scholarly journals Detection of SARS-CoV-2 nucleocapsid antigen from serum can aid in timing of COVID-19 infection

2021 ◽  
Author(s):  
MJ Ahava ◽  
S Kurkela ◽  
S Kuivanen ◽  
M Lappalainen ◽  
H Jarva ◽  
...  
Keyword(s):  
Enzyme Linked Immunosorbent Assay ◽  
Upper Respiratory Tract ◽  
Antigen Test ◽  
Sample Collection ◽  
Antibody Testing ◽  
Serum Samples ◽  
Diagnostic Pcr ◽  
Test Sensitivity ◽  
Specificity And Sensitivity ◽  
Kinetics Of

AbstractSARS-CoV-2 RNA can be detected in respiratory samples for weeks or even months after onset of COVID-19 disease. Therefore, one of the diagnostic challenges of PCR positive cases is differentiating between acute COVID-19 disease and convalescent phase. Recently, the presence of SARS-CoV-2 nucleocapsid antigen in serum samples of COVID-19 patients was published [Le Hingrat et al. Detection of SARS-CoV-2 N-antigen in blood during acute COVID-19 provides a sensitive new marker and new testing alternatives, Clinical Microbiology and Infection, 2020].Our study aimed to characterize the analytical specificity and sensitivity of an enzyme-linked immunosorbent assay (Salocor SARS-CoV-2 Antigen Quantitative Assay Kit© (Salofa Ltd, Salo, Finland)) for the detection of SARS-CoV-2 antigen in serum, and to characterize the kinetics of antigenemia. The evaluation material included a negative serum panel of 155 samples, and 126 serum samples from patients with PCR-confirmed COVID-19.The specificity of the Salocor SARS-CoV-2 serum N antigen test was 98.0%. In comparison with simultaneous positive PCR from upper respiratory tract (URT) specimens, the test sensitivity was 91.7%. In a serum panel in which the earliest serum sample was collected two days before the collection of positive URT specimen, and the latest 48 days after (median 1 day post URT sample collection), the serum N antigen test sensitivity was 94% within 14 days post onset of symptoms. The antigenemia resolved approximately two weeks after the onset of disease and diagnostic PCR.The combination of simultaneous SARS-CoV-2 antigen and antibody testing appeared to provide useful information for the timing of COVID-19. Our results suggest that SARS-CoV-2 N-antigenemia may be used as a diagnostic marker in acute COVID-19.

scholarly journals Seroprevalence of avian metapneumovirus infection in broiler and broiler breeder chickens in Iran

2011 ◽  
Vol 56 (No. 8) ◽  
pp. 395-399 ◽  
Author(s):  
M. Rahimi
Keyword(s):  
Broiler Chickens ◽  
Economic Losses ◽  
Enzyme Linked Immunosorbent Assay ◽  
Upper Respiratory Tract ◽  
Serum Samples ◽  
Broiler Breeder ◽  
Blood Samples ◽  
Avian Metapneumovirus ◽  
Commercial Chicken ◽  
Future Work

Avian metapneumovirus causes an acute highly contagious upper respiratory tract infection primarily of turkeys and chickens. The disease can cause significant economic losses in turkey and chicken flocks, particularly when exacerbated by secondary pathogens. The purpose of this study was to determine the prevalence of avian metapneumovirus antibodies in broiler and broiler breeder flocks in Kermanshah province, west of Iran. All the flocks had not been vaccinated against avian metapneumovirus. The province were divided into four geographic areas; southwest, southeast, northwest, and northeast. Flocks in each area, and 14–15 birds in each flock, were randomly sampled. The blood samples were taken regardless of the presence of any signs of respiratory or any other clinical disease in the flocks. A total of 435 blood samples were collected from 30 commercial chicken flocks (24 broiler flocks, aged between six and eight weeks, and six broiler breeder flocks, aged between 56 and 72 weeks). The presence of antibodies against avian metapneumovirus in each serum sample was tested twice by enzyme-linked immunosorbent assay using a commercial kit which was able to determine antibodies against A, B and C subtypes of avian metapneumovirus. Out of 347 serum samples obtained from broiler chickens, 167 (48.1%) were positive to avian metapneumovirus antibodies, which represented 20 (83.3%) of 24 examined broiler flocks. Out of 88 samples obtained from broiler breeder chickens, 82 (93.2%) were positive to avian metapneumovirus antibodies, which belonged to six (100%) of examined broiler breeder flocks. Detection of anti-avian metapneumovirus antibodies among broiler breeder (100%) was higher than broiler (83.3%) flocks. A higher rate of seropositivity (83.3% of samples and 100% of broiler flocks) was observed in northwest. The results of this study may indicate the possible involvement of avian metapneumovirus in the respiratory disease we are seeing in chickens in Iran. Its prevalence has to be investigated in other parts of Iran. Future work may and should include the use of molecular methods and isolation of the virus. Isolation of avian metapneumovirus will allow the possibility of making autogenous vaccines.

scholarly journals An enzyme-linked immunosorbent assay for the detection of IgG antibodies against Babesia equi in horses

2004 ◽  
Vol 34 (5) ◽  
pp. 1525-1529 ◽  
Author(s):  
Cristiane Divan Baldani ◽  
Rosangela Zacarias Machado ◽  
Paulo de Tarso Landgraf Botteon ◽  
Felipe Santoro Takakura ◽  
Carlos Luiz Massard
Keyword(s):  
Immunosorbent Assay ◽  
Serological Test ◽  
Epidemiological Studies ◽  
Sao Paulo ◽  
Enzyme Linked Immunosorbent Assay ◽  
São Paulo ◽  
Igg Antibodies ◽  
Serum Samples ◽  
Babesia Equi ◽  
Specificity And Sensitivity

A crude antigenic preparation of Babesia equi was used to develop and establish the suitability of an enzyme-linked immunosorbent assay (ELISA) for the detection of parasite carriers. Optimal dilutions of the antigen, using positive and negative reference sera, were determined by checkboard titrations. The specificity and sensitivity of the ELISA were 100 %. A total of 90 serum samples were taken from horses from the Northeast region of São Paulo State and examined for diagnosis of equine B. equi infection by ELISA. Approximately 75% (n=67) of all the horses tested were found serologically positive for B. equi. These results suggest that the ELISA described may prove to be an appropriate serological test for epidemiological studies on B. equi infections in the field and that equine piroplasmosis is a cause for serious concern in the State of São Paulo, Brazil.

scholarly journals Clinical and experimental factors that affect the reported performance characteristics of rapid testing for SARS-CoV-2

2021 ◽  
Author(s):  
Valentin Parvu ◽  
Devin Gary ◽  
Joseph Mann ◽  
Yu-Chih Lin ◽  
Dorsey Mills ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Disease Diagnosis ◽  
Upper Respiratory Tract ◽  
Antigen Test ◽  
Test Sensitivity ◽  
Viral Culture ◽  
Upper Respiratory ◽  
Asymptomatic Individuals ◽  
Design Factors

ABSTRACT Tests that detect the presence of SARS-CoV-2 antigen in clinical specimens from the upper respiratory tract can provide a rapid means of COVID-19 disease diagnosis and help identify individuals that may be infectious and should isolate to prevent SARS-CoV-2 transmission. This systematic review assesses the diagnostic accuracy of SARS-CoV-2 antigen detection in COVID-19 symptomatic and asymptomatic individuals compared to RT-qPCR, and summarizes antigen test sensitivity using meta-regression. In total, 83 studies were included that compared SARS-CoV-2 rapid antigen lateral flow testing (RALFT) to RT-qPCR for SARS-CoV-2. Generally, the quality of the evaluated studies was inconsistent, nevertheless, the overall sensitivity for RALFT was determined to be 75.0% (95% confidence interval [CI]: 71.0-78.0). Additionally, RALFT sensitivity was found to be higher for symptomatic versus asymptomatic individuals and was higher for a symptomatic population within 7 days from symptom onset (DSO) compared to a population with extended days of symptoms. Viral load was found to be the most important factor for determining SARS-CoV-2 antigen test sensitivity. Other design factors, such as specimen storage and anatomical collection type, also affect the performance of RAFLT. RALFT and RT-qPCR testing both achieve high sensitivity when compared to SARS-CoV-2 viral culture.

scholarly journals Serodiagnosis of Human Granulocytic Ehrlichiosis by a Recombinant HGE-44-Based Enzyme-Linked Immunosorbent Assay

1999 ◽  
Vol 37 (11) ◽  
pp. 3540-3544 ◽  
Author(s):  
Jacob W. Ijdo ◽  
Caiyun Wu ◽  
Louis A. Magnarelli ◽  
Erol Fikrig
Keyword(s):  
Immunosorbent Assay ◽  
Fluorescent Antibody ◽  
Immunoblot Analysis ◽  
Normal Serum ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antibody Testing ◽  
Serum Samples ◽  
Granulocytic Ehrlichiosis ◽  
Healthy Humans ◽  
Human Granulocytic Ehrlichiosis

Current antibody testing for human granulocytic ehrlichiosis relies predominantly on indirect fluorescent-antibody assays and immunoblot analysis. Shortcomings of these techniques include high cost and variability of test results associated with the use of different strains of antigens derived from either horses or cultured HL-60 cells. We used recombinant protein HGE-44, expressed and purified as a maltose-binding protein (MBP) fusion peptide, as an antigen in a polyvalent enzyme-linked immunosorbent assay (ELISA). Fifty-five normal serum samples from healthy humans served as a reference to establish cutoff levels. Thirty-three of 38 HGE patient serum samples (87%), previously confirmed by positive whole-cell immunoblotting, reacted positively in the recombinant ELISA. In specificity analyses, serum samples from patients with Lyme disease, syphilis, rheumatoid arthritis, and human monocytic ehrlichiosis (HME) did not react with HGE-44–MBP antigen, except for one sample (specificity, 98%). We conclude that recombinant HGE-44 antigen is a suitable antigen in an ELISA for the laboratory diagnosis and epidemiological study of HGE.

scholarly journals Cysticercus antibodies and antigens in serum from blood donors from Pondicherry, India

2005 ◽  
Vol 47 (4) ◽  
pp. 227-230 ◽  
Author(s):  
Subhash Chandra Parija ◽  
N. Balamurungan ◽  
Priyadarshi Soumyaranjan Sahu ◽  
S.P. Subbaiah
Keyword(s):  
Immunosorbent Assay ◽  
Tamil Nadu ◽  
Blood Donors ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antibody Testing ◽  
Specific Detection ◽  
Serum Samples ◽  
Blood Samples ◽  
Tamil Nadu State ◽  
Apparently Healthy

The aim of the present study was to screen the serum of blood donors, which are apparently healthy and residing in Pondicherry or its neighboring districts of Tamil Nadu State, for specific detection of Cysticercus antigens and antibodies. A total of 216 blood samples were collected from blood donors at the Central Blood Bank, JIPMER Hospital, Pondicherry, India during January and February 2004. Enzyme-linked immunosorbent assay (ELISA) was used to demonstrate anti-Cysticercus antibodies and the Co-agglutination (CoA) was used to detect antigen in sera. 14 (6.48 %) males were positive for either anti-Cysticercus antibodies or antigens. Of these eight sera were positive for anti-Cysticercus antibodies and six were positive for antigens. Results of the present study show that serum Cysticercus antigen detection may be a useful adjunct to antibody testing for seroprevalence studies of cysticercosis in the community. The present study is the first kind of study, carried out to determine both cysticercal antibodies as well as antigens in the serum samples collected from the healthy blood donors.

Development and preliminary application of gE enzyme-linked immunosorbent assay for detection of the antibody to gE protein ofPseudorabies virusin pigs

2005 ◽  
Vol 2 (2) ◽  
pp. 79-83 ◽  
Author(s):  
Tang Yong ◽  
Chen Huan-Chun ◽  
Qin Ya-Li ◽  
He Qi-Gai ◽  
Jin Mei-Lli ◽  
...  
Keyword(s):  
Immunosorbent Assay ◽  
Pseudorabies Virus ◽  
Enzyme Linked Immunosorbent Assay ◽  
Diagnostic Specificity ◽  
Serum Samples ◽  
Agreement Rate ◽  
Glycoprotein E ◽  
Recombinant Glycoprotein ◽  
Specificity And Sensitivity ◽  
Preliminary Application

AbstractTo differentiate pigs infected withPseudorabies virus(PrV) from pigs vaccinated with gE-PrV, a glycoprotein E enzyme-linked immunosorbent assay (gE-ELISA) based on recombinant glycoprotein E (gE) (which was expressed byEscherichia coli, purified, denatured and renatured) was developed. By testing 115 serum samples, the diagnostic specificity and sensitivity of the developed gE-ELISA were evaluated to be 94.5% and 96.7%, respectively. Five serum samples were tested with plates from five lots, and the results had a coefficient of variation of less than 10%, showing good reproducibility of gE-ELISA. This gE-ELISA was compared with a commercial blocking ELISA by testing 356 serum samples. The agreement rate of the two assays was 92.13% (328/356). These results suggested that the gE-ELISA developed in our laboratory could be used in differentiating PrV-infected and gE-PrV-vaccinated pigs.

scholarly journals Mycoplasma agassizii Strain Variation and Distinct Host Antibody Responses Explain Differences between Enzyme-Linked Immunosorbent Assays and Western Blot Assays

2010 ◽  
Vol 17 (11) ◽  
pp. 1739-1745 ◽  
Author(s):  
Lori D. Wendland ◽  
Paul A. Klein ◽  
Elliott R. Jacobson ◽  
Mary B. Brown
Keyword(s):  
Western Blot ◽  
Goodness Of Fit ◽  
False Negative ◽  
Well Being ◽  
Management Decision ◽  
Enzyme Linked Immunosorbent Assay ◽  
Upper Respiratory Tract ◽  
Strain Variation ◽  
Serum Samples ◽  
Mycoplasma Agassizii

ABSTRACT The precarious status of desert (Gopherus agassizii) and gopher (G. polyphemus) tortoises has resulted in conservation efforts that now include health assessment as an important component of management decision-making. Mycoplasmal upper respiratory tract disease (URTD) is one of very few diseases in chelonians for which comprehensive and rigorously validated diagnostic tests exist. In this study, serum samples obtained from eight Gopherus tortoises documented at necropsy to (i) be enzyme-linked immunosorbent assay (ELISA) seropositive using the PS6 antigen, (ii) be infected with Mycoplasma agassizii as indicated by direct isolation of the pathogen from the respiratory surfaces, and (iii) have histological lesions of mycoplasmal URTD were used to evaluate four distinct clinical isolates of M. agassizii as antigens for ELISA and Western blot analyses. Each animal sample reacted in the Western blot with its homologous M. agassizii strain, but recognition of heterologous M. agassizii strains was variable. Further, individual animals varied significantly with respect to the specific proteins recognized by the humoral immune response. An additional 114 Gopherus serum samples were evaluated using ELISA antigens prepared from the four distinct M. agassizii strains; A 405 values were significantly correlated (r 2 goodness of fit range, 0.708 to 0.771; P < 0.0001) for all antigens tested. The results confirm that strain variation is responsible for the observed differences between Western blot binding patterns. Thus, reliance on a single M. agassizii strain as an antigen in Western blot assays may provide false-negative results. This could have adverse consequences for the well-being of these environmentally sensitive hosts if false-negative animals were relocated to sites consisting of true-negative populations.

scholarly journals Serovar prevalence of Leptospira in semirural India and the development of an IgM-based indirect ELISA

2017 ◽  
Vol 11 (03) ◽  
pp. 234-241 ◽  
Author(s):  
Sara Chandy ◽  
Lokeshwaran Kirubanandhan ◽  
Priya Hemavathy ◽  
Anees Mohammad Khadeeja ◽  
Siby Jacob Kurian ◽  
...  
Keyword(s):  
Tamil Nadu ◽  
Polymerase Chain Reaction Amplification ◽  
Public Health Problem ◽  
Cloning And Expression ◽  
Enzyme Linked Immunosorbent Assay ◽  
Major Public Health Problem ◽  
Diagnostic Systems ◽  
Serum Samples ◽  
Specificity And Sensitivity ◽  
Leptospira Serovars

Introduction: Leptospirosis is a major public health problem in India. However, it has been underreported and under-diagnosed due to a lack of awareness of the disease, a functional surveillance system, and appropriate laboratory diagnostic facilities. Methodology: This multicenter study aimed to understand the Leptospira serovars causing leptospirosis in seven secondary-level hospitals in six states in India. Since early and accurate diagnosis of leptospirosis is one of the challenges faced by clinicians in India due to the poor specificity and sensitivity of commercially available diagnostic systems, an in-house indirect enzyme-linked immunosorbent assay (ELISA) was developed. Genomic DNA from L. interrogans serovar Canicola was used for polymerase chain reaction amplification, cloning, and expression of the lipL32 gene in E. coli to amplify, clone, and express the lipL32 gene. Results: Australis was the common serovar seen at all the study centers. Serovar Icterohaemorrhagiae was seen in samples from Tamil Nadu and Assam. In-house ELISA was standardized using the purified recombinant LipL32 polypeptide and was used to evaluate serum. Subsequently, acute serum samples from leptospirosis patients (n = 60) were screened. Compared to the gold standard, the microscopic agglutination test, sensitivity and specificity of the in-house ELISA was 95% and 90%, respectively. Conclusions: Understanding Leptospira serovars circulating in leptospirosis-endemic areas will help to formulate better vaccines. LipL32-based ELISA may serve as a valuable tool for early diagnosis of leptospirosis.

scholarly journals Rapid Competitive Enzyme-Linked Immunosorbent Assay for Detection of Antibodies to Peste des Petits Ruminants Virus

2005 ◽  
Vol 12 (4) ◽  
pp. 542-547 ◽  
Author(s):  
Kang-Seuk Choi ◽  
Jin-Ju Nah ◽  
Young-Joon Ko ◽  
Shien-Young Kang ◽  
Nam-In Jo
Keyword(s):  
Immunosorbent Assay ◽  
Small Ruminants ◽  
Viral Disease ◽  
Turnaround Time ◽  
Enzyme Linked Immunosorbent Assay ◽  
Peste Des Petits Ruminants ◽  
Rinderpest Virus ◽  
Serum Samples ◽  
Specificity And Sensitivity ◽  
Relative Specificity

ABSTRACT Peste des petits ruminants (PPR) is a contagious viral disease of small ruminants that is of economic importance in Africa, the Middle East, and Asia. We developed a rapid competitive enzyme-linked immunosorbent assay (rapid c-ELISA) for the diagnosis and surveillance of PPR. This assay detects PPR virus (PPRV) antibodies in serum samples by quantifying the amount of monoclonal antibody (MAb) P-3H12 after 30 min of incubation of a serum-MAb conjugate mixture on plates coated with a PPRV recombinant nucleocapsid protein (rPPRV-N). We tested 249 PPRV-positive serum samples and 733 PPRV-negative serum samples from field ruminants. The threshold of percent inhibition (PI) was determined to be <50 on the basis of the mean PI plus 3 standard deviations for sera from PPRV-negative ruminants. The relative specificity and sensitivity of the rapid c-ELISA were 98.5% (722 of 733 serum samples) and 93.4% (234 of 249 serum samples), respectively. The rapid c-ELISA sensitively detected PPRV antibodies in hyperimmune sera (virus neutralization test [VNT] titer, >512), even at dilutions ≥512 in normal goat serum, and as early as 6 to 13 days postinfection from 12 goats, each of which was infected with one of the four PPRV lineages. Hyperimmune sera from animals experimentally vaccinated with rinderpest virus gave positive results by the rapid c-ELISA when the rinderpest virus VNT titers were >512, although the rapid c-ELISA titers were very low (2 to 16). However, the rapid c-ELISA was negative when the rinderpest virus VNT titer was ≤128. The rapid c-ELISA developed in the present work provides a short turnaround time and could be a useful tool for the diagnosis of PPR and screening for PPRV in the field.

scholarly journals Kinetics of the Human Antibody Response against Salmonella enterica Serovars Enteritidis and Typhimurium Determined by Lipopolysaccharide Enzyme-Linked Immunosorbent Assay

2007 ◽  
Vol 14 (6) ◽  
pp. 741-747 ◽  
Author(s):  
Mette A. Strid ◽  
Tine Dalby ◽  
Kåre Mølbak ◽  
Karen A. Krogfelt
Keyword(s):  
Salmonella Enterica ◽  
Blood Donors ◽  
Enzyme Linked Immunosorbent Assay ◽  
Human Antibody ◽  
Specificity And Sensitivity ◽  
Iga Antibodies ◽  
Serovar Typhimurium ◽  
Antibody Levels ◽  
Kinetics Of ◽  
Very High

ABSTRACT Two indirect enzyme-linked immunosorbent assays (ELISAs) were employed to measure levels of immunoglobulin G (IgG), IgM, and IgA antibodies against Salmonella in sera from 303 Danish patients diagnosed by fecal culture with either Salmonella enterica serovar Enteritidis or Salmonella enterica serovar Typhimurium infections. The ELISAs were based on serovar Enteritidis lipopolysaccharide (LPS) and serovar Typhimurium LPS. The antibody levels were assessed approximately 1, 3, 6, and 12 months after the onset of salmonellosis. Sera from 164 healthy blood donors were analyzed to establish cutoff values for each analysis. One month after the onset of symptoms, the sensitivities of the assays were 95% for patients recovering from a serovar Enteritidis infection and 89% for patients recovering from a serovar Typhimurium infection. Three months after the onset of symptoms, these values had decreased to 85% and 55%. At 6 months they were 62% and 40%, and at 12 months they were 40% and 16%, respectively. The specificities of the assays were 97% for the serovar Enteritidis LPS ELISA and 94% for the serovar Typhimurium LPS ELISA. The high values for both sensitivity and specificity make these two ELISAs useful for serodiagnoses of Salmonella infection shortly after the acute phase of the infection and of Salmonella-associated reactive arthritis, as well as for seroepidemiological studies. A mixed ELISA consisting of both antigens, i.e., serovar Enteritidis and serovar Typhimurium LPS, was developed as a diagnostic tool with very high values for both specificity and sensitivity.

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