition of viral lineages circulating in the country.
Background The pandemic of SARS COV-2 raised the attention toward bacterial coinfection and their role in COVID-19 disease. This study aims to systematically review and identify the pooled prevalence of the bacterial coinfection in the related articles. Methods A comprehensive search was conducted in international databases, including Medline, Scopus, Web of Science, and Embase, to identify the articles on the prevalence of Bacterial coinfections in COIVD-19 patients from December 1, 2019, until December 30, 2020. All observational epidemiological studies that evaluated the prevalence of bacterial coinfections in COVID-19 patients included without any restriction. Results Forty two studies including total sample size of 54695 were included in the analysis. The pooled estimate for prevalence of bacterial coinfections was 20.97% (95% CI: 15.95 to 26.46) the pooled prevalence of bacterial coinfections was 5.20% (95% CI: 2.39 to 8.91) for Respiratory subtype and 4.79% (95% CI: 0.11 to 14.61) for Gastrointestinal subtype. The pooled prevalence for Eastern Mediterranean Regional Office (EMRO) and South-East Asia Regional Office (SEARO) was 100 % (95% CI: 82.35 to 100.00) and 2.61 % (95% CI: 1.74 to 3.62). Conclusion This rate of coinfection poses a great danger toward patients especially those in critical condition. Although there are multiple complication and adverse effect related to extensive use of antibiotics to treat COVID-19 patients but it seems there is no other option except the applying them and it needs to be done carefully.
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