ABSTRACT
OBJECTIVES: Infectious mononucleosis (IM) is a clinical syndrome that is characterised by lymphadenopathy, fever and sore throat. Although generally not considered a serious illness, IM can lead to significant loss of time from school or work due to profound fatigue, or the development of chronic illness. This study aimed to derive and externally validate clinical prediction rules (CPRs) for IM caused by Epstein-Barr virus (EBV). DESIGN: Prospective cohort study. SETTING AND PARTICIPANTS: 328 participants were recruited prospectively for the derivation cohort, from seven university-affiliated student health centres in Ireland. Participants were young adults (17-39 years old, mean age 20.6 years) with sore throat and one other additional symptom suggestive of IM. The validation cohort was a retrospective cohort of 1498 participants from a student health centre at the University of Georgia, USA. MAIN OUTCOME MEASURES: Regression analyses were used to develop four CPR models, internally validated in the derivation cohort. External validation was carried out in the geographically separate validation cohort. RESULTS: In the derivation cohort, there were 328 participants, of whom 42 (12.8%) had a positive EBV serology test result. Of 1498 participants in the validation cohort, 243 (16.2%) had positive heterophile antibody tests for IM. Four alternative CPR models were developed and compared. There was moderate discrimination and good calibration for all models. The sparsest CPR included presence of enlarged/tender posterior cervical lymph nodes and presence of exudate on the pharynx. This model had moderate discrimination (area under the receiver operating characteristic curve (AUC): 0.70; 95% CI: 0.62-0.79) and good calibration. On external validation, this model demonstrated reasonable discrimination (AUC: 0.69; 95% CI: 0.67-0.72) and good calibration. CONCLUSIONS: The alternative CPRs proposed can provide quantitative probability estimates of IM. Used in conjunction with serological testing for atypical lymphocytosis and immunoglobulin testing for viral capsid antigen, CPRs can enhance diagnostic decision-making for IM in community settings.
Subject(s)
Epstein-Barr Virus Infections , Infectious Mononucleosis , Pharyngitis , Young Adult , Humans , Adult , Adolescent , Infectious Mononucleosis/diagnosis , Herpesvirus 4, Human , Clinical Decision Rules , Prospective Studies , Retrospective Studies , Antigens, Viral , PainABSTRACT
The heterophile antibody (also known as the Monospot) test is a useful screening tool for infectious mononucleosis (IM) resulting from primary Epstein-Barr virus (EBV) infection. However, up to 10% of patients with IM are heterophile negative. Heterophile-negative patients who have lymphocytosis or atypical lymphocytes on peripheral blood smear should be further tested for EBV serologies, which include testing for specific IgM and IgG antibodies against viral capsid antigens, early antigens and EBV nuclear antigen proteins. A diagnostic dilemma arises when the patient has clinical and laboratory features of IM, but is both heterophile negative and seronegative for IM, as illustrated in this case presentation. To avoid missed diagnoses of IM, misdiagnosis of mononucleosis-like illnesses and unnecessary testing, knowledge of test characteristics and the evolving course of EBV serologies is important to assure and inform both the physician and the patient.
Subject(s)
Epstein-Barr Virus Infections , Infectious Mononucleosis , Lymphocytosis , Humans , Herpesvirus 4, Human , Lymphocytosis/diagnosis , Infectious Mononucleosis/diagnosis , Antigens, Viral , Fever , Antibodies, ViralABSTRACT
Understanding immune responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is crucial to contain the COVID-19 pandemic. Using a multiplex approach, serum IgG responses against the whole SARS-CoV-2 proteome and the nucleocapsid proteins of endemic human coronaviruses (HCoVs) were measured in SARS-CoV-2-infected donors and healthy controls. COVID-19 severity strongly correlated with IgG responses against the nucleocapsid (N) of SARS-CoV-2 and possibly with the number of viral antigens targeted. Furthermore, a strong correlation between COVID-19 severity and serum responses against N of endemic alpha- but not betacoronaviruses was detected. This correlation was neither caused by cross-reactivity of antibodies, nor by a general boosting effect of SARS-CoV-2 infection on pre-existing humoral immunity. These findings raise the prospect of a potential disease progression marker for COVID-19 severity that allows for early stratification of infected individuals.
Subject(s)
Alphacoronavirus , COVID-19 , Antibodies, Viral , Antigens, Viral , Humans , Immunoglobulin G , Nucleocapsid Proteins , Pandemics , Proteome , SARS-CoV-2 , Spike Glycoprotein, CoronavirusABSTRACT
In recent years, the prevalence of hand, foot, and mouth disease (HFMD) caused by enteroviruses other than enterovirus A71 (EV-A71) and coxsackievirus A16 (CVA16) has gradually increased. The throat swab specimens of 2701 HFMD cases were tested, the VP1 regions of CVA10 RNA were amplified using RT-PCR, and phylogenetic analysis of CVA10 was performed. Children aged 1-5 years accounted for the majority (81.65%) and boys were more than girls. The positivity rates of EV-A71, CVA16, and other EVs were 15.22% (219/1439), 28.77% (414/1439), and 56.01% (806/1439), respectively. CVA10 is one of the important viruses of other EVs. A total of 52 CVA10 strains were used for phylogenetic analysis based on the VP1 region, 31 were from this study, and 21 were downloaded from GenBank. All CVA10 sequences could be assigned to seven genotypes (A, B, C, D, E, F, and G), and genotype C was further divided into C1 and C2 subtypes, only one belonged to subtype C1 and the remaining 30 belonged to C2 in this study. This study emphasized the importance of strengthening the surveillance of HFMD to understand the mechanisms of pathogen variation and evolution, and to provide a scientific basis for HFMD prevention, control, and vaccine development.
Subject(s)
Enterovirus Infections , Enterovirus , Hand, Foot and Mouth Disease , Male , Child , Female , Humans , Hand, Foot and Mouth Disease/epidemiology , Phylogeny , Enterovirus/genetics , Antigens, Viral/genetics , China/epidemiologyABSTRACT
Introduction: There remains a need to better identify patients at highest risk for developing severe Coronavirus Disease 2019 (COVID-19) as additional waves of the pandemic continue to impact hospital systems. We sought to characterize the association of receptor for advanced glycation end products (RAGE), SARS-CoV-2 nucleocapsid viral antigen, and a panel of thromboinflammatory biomarkers with development of severe disease in patients presenting to the emergency department with symptomatic COVID-19. Methods: Blood samples were collected on arrival from 77 patients with symptomatic COVID-19, and plasma levels of thromboinflammatory biomarkers were measured. Results: Differences in biomarkers between those who did and did not develop severe disease or death 7 days after presentation were analyzed. After adjustment for multiple comparisons, RAGE, SARS-CoV-2 nucleocapsid viral antigen, interleukin (IL)-6, IL-10 and tumor necrosis factor receptor (TNFR)-1 were significantly elevated in the group who developed severe disease (all p<0.05). In a multivariable regression model, RAGE and SARS-CoV-2 nucleocapsid viral antigen remained significant risk factors for development of severe disease (both p<0.05), and each had sensitivity and specificity >80% on cut-point analysis. Discussion: Elevated RAGE and SARS-CoV-2 nucleocapsid viral antigen on emergency department presentation are strongly associated with development of severe disease at 7 days. These findings are of clinical relevance for patient prognostication and triage as hospital systems continue to be overwhelmed. Further studies are warranted to determine the feasibility and utility of point-of care measurements of these biomarkers in the emergency department setting to improve patient prognostication and triage.
Subject(s)
COVID-19 , Humans , SARS-CoV-2 , Receptor for Advanced Glycation End Products , Nucleocapsid , Antigens , Biomarkers , Antigens, ViralABSTRACT
The presentation of viral antigens on nanoparticles in multivalent arrays has emerged as a valuable technology for vaccines. On the nanoparticle surface, highly ordered, repetitive arrays of antigens can mimic their geometric arrangement on virion surfaces and elicit stronger humoral responses than soluble viral antigens. More recently, bacterial antigens have been presented on self-assembling protein nanoparticles and have elicited protective antibody and effective T-helper responses, further supporting the nanoparticle platform as a universal approach for stimulating potent immunogenicity. Here, we present the rational design, structural analysis, and immunogenicity of self-assembling ferritin nanoparticles displaying eight copies of the Neisseria meningitidis trimeric adhesin NadA. We engineered constructs consisting of two different NadA fragments, head only and head with stalk, that we fused to ferritin and expressed in Escherichia coli. Both fusion constructs self-assembled into the expected nanoparticles as determined by Cryo electron microscopy. In mice, the two nanoparticles elicited comparable NadA antibody levels that were 10- to 100-fold higher than those elicited by the corresponding NadA trimer subunits. Further, the NadAferritin nanoparticles potently induced complement-mediated serum bactericidal activity. These findings confirm the value of self-assembling nanoparticles for optimizing the immunogenicity of bacterial antigens and support the broad applicability of the approach to vaccine programs, especially for the presentation of trimeric antigens.
Subject(s)
Nanoparticles , Neisseria meningitidis , Mice , Animals , Ferritins , Antigens, Bacterial , Antigens, Viral , Antibodies, Blocking , Vaccines, Combined , Nanoparticles/chemistryABSTRACT
The nasal mucosa is the main gateway for entry, replication and elimination of the SARS-CoV-2 virus, the pathogen that causes severe acute respiratory syndrome (COVID-19). The presence of the virus in the epithelium causes damage to the nasal mucosa and compromises mucociliary clearance. The aim of this study was to investigate the presence of SARS-CoV-2 viral antigens in the nasal mucociliary mucosa of patients with a history of mild COVID-19 and persistent inflammatory rhinopathy. We evaluated eight adults without previous nasal diseases and with a history of COVID-19 and persistent olfactory dysfunction for more than 80 days after diagnosis of SARS-CoV-2 infection. Samples of the nasal mucosa were collected via brushing of the middle nasal concha. The detection of viral antigens was performed using immunofluorescence through confocal microscopy. Viral antigens were detected in the nasal mucosa of all patients. Persistent anosmia was observed in four patients. Our findings suggest that persistent SARS-CoV-2 antigens in the nasal mucosa of mild COVID-19 patients may lead to inflammatory rhinopathy and prolonged or relapsing anosmia. This study sheds light on the potential mechanisms underlying persistent symptoms of COVID-19 and highlights the importance of monitoring patients with persistent anosmia and nasal-related symptoms.
Subject(s)
COVID-19 , Adult , Humans , COVID-19/complications , COVID-19/diagnosis , SARS-CoV-2 , Anosmia/diagnosis , Anosmia/etiology , COVID-19 Testing , Nasal Mucosa , Antigens, ViralABSTRACT
A significant number of persons with coronavirus disease 2019 (COVID-19) experience persistent, recurrent, or new symptoms several months after the acute stage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This phenomenon, termed post-acute sequelae of SARS-CoV-2 (PASC) or long COVID, is associated with high viral titers during acute infection, a persistently hyperactivated immune system, tissue injury by NETosis-induced micro-thrombofibrosis (NETinjury), microbial translocation, complement deposition, fibrotic macrophages, the presence of autoantibodies, and lymphopenic immune environments. Here, we review the current literature on the immunological imbalances that occur during PASC. Specifically, we focus on data supporting common immunopathogenesis and tissue injury mechanisms shared across this highly heterogenous disorder, including NETosis, coagulopathy, and fibrosis. Mechanisms include changes in leukocyte subsets/functions, fibroblast activation, cytokine imbalances, lower cortisol, autoantibodies, co-pathogen reactivation, and residual immune activation driven by persistent viral antigens and/or microbial translocation. Taken together, we develop the premise that SARS-CoV-2 infection results in PASC as a consequence of acute and/or persistent single or multiple organ injury mediated by PASC determinants to include the degree of host responses (inflammation, NETinjury), residual viral antigen (persistent antigen), and exogenous factors (microbial translocation). Determinants of PASC may be amplified by comorbidities, age, and sex.
Subject(s)
COVID-19 , Post-Acute COVID-19 Syndrome , Humans , SARS-CoV-2 , Leukocytes , Antigens, Viral , Autoantibodies , Disease ProgressionABSTRACT
Surface antigens of pathogens are commonly targeted by vaccine-elicited antibodies but antigenic variability, notably in RNA viruses such as influenza, HIV and SARS-CoV-2, pose challenges for control by vaccination. For example, influenza A(H3N2) entered the human population in 1968 causing a pandemic and has since been monitored, along with other seasonal influenza viruses, for the emergence of antigenic drift variants through intensive global surveillance and laboratory characterisation. Statistical models of the relationship between genetic differences among viruses and their antigenic similarity provide useful information to inform vaccine development, though accurate identification of causative mutations is complicated by highly correlated genetic signals that arise due to the evolutionary process. Here, using a sparse hierarchical Bayesian analogue of an experimentally validated model for integrating genetic and antigenic data, we identify the genetic changes in influenza A(H3N2) virus that underpin antigenic drift. We show that incorporating protein structural data into variable selection helps resolve ambiguities arising due to correlated signals, with the proportion of variables representing haemagglutinin positions decisively included, or excluded, increased from 59.8% to 72.4%. The accuracy of variable selection judged by proximity to experimentally determined antigenic sites was improved simultaneously. Structure-guided variable selection thus improves confidence in the identification of genetic explanations of antigenic variation and we also show that prioritising the identification of causative mutations is not detrimental to the predictive capability of the analysis. Indeed, incorporating structural information into variable selection resulted in a model that could more accurately predict antigenic assay titres for phenotypically-uncharacterised virus from genetic sequence. Combined, these analyses have the potential to inform choices of reference viruses, the targeting of laboratory assays, and predictions of the evolutionary success of different genotypes, and can therefore be used to inform vaccine selection processes.
Subject(s)
COVID-19 , Influenza A virus , Influenza, Human , Humans , Influenza, Human/prevention & control , Influenza A Virus, H3N2 Subtype/genetics , Bayes Theorem , Hemagglutinin Glycoproteins, Influenza Virus/genetics , SARS-CoV-2 , Antigens, Viral/genetics , Genotype , Phenotype , Antibodies, Viral/geneticsABSTRACT
BACKGROUND: Nasopharyngeal antigen Rapid Diagnostic Tests (RDTs), saliva RT-PCR and nasopharyngeal (NP) RT-PCR have shown different performance characteristics to detect patients infected by SARS-CoV-2, according to the viral load (VL)-and thus transmissibility. METHODS: In October 2020, we conducted a prospective trial involving patients presenting at testing centres with symptoms of COVID-19. We compared detection rates and performance of RDT, saliva PCR and nasopharyngeal (NP) PCR, according to VL and symptoms duration. RESULTS: Out of 949 patients enrolled, 928 patients had all three tests performed. Detection rates were 35.2% (95%CI 32.2-38.4%) by RDT, 39.8% (36.6-43.0%) by saliva PCR, 40.1% (36.9-43.3%) by NP PCR, and 41.5% (38.3-44.7%) by any test. For those with viral loads (VL) ≥106 copies/ml, detection rates were 30.3% (27.3-33.3), 31.4% (28.4-34.5), 31.5% (28.5-34.6), and 31.6% (28.6-34.7%) respectively. Sensitivity of RDT compared to NP PCR was 87.4% (83.6-90.6%) for all positive patients, 94.5% (91.5-96.7%) for those with VL≥105 and 96.5% (93.6-98.3%) for those with VL≥106. Sensitivity of STANDARD-Q®, Panbio™ and COVID-VIRO® Ag tests were 92.9% (86.4-96.9%), 86.1% (78.6-91.7%) and 84.1% (76.9-89.7%), respectively. For those with VL≥106, sensitivity was 96.6% (90.5-99.3%), 97.8% (92.1-99.7%) and 95.3% (89.4-98.5%) respectively. No patient with VL<104 was detected by RDT. Specificity of RDT was 100% (99.3-100%) compared to any PCR. RDT sensitivity was similar <4 days (87.8%, 83.5-91.3%) and ≥4 days (85.7%, 75.9-92.6%) after symptoms onset (p = 0.6). Sensitivity of saliva and NP PCR were 95.7% (93.1-97.5%) and 96.5% (94.1-98.1%), respectively, compared to the other PCR. CONCLUSIONS: RDT results allow rapid identification of COVID cases with immediate isolation of most contagious individuals. RDT can thus be a game changer both in ambulatory care and community testing aimed at stopping transmission chains, and even more so in resource-constrained settings thanks to its very low price. When PCR is performed, saliva could replace NP swabbing. TRIAL REGISTRATION: ClinicalTrial.gov Identifier: NCT04613310 (03/11/2020).
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Antigens, Viral , COVID-19 Testing , Polymerase Chain Reaction , Prospective Studies , Saliva , Sensitivity and SpecificityABSTRACT
BACKGROUND: Coronavirus disease 2019 (COVID-19) has been especially dangerous for elderly people. To reduce the risk of transmission from healthcare workers to elderly people, it is of utmost importance to detect possible severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive healthcare workers as early as possible. We aimed to determine whether the Abbott Panbio™ COVID-19 antigen detection rapid diagnostic test (Ag-RDT) could be used as an alternative to reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The second aim was to compare the cycle threshold (Ct) in RT-qPCR with the results of the Ag-RDT. METHODS: A prospective diagnostic evaluation of the Abbott Panbio™ COVID-19 Ag-RDT among healthcare workers across three elderly care facilities as well as home-based elderly care workers who met clinical criteria for COVID-19 during the second wave of the COVID-19 pandemic. Per healthcare worker, the first nasopharyngeal swab was obtained to perform the Ag-RDT and the second swab for RT-qPCR. A Ct-value of < 40 was interpreted as positive, ≥ 40 as negative. RESULTS: A total of 683 healthcare workers with COVID-19 symptoms were sampled for detection of SARS-CoV-2 by both Ag-RDT and RT-qPCR. Sixty-three healthcare workers (9.2%) tested positive for SARS-CoV-2 by RT-qPCR. The overall sensitivity of Ag-RDT was 81.0% sensitivity (95%CI: 69.6-88.8%) and 100% specificity (95%CI: 99.4-100%). Using a cut-off Ct-value of 32, the sensitivity increased to 92.7% (95% CI: 82.7-97.1%). Negative Ag-RDT results were moderately associated with higher Ct-values (r = 0.62) compared to positive Ag-RDT results. CONCLUSION: The Panbio™ COVID-19 Ag-RDT can be used to quickly detect positive SARS-CoV-2 healthcare workers. Negative Ag-RDT should be confirmed by RT-qPCR. In case of severe understaffing and with careful consideration, fully vaccinated healthcare workers with Ag-RDT negative results could work with a mask pending PCR results.
Subject(s)
COVID-19 , Humans , Aged , SARS-CoV-2 , Pandemics , Prospective Studies , Rapid Diagnostic Tests , Health Personnel , Sensitivity and Specificity , Antigens, Viral , COVID-19 TestingABSTRACT
BACKGROUND: Porcine epidemic diarrhea (PED), caused by PED virus (PEDV), is a severe enteric disease burdening the global swine industry in recent years. Especially, the mortality of PED in neonatal piglets approaches 100%. Maternal antibodies in milk, particularly immunoglobulin A (IgA) antibodies, are of great importance for protection neonatal suckling piglets against PEDV infection as passive lactogenic immunity. Therefore, appropriate detection methods are required for detecting PEDV IgA antibodies in milk. In the current study, we prepared monoclonal antibodies (mAbs) against PEDV spike (S) glycoprotein. An enzyme-linked immunosorbent assay (ELISA) was subsequently developed based on PEDV antigen capture by a specific anti-S mAb. RESULTS: The developed ELISA showed high sensitivity (the maximum dilution of milk samples up to 1:1280) and repeatability (coefficient of variation values < 10%) in detecting PEDV IgA antibody positive and negative milk samples. More importantly, the developed ELISA showed a high coincidence rate with a commercial ELISA kit for PEDV IgA antibody detection in clinical milk samples. CONCLUSIONS: The developed ELISA in the current study is applicable for PEDV IgA antibody detection in milk samples, which is beneficial for evaluating vaccination efficacies and neonate immune status against the virus.
Subject(s)
Coronavirus Infections , Porcine epidemic diarrhea virus , Swine Diseases , Animals , Swine , Milk , Antibodies, Viral , Antigens, Viral , Coronavirus Infections/diagnosis , Coronavirus Infections/veterinary , Coronavirus Infections/prevention & control , Enzyme-Linked Immunosorbent Assay/veterinary , Enzyme-Linked Immunosorbent Assay/methods , Antibodies, Monoclonal , Immunoglobulin ASubject(s)
COVID-19 , SARS-CoV-2 , Humans , Adolescent , Child , COVID-19/diagnosis , Sensitivity and Specificity , Antigens, ViralABSTRACT
Antigenic characterization of emerging and re-emerging viruses is necessary for the prevention of and response to outbreaks, evaluation of infection mechanisms, understanding of virus evolution, and selection of strains for vaccine development. Primary analytic methods, including enzyme-linked immunosorbent/lectin assays, hemagglutination inhibition, neuraminidase inhibition, micro-neutralization assays, and antigenic cartography, have been widely used in the field of influenza research. These techniques have been improved upon over time for increased analytical capacity, and some have been mobilized for the rapid characterization of the SARS-CoV-2 virus as well as its variants, facilitating the development of highly effective vaccines within 1 year of the initially reported outbreak. While great strides have been made for evaluating the antigenic properties of these viruses, multiple challenges prevent efficient vaccine strain selection and accurate assessment. For influenza, these barriers include the requirement for a large virus quantity to perform the assays, more than what can typically be provided by the clinical samples alone, cell- or egg-adapted mutations that can cause antigenic mismatch between the vaccine strain and circulating viruses, and up to a 6-month duration of vaccine development after vaccine strain selection, which allows viruses to continue evolving with potential for antigenic drift and, thus, antigenic mismatch between the vaccine strain and the emerging epidemic strain. SARS-CoV-2 characterization has faced similar challenges with the additional barrier of the need for facilities with high biosafety levels due to its infectious nature. In this study, we review the primary analytic methods used for antigenic characterization of influenza and SARS-CoV-2 and discuss the barriers of these methods and current developments for addressing these challenges.
Subject(s)
COVID-19 , Influenza Vaccines , Influenza, Human , Antigens, Viral , Hemagglutinin Glycoproteins, Influenza Virus , Humans , Influenza, Human/epidemiology , Influenza, Human/prevention & control , SARS-CoV-2ABSTRACT
Early detection of SARS-CoV-2 infection is crucial to prevent its spread. This study aimed to document test sensitivity/specificity, correlation with cycle threshold value from polymerase chain reaction (PCR), fitness-for-use in different populations and settings, and user perspectives that could inform large-scale implementation. In this study, we evaluated the performance of a rapid antigen detection test, BD Veritor, and compared this (and another rapid test, Standard Q) against reverse transcription PCR (RT-PCR) in terms of sensitivity and specificity in 130 symptomatic and 130 asymptomatic adults. In addition, we evaluated the suitability and ease of use of the BD Veritor test in a subsample of study participants (n = 42) and implementers (n = 5). At 95% confidence interval, the sensitivity of the BD Veritor and Standard Q test were 70% and 63% in symptomatic and 87% and 73% in asymptomatic individuals, respectively, regarding positive SARS-CoV-2 RT-PCR results. Overall, the BD Veritor test was 78% sensitive and 99.5% specific compared with RT-PCR irrespective of the cycle threshold. This warrants large field evaluation as well as use of the rapid antigen test for quick assessment of SARS-CoV-2 for containment of epidemics in the country.
Subject(s)
COVID-19 , SARS-CoV-2 , Adult , Antigens, Viral , Bangladesh/epidemiology , COVID-19/diagnosis , COVID-19 Testing , Humans , Sensitivity and SpecificityABSTRACT
Although very different, in terms of their genomic organization, their enzymatic proteins, and their structural proteins, HIV and SARS-CoV-2 have an extraordinary evolutionary potential in common. Faced with various selection pressures that may be generated by treatments or immune responses, these RNA viruses demonstrate very high adaptive capacities, which result in the continuous emergence of variants and quasi-species. In this retrospective analysis of viral proteins, ensuring the adhesion of these viruses to the plasma membrane of host cells, we highlight many common points that suggest the convergent mechanisms of evolution. HIV and SARS-CoV-2 first recognize a lipid raft microdomain that acts as a landing strip for viral particles on the host cell surface. In the case of mucosal cells, which are the primary targets of both viruses, these microdomains are enriched in anionic glycolipids (gangliosides) forming a global electronegative field. Both viruses use lipid rafts to surf on the cell surface in search of a protein receptor able to trigger the fusion process. This implies that viral envelope proteins are both geometrically and electrically compatible to the biomolecules they select to invade host cells. In the present study, we identify the surface electrostatic potential as a critical parameter controlling the convergent evolution dynamics of HIV-1 and SARS-CoV-2 surface envelope proteins, and we discuss the impact of this parameter on the phenotypic properties of both viruses. The virological data accumulated since the emergence of HIV in the early 1980s should help us to face present and future virus pandemics.
Subject(s)
COVID-19 , HIV Infections , Humans , SARS-CoV-2 , COVID-19/metabolism , Retrospective Studies , Viral Proteins/metabolism , Receptors, Cell Surface/metabolism , Antigens, Viral/metabolism , HIV Infections/metabolism , Membrane Microdomains/metabolism , Glycoproteins/metabolismABSTRACT
Live attenuated vaccines (LAVs) replicate in the respiratory/oral mucosa, mimic natural infection, and can induce mucosal and systemic immune responses to the full repertoire of SARS-CoV-2 structural/nonstructural proteins. Generally, LAVs produce broader and more durable protection than current COVID-19 vaccines. We generated a temperature-sensitive (TS) SARS-CoV-2 mutant TS11 via cold-adaptation of the WA1 strain in Vero E6 cells. TS11 replicated at >4 Log10-higher titers at 32 °C than at 39 °C. TS11 has multiple mutations, including those in nsp3, a 12-amino acid-deletion spanning the furin cleavage site of the S protein and a 371-nucleotide-deletion spanning the ORF7b-ORF8 genes. We tested the pathogenicity and protective efficacy of TS11 against challenge with a heterologous virulent SARS-CoV-2 D614G strain 14B in Syrian hamsters. Hamsters were randomly assigned to mock immunization-challenge (Mock-C) and TS11 immunization-challenge (TS11-C) groups. Like the mock group, TS11-vaccinated hamsters did not show any clinical signs and continuously gained body weight. TS11 replicated well in the nasal cavity but poorly in the lungs and caused only mild lesions in the lungs. After challenge, hamsters in the Mock-C group lost weight. In contrast, the animals in the TS11-C group continued gaining weight. The virus titers in the nasal turbinates and lungs of the TS11-C group were significantly lower than those in the Mock-C group, confirming the protective effects of TS11 immunization of hamsters. Histopathological examination demonstrated that animals in the Mock-C group had severe pulmonary lesions and large amounts of viral antigens in the lungs post-challenge; however, the TS11-C group had minimal pathological changes and few viral antigen-positive cells. In summary, the TS11 mutant was attenuated and induced protection against disease after a heterologous SARS-CoV-2 challenge in Syrian hamsters.
Subject(s)
COVID-19 , SARS-CoV-2 , Animals , Cricetinae , Antibodies, Neutralizing , Antibodies, Viral , Antigens, Viral , COVID-19/prevention & control , COVID-19 Vaccines , Mesocricetus , SARS-CoV-2/genetics , Temperature , Vaccines, Attenuated/geneticsABSTRACT
During the ongoing COVID-19 pandemic, rapid and reliable detection of SARS-CoV-2 is important to enable proper care of patients and to prevent further transmission. The aim of this study was to evaluate the performance of the Roche SARS-CoV-2 Rapid Antigen Test (Ag-RDT) in an emergency care setting during a high pandemic period. The analytical performance of the Ag-RDT was compared to real-time reverse transcriptase polymerase chain reaction (rRT-PCR). A total of 132 patient samples, previously analyzed with rRT-PCR, were reanalyzed with the Ag-RDT. Tenfold serial dilutions of five different patient strains containing the pangolin variants BA.1, BA.2, B.1.1.7, B.1.160, and B.1.177 were analyzed in parallel with the Ag-RDT and rRT-PCR. A clinical evaluation was performed in which 1911 consecutive patients admitted to the emergency wards in Region Gävleborg, Sweden, were included. Paired samples were collected and analyzed with the Ag-RDT on-site and with rRT-PCR at the microbiology laboratory. The overall sensitivity and specificity of the Ag-RDT in the clinical evaluation were 71.3% and 99.7%, respectively. When samples with cycle threshold (Ct) values above 30 were excluded, the sensitivity was 86.5%. Eleven of the admitted patients who were positive for both the Ag-RDT and rRT-PCR (Ct-range 16.9-30.4) showed no symptoms of COVID-19. Using the Ag-RDT shortened the detection time by an average of 11 h. The Ag-RDT is a useful tool for preliminary screening of SARS-CoV-2 because it enables rapid detection in infectious individuals and therefore, can counteract unnecessary spread of infection at an early stage.
Subject(s)
COVID-19 Testing , COVID-19 , Animals , Humans , Antigens, Viral , Pandemics , Pangolins , SARS-CoV-2 , Sensitivity and Specificity , SwedenABSTRACT
BACKGROUND: Accurate and timely diagnosis is essential in limiting the spread of SARS-CoV-2 infection. The reference standard, rRT-PCR, requires specialized laboratories, costly reagents, and a long turnaround time. Antigen RDTs provide a feasible alternative to rRT-PCR since they are quick, relatively inexpensive, and do not require a laboratory. The WHO requires that Ag RDTs have a sensitivity ≥80% and specificity ≥97%. METHODS: This evaluation was conducted at 11 health facilities in Kenya between March and July 2021. We enrolled persons of any age with respiratory symptoms and asymptomatic contacts of confirmed COVID-19 cases. We collected demographic and clinical information and two nasopharyngeal specimens from each participant for Ag RDT testing and rRT-PCR. We calculated the diagnostic performance of the Panbio™ Ag RDT against the US Centers for Disease Control and Prevention's (CDC) rRT-PCR test. RESULTS: We evaluated the Ag RDT in 2,245 individuals where 551 (24.5%, 95% CI: 22.8-26.3%) tested positive by rRT-PCR. Overall sensitivity of the Ag RDT was 46.6% (95% CI: 42.4-50.9%), specificity 98.5% (95% CI: 97.8-99.0%), PPV 90.8% (95% CI: 86.8-93.9%) and NPV 85.0% (95% CI: 83.4-86.6%). Among symptomatic individuals, sensitivity was 60.6% (95% CI: 54.3-66.7%) and specificity was 98.1% (95% CI: 96.7-99.0%). Among asymptomatic individuals, sensitivity was 34.7% (95% CI 29.3-40.4%) and specificity was 98.7% (95% CI: 97.8-99.3%). In persons with onset of symptoms <5 days (594/876, 67.8%), sensitivity was 67.1% (95% CI: 59.2-74.3%), and 53.3% (95% CI: 40.0-66.3%) among those with onset of symptoms >7 days (157/876, 17.9%). The highest sensitivity was 87.0% (95% CI: 80.9-91.8%) in symptomatic individuals with cycle threshold (Ct) values ≤30. CONCLUSION: The overall sensitivity and NPV of the Panbio™ Ag RDT were much lower than expected. The specificity of the Ag RDT was high and satisfactory; therefore, a positive result may not require confirmation by rRT-PCR. The kit may be useful as a rapid screening tool only for symptomatic patients in high-risk settings with limited access to rRT-PCR. A negative result should be interpreted based on clinical and epidemiological information and may require retesting by rRT-PCR.
Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Antigens, Viral , COVID-19/diagnosis , COVID-19 Testing , Health Facilities , Kenya/epidemiology , Polymerase Chain Reaction , SARS-CoV-2/genetics , Sensitivity and SpecificityABSTRACT
In the face of the COVID-19 pandemic, the need for rapid serological tests that allow multiplexing emerged, as antibody seropositivity can instruct about individual immunity after an infection with SARS-CoV-2 or after vaccination. As many commercial antibody tests are either time-consuming or tend to produce false negative or false positive results when only one antigen is considered, we developed an automated, flow-based chemiluminescence microarray immunoassay (CL-MIA) that allows for the detection of IgG antibodies to SARS-CoV-2 receptor-binding domain (RBD), spike protein (S1 fragment), and nucleocapsid protein (N) in human serum and plasma in less than 8 min. The CoVRapid CL-MIA was tested with a set of 65 SARS-CoV-2 serology positive or negative samples, resulting in 100% diagnostic specificity and 100% diagnostic sensitivity, thus even outcompeting commercial tests run on the same sample set. Additionally, the prospect of future quantitative assessments (i.e., quantifying the level of antibodies) was demonstrated. Due to the fully automated process, the test can easily be operated in hospitals, medical practices, or vaccination centers, offering a valuable tool for COVID-19 serosurveillance. Graphical abstract.