Incidence and sero-surveillance of feline viruses in Korean cats residing in Gyeonggi-do

Incidences of major feline viral diseases provide basic information for preventing viral disease in cats. Despite the growing interest in feline viral diseases, sero-surveillances have been lacking. In this study, we analyzed the diagnoses of feline viral diseases and conducted a sero surveillance of feline panleukopenia virus (FPV), feline calicivirus (FCV), feline herpesvirus-1 (FHV-1), and feline infectious peritonitis virus (FIPV) in Korean cats. Of the 204 confirmed cases since 2015, the numbers of diagnoses for FPV, FIPV, FCV, feline influenza virus, and FHV-1 were 156, 32, 12, 3, and 1 case, respectively. In total, 200 sera, collected between 2019 and 2021, were screened for the presence of antibodies against FPV, 2 FCVs, FHV-1, and FIPV using a hemagglutination inhibition test and a virus-neutralizing assay (VNA). The overall seropositive rates in cats tested for FPV, the 2 FCVs, FHV-1, and FIPV were 92.5%. 42.0%, 37.0%, 52.0%, and 14.0%, respectively. A low correlation (r = 0.466) was detected between the VNA titers of 2 FCV strains. The highest incidence and seropositive rate of FPV reveal that FPV is circulating in Korean cats. The low r-value between 2 FCVs suggests that a new feline vaccine containing the 2 kinds of FCVs is required.

Preparation and identification of broad-spectrum monoclonal antibodies against N protein of avian infectious bronchitis virus

[Objective] To prepare broad-spectrum monoclonal antibody against N protein of avian infectious bronchitis virus (IBV), so as to lay a foundation for identifying conservative domain epitope of N protein and establish a universal IBV detection method. [Method] N protein of GX-YL5, a representative strain of IBV dominant serotype in Guangxi, was expressed in prokaryote. BALB/c mice were immunized with the purified protein. After the serum titer of the immunized mice reached 104 or more, the splenocytes were fused with SP2/0 myeloma cells. After screening by indirect ELISA, monoclonal antibody was prepared by ascites-induced method. Western blotting, IFA and indirect ELISA were used to identify the titer, subtype, reaction specificity and cross-reaction spectrum. And the prepared monoclonal antibody was used for immunohistochemical detection. And the prepared monoclonal antibody was used to detect the IBV in the trachea and kidney tissues of SPF chickens artificially infected with 4 representative IBV variants (GX-N130048, GX-N160421, GX-QZ171023 and GX-QZ170728). [Result] The prepared monoclonal antibody N2D5 had a titer greater than 217 and its subtype was IgG2b. The Western blotting and IFA results showed that the monoclonal antibody N2D5 only reacted with IBV, and were negative with Newcastle disease virus (NDV), infectious laryngotracheitis virus (ILTV), avian metapneumovirus (aMPV), infectious bursal disease virus (IBDV), avian leukosis virus (ALV) and Marek's disease virus (MDV). Monoclonal antibody N2D5 reacted with many genotypes in China and all 7 serotypes of IBV currently prevalent in Guangxi, including commonly used standard strains, vaccine strains and field strains. Immunohistochemistry showed that the virus signals could be detected in the trachea and kidney tissues of SPF chickens at different time after artificial infection of 3 representative IBV strains from chicken and 1 isolated strain from duck, which further proved its broad spectrum. [Conclusion] The monoclonal antibody N2D5 of IBV prepared based on hybridoma technology belongs to the IgG2b subtype. It has the characteristics of high specificity, wide response spectrum and strong binding ability with IBV. It can be used as a specific diagnostic antibody for clinical diagnosis of IBV and the study of virus distribution.

Rapid cassette test results in anti-SARS-CoV-2 antibody screening verification by electrochemiluminescence immunoassay method

Objective: Since the resumption of face-to-face education in October 2020, which was suspended due to the COVID-19 pandemic, coincides with the period when SARS-CoV-2 infection rates in young adults are on the rise. This study focuses on the 2019 corona virus outbreak in young adults, the largest link in the chain of transmission, which can be defined as silent contagious agents. It is aimed to provide epidemiological data by detecting virus disease (COVID-19) seropositivity with two different serological methods, and to evaluate the symptom-test performance relationship of asymptomatic/mild symptom/symptomatic cases. Methods: A cross-sectional study was conducted with students studying at Cappadocia University health programs between December 2020 and February 2021 and who will attend practice courses face-to-face. Participants were surveyed about their COVID-19 symptoms and disease histories based on SARS-CoV-2 exposure. For SARS-CoV-2 antibody detection, blood samples were taken from the participants and investigated with a single lateral flow immunoAssay (LFIA, Novatech, Turkey) cassette test. The samples with positive test result were then SARS-CoV-2 Anti-N IgM+IgG;SARS-CoV-2 Anti-S IgM+IgG;SARS-CoV-2 Anti-RBD IgG;It was re-evaluated using the electrochemiluminescence immunoassay (ECLIA) method with the anti-SARS-CoV-2 kit (Roche, Germany). Results: Of the 239 samples participating in the study, 50 (20.9%) samples that were positive for SARS-CoV2 IgM/ IgG according to the LFIA method were then studied again with the ECLIA method. According to the ECLIA result, 72% (36/50) of individuals against both nucleocapsid (N) and spike (S) antigens, and 70% (35) against RBD antigen were seropositive. Based on the ECLIA test results, 239 samples were studied and 50 samples were found to be IgM/IgG positive, with a sensitivity of 64% and a specificity of 93%. Contingence history was reported in 46% (n=23) of patients who were seropositive by both methods, while 30% (n=15) showed a COVID-19 clinic. Fifty four percent (n=27) of the participants reported that they did not have a PCR (polymerase chain reaction) test, but antibody response was observed in all of them. Only 28% (n=14) of seropositive patients reported positive PCR results, and 4% of them stated that they had a chronic disease. It will be important to continue to observe the serological status of young people, particularly in the context of new COVID-19 variants and in the low interest in mass vaccination campaigns targeting young people. Conclusion: It is thought that the performance of ECLIA with rapid casette test does not have a good degree of agreement and confirmation with different immunoassay tests would be more useful for epidemiological surveillance. Especially the new COVID-19 in the context of the variants and targeting youth due to the lack of interest in vaccination champaigns continue to monitor the serological status of young people it will be important.

Evaluation of the risks associated with the transmission of SARS-CoV-2 during a professional football club's training in Brazil

COVID-19 is an infectious disease with respiratory transmission caused by the new coronavirus. Due to the high viral transmissibility, sports activities were severely impacted all over the world and in Brazil football was paralyzed for about four months. The objective of this study was to identify the activities with the highest risk of Covid-19 transmission in a professional soccer club in Rio de Janeiro based on a cross-sectional study with a semi-quantitative emphasis. The results showed that physical training showed a greater number of touches (105) with a high prevalence of hand on the ball (94%). The antibody search found that 24,2% tested positive for IgG during the study. During the training phase, no cases of SARS-CoV-2 transmission between players and staff were identified. It is believed that biosafety measures and the individual and collective commitment of everyone to social isolation and hygiene measures are an important strategy for the viability of sports activities.

Comparative evaluation of Luminex based assays for detection of SARS-CoV-2 antibodies in a transplantation laboratory.

BACKGROUND: Detection of SARS-CoV-2 antibodies is essential in establishing the parameters of an individual's immune response to COVID-19, from both natural infection and vaccination. Despite this, there is currently limited clinical guidance or recommendations for serological methods for their measurement. Here, we evaluate and compare four Luminex-based assays for the multiplex detection of IgG SARS-CoV-2 antibodies. METHODS: The four assays tested were Magnetic Luminex Assay, MULTICOV-AB Assay, Luminex xMAP SARS-CoV-2 Multi-Antigen IgG Assay and LABScreen COVID Plus Assay. Each assay's ability to detect antibodies to SARS-CoV-2 Spike (S), Nucleocapsid (N) and Spike-Receptor Binding Domain (RBD) was evaluated using 50 test samples (25 positive, 25 negative), previously tested by a widely used ELISA technique. RESULTS: The MULTICOV-AB Assay had the highest clinical performance detecting antibodies to S trimer and RBD in 100% (n = 25) of known positive samples. Both the Magnetic Luminex Assay and LABScreen COVID Plus Assay showed significant diagnostic accuracy with sensitivities of 90% and 88% respectively. The Luminex xMAP SARS-CoV-2 Multi-Antigen IgG Assay demonstrated limited detection of antibodies to the S antigen resulting in a sensitivity of 68%. CONCLUSION: Luminex-based assays provide a suitable serological method for multiplex detection of SARS-CoV-2 specific antibodies, with each assay able to detect antibodies to a minimum of 3 different SARS-CoV-2 antigens. Assay comparison identified there is moderate performance variability between manufacturers and further inter-assay variation of antibodies detected to different SARS-CoV-2 antigens.

Specific antibodies of 95 health care workers vaccinated with inactivated 2019-nCoV vaccines

OBJECTIVE: To investigate the immune antibodies in blood specimens of 95 health care workers vaccinated with inactivated 2019-nCoV vaccines and explore the rules and characteristics of production of antibodies after vaccination. METHODS: From Oct 2020 to Jul 2021, the venous blood specimens were collected from 95 health care workers of the 305 Hospital of PLA after the injection of 2 doses of 2019-nCoV vaccines fo30 days, 65 days, 91 days, 6 months and 9 months. SARS-CoV-2 immunoglobin(Ig) M, IgG and titers of neutralizing antibodies and total antibodies were detected by chemiluminescence immunoassay, the results of antibody tests were dynamically analyzed, the immune durability of the antibody, influencing factors and correlation were determined. RESULTS: Almost all of the subjects produced IgG, neutralizing antibody and total antibody, some subjects retained high level of IgM titer. Smoking could affect the production of total antibody. The subjects of the low body weight group produced higher level of IgG, and there was no significant difference when the weight was over 60 kg. The titers of the four types of antibodies decreased significantly at the following time points, and the positive rates of all the antibodies were less than 50% except for IgG after the vaccination for 9 months. CONCLUSION: Specific IgM and IgG, neutralizing antibody and total antibody can be produced after the 2-doses vaccination of inactivated 2019-nCoV vaccines. But the titers and positive rates of the antibodies decrease with time, which means the protective effects on the body decrease. Therefore, in order to improve the autoimmunity against novel coronavirus, one booster vaccination of an inactivated 2019-nCoV vaccine will be necessary after the 2 doses of vaccination for 6 months.

Analysis of serum SARS-CoV-2 antibody IgG tests after booster vaccination of COVID-19 vaccine in 205 individuals

Objective To analyze IgG test results of serum SARS-CoV-2 antibody in people after booster vaccinations against SARS-CoV-2, and to provide a basis for the booster vaccination. Methods There were 314 healthy individuals who had been vaccinated with the COVID-19 vaccine. Depending on their inoculation situation, they were divided into three groups:the booster injection group(1 week to 2 months after booster vaccination)of 205 cases, <180 days after two doses group(<180 days after two doses of COVID-19 vaccine)of 49 cases, and >180 days after two doses group(>180 days after two doses of COVID-19 vaccine)of 60 cases. The positive rate of IgG in serum of the three groups was measured using the colloidal gold method. Results The serum COVID-19 antibody IgG positive rates were 83.9% in the booster injection group, 18.4% in the <180 days after two doses group, and 5.0% in the >180 days after two doses group, with statistically significant difference between any two groups(all P < 0.05). In the booster injection group, the serum COVID-19 antibody IgG positive rate was 85.2% in people who received a booster injection more than a month, while those who received a booster injection less than a month had a positive rate of 75.9%, and there was no significant difference between these two groups(P > 0.05). In the booster injection group, the positive rates of serum COVID-19 antibody IgG were 85.1% in males and 82.4% in females, with no significant difference(P > 0.05). In the booster injection group, people at the age of 18 and 50 had a positive serum COVID-19 antibody IgG rate of 86.0%, while those over 50 had a positive rate of 58.3%, and there was significant difference between them(P < 0.05). Conclusions Compared with two injections of the COVID-19 vaccine, the booster injection can significantly increase the positive rate of the antibody IgG of COVID-19, which results in a stronger immune response. There is a lower IgG positive rate of COVID-19 antibodies in those aged over 50 years following the booster dose of COVID-19 vaccine than in those aged 18- 50 years.

Differentiating infectious from non-infectious respiratory disease in the cat and dog

This paper describes the clinical signs and use of differential laboratory diagnostic techniques (computed tomography, cytology, histopathology, antigen/antibody detection and polymerase chain reaction) for infectious (viral, bacterial, fungal and parasitic) and non-infectious (inflammatory/immune mediated, neoplastic, cardiac, malformation, foreign body, smoke inhalation, aspiration of caustic material, non-cardiogenic, pulmonary oedema, traumativ, pneumothorax, pulmonary contusions and idiopathic) causes of respiratory diseases in cats and dogs in Ontario, Canada.

The Avon Longitudinal Study of Parents and Children - A resource for COVID-19 research: Antibody testing results, April - June 2021.

The Avon Longitudinal Study of Parents and Children (ALSPAC) is a prospective population-based cohort which recruited pregnant women in 1990-1992 and has followed these women, their partners (Generation 0; G0) and their offspring (Generation 1; G1) ever since. The study reacted rapidly and repeatedly to the coronavirus disease 2019 (COVID-19) pandemic, deploying multiple online questionnaires and a previous home-based antibody test in October 2020. A second antibody test, in collaboration with ten other longitudinal population studies, was completed by 4,622 ALSPAC participants between April and June 2021. Of 4,241 participants with a valid spike protein antibody test result (8.2% were void), indicating antibody response to either COVID-19 vaccination or natural infection, 3,172 were positive (74.8%). Generational differences were substantial, with 2,463/2,555 G0 participants classified positive (96.4%) compared to 709/1,686 G1 participants (42.1%). Of 4,199 participants with a valid nucleocapsid antibody test result (9.2% were void), suggesting potential and recent natural infection, 493 were positive (11.7%); 248/2,526 G0 participants (9.8%) and 245/1,673 G1 participants (14.6%) tested positive, respectively. We also compare results for this round of testing to that undertaken in October 2020. Future work will combine these test results with additional sources of data to identify participants' COVID-19 infection and vaccination status. These ALSPAC COVID-19 serology data are being complemented with linkage to health records and Public Health England pillar testing results as they become available, in addition to four previous questionnaire waves and a prior antibody test. Data have been released as an update to the previous COVID-19 datasets. These comprise: 1) a standard dataset containing all participant responses to all four previous questionnaires with key sociodemographic factors; and 2) individual participant-specific release files enabling bespoke research across all areas supported by the study. This data note describes the second ALSPAC antibody test and the data obtained from it.

SARS-CoV-2 Seroprevalence Compared with Confirmed COVID-19 Cases among Children, Colorado, USA, May-July 2021.

To compare SARS-CoV-2 antibody seroprevalence among children with seropositive confirmed COVID-19 case counts (case ascertainment by molecular amplification) in Colorado, USA, we conducted a cross-sectional serosurvey during May-July 2021. For a convenience sample of 829 Colorado children, SARS-CoV-2 seroprevalence was 36.7%, compared with prevalence of 6.5% according to individually matched COVID-19 test results reported to public health. Compared with non-Hispanic White children, seroprevalence was higher among Hispanic, non-Hispanic Black, and non-Hispanic other race children, and case ascertainment was significantly lower among Hispanic and non-Hispanic Black children. This serosurvey accurately estimated SARS-CoV-2 prevalence among children compared with confirmed COVID-19 case counts and revealed substantial racial/ethnic disparities in infections and case ascertainment. Continued efforts to address racial and ethnic differences in disease burden and to overcome potential barriers to case ascertainment, including access to testing, may help mitigate these ongoing disparities.

Optimal classification and generalized prevalence estimates for diagnostic settings with more than two classes.

An accurate multiclass classification strategy is crucial to interpreting antibody tests. However, traditional methods based on confidence intervals or receiver operating characteristics lack clear extensions to settings with more than two classes. We address this problem by developing a multiclass classification based on probabilistic modeling and optimal decision theory that minimizes the convex combination of false classification rates. The classification process is challenging when the relative fraction of the population in each class, or generalized prevalence, is unknown. Thus, we also develop a method for estimating the generalized prevalence of test data that is independent of classification of the test data. We validate our approach on serological data with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) naïve, previously infected, and vaccinated classes. Synthetic data are used to demonstrate that (i) prevalence estimates are unbiased and converge to true values and (ii) our procedure applies to arbitrary measurement dimensions. In contrast to the binary problem, the multiclass setting offers wide-reaching utility as the most general framework and provides new insight into prevalence estimation best practices.

Low detection rate of RT-PCR-confirmed COVID-19 using IgM/IgG rapid antibody tests in a large community sample in Lima, Peru.

BACKGROUND: Rapid IgM/IgG antibody tests were largely used in lieu of RT-PCR tests as part of COVID-19 public health response activities in Lima, Peru. To assess their utility, we explored the relationship between the time since onset of several COVID-19-related symptoms and the sensitivity of a rapid combined IgM/IgG antibody test. METHODS: We collected data from a community sample of individuals (n = 492) who received concurrent RT-PCR and rapid IgM/IgG antibody testing between May 2020 and March 2021. We estimated the sensitivity of the antibody test, against the RT-PCR test, by weeks since symptom onset via segmented regression analysis. RESULTS: The overall sensitivity of the rapid IgM/IgG antibody test was 46.7% (95% CI, 42.4-51.2%). Among 372 (75.6%) participants who reported COVID-19-related symptoms, sensitivity increased from 30.4% (95% CI, 24.7-36.6%) in week 1 after symptom onset to 83.3% (95% CI, 41.6-98.4%) in week 4. The test sensitivity increased by 31.9% (95% CI, 24.8-39.0%) per week until week 2 to 3, then decreased by - 6.0% (95% CI, - 25.7-13.7%) per week thereafter. CONCLUSION: Rapid antibody tests are a poor substitute for RT-PCR testing, regardless of presenting symptoms. This highlights the need for future pandemic planning to include timely and equitable access to gold-standard diagnostics, treatment, and vaccination.

Prevalence estimation and optimal classification methods to account for time dependence in antibody levels.

Serology testing can identify past infection by quantifying the immune response of an infected individual providing important public health guidance. Individual immune responses are time-dependent, which is reflected in antibody measurements. Moreover, the probability of obtaining a particular measurement from a random sample changes due to changing prevalence (i.e., seroprevalence, or fraction of individuals exhibiting an immune response) of the disease in the population. Taking into account these personal and population-level effects, we develop a mathematical model that suggests a natural adaptive scheme for estimating prevalence as a function of time. We then combine the estimated prevalence with optimal decision theory to develop a time-dependent probabilistic classification scheme that minimizes the error associated with classifying a value as positive (history of infection) or negative (no such history) on a given day since the start of the pandemic. We validate this analysis by using a combination of real-world and synthetic SARS-CoV-2 data and discuss the type of longitudinal studies needed to execute this scheme in real-world settings.

Special Issue: Detection of SARS-CoV-2 antibodies in diagnosis and treatment of COVID-19. (Special Issue: Detection of SARS-CoV-2 antibodies in diagnosis and treatment of COVID-19.)

This special issue contains 8 reviews describing the timing and durability of antibody responses, which are critical factors in the interpretation of these serology results. The distinction between detection of binding antibodies and neutralizing antibodies that may confer clinical immunity is another important recurring theme. There are also important perspectives that are shared between multiple reviews, including information and guidelines on the evaluation of different assays. Some articles detail the immunologic responses involved in immune responses to SARS-CoV-2, along with some that comment on implications of new SARS-CoV-2 variants. Finally, there are perspectives about the importance of antibodies in clinical management and vaccination.

Source tracing of the COVID-19 infection case in Guangxi, China

The study describing the process of discovery and source tracing of a native case of coronavirus disease 2019 (COVID-19) infection on Jan 2021, in Guangxi, China, to provide methodology for source investigation better in the future. Following the Epidemiological Investigation Plan for COVID-19 (version 7), information of the native COVID-19 case and related close contacts were collected. Real time reverse transcription-quantitative polymerase chain reaction was performed to detect the nucleic acids of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in samples collected from the infection case, related close contacts, and the environment, combined with serum specific antibody detection. The positive nucleic acid samples were undergone whole genome sequencing, phylogenetic analysis and analyses of variation of amino acids. The whole genome sequence from the native case and the imported asymptomatic infected case from Indonesia containing 25 nucleotide mutation sites belong to L-Lineage European Branch II. 3. The imported asymptomatic case was the source of infection of this native case. The possible route of infection was that native case was exposed to contaminated environment by imported case, due to improper personal protective equipment. A focus on local outbreaks of COVID-19 caused by SARS-CoV-2-infected people from outside China is needed.

Preparation of antibodies against the spike glycoprotein of SARS -CoV- 2 and establishment of a double antibody sandwich ELISA for detection of the spike glycoprotein

The coronavirus disease 2019 (COVID-19) pandemic poses a serious threat to human life and health. To establish a method for quantitative detection of detection of the spike glycoprotein of severe acute respiratory syndrome coronavirus'Z (SARS-CoV-Z) in vaccines. Goat anti-SARS-CoV-Z polyclonal antibody and mouse anti -SARS -CoV-Z spike glycoprotein monoclonal antibody were prepared to establish a double antibody sandwich enzymerlinked immunosorbent assay (ELISA) for detection of the spike glycoprotein. The ELISA system was optimized and the linear range, sensitivity, specificity, repeatability and coincidence rate were tested. The linear range was 1-64 U and correlation coefficient (R2) > 0.99. There was no reaction with the nucleocapsid protein, Vero-cell debris or influenza Viruses, etc, indicating the high specificity of our method. The sensitivity was 92.1% and the variations in intra- and inter' assay repeatability were 2.5%-11.7% and 1.3% -14.8%, respectively. The samples showed a coincidence rate Of 96.7% with known background. Our method had high specificity, sensitivity, stability and accuracy, and could be used for determination of spike - glycoprotein antigen content in vaccine.

The analytical strategy of GICA and CLIA combination in SARS-CoV-2 antibodies detection

To evaluate the effect of colloidal gold immunochromatographic assay (GCIA) combined with chemiluminescent immunoassay (CLIA) in reducing the false positive of antibodies against severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Thirty-three serum samples from 19 patients with SARS-CoV-2 infection at different times, and 55 serum samples from 55 patients not infected with SARS-CoV-2. but infected instead with other pathogens or suffering from autoimmune diseases were collected from the Affiliated Hospital of North Sichuan Medical College and Nanchong Central Hospital from 22 January to 5 March 2020. Serum IgM and IgG against SARS-CoV-2 were detected by GICA and CLIA respectively, and the results were analyzed. The sensitivity of GCIA for detection of IgM and IgG against SARS - CoV - 2 was 100.0% and 94.74%. respectively, values that were similar with those for CLIA (92.86% and 100.0%) (P = 1.000). The specificity of GCIA for IgM and IgG against SARS-CoV-2 was 70.91% and 74.55% respectively, which was significantly lower than that of CLIA (98.18% and 89.09%) (P < 0.01). The results of IgM and IgG against SARS-CoV-2 detected by the two methods were consistent (P=0.000) . and their Kappa was 0.434 and 0.406. respectively. Analyses of ROC curves showed that the AUC of IgM and IgG against SARS-CoV-2 detected by GCIA was 0.855 and 0.846. respectively, which was significantly lower than that of CLIA (0.955 and 0.945, respectively) (PC0.05). The sensitivity of combined detection of IgM and IgG against SARS -CoV-2 was 92.86% and 94.74%. and the specificity was 100.0% and 100.0%, respectively. Analyses of ROC curves showed that the AUC of combined detection of IgM and IgG against SARS-CoV-2 was 0.964 and 0.974. respectively, which was higher titan that of each method alone. GCIA combined with CLIA can improve the specificity of detection of IgM and IgG against SARS-CoV-2, which may merit clinical application.

COVID-19 Diagnostic Methods and Detection Techniques

Coronavirus disease 2019 (COVID-19) is an emerging human-to-human infectious disease that broke out in early December 2019 and threatens global public health, causing widespread concern. This respiratory disease is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The development of rapid and reliable techniques for COVID-19 diagnosis is a significant step to prevent further infections. Combinations of genome sequencing, nucleic acid molecular testing, clustered regularly interspaced short palindromic repeats editing technology, antigen/antibody detection, and computed tomography imaging have been implemented to identify and screen COVID-19 infections. Moreover, other new diagnosis methods such as dried blood spots and biosensors are being developed and are summarized here. This manuscript reviews currently available methods for SARS-CoV-2 detection with the aim of helping researchers develop timely and effective technologies to detect this emerging virus and its variants.

Evaluation of two different domestic colloidal gold assay kit fornew coronavirus antibody in low endemic areas

This study aimed to evaluate the application and diagnostic efficacy of two different colloidal gold kits for the detection of 2019-nCoV immunoglobulin M antibody (anti-IgM) and immunoglobulin G antibody (anti-IgG) in Beijing, a low endemic area, and to guide the rational clinical application. The sera of 29 patients with confirmed novel coronavirus pneumonia (COVID-19) and 19 411 patients from the non-infected screening population were selected to evaluate the sensitivity, specificity and false-positive rate of the 2019-nCoV antibody test kits from Zhuhai Lizhu and Tangshan Innotek using colloidal gold immunochromatography. The sensitivity of Inotec 2019-nCoV was slightly higher than that of Lizhu 2019-nCoV, with a sensitivity of 58.62% and 55.17%, respectively;the specimen collection time of the all-negative group was significantly less than that of the antibody-positive group (P < 0.05);the false-positive rate of the two reagents in the low-prevalence area was 0.16%, and the false-positive rate of 2019-nCoV IgG was higher in Inotec than in Lizhu. The false positive rate for 2019-nCoV IgM was significantly higher than that for IgG for the same brand (Inotec ?2=14.756 09, P=0.000 0;Lizhu ?2=27.492 62, P=0.000). Conclusion The 2019-nCoV antibody test is rapid, simple and easy to perform, with high specificity, and can be used as a rapid screening indicator for new crowns;the specificity, correctness and negative predictive value of the two kits are good, and the application of the other kit for retesting when a positive result occurs can reduce the false positive rate of informing the clinic;the application and analysis of positive reports of new crown antibodies should be combined with the endemic area and clinical comprehensive judgment.