scholarly journals Seroprevalence of COVID-19 IgM and IgG antibodies among asymptomatic individuals in Khartoum State-2020

2021 ◽  
Vol 9 (3) ◽  
pp. 68-70
Author(s):  
Mohammed Ahmed Ibrahim Ahmed ◽  
Magdi Babikir Omer ◽  
Abduwahab Abakar Fadil ◽  
Nahla Ahmed Mohammed Abdelrahman ◽  
Nassreldeen Khalid Abdelrahman Adam ◽  
...  
Keyword(s):  
Igg Antibodies ◽  
Asymptomatic Individuals

scholarly journals Occurrence of COVID-19 Symptoms During SARS-CoV-2 Infection Defines Waning of Humoral Immunity

2021 ◽  
Vol 12 ◽  
Author(s):  
Jun Wu ◽  
Bo-Yun Liang ◽  
Yao-Hui Fang ◽  
Hua Wang ◽  
Xiao-Li Yang ◽  
...  
Keyword(s):  
Humoral Immunity ◽  
Antibody Responses ◽  
Surveillance Program ◽  
Igg Antibodies ◽  
Immunization Programs ◽  
Specific Igg ◽  
Asymptomatic Infections ◽  
Asymptomatic Individuals ◽  
Specific Igg Antibodies

Approximately half of the SARS-CoV-2 infections occur without apparent symptoms, raising questions regarding long-term humoral immunity in asymptomatic individuals. Plasma levels of immunoglobulin G (IgG) and M (IgM) against the viral spike or nucleoprotein were determined for 25,091 individuals enrolled in a surveillance program in Wuhan, China. We compared 405 asymptomatic individuals who mounted a detectable antibody response with 459 symptomatic COVID-19 patients. The well-defined duration of the SARS-CoV-2 endemic in Wuhan allowed a side-by-side comparison of antibody responses following symptomatic and asymptomatic infections without subsequent antigen re-exposure. IgM responses rapidly declined in both groups. However, both the prevalence and durability of IgG responses and neutralizing capacities correlated positively with symptoms. Regardless of sex, age, and body weight, asymptomatic individuals lost their SARS-CoV-2-specific IgG antibodies more often and rapidly than symptomatic patients did. These findings have important implications for immunity and favour immunization programs including individuals after asymptomatic infections.

scholarly journals Seroprevalence of SARS-CoV-2 IgM and IgG antibodies in an asymptomatic population in Sergipe, Brazil

2020 ◽  
Vol 44 ◽  
pp. 1
Author(s):  
Lysandro Pinto Borges ◽  
Aline Fagundes Martins ◽  
Mônica Santos de Melo ◽  
Makson Gleydson Brito de Oliveira ◽  
José Melquiades de Rezende Neto ◽  
...  
Keyword(s):  
Health Workers ◽  
Cross Sectional Study ◽  
Igg Antibodies ◽  
Sample Collection ◽  
Exclusion Criteria ◽  
Cross Sectional ◽  
High Prevalence ◽  
The Mean ◽  
Asymptomatic Individuals ◽  
Group D

Objective: To estimate the prevalence of SARS-CoV-2 antibodies in an asymptomatic population in the state of Sergipe, Brazil. Methods: This cross-sectional study with stratified sampling (sex and age) includeD serological immunofluorescent tests for IgM and IgG on samples from 3 046 asymptomatic individuals. Sample collection was performed in wet-markets of the 10 most populous cities of Sergipe, Brazil. Exclusion criteria included symptomatic individuals and health workers. The presence of comorbidities was registered. Results: Of the 3 046 participants, 1 577 (51.8%) were female and 1 469 (48.2%) were male; the mean age was 39.76 (SD 16.83) years old. 2 921 tests were considered valid for IgM and 2 635 for IgG. Of the valid samples, 347 (11.9% [CI 10.7%–13.1%]) tested positive for IgM and 218 (8.3% CI 7.2%–9.4%]) tested positive for IgG. Women over 40 had the highest prevalence for IgM (group C, p=0.006; group D p=0.04). The capital Aracaju displayed the highest prevalence for both antibodies; 83 (26.3% [CI 21.6%-31.6%]) tested positive for IgM and 35 (14.6% [CI 10.4%-19.7%]) for IgG. The most prevalent comorbidities were hypertension (64/123 individuals) and diabetes (29/123). Conclusions: A high prevalence of SARS-CoV-2 antibodies was found among asymptomatic persons in Sergipe. Women over 40 showed the highest rates. The capital, Aracaju, displayed the highest seroprevalence. Surveys like this one are important to understand how the virus spreads and to help authorities to plan measures to control it. Repeated serologic testing are required to track the progress of the epidemic.

scholarly journals Detectable SARS-CoV-2 RNAemia in Critically Ill Patients, but Not in Mild and Asymptomatic Infections

2021 ◽  
Vol 48 (3) ◽  
pp. 154-160
Author(s):  
Enrico Richter ◽  
Doaa Al Arashi ◽  
Bianca Schulte ◽  
Christian Bode ◽  
Benjamin Marx ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Blood Donation ◽  
Igg Antibodies ◽  
Blood Samples ◽  
Exact Test ◽  
Asymptomatic Patients ◽  
Neutralizing Capacity ◽  
Asymptomatic Individuals ◽  
Pcr Targeting

<b><i>Background:</i></b> The SARS-CoV-2 pandemic has challenged many of our current routine practices in the treatment and care of patients. Given the critical importance of blood donation and transfusion we analyzed 92 blood samples of individuals infected with SARS-CoV-2 stratified by symptoms. <b><i>Study Design and Methods:</i></b> We therefore tested blood samples for SARS-CoV-2 via RT-PCR targeting the E gene. In addition, we tested each blood sample for anti-SARS-CoV-2 IgG antibodies via ELISA and performed plaque reduction neutralization tests. <b><i>Results:</i></b> SARS-CoV-2 RNA was absent in the blood of mild to asymptomatic patients (57 individuals) and only detectable in individuals with severe COVID-19 who were admitted to the intensive care unit (35 individuals) (<i>n</i> = 6/92 [6.5%]; <i>p</i> = 0.023 Fisher’s exact test). Interestingly, anti-spike IgG antibodies were not significantly higher in intensive care unit patients compared to mild patients, but we found that their neutralizing capacity was disproportionately increased (<i>p</i> &#x3c; 0.001). <b><i>Conclusion:</i></b> Our observations support the hypothesis that there are no potential hazards from blood or plasma transfusion of SARS-CoV-2-positive individuals with mild flu-like symptoms and more importantly of asymptomatic individuals.

scholarly journals Occurrence of COVID-19 symptoms during SARS-CoV-2 infection defines waning of humoral immunity

2021 ◽  
Author(s):  
Jun Wu ◽  
Boyun Liang ◽  
Yaohui Fang ◽  
Hua Wang ◽  
Xiaoli Yang ◽  
...  
Keyword(s):  
Humoral Immunity ◽  
Antibody Responses ◽  
Surveillance Program ◽  
Igg Antibodies ◽  
Immunization Programs ◽  
Specific Igg ◽  
Asymptomatic Infections ◽  
Asymptomatic Individuals ◽  
Specific Igg Antibodies

Approximately half of the SARS-CoV-2 infections occur without apparent symptoms, raising questions regarding long-term humoral immunity in asymptomatic individuals. Plasma levels of immunoglobulin G (IgG) and M (IgM) against the viral spike or nucleoprotein were determined for 25,091 individuals enrolled in a surveillance program in Wuhan, China. We compared 405 asymptomatic individuals with 459 symptomatic COVID-19 patients. The well-defined duration of the SARS-CoV-2 endemic in Wuhan allowed a side-by-side comparison of antibody responses following symptomatic and asymptomatic infections without subsequent antigen re-exposure. IgM responses rapidly declined in both groups. However, both the prevalence and durability of IgG responses and neutralizing capacities correlated positively with symptoms. Regardless of sex, age, and body weight, asymptomatic individuals lost their SARS-CoV-2-specific IgG antibodies more often and rapidly than symptomatic patients. These findings have important implications for immunity and favour immunization programs including individuals after asymptomatic infections.

scholarly journals Defining the features and duration of antibody responses to SARS-CoV-2 infection associated with disease severity and outcome

2020 ◽  
Vol 5 (54) ◽  
pp. eabe0240 ◽  
Author(s):  
Katharina Röltgen ◽  
Abigail E. Powell ◽  
Oliver F. Wirz ◽  
Bryan A. Stevens ◽  
Catherine A. Hogan ◽  
...  
Keyword(s):  
Acute Illness ◽  
Antibody Responses ◽  
Serological Response ◽  
Receptor Binding Domain ◽  
Igg Antibodies ◽  
Angiotensin Converting Enzyme 2 ◽  
Inpatient Outcomes ◽  
Plasma Antibody ◽  
Longitudinal Plasma ◽  
Asymptomatic Individuals

SARS-CoV-2-specific antibodies, particularly those preventing viral spike receptor binding domain (RBD) interaction with host angiotensin-converting enzyme 2 (ACE2) receptor, can neutralize the virus. It is, however, unknown which features of the serological response may affect clinical outcomes of COVID-19 patients. We analyzed 983 longitudinal plasma samples from 79 hospitalized COVID-19 patients and 175 SARS-CoV-2-infected outpatients and asymptomatic individuals. Within this cohort, 25 patients died of their illness. Higher ratios of IgG antibodies targeting S1 or RBD domains of spike compared to nucleocapsid antigen were seen in outpatients who had mild illness versus severely ill patients. Plasma antibody increases correlated with decreases in viral RNAemia, but antibody responses in acute illness were insufficient to predict inpatient outcomes. Pseudovirus neutralization assays and a scalable ELISA measuring antibodies blocking RBD-ACE2 interaction were well correlated with patient IgG titers to RBD. Outpatient and asymptomatic individuals’ SARS-CoV-2 antibodies, including IgG, progressively decreased during observation up to five months post-infection.

scholarly journals SARS-CoV-2 serology in 4000 health care and administrative staff across seven sites in Lombardy, Italy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Maria Teresa Sandri ◽  
Elena Azzolini ◽  
Valter Torri ◽  
Sara Carloni ◽  
Chiara Pozzi ◽  
...  
Keyword(s):  
Geographical Location ◽  
Self Report ◽  
Administrative Staff ◽  
Family Interactions ◽  
Igg Antibodies ◽  
Healthcare Facilities ◽  
Asymptomatic Individuals ◽  
Number Of Individuals ◽  
Comparable Magnitude ◽  
Positive Population

AbstractLombardy is the Italian region most affected by COVID-19. We tested the presence of plasma anti-SARS-CoV-2 IgG antibodies in 3985 employees across 7 healthcare facilities in areas of Lombardy with different exposure to the SARS-CoV-2 epidemic. Subjects filled a questionnaire to self-report on COVID-19 symptoms, comorbidities, smoking, regular or remote working, and the exposure to COVID-infected individuals. We show that the number of individuals exposed to the virus depended on the geographical location of the facility, ranging between 3 and 43%, consistent with the spatial variation of COVID-19 incidence in Lombardy, and correlated with family interactions. We observed a higher prevalence of females than males positive for IgG, however the level of antibodies was similar, suggesting a comparable magnitude of the anti-spike antibody response. IgG positivity among smokers was lower (7.4% vs 13.5%) although without difference in IgG plasma levels. We observed 11.9% of IgG positive asymptomatic individuals and another 23.1% with one or two symptoms. Interestingly, among the IgG positive population, 81.2% of subjects with anosmia/dysgeusia and fever were SARS-CoV-2 infected, indicating that these symptoms are strongly associated to COVID-19. In conclusion, the frequency of IgG positivity and SARS-CoV-2 infection is dependent on the geographical exposure to the virus and primarily to family rather than hospital exposure.

scholarly journals IgG serology in health care and administrative staff populations from 7 hospitals representative of different exposures to SARS-CoV-2 in Lombardy, Italy

2020 ◽  
Author(s):  
Maria Teresa Sandri ◽  
Elena Azzolini ◽  
Valter Torri ◽  
Sara Carloni ◽  
Michele Tedeschi ◽  
...  
Keyword(s):  
Health Care ◽  
Geographical Area ◽  
Self Report ◽  
Administrative Staff ◽  
Igg Antibodies ◽  
Lombardy Region ◽  
Smart Working ◽  
Asymptomatic Individuals ◽  
Number Of Individuals ◽  
Comparable Magnitude

AbstractLombardy is one of the regions in Italy most affected by COVID-19. We assessed the diffusion of the virus via testing plasma anti-SARS-CoV-2 IgG antibodies in 3985 employees of 7 different hospitals, located across the Lombardy region in areas with different exposure to the epidemic. Subjects filled an anamnestic questionnaire to self-report on COVID-19 symptoms, co-morbidities, smoking, regular or smart-working, and the exposure to COVID-19-infected individuals. We show that the number of individuals exposed to the virus depended on the geographical area where the hospital was located and ranged between 3 to 43% which correlated with the incidence of COVID-19 in Lombardy. There was a higher prevalence of females than males positive for IgG, however the level of antibodies was similar, suggesting a comparable magnitude of the response. We observed 10% of IgG positive asymptomatic individuals and another 20% with one or two symptoms. 81% of individuals presenting both anosmia/ageusia and fever resulted SARS-CoV-2 infected. IgG positivity correlated with family contacts.In conclusion, the frequency of IgG positivity and SARS-CoV-2 infection is dependent on the geographical exposure to the virus and to extra-hospital exposure.

The Application of Protein A-Gold Immunocytochemistry to Studies of Protein Secretion

1985 ◽  
Vol 43 ◽  
pp. 426-429
Author(s):  
George H. Herbener ◽  
Antonio Nanci ◽  
Moise Bendayan
Keyword(s):  
Tissue Section ◽  
Colloidal Gold ◽  
Unit Area ◽  
Protein A ◽  
Extracellular Proteins ◽  
Gold Complex ◽  
Second Step ◽  
Igg Antibodies ◽  
Tissue Sections ◽  
Antigenic Sites

Protein A-gold immunocytochemistry is a two-step, post-embedding labeling procedure which may be applied to tissue sections to localize intra- and extracellular proteins. The key requisite for immunocytochemistry is the availability of the appropriate antibody to react in an immune response with the antigenic sites on the protein of interest. During the second step, protein A-gold complex is reacted with the antibody. This is a non- specific reaction in that protein A will combine with most IgG antibodies. The ‘label’ visualized in the electron microscope is colloidal gold. Since labeling is restricted to the surface of the tissue section and since colloidal gold is particulate, labeling density, i.e., the number of gold particles per unit area of tissue section, may be quantitated with ease and accuracy.

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