rRT-PCR Assay Research Articles

Discriminating North American Swine Influenza Viruses with a Portable, One-Step, Triplex Real-Time RT-PCR Assay, and Portable Sequencing.

Swine harbors a genetically diverse population of swine influenza A viruses (IAV-S), with demonstrated potential to transmit to the human population, causing outbreaks and pandemics. Here, we describe the development of a one-step, triplex real-time reverse transcription-polymerase chain reaction (rRT-PCR) assay that detects and distinguishes the majority of the antigenically distinct influenza A virus hemagglutinin (HA) clades currently circulating in North American swine, including the IAV-S H1 1A.1 (α), 1A.2 (β), 1A.3 (γ), 1B.2.2 (δ1) and 1B.2.1 (δ2) clades, and the IAV-S H3 2010.1 clade. We performed an in-field test at an exhibition swine show using in-field viral concentration and RNA extraction methodologies and a portable real-time PCR instrument, and rapidly identified three distinct IAV-S clades circulating within the N.A. swine population. Portable sequencing is used to further confirm the results of the in-field test of the swine triplex assay. The IAV-S triplex rRT-PCR assay can be easily transported and used in-field to characterize circulating IAV-S clades in North America, allowing for surveillance and early detection of North American IAV-S with human outbreak and pandemic potential.

Validation of a direct multiplex real-time reverse transcription PCR assay for rapid detection of African swine fever virus using swine field samples in Vietnam

ObjectiveThis study validates a direct multiplex real-time reverse transcription polymerase chain reaction (rRT-PCR) assay which was previously established for enabling rapid and simultaneous detection of African swine fever (ASF) virus (ASFV) and classical swine fever virus. The assay eliminates the need for viral nucleic acid purification using a buffer system for crude extraction and an impurity-tolerant enzyme. However, the assay had not yet been validated using field samples of ASFV-infected pigs. Therefore, to address this gap, we tested 101 samples collected from pigs in Vietnam during 2018 and 2021 for validation.ResultsThe rRT-PCR assay demonstrated a diagnostic sensitivity of 98.8% and a specificity of 100%. Remarkably, crude samples yielded results comparable to those of purified samples, indicating the feasibility of using crude samples without compromising accuracy in ASFV detection. Our findings emphasize the effectiveness of the rRT-PCR assay for the prompt and accurate diagnosis of both swine fever viruses, which is essential for effective disease prevention and control in swine populations.

Workplace Safety and Screening of Healthcare Workers for SARS-CoV-2 at a Tertiary Care Hospital in the Northern Emirates of United Arab Emirates

Background: Coronavirus disease 2019 (COVID-19) was first reported in December 2019 in Wuhan, People’s Republic of China, and caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), As the virus took hold in the world, health experts paced efforts to solve the unknown nature of this threat. Methodology: We studied the clinical characteristics, laboratory biomarkers of healthcare workers in the single center, analytical cross-sectional study conducted in tertiary care hospital of the UAE. Sample size of 600 HCWs were screened for SARS-CoV-2 by real-time reverse transcription polymerase chain reaction (rRT-PCR) assay using Seegene Allplex and Andis FAST SARS-CoV-2 RT-qPCR detection kits for a period of 6 months. Findings: All the health care workers (HCWs) were vaccinated for the SARS-CoV-2. Out of these, 240 HCWs were reported to be positive. rRT-PCR with a Ct value of <38 was taken as positive >38. The laboratory investigations of the positive cases were collected and analysed further. A comparison of the laboratory tests was made between (I) COVID severe (Ct < 25) and nonsevere (Ct > 25) groups and (II) frontline workers and non-frontline workers. Besides finding short-term and sudden relief, investigators directed their efforts to provide a long-term solution for an ensuing pandemic that influenced all areas of life in unprecedented ways. Conclusion: Awareness among healthcare workers and further long-term studies focusing on their mental health the overall wellness and especially the psychological burden on doctors have received heightened awareness in media and research publications. This information can assist in developing surveillance and infection and control policies and preparedness for future COVID epidemics in similar scenarios in the future.

An Evaluation of the Sensitivity and Specificity of Three COVID-19 Rapid Immunochromatographic Test Kits Compared to Real-Time Reverse Transcriptase-Polymerase Chain Reaction (rRT-PCR) Among Clinical Samples.

Background and objective The coronavirus disease 2019 (COVID-19) pandemic has imposed a significant burden on healthcare systems worldwide. This highlights the need for simple, rapid, and affordable diagnostic tests that can serve as alternatives tothe existing costly and demanding polymerase chain reaction (PCR) assay, especially in resource-limited countries like Ghana. In light of this, we aimed to assess thediagnostic efficacy of threeCOVID-19 rapid immunochromatographic antigen test kits vs. real-time reverse transcriptase-PCR (rRT-PCR). Methods This study evaluated the sensitivity and specificity of threeCOVID-19 rapid immunochromatographic antigen test kits: DG Rapid, SD Rapid, and SS Rapid. They were compared with the gold standard RT-PCRfor the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid antigen in 75 randomly selected archived nasopharyngeal samples. Results Of the 75 samples tested, 38 (50.7%) were positive and 37 (49.3%) were negative for SARS-CoV-2 RNA by rRT-PCR assay. No false positives were recorded. On the other hand, the DG Rapid kit detected 30 (78.9%) true positives and eight (21.1%) false negatives. SD Rapid kit detected 28 (73.7%) true positives and 10 (26.3%) false negatives, while the SS Rapid kit detected 19 (50.0%) true positives and 19 (50.0%) false negatives. While the specificity of each test kit was 100% (95% CI),the sensitivity of the DG Rapid, SD Rapid, and SS Rapid kits was 79%, 74%, and 50% (95% CI), respectively. Higher sensitivitieswere recorded among samples with cycle threshold (Ct) values <29.99 for each kit. Also, the DG Rapid kit demonstrated 79% excellent agreement with rRT-PCR, while the SD Rapid and SS Rapid kits demonstrated good agreement with rRT-PCR with 73% and 50% Cohen's kappa values, respectively. Conclusions Based on our findings,DG Rapid and SD Rapid kits are reliable alternatives to rRT-PCR for the detection of SARS-CoV-2 infection, especially in resource-limited settings like Ghana.

Evaluating the efficiency of ELISA, monoplex and multiplex probe-based real-time reverse-transcription PCR assays in the detection of SARS-CoV-2 (COVID-19) and influenza A and B viruses: A cross-sectional study.

The current study aimed to evaluate the efficiency of Enzyme-linked immunosorbent assay (ELISA) assay and monoplex and multiplex real-time reverse-transcription PCR (rRT-PCR) in the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and influenza A and B viruses (Flu A and Flu B). The SARS-CoV-2 -specific IgG and IgM antibodies, as well as, Flu A (H1N1 and H3N2 serotypes) and Flu B virus antibodies were determined by ELISA assay. The one-step qRT-PCR method was used to detect the SARS-CoV-2 in nasopharyngeal swab samples. Furthermore, the presence of Flu A and B viruses was evaluated using probe-based RT-PCR. Simultaneous detection of SARS-CoV-2, Flu A and B viruses was performed by multiplex rRT-PCR assay. SARS CoV-2 IgM and IgG antibodies were detected in 33.3% and 58.3% of patients, respectively. In contrast, the SARS CoV-2 genome was detected in 50% of patients using the one-step monoplex RT-PCR assay. Flu A serotypes H1N1 and H3N2 were found in 16.7% and 8.3% of patients. Probe-based RT-PCR revealed that 39.3% of patients were positive for the Flu A virus. Multiplex rRT-PCR detect the SARS-CoV-2, Flu A, and Flu B in 50%, 39.3%, and 19% of samples, respectively. The sensitivity and specificity of multiplex rRT-PCR assay in comparison to monoplex RT-PCR were 100% and 55%, respectively. Coinfection with SARS-CoV-2, Flu A, and Flu B viruses was found in 9.5% of patients. Multiplex rRT-PCR can be used as a repaid, cost-effective and suitable tool for molecular surveillance of SARS-CoV-2 and Flu A/B viruses.

Development and evaluation of a multiplex real-time RT-PCR assay for simultaneous detection of H5, H7, and H9 subtype avian influenza viruses

H5, H7 and H9 are the major subtypes of avian influenza virus (AIV) that cause economic losses in the poultry industry and sporadic zoonotic infection. Early detection of AIV is essential for preventing disease spread. Therefore, molecular diagnosis and subtyping of AIV via real-time RT-PCR (rRT-PCR) is preferred over other classical diagnostic methods, such as egg inoculation, RT-PCR and HI test, due to its high sensitivity, specificity and convenience. The singleplex rRT-PCRs for the Matrix, H5 and H7 gene used for the national surveillance program in Korea have been developed in 2017; however, these methods were not designed for multiplexing, and does not reflect the sequences of currently circulating strains completely. In this study, the multiplex H5/7/9 rRT-PCR assay was developed with sets of primers and probe updated or newly designed to simultaneously detect the H5, H7 and H9 genes. Multiplex H5/7/9 rRT-PCR showed 100% specificity without cross-reactivity with other subtypes of AIVs and avian disease-causing viruses or bacteria, and the limit of detection was 1–10 EID50/0.1 ml (50% egg infectious dose). Artificial mixed infections with the three different subtypes could be detected accurately with high analytical sensitivity even under highly biased relative molecular ratios by balancing the reactivities of each subtype by modifying the concentration of the primers and probes. The multiplex H5/7/9 rRT-PCR assay developed in this study could be a useful tool for large-scale surveillance programs for viral detection as well as subtyping due to its high specificity, sensitivity and robustness in discriminating viruses in mixed infections, and this approach would greatly decrease the time, cost, effort and chance of cross-contamination compared to the conventional method of testing three subtypes by different singleplex rRT-PCR methods in parallel or in series.

Detection of SARS-CoV-2 variants distributed from March 2020 to May 2022 and their effect on the infection severity in Iraqi population

New SARS-CoV-2 variants appeared in late December 2020 as Mutations accumulated in the original virus. This study aimed to provide a local database about variants of COVID-19 circulating in the Iraqi population from 2020 to 2022 and the time of emergence of new strains each month since very few local studies have documented its existence in the country. Real-time reverse transcriptase polymerase chain reaction (rRT-PCR) assays were employed to 319 collected and analyzed nasal swabs to determine whether an infection had occurred. A sophisticated diagnostic kit that sorted the distinctive mutations was implemented to evaluate the variants. Results showed Younger patients were more likely to be infected with the Alpha variant (66 patients) than older people (43 patients). Additionally, patients with wild-type infestations had more robust viral load and lower Ct threshold values, culminating in an increase in severity during infection with wild-type virus 26/32 (81.250). Meanwhile, 65/109(59.63%) of patients infected with the Alpha variant developed severe and critical illness and 51/84(60.71%)were infected with Delta or Delta plus variants. In conclusion, the Alpha variant had the highest infection percentage of 109(46.6%), followed by Delta or Delta plus variant 84(26.33%), Beta or Gamma variants 47(20.1%), Omicron variant 46(19.6%), and finally wild-type virus of 32(13.7%). February 2020 witnessed a preliminary finding of the wild-type, while the Alpha variant emerged in December 2020, Beta/Gamma variances were recognized in December 2020, Delta/Delta plus variances began in April 2021, and the Omicron variant debuted in March 2022. Keywords: SARS-CoV-2, Mutation, rRT-PCR, Coronavirus disease 2019, TaqPath, cycle threshold (Ct) value

Detection of SARS-CoV-2 variants distributed from March 2020 to May 2022 and their effect on the infection severity in Iraqi population

New SARS-CoV-2 variants appeared in late December 2020 as Mutations accumulated in the original virus. This study aimed to provide a local database about variants of COVID-19 circulating in the Iraqi population from 2020 to 2022 and the time of emergence of new strains each month since very few local studies have documented its existence in the country. Real-time reverse transcriptase polymerase chain reaction (rRT-PCR) assays were employed to 319 collected and analyzed nasal swabs to determine whether an infection had occurred. A sophisticated diagnostic kit that sorted the distinctive mutations was implemented to evaluate the variants. Results showed Younger patients were more likely to be infected with the Alpha variant (66 patients) than older people (43 patients). Additionally, patients with wild-type infestations had more robust viral load and lower Ct threshold values, culminating in an increase in severity during infection with wild-type virus 26/32 (81.250). Meanwhile, 65/109(59.63%) of patients infected with the Alpha variant developed severe and critical illness and 51/84(60.71%)were infected with Delta or Delta plus variants. In conclusion, the Alpha variant had the highest infection percentage of 109(46.6%), followed by Delta or Delta plus variant 84(26.33%), Beta or Gamma variants 47(20.1%), Omicron variant 46(19.6%), and finally wild-type virus of 32(13.7%). February 2020 witnessed a preliminary finding of the wild-type, while the Alpha variant emerged in December 2020, Beta/Gamma variances were recognized in December 2020, Delta/Delta plus variances began in April 2021, and the Omicron variant debuted in March 2022. Keywords: SARS-CoV-2, Mutation, rRT-PCR, Coronavirus disease 2019, TaqPath, cycle threshold (Ct) value

Validation of improved automated nucleic acid extraction methods for direct detection of polioviruses for global polio eradication

Polioviruses (PV), the main causative agent of acute flaccid paralysis (AFP), are positive-sense single-stranded RNA viruses of the family Picornaviridae. As we approach polio eradication, accurate and timely detection of poliovirus in stool from AFP cases becomes vital to success for the eradication efforts. Direct detection of PV from clinical diagnostic samples using nucleic acid (NA) extraction and real-time reverse transcriptase polymerase chain reaction (rRT-PCR) instead of the current standard method of virus isolation in culture, eliminates the long turn-around time to diagnosis and the need for high viral titer amplification in laboratories. An essential component of direct detection of PV from AFP surveillance samples is the efficient extraction of NA. Potential supply chain issues and lack of vendor presence in certain areas of the world necessitates the validation of multiple NA extraction methods. Using retrospective PV-positive surveillance samples (n=104), two extraction kits were compared to the previously validated Zymo Research Quick-RNA™ Viral Kit. The Roche High Pure Viral RNA Kit, a column-based manual extraction method, and the MagMaX™ Pathogen RNA/DNA kit used in the automated Kingfisher Flex system were both non-inferior to the Zymo kit, with similar rates of PV detection in pivotal rRT-PCR assays, such as pan-poliovirus (PanPV), poliovirus serotype 2 (PV2), and wild poliovirus serotype 1 (WPV1). These important assays allow the identification and differentiation of PV genotypes and serotypes and are fundamental to the GPLN program. Validation of two additional kits provides feasible alternatives to the current piloted method of NA extraction for poliovirus rRT-PCR assays.

Establishing a molecular toolbox of lineage-specific real-time RT-PCR assays for the characterization of foot-and-mouth disease viruses circulating in Asia

Foot-and-mouth disease (FMD) is endemic in many Asian countries, with outbreaks occurring regularly due to viruses from serotypes O, A, and Asia1 that co-circulate in the region. The ability to rapidly characterize new virus occurrences provides critical information to understand the epidemiology and risks associated with field outbreaks, and helps in the selection of appropriate vaccines to control the disease. FMD lineage-specific characterization is usually determined through sequencing; however, this capacity is not always readily available. In this study, we provide a panel of real-time RT-PCR (rRT-PCR) assays to allow differentiation of the FMD virus (FMDV) lineages known to have been co-circulating in Asia during 2020. This panel included five new rRT-PCR assays designed to detect lineages O/ME-SA/PanAsia-PanAsia-2, O/ME-SA/Ind-2001, O/SEA/Mya-98, O/CATHAY, and A/ASIA/Sea-97, along with three published rRT-PCR assays for A/ASIA/Iran-05, A/ASIA/G-VII, and Asia1 serotypes. Samples of known FMD lineage (n = 85) were tested in parallel with all eight lineage-specific assays and an established 3D pan-FMD rRT-PCR assay, and comparative limit of detection (LOD) experiments were conducted for the five newly developed assays. All samples (85/85) were assigned to the correct serotype, and the correct lineage was assigned for 70 out of 85 samples where amplification only occurred with the homologous assay. For 13 out of 85 of the samples, there was amplification in two assays; however, the correct lineage could be designated based on the strongest Ct values for 12 out of 13 samples. An incorrect lineage was assigned for 3 out of 85 samples. The amplification efficiencies for the five new rRT-PCR assays ranged between 79.7 and 100.5%, with nucleic acid dilution experiments demonstrating broadly equivalent limits of detection when compared to the 3D pan-FMD rRT-PCR assay. These new tests, together with other published lineage-specific rRT-PCR assays, constitute a panel of assays (or molecular toolbox) that can be selected for use in FMD endemic countries (individually or a subset of the assays depending on region/lineages known to be circulating) for rapid characterization of the FMDV lineages circulating in Asia at a relatively low cost. This molecular toolbox will enhance the ability of national laboratories in endemic settings to accurately characterize circulating FMDV strains and facilitate prompt implementation of control strategies, and may be particularly useful in settings where it is difficult to access sequencing capability.

Real-time RT-PCR for Venezuelan equine encephalitis complex, Madariaga, and Eastern equine encephalitis viruses: application in human and mosquito public health surveillance in Panama.

Eastern equine encephalitis virus (EEEV), Madariaga virus (MADV), and Venezuelan equine encephalitis virus complex (VEEV) are New World alphaviruses transmitted by mosquitoes. They cause febrile and sometimes severe neurological diseases in human and equine hosts. Detecting them during the acute phase is hindered by non-specific symptoms and limited diagnostic tools. We designed and clinically assessed real-time reverse transcription polymerase chain reaction assays (rRT-PCRs) for VEEV complex, MADV, and EEEV using whole-genome sequences. Validation involved 15 retrospective serum samples from 2015 to 2017 outbreaks, 150 mosquito pools from 2015, and 118 prospective samples from 2021 to 2022 surveillance in Panama. The rRT-PCRs detected VEEV complex RNA in 10 samples (66.7%) from outbreaks, with one having both VEEV complex and MADV RNAs. VEEV complex RNA was found in five suspected dengue cases from disease surveillance. The rRT-PCR assays identified VEEV complex RNA in three Culex (Melanoconion) vomerifer pools, leading to VEEV isolates in two. Phylogenetic analysis revealed the VEEV ID subtype in positive samples. Notably, 11.9% of dengue-like disease patients showed VEEV infections. Together, our rRT-PCR validation in human and mosquito samples suggests that this method can be incorporated into mosquito and human encephalitic alphavirus surveillance programs in endemic regions.

Swish and gargle saliva sampling is a patient-friendly and comparable alternative to nasopharyngeal swabs to detect SARS-CoV-2 in outpatient settings for adults and children.

Nasopharyngeal swabs (NPS) are considered the standard specimen for SARS-CoV-2 detection by PCR. We aimed to compare detection performance and patient experience of NPS with swish and gargle saliva (SGS) to determine its potential as an accurate, easy-to-collect, and comfortable alternative. We conducted a prospective study from March to May 2021 and recruited pediatric and adult outpatients seeking COVID-19 testing. Paired NPS and 5-mL SGS were collected from each participant during the same visit and tested in parallel using validated rRT-PCR assays. Variant of concern (VOC) analysis was performed for positive NPS specimens. The participant completed the surveys regarding their experience with the two collection methods. We included 238 participants in the SARS-CoV-2 detection performance analysis. Thirty-two participants tested positive for both NPS and SGS. In comparison to NPS, the sensitivity and specificity of SGS to detect SARS-CoV-2 were 94.1% (95%CI; 80.3%-99.3%) and 97.1% (95%CI; 93.7%-98.9%), respectively. Six participants tested positive only with SGS and only two with NPS. NPS is an imperfect gold standard. Thus, when compared to the COVID-19 case, that is, a patient with positive NPS and/or SGS, the sensitivity for NPS and SGS were 85.0% and 95.0%, respectively. VOC results (n = 26) revealed that 92% of the cases were alpha. From the 238 surveys, 89.9% of the participants described SGS collection as comfortable or very comfortable compared to 15.1% for NPS; 90.2% of the participants were likely or very likely to return for SGS collection compared to 59.3% for NPS. SGS is an alternative to NPS for SARS-CoV-2 detection in adult and pediatric outpatients as it is more patient-friendly while still maintaining comparable performance.IMPORTANCEWidespread and frequent testing for COVID-19 was an important strategy to identify infected patients to isolate and control the spread of the disease during the pandemic. The nasopharyngeal swab (NPS) global supply chain and access to trained healthcare professionals for standard NPS collection were often compromised. Patient discomfort and limited access challenged health systems to reach large numbers for testing in adult and pediatric populations. Our study revealed that swish and gargle saliva (SGS) was comparable to NPS in detecting SARS-CoV-2 and more patient-friendly than NPS. Patients were more likely to repeat the test with SGS. SGS was amenable to self-collection instead of relying on skilled professionals. This comprehensive evaluation highlights the challenges of comparing the accuracy of new methods to imperfect gold standards and identifies additional patient-centric factors that should be considered when defining such standards. Thus, SGS is an advantageous alternative specimen collection for outpatient en masse testing.

Comparison of Positive/Inconclusive Xpert Xpress SARS-CoV-2 with the Standard M nCoV Real-Time Detection.

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), can be diagnosed using rapid real-time PCR, real-time reverse transcription PCR (rRT-PCR), or rapid antigen testing. Among these, rRT-PCR is considered the gold standard assay. The Xpert Xpress SARS-CoV-2 assay is a rapid real-time PCR test, approved by the Korean Disease Control and Prevention Agency in 2020. The overall concordance and positive concordance rates of the Xpert assay with the STANDARD M nCoV Real-Time Detection kit were determined. All samples with positive or inconclusive Xpert test results from July 2021 to February 2023 that underwent confirmatory testing using the reference rRT-PCR assay were included in the analysis. Samples from 224 patients (93 men and 131 women) with a median age of 59 years (range 15 - 90 years) were included. Of 212 samples that tested positive using Xpert, 112 (52.8%) were true positves and 100 (47.2%) were false positives on rRT-PCR testing. The overall concordance and positive concordance rates were 52.8% (112/212) and 54.5% (112/224), respectively. In the Xpert positive group, the samples had a lower Ct value for the E gene than the N2 gene. The Ct values for the E and N2 genes were significantly lower in the positive group than in the inconclusive group. Positive or inconclusive Xpert results should be confirmed by the gold standard rRT-PCR for early control of this disease. Furthermore, Korea's policy should be reconsidered given the high false-positive rate of the rapid real-time PCR Xpert Xpress SARS-CoV-2 assay.

Development of a Novel Korean H9-Specific rRT-PCR Assay and Its Application for Avian Influenza Virus Surveillance in Korea.

Since the 2000s, the Y439 lineage of H9N2 avian influenza virus (AIV) has been the predominant strain circulating in poultry in Korea; however, in 2020, the Y280 lineage emerged and spread rapidly nationwide, causing large economic losses. To prevent further spread and circulation of such viruses, rapid detection and diagnosis through active surveillance programs are crucial. Here, we developed a novel H9 rRT-PCR assay that can detect a broad range of H9Nx viruses in situations in which multiple lineages of H9 AIVs are co-circulating. We then evaluated its efficacy using a large number of clinical samples. The assay, named the Uni Kor-H9 assay, showed high sensitivity for Y280 lineage viruses, as well as for the Y439 lineage originating in Korean poultry and wild birds. In addition, the assay showed no cross-reactivity with other subtypes of AIV or other avian pathogens. Furthermore, the Uni Kor-H9 assay was more sensitive, and had higher detection rates, than reference H9 rRT-PCR methods when tested against a panel of domestically isolated H9 AIVs. In conclusion, the novel Uni Kor-H9 assay enables more rapid and efficient diagnosis than the "traditional" method of virus isolation followed by subtyping RT-PCR. Application of the new H9 rRT-PCR assay to AI active surveillance programs will help to control and manage Korean H9 AIVs more efficiently.

Clinical Characteristics of the SARS-CoV-2 Alpha, Delta, Delta plus and Omicron Variants versus the Wild Type in Iraqi Patients

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome called coronavirus 2 (SARS-CoV-2). Due to its concerning rate of transmission and intensity, coronavirus was classified as a pandemic on March 11, 2020. With the continuous evolution of the viral genome and mutations that may alter infectivity, disease severity or interactions with host immunity, SARS-CoV-2 has evolved into many variants: Alpha (B.1.1.7 lineage), Delta (B.1.617.2 lineage), Delta plus (B.1.617.2.1), Omicron (B.1.1.529 lineage) and other variants. Thus, this study aimed to find and provide database for local clinical characteristics of different variants of SARS-COV-2 and severity of infection with viral load compared with the wild type. A total of 247 nasal swabs were collected from COVID-19 positive patients between March 2021 to March 2022. Specimens were tested by using real time reverse transcriptase polymerase chain reaction rRT-PCR assay to confirm the infection after RNA extraction by specialized kits. Results showed Alpha, Delta, Delta plus and Omicron variants presence in local population at the same time of their global spread at high rates with different cases of severity. The finding showed increase in severity with Alpha 79/87 (90%), wild type 26/32 (81%) (with 3 mortality cases), Delta/ Delta plus 68/84 (80%) and Kappa only one case. Also, Alpha along with the wild type was more associated to severe and critical cases, while mild to moderate group appeared with Omicron variant (32/43 (74%)). In addition, there was an increase in the severity among older patients (&gt;40) and in men more than the women. Results indicate that although the wild type was no less dangerous or severe than Alpha or other variants, but with continuous appearence of new variants led to its reduced prevalence. In conclusion, findings demonstrated that most of the severe and critical cases had infection with Alpha, wild type than Delta or Delta plus variants. Whereas mild to moderate cases occurred in Omicron variants.

The Frequency of Intestinal Parasitic Infections in COVID-19 Patients: A Case-Control Study in Tehran, Capital of Iran.

The present study was done to evaluate the prevalence of intestinal parasitic infections (IPIs) in patients with COVID-19 in health care centers (Imam Reza and Golestan hospitals), Tehran, capital of Iran. By designing a matched case-control study, 200 fecal samples were collected for each of the COVID-19 patients and healthy individuals. Nasopharyngeal/oropharyngeal swab samples were collected from all participants for the diagnosis of COVID-19. RNA extraction was performed, and then real time reverse-transcription polymerase chain reaction (rRT-PCR) assay was applied to detect viral RNA. Considering the lung complications, 25%> lung complications was detected in 49 patients, 25-49% in 42 patients, and 50%≤ in 109 patients. Fecal samples were examined using different parasitological techniques. After nested-PCR, sequencing was applied to identify Cryptosporidium spp. and microsporidia spp. A relatively lower prevalence of IPIs was detected among control group (7.5%), than in COVID-19 patients (13%), though not significant (P=0.13). The most prevalent parasite among patients was Blastocystis sp. (6%). Also, 13.76% of IPIs were detected in inpatients with more than 50% lung complication. As well, a remarkably significant difference in IPIs was observed among diarrheic COVID-19 patients, in comparison with nondiarrheic patients (P < 0.00001). Moreover, the isolated sequences in the present study belonged to C. parvum subtype IIa and Enterocytozoon bieneusi genotypes D and Peru 8. In conclusion, more epidemiological and clinical research studies are needed to better understand the status and interaction of IPI in COVID-19 in Iran and other countries.

Impact of SARS-COV-2 Variants on the Infection Severity among Iraqi Patients

Severe acute respiratory corona viruses (SARS-COVs) are a particular category of RNA viruses that have emerged as a potential danger to the human population, triggering epidemics and pandemics that have resulted in catastrophic human mortality. The SARS-CoV2, responsible for the COVID-19 pandemic that began on December 12, 2019 in Wuhan, China, has been linked to bats. A new SARS-CoV-2 variant appeared in late December 2020. Mutations with variants continued to appear until the time of this study. Thus, this study aimed to provide a local database among Iraqi patients about SARS-COV-2 variants as there have been very few local studies documenting its existence and its relationship with the progression and severity of infection. For this study 234 nasal swabs were collected from COVID-19 positive individuals between March 2021 to March 2022. RNA was extracted and tested by using real-time reverse transcriptase polymerase chain reaction (rRT-PCR) assay to confirm infection, and the variants were detected by using a special kit that stratified the characteristic mutations. Results showed the presence of Alpha, Beta or Gamma and Omicron variants in our population at the same time as their global spread at high rates with different severity of cases. It increased in severity during infections with wild type 26/32 (81.25%) and Alpha 82/109 (75.23%) variants but a high incidence of Beta or Gamma 28/38 (73.68%) and Omicron 35/46 (76.09%) variants within mild-moderate infections. Moreover, there was a significant increase in severity in older age groups than younger. Hence, we can conclude that most severe infections with SARS-COV-2 appeared in wild type and during the appearance of Alpha variant which provided a unique database of variants of COVID-19 circulating in the Iraqi population and also assisted in determining the severity of disease. More research is needed on this subject.

Utility of CDC DENV1-4 real time PCR assay and trioplex assay for the diagnosis of dengue in patients with acute febrile illness.

Nucleic acid amplification tests (NAATs) have revolutionized reliable detection of dengue virus (DENV) during acute phase of infection. The study evaluated performance of CDC DENV-1-4 real-time assay, trioplex RT-PCR and heminested conventional RT-PCR assay in the diagnosis of DENV. The three NAATs were performed on 107 consecutive samples collected from patients suspected of DENV infection during acute phase of illness. Their performance was compared against composite reference standard, consisting of DENV NS1 antigen ELISA and DENV IgM ELISA. 88/107 study samples were positive by DENV ELISA, either NS1Ag (80), IgM (3) or both (5). The overall sensitivity of CDC DENV-1-4 RT-PCR assay, trioplex RT-PCR assay and conventional multiplex RT-PCR was 68.18%, 54.55% and 38.64%, respectively in diagnosing dengue during acute phase, with an area under the curve of 0.841, 0.773 and 0.693 respectively when compared against composite reference standard. The sensitivity was 82.93%, 73.17% and 51.22%, respectively within three days of illness and 60%, 42.86% and 28.57%, respectively between 4 and 5th day of illness. All the three molecular assays had 100% specificity. Maximum concordance values of 86.9% were recorded among CDC DENV-1-4 rRT-PCR assay and trioplex assay with kappa value of 0.74, suggestive of substantial agreement. CDC DENV-1-4 rRT-PCR assay can be used as a reliable and accurate test for diagnosis of DENV during acute phase of illness.

Diversity and Genetic Reassortment of Keystone Virus in Mosquito Populations in Florida.

Keystone orthobunyavirus (KEYV), a member of the genus Orthobunyavirus, was first isolated in 1964 from mosquitoes in Keystone, Florida. Although data on human infections are limited, the virus has been linked to a fever/rash syndrome and, possibly, encephalitis, with early studies suggesting that 20% of persons in the Tampa, Florida, region had antibodies to KEYV. To assess the distribution and diversity of KEYV in other regions of Florida, we collected >6,000 mosquitoes from 43 sampling sites in St. Johns County between June 2019 and April 2020. Mosquitoes were separated into pools by species and collection date and site. All pools with Aedes spp. (293 pools, 2,171 mosquitoes) were screened with a real-time reverse transcriptase polymerase chain reaction (rRT-PCR) assay that identifies KEYV and other closely related virus species of what was previously designated as the California encephalitis serogroup. In 2020, screening for KEYV was expanded to include 211 pools of Culex mosquitoes from sites where KEYV-positive Aedes spp. had been identified. rRT-PCR-positive samples were inoculated into cell cultures, and five KEYV isolates from Aedes atlanticus pools were isolated and sequenced. Analyses of the KEYV large genome segment sequences revealed two distinct KEYV clades, whereas analyses of the medium and small genome segments uncovered past reassortment events. Our data documented the ongoing seasonal circulation of multiple KEYV clades within Ae. atlanticus mosquito populations along the east coast of Florida, highlighting the need for further studies of the impact of this virus on human health.

Low infectivity among asymptomatic patients with a positive SARS-CoV-2 admission test at a tertiary-care center, 2020–2022

Background: Many hospitals have implemented admission SARS-CoV-2 testing to evaluate for the need for transmission-based precautions. However, a positive test in an asymptomatic patient may represent (1) active infection, signifying infectiousness; (2) false positivity; or (3) past infection with prolonged viral shedding. We used a strand-specific SARS-CoV-2 reverse real-time polymerase chain reaction (rRT-PCR) assay to assess infectivity among asymptomatic patients with a positive SARS-CoV-2 PCR admission test. Methods: We used a 2-step rRT-PCR specific to the minus strand of the SARS-CoV-2 envelope gene. We reviewed records of patients with a positive SARS-CoV-2 PCR who were also tested for the strand-specific SARS-CoV-2 PCR within 2 days of admission at Stanford Health Care during July 2020–April 2022. We restricted our analysis to each patient’s first test. We calculated the percentage of detectable minus strand-specific tests among asymptomatic patients over time and gathered descriptive statistics for age, sex, and immunocompromised state. Results: In total, 848 admitted patients had strand-specific SARS-CoV-2 assays performed. Of 532 patients with a strand-specific assay done within 2 days of admission, 242 (45%) were asymp tomatic. Among asymptomatic patients, the mean age was 56 years (range, 19–99), 133 (55%) were male, 50 (21%) had immunocompromising conditions, and 30 (12%) were admitted for a surgical procedure. In total, 21 (9%; range, 4%–25% per quarter) had detectable minus strand-specific assays (Fig. 1). Conclusions: Most asymptomatic patients tested for SARS-CoV-2 on admission were not infectious. Hospitals using SARS-CoV-2 PCR admission testing may need to re-evaluate the continued use of this practice.Fig. 1. Minus strand-specific SARS-CoV-2 assay percentage positivity per quarter among asymptomatic patients tested within 2 days of admission. The peak positivity in November 2021–January 2022 quarter coincided with the SARS-CoV-2 omicron variant surge in our county.Disclosure: None