Detection Of IgG Antibodies Research Articles

Prevalence and risk factors of Toxoplasma gondii infection in dairy cattle from the Western Region of Thailand.

In total, 901 dairy cow sera and data were collected from 51 farms in Nakhon Pathom, Ratchaburi and Kanchanaburi provinces (Western Region of Thailand). Serum samples were processed via the multispecies ELISA method to detect IgG antibodies against Toxoplasma gondii infection. The results demonstrated that the calculated true prevalence was 1.48% (95% CI, 0.64-2.75%) for the individual-level and 29.41% (95% CI, 18.71-43%) for the farm-level. The univariate risk factor analysis showed that the number of total owned cats, the presence of stray cats, and the frequency of cleaning per day were significant factors (p<0.2). These three factors were subjected to logistic regression analysis, and the results revealed that the frequency of cleaning farms per day was a potential risk factor for T. gondii-seropositive farms (OR=2.745, 95% CI, 1.15-8.69, p=0.02). The frequency of cleaning might increase the T. gondii oocyst distribution within the barn area, thus increasing the possibility of infection. Our findings show that T. gondii continues to circulate in the dairy cow population in the western part of Thailand. The presence of cats on farms was not found to be associated with T. gondii infection, but the high frequency of cleaning the floor was, and contributed to the potential risk of infection.

West Nile virus seropositivity in Alanya, a coastal city in the Mediterranean region of Turkey.

West Nile virus (WNV)-related illness is a global health problem. Understanding the seropositivity rates and identifying the risk factors related to WNV in various animal species including humans is crucial for the implementation of effective prevention strategies. Assess the rate of seropositivity and the risk factors associated with WNV seropositivity. Descriptive, cross-sectional. Microbiology and virology departments in a veterinary college. In a sample of healthy human participants in Alanya, located close to regions where WNV activity has been detected, anti-WNV IgG antibody detection was performed using enzyme-linked immunosorbent assays. The positive results were confirmed by virus neutralization tests (VNTs). The sample was compared with a second group of age- and gender-matched healthy subjects selected from a previous cross-sectional study. Determination of the seropositivity and risk factors that were associated with WNV in healthy humans. 87 in current study; 356 in previous study. The first group of 87, which had a high risk of encountering vector mosquitoes, had a positivity rate of 8% (7/87), whereas positivity in the second group was 4.5% (16/356; P=.181). In the entire sample, the anti-WNV IgG antibody was positive in 23 out of 443 (5.2%) samples by the ELISA test. Among these 23 samples, ten were confirmed as positive using VNTs. Therefore, the WNV IgG seropositivity was 2.3% (10/442). Confirmed IgG seropositivity rates were higher among male (3.8%) than female participants (0.9%; P=.054) and among adults aged ≥45 years (4%) than those aged 18-44 years (0.8%; P=.048). This study highlights the presence of WNV infection in the research region. More comprehensive and multidisciplinary studies are required to increase our knowledge about this zoonotic infection including risk factors in line with the One Health approach. Small sample size.

The Susceptibility to Rubella Virus Infection among Pregnant Women Attending Antenatal Clinics in Unguja, Zanzibar: The Need to Employ Multiple Strategies to Control Congenital Rubella Syndrome in Tanzania

Aims: This study was conducted to determine the proportion of pregnant women susceptible to Rubella virus infection in Zanzibar, the information that might be useful in future control interventions.&#x0D; Study Design: A cross-sectional hospital-based study.&#x0D; Place and Duration of Study: The study was conducted in Unguja Zanzibar between May 2023 and July 2023.&#x0D; Methodology: Sociodemographic and other relevant information were collected from pregnant women attending antenatal clinics using structured questionnaires. Blood samples were collected from each consented woman. Detection of Rubella IgG antibodies was done by an indirect Enzyme Linked Immunosorbent Assay. Data analysis was done by using STATA version 15.&#x0D; Results: The median age of enrolled participants was 27[Interquartile range (IQR): 23-31] years while the median gestation age was 28 [IQR: 20-32] weeks. Out of 171 participants, 10/171(5.8%) [95% Cl:2-9.6%] were negative to Rubella virus IgG antibodies indicating susceptibility to active Rubella virus infection that can lead to Congenital Rubella Syndrome. On multivariate analysis, history of congenital malformations (OR: 27.4, 95% CI: 1.29-580.5, p=0.033) was significantly associated with susceptibility to Rubella virus infection.&#x0D; Conclusion: Despite high level of natural immunity, there is a considerable proportion of pregnant women in Zanzibar susceptible to Rubella virus infection necessitating the need for multiple strategies to reach a goal of Congenital Rubella Syndrome elimination.

Manyetik Kantilever ile IgG antikorlarının tespiti

Bu çalışmada, IgG antikorlarını algılamak için kantilever olarak Fe40Ni38Mo4B18 amorf ferromanyetik şerit kullanılmıştır. Sensör yüzeyi IgG dedektesi için fonksiyonel hale getirilmiş ve daha sonra yapılan ölçümlerde ppm ya da ng mertebesinde IgG algılaması yapılmışt

Investigation and analysis on the detection of IgG antibodies against the rubella virus among rural childbearing-age women in preconception period in Yunnan Province from 2013 to 2019

A study was conducted on rural women of childbearing age aged 20-49 who underwent the National Free Preconception Health Examination Project (NFPHEP)in Yunnan Province from 2013 to 2019. Descriptive analysis was conducted to determine the negative rate of IgG antibodies against the rubella virus and its differences among various socio-demographic characteristics. Among the 1 511 203 study subjects, the negative rate of IgG antibodies against the rubella virus was 24.36%. Only 2.64% of the population had received rubella virus vaccine. The negative rate of IgG antibodies among rural childbearing-age women in the preconception period in Yunnan Province decreased with age and educational level (Ptrend<0.001). The negative rate of IgG antibodies in ethnic minority women of childbearing age in the preconception period (25.19%) was higher than that of Han women (23.88%). Among the 22 ethnic groups with over 1 000 participants, the negative rates of IgG antibodies in women of childbearing age from the Blang (32.85%), Bouyei (31.03%), Zhuang (31.01%), and Miao (30.70%) ethnic groups were higher than those of women from other ethnic groups. Among the 16 states (cities) in Yunnan Province, the negative rate of IgG antibodies in pregnant women of childbearing age in Wenshan Zhuang and Miao Autonomous Prefecture (38.06%) and Lincang City (32.63%) was higher than that in other states (cities). The negative rate of serum IgG antibodies in women who reported having received rubella virus vaccine (18.60%) was lower than that in other non-vaccinated populations (24.52%). The proportion of rural women of childbearing age in Yunnan Province who were susceptible to the rubella virus before pregnancy was still high. It is necessary to promote rubella vaccination among people susceptible to rubella, especially pregnant women, to prevent rubella virus infection and reduce the incidence rate and disease burden of rubella people.

Serological evaluation of toxocarosis in Amedyia District, Duhok Governorate, Kurdistan Region Iraq

The ova of Toxocara canis is common environmental contaminants of human habitation, due to the fact that dogs serve as final hosts. The presence of Toxocara ova in the soil which considerable as a risky factor for human public health. Humans, particularly children, frequently ingest these ova accidently and infected with disease. Infection in humans, in contrast to their definitive hosts, remains unusual host, often resulting in disease caused by the migrating larval stages without development to adult stage. This study is the first study in Duhok Governorate and Kurdistan region to determine the seroprevalance of toxocarosis among human population and the relation of the associated factors. A total of 600 blood samples were collected from children and adults of different ages (5-70) years and both genders. Blood samples were collected in a gel tubes, then centrifuged for isolation of sera. The sera were kept at -20ºC until used for detection of anti Toxocara canis IgG antibodies using ELISA. Out of 600 serum samples 38 (6.3 %) were seropositive. The rate of infection was higher in females 22/285 (7.7%) than males 16/315 (5.1%). The individuals belong the age group less than 5 years were more prevalent (21.4%) than other groups followed by age group (5-14) year with infection rate (9.6%). Toxocarosis is prevalent in adults and children of Amedyia district. These results require periodical studies on the rate of infection and associated risk factors in other areas of Duhok Governorate and Kurdistan region.

Detection of IgG antibodies against Borrelia burgdorferi in adults

&#x0D; &#x0D; &#x0D; The aim of this study was to determine the prevalence of IgG antibodies against Borrelia burgdorferi in adults who were bitten by a tick at least once and did not have classical signs and symptoms of Lyme disease. A total of 88 people from different cities in Lithuania were tested for the presence of Lyme disease IgG. The results showed that the prevalence of infection among participants was 11.4%. Unit values ranged from 12.26 U to 44.78 U. A higher number of Lyme disease cases was observed in older people and those who actively spend their time outdoors. This study shows the importance of the use of serological tests in the diagnosis of Lyme disease for patients with non-specific symptoms.&#x0D; &#x0D; &#x0D;

Persistence of T-Cell Immunity Responses against SARS-CoV-2 for over 12 Months Post COVID-19 Infection in Unvaccinated Individuals with No Detectable IgG Antibodies.

Immune response to SARS-CoV-2 is crucial for preventing reinfection or reducing disease severity. T-cells' long-term protection, elicited either by COVID-19 vaccines or natural infection, has been extensively studied thus far; however, it is still attracting considerable scientific interest. The aim of the present epidemiological study was to define the levels of T-cellular immunity response in a specific group of unvaccinated individuals from the general population with a prior confirmed COVID-19 infection and no measurable levels of IgG antibodies. We performed a retrospective descriptive analysis of data collected from the medical records of consecutive unvaccinated individuals recovered from COVID-19, who had proceeded to a large private medical center in the Attica region from September 2021 to September 2022 in order to be examined on their own initiative for SARS-CoV-2 T-cell immunity response. The analysis of T-cell responses was divided into three time periods post infection: Group A: up to 6 months; Group B: 6-12 months; Group C: >12 months. The SARS-CoV-2 T-cell response was estimated against spike (S) and nucleocapsid (N) structural proteins by performing the T-SPOT. COVID test methodology. SARS-CoV-2 IgG antibody levels were measured by the SARS-CoV-2 IgG II Quant assay (Abbott Diagnostics). A total of 182 subjects were retrospectively included in the study, 85 females (46.7%) and 97 (53.3%) males, ranging from 19 to 91 years old (mean 50.84 ± 17.2 years). Among them, 59 (32.4%) had been infected within the previous 6 months from the examination date (Group A), 69 (37.9%) had been infected within a time period > 6 months and <1 year (Group B) and 54 (29.7%) had been infected within a time period longer than 1 year from the examination date (Group C). Among the three groups, a positive T-cell reaction against the S antigen was reported in 47/58 (81%) of Group A, 61/69 (88.4%) of Group B and 40/54 (74.1%) of Group C (chi square, p = 0.27). T-cell reaction against the N antigen was present in 45/58 (77.6%) of Group A, 61/69 (88.4%) of Group B and 36/54 (66.7%) of Group C (chi square, p = 0.02). The median Spot-Forming Cells (SFC) count for the S antigen was 18 (range from 0-160) in Group A, 19 (range from 0-130) in Group B and 17 (range from 0-160) in Group C (Kruskal-Wallis test, p = 0.11; pairwise comparisons: groups A-B, p = 0.95; groups A-C, p = 0.89; groups B-C, p = 0.11). The median SFCs count for the N antigen was 14.5 (ranging from 0 to 116) for Group A, 24 (ranging from 0-168) in Group B and 16 (ranging from 0-112) for Group C (Kruskal-Wallis test, p = 0.01; pairwise comparisons: groups A-B, p = 0.02; groups A-C, p = 0.97; groups B-C, p = 0.03). Our data suggest that protective adaptive T-cellular immunity following natural infection by SARS-CoV-2 may persist for over 12 months, despite the undetectable humoral element.

2070. Outbreak of Crimean-Congo Hemorrhagic Fever in Kyzylorda region, Kazakhstan, March-July 2022

Abstract Background Crimean-Congo Hemorrhagic Fever (CCHF) is a viral tick-borne disease with a high mortality rate. It is endemic in Kazakhstan. The Kyzylorda region reported higher-than-expected cases from March to July 2022 (15 compared to 10 in the previous year). We conducted an investigation to identify additional cases, determine risk factors, and assess CCHF knowledge and practices. Methods We conducted a case-control study in July 2022. We defined cases as PCR-confirmed or hospitalized with CCHF symptoms. The control group was made up of regional contacts including neighbors and household members at a 1:2 ratio. We reviewed medical records from April to July. We conducted face-to-face interviews using structured questionnaires. Blood collected from the control group was tested with PCR and ELISA for detection of IgM and IgG antibodies. We also collected ticks from domestic animals for PCR-testing. We used logistic regression to assess factors associated with CCHF. Results We identified 38 cases (n=15 confirmed, n=7 probable and n=16 suspected cases) and 71 controls. Cases were mostly male (74%) with mean age of 45 (range 17-81); 27% died. Top patient symptoms (n=38) were weakness (100%), headache (97%), fever (84%) and loss of appetite (55%). Risk factors for CCHF were being male (odds ratio and 95% confidence interval: 5.5, CI: 2.3-13.1), animal husbandry (3.1, 1.3-7.2), crop production (4.0, 1.5-10.5), tick contact (262.5, CI: 31.4-2192.2), tick bite (70.0, 8.8-556.9), contact with tick blood (18.7, 2.2-155.9), ticks on the body or clothing (77.8, 9.8-618.9) and having been in places with high tick risk (15.1, CI: 4.6-49.7). The control group were more likely to have awareness of CCHF, know that they can protect themselves from CCHF, refrained from visiting forests and rural areas, used repellents, and taken protective measures to reduce ticks in domestic animals. Of 55 controls tested: one was IgG positive. Of 163 ticks tested, one was PCR-positive. Conclusion Exposure to activities that are high risk for exposure to ticks increased odds of CCHF. Improved awareness of prevention to exposure from ticks, CCHF associated risk factors, and the importance of seeking early treatment is needed. This can be achieved by increasing population awareness and educating medical providers. Disclosures All Authors: No reported disclosures

Evaluation of the Panbio™ COVID-19 IgG rapid test device performance

BackgroundThe Panbio™ COVID-19 IgG Rapid Test Device (“Panbio™”) detects IgG antibodies against the SARS-CoV-2 spike protein from viral infection or vaccination. ObjectivesTo determine the diagnostic sensitivity and specificity of the Panbio™ professional use test, using fingerstick whole blood and venous plasma. Study designFingerstick whole blood and venous plasma from each participant were tested with Panbio™ and compared against the SARS-CoV-2 IgG II assay on the Abbott Architect™ platform (Europe) or the equivalent AdviseDx SARS-CoV-2 IgG II Abbott Alinity i™ platform (US). 447 evaluable participants were enrolled across 6 US and 9 European clinical centers. ResultsFor unvaccinated participants with PCR-confirmed infection ≥21 days post-symptom onset, the Panbio™ sensitivity with fingerstick whole blood was 92.6 % (95 % CI: 85.9, 96.7), and the specificity was 97.0 % (95 % CI: 93.1, 99.0). For venous plasma, the sensitivity was 90.0 % (95 % CI: 79.5, 96.2) for participants with PCR-confirmed infection and symptom onset 22–180 days ago; the specificity was 96.3 % (92.2, 98.6). For vaccinated participants, the sensitivity was 98.4 % (95 % CI: 91.2, 100.0) for fingerstick whole blood and 96.7 % (95 % CI: 88.7, 99.6) for venous plasma. ConclusionThe Panbio™ test had high sensitivity and specificity for detecting IgG against the SARS-CoV-2 spike protein.

Detection of IgG antibodies against T. gondii and associated risk factors in domestic and stray cats in Lusaka, Zambia

Toxoplasma gondii (T. gondii) is a nearly ever-present organism that infects humans, wildlife, birds, and domestic and food animals. T. gondii has been reported in pigs, chickens, sheep, goats, and cattle (1). However, only members of the cat family (Felidae) are the definitive host and shed the environmentally resistant oocyst form of the organism in their faeces. Transmission to humans usually occurs by ingesting cysts in undercooked meat and exposure to soil water which is contaminated by oocysts (2). Feline infections are typically subclinical; congenitally infected kittens are the ones that are most likely to have clinical signs of infection, but previously clinically healthy adult cats may also be affected (3). Despite the disease’s significance in public health, very few studies have been done on T. gondii in Zambia. This study was a cross-sectional survey to investigate the seroprevalence and risk factors of Toxoplasmosis. A survey was carried out using a questionnaire that was distributed to cat owners who attended the veterinary clinics. The questionnaire had demographic data for the cats, questions related to the risk factors of Toxoplasmosis in cats, and practices surrounding the cat owners, like how they handle cat litter, whether their cat was indoor or outdoor, contact of the cat with other cats, and straying behaviour of their cat. A total of 178 blood samples were collected from both stray and domestic cats in this study. Of the 178 samples tested for T. gondii IgG antibodies, 88 were from domestic cats and 90 from stray cats. 30 out of 178 samples were positive for antibodies, indicating an overall seroprevalence of 16.85%. Of the 30 positive seropositive samples, 60% (18) came from domestic cats and 40% (12) from stray cats. The seroprevalence for domestic cats was found to be 20.4% and that of strays 13.3%. The two risk factors found to be associated with toxoplasma Seropositivity were sex (p=0.007, 95%, CI 0.071,0.976) and diet (p=0.038, 95%, CI 1.395,95.418) It was concluded that Toxoplasma gondii was widely spread in the study population. The presence of the antibodies indicated that at one point in their lives, these cats were actively infected and shedding oocysts in the environment, thereby posing a risk to humans and other species like sheep and chickens.

No Association of Trichomonas vaginalis Seropositivity with Advanced Prostate Cancer Risk in the Multiethnic Cohort: A Nested Case-Control Study.

The potential involvement of a sexually transmitted agent has been suggested to contribute to the high number of prostate cancers in the United States and worldwide. We investigated the relationship of Trichomonas vaginalis seropositivity with prostate cancer risk in a nested case-control study within the Multiethnic Cohort in Hawaii and California using blood samples collected prior to cancer diagnoses. Incident cases of advanced prostate cancer (intermediate- to high-grade based on Gleason score ≥ 7 and/or disease spread outside the prostate) were matched to controls by age, ethnicity, and the date of blood collection. T. vaginalis serostatus was measured using an ELISA detecting IgG antibodies against a recombinant T. vaginalis α-actinin protein. Seropositivity to T. vaginalis was observed in 35 of 470 (7.4%) cases and 26 of 470 (5.5%) controls (unadjusted OR = 1.47, 95% CI 0.82-2.64; adjusted OR = 1.31, 95% CI 0.67-2.53). The association was similarly not significant when cases were confined to extraprostatic tumors having regional or distant spread (n = 121) regardless of grade (unadjusted OR = 1.37, 95% CI 0.63-3.01; adjusted OR = 1.20, 95% CI 0.46-3.11). The association of T. vaginalis with prostate cancer risk did not vary by aspirin use. Our findings do not support a role for T. vaginalis in the etiology of advanced prostate cancer.

One health approach to toxocariasis in quilombola communities of southern Brazil

BackgroundToxocariasis has been listed among the most neglected parasitic diseases worldwide, with approximately one fifth of the global population exposed, particularly those living under poverty. In Brazil, communities of descendants of enslaved blacks (quilombola) have historically had some of the highest rates of vulnerability and poverty, characterized by lack of health assistance, poor quality of life, and nutritional insecurity.MethodsA cross-sectional sampling of quilombola individuals living in four communities of southern Brazil, as well as their dogs and the soil, was carried out from December 2021 to March 2022. Sociodemographic and other information such as water source, alimentary habits, and dog and cat ownership were gathered using a semi-structured questionnaire for assessing toxocariasis risk factors. Human serum samples were tested by ELISA for anti-Toxocara spp. IgG antibody detection was carried out on dog feces and hair, and soil samples were surveyed for presence of Toxocara spp. eggs.ResultsOverall, 172/208 individuals (82.7%, 95% CI = 77.0–87.2) were seropositive, the highest seroprevalence rate to date in Brazil. Male gender (P = 0.029), educational level (P = 0.026), and drinking water source (P = 0.043) were associated with seropositivity by univariate analysis. Final logistic regression revealed increased odds (P = 0.017, OR = 7.6, 95% CI = 1.5–42.7) to have seropositivity in individuals > 50 years old (< 10 years old). As expected, individuals with soil contact were more likely seropositive (P = 0.038, OR = 4.4, 95% CI = 1.1–18.8). Although retrieved in only 5/96 (5.2%) dog feces, Toxocara spp. eggs were found in 18/60 (30.0%) soil samples.ConclusionsThe high vulnerability and seroprevalence observed in quilombola communities clearly demand a One Health approach for detection, monitoring, and prevention of infection by Toxocara spp. in both human and dog populations.Graphical

Bimetallic nickel/cobalt metal-organic framework-based electrochemical sensor for trace level detection of IgG in simulated human blood serum

Electrochemical sensing is a widely used technique for the detection of biomolecules because of its low cost, high sensitivity, and versatility in terms of the various techniques that can be employed. In this study, we report a facile, cost-effective, and highly selective bimetallic Ni/Co-MOF (Nickel/Cobalt-Metal Organic Framework) on Nickel foam (NF) based electrochemical sensor for the trace-level detection of IgG (Human Immunoglobulin) antibodies in the human blood serum. In this direction, we used a simple and efficient solvothermal method to synthesize the Ni/Co-MOF, and the morphological, structural, and chemical states of the elements are studied using different material characterization techniques like TEM, FESEM, XRD, XPS, etc. The Ni/Co-MOF modified NF sensor showed a dynamic range of detection (30 fM to 10 nM) having superior sensitivity of 28 µA cm−2 mol−1 with a lower limit of detection 27.2 fM. Ni/Co-MOF/NF is highly selective over other interfering species (UA, Cl−, Ca2+, Urea, Sulphate, BSA and HAS). Real-time analysis was done using the DPV technique by the standard addition method and the sensor shows an excellent recovery percentage ̴ 97 to 98 %. Also, the addition of Ni2+ to Co enhances the electrochemical properties of a material by raising the valence of Ni2+ in Ni/Co-MOF by transferring partial electrons from Ni2+ to Co2+. The work presented here confirms Ni/Co-MOF/NF as a flexible, high-performance electrode that can be used to detect other biomolecules used in clinical diagnosis and biomedical research.

Vaccination against tick-borne encephalitis elicits a detectable NS1 IgG antibody response

Vaccine-induced protection against tick-borne encephalitis virus (TBEV) is mediated by antibodies to the viral particle/envelope protein. The detection of non-structural protein 1 (NS1) specific antibodies has been suggested as a marker indicative of natural infections. However, recent work has shown that TBEV vaccines contain traces of NS1, and immunization of mice induced low amounts of NS1-specific antibodies. In this study, we investigated if vaccination induces TBEV NS1-specific antibodies in humans. Healthy army members (n = 898) were asked to fill in a questionnaire relating to flavivirus vaccination or infection, and blood samples were collected. In addition, samples of 71 suspected acute TBE cases were included. All samples were screened for the presence of TBEV NS1-specific IgG antibodies using an in-house developed ELISA. Antibodies were quantified as percent positivity in reference to a positive control. For qualitative evaluation, cut-off for positivity was defined based on the mean OD of the lower 95% of the vaccinated individuals + 3 SD. We found significantly higher NS1-specific IgG antibody titers (i.e., quantitative evaluation) in individuals having received 2, 3, or 4 or more vaccine doses than in non-vaccinated individuals. Similarly, the percentage of individuals with a positive test result (i.e., qualitative evaluation) was higher in individuals vaccinated against tick-borne encephalitis than in unvaccinated study participants. Although NS1-specific IgG titers remained at a relatively low level when compared to TBE patients, a clear distinction was not always possible. Establishing a clear cut-off point in detection systems is critical for NS1-specific antibodies to serve as a marker for distinguishing the immune response after vaccination and infection.

Two-center validation of assays for the detection of binding and neutralizing anti-factor VIII antibodies.

Patients with hemophilia A treated with coagulation Factor VIII (FVIII) products are at risk for developing anti-FVIII antibodies. The ABIRISK Consortium aimed to provide knowledge on the formation and detection of anti-drug antibodies against biopharmaceutical products, including FVIII. Accordingly, standardized and validated assays for the detection of binding (total) and neutralizing antibodies are needed. Two-center validation of an ELISA for the detection of total FVIII-binding IgG-antibodies and Nijmegen-Bethesda assays for the quantification of FVIII-neutralizing antibodies according to consensus validation guidelines. Validation of assays at both sites was done according to published recommendations and included preanalytics, the determination of key assay parameters, including cut-points, assay sensitivity, precision, and FVIII interference. The validated assays reproducibly detected FVIII-binding and -neutralizing antibodies with comparable performance in both laboratories. Floating screening cut-points were established for both assays. Determined mass-based sensitivity of both assays (all values ≤66ng/mL) complied with the minimum sensitivity for the detection of anti-drug antibodies as recommended by the FDA (<100ng/mL). Intra- and inter-assay coefficients of variation did not exceed 25%. Assay validation further revealed that pre-analytical heat treatment led to potentially false-positive ELISA results, while up to 0.15 IU/mL, residual FVIII showed no significant impact. Overall, good agreement of results was found for patient samples analyzed at both study sites. Comprehensive validation of different anti-FVIII-antibody assays in two laboratories gave novel insights into the impact of pre-analytical sample treatment as well as the comparability of test results generated by the use of methodically different assays.

Comparative evaluation of SARS-CoV-2 serological tests shows significant variability in performance across different years of infection and between the tests

IntroductionWhile the global COVID-19 pandemic is slowly coming under control, current efforts are focused on understanding the epidemiology of endemic SARS-CoV-2. The tool of choice for doing so remains serological tests that detect SARS-CoV-2 induced antibodies. However, the performance of these tests should be evaluated to ensure they comply with the specific performance criteria desired by each country that they are used in. MethodsHere, we use pre-COVID-19 plasma and plasma from SARS-CoV-2-infected individuals collected in 2020, 2021 and 2022 to evaluate the performance of two commercial Rapid Lateral Flow (RLF) tests (the PANBIO™ COVID-19 IgG/IgM rapid test and the LABNOVATION™ COVID-19 (SARS-CoV-2) IgG/IgM rapid test) and one commercial ELISA test (the PLATELIA™ SARS-CoV-2 total Ab). ResultsWe find that whereas the specificity of the two RLF tests is ≥ 95%, it was 91% for the ELISA tests. However, at 14 days post-COVID-19 date of diagnosis (DoD), only the ELISA test constantly achieved a sensitivity of ≥80% over all the three years. In addition, the rate of detection of the two RLF tests varied across the years with a sensitivity ranging from <80% in 2021 to >80% in 2022. More importantly the capacity of these two RLF tests to detect IgG antibodies decreased with time. On the contrary, the sensitivity of the ELISA test was still above 80% more than six months post DoD. ConclusionWe recommend that sero-epidemiological surveys focused on testing antibodies should not rely on performances reported by the assay manufacturers. They should include a formal evaluation of the selected assays to ensure its limitations and strengths conform with the data-accuracy requirements of the surveys.

Serological Prevalence of Latent Epstein-Barr Virus Infection in Children and Adolescents

Background: Epstein-Barr Virus (EBV), first discovered in 1946, is one of the most common viruses, which found over the world causing latent infection or different undistinguishable symptoms ranged from mild to severe. This prevalence and age distribution of this latent infection varies significantly in different populations. Aim: Serological detection of anti-EBV IgG antibodies in children and adolescents using of the sandwich enzyme-linked immunosorbent assay (ELISA), and estimating the association of seropositivity to sex of study population. Materials and Methods: A total of 182 serum samples were obtained randomly from the study population that involved children (5-12 years old) and adolescents (13-17 years old) of both sexes in Sulaymaniyah province (Iraq) during January-February (2023). Results: Sera of an overall 29.12% study individuals were showed a serological positive reactivity to EBV-IgG antibodies. Significantly (P&lt;0.0289), latent EBV was higher in adolescents (42.86%) than those observed in children (15.39%). Concerning the association of seropositivity to sex of study population, there was a significant increase (P&lt;0.0224) in prevalence of anti-EBV-IgG antibodies among females (42.47%) than males (20.18%). Also, females were appeared significantly (P&lt;0.0001) at higher risk of infection (2.104) than males (0.475). Conclusion: The seroprevalence of latent EBV infection in female adolescent was higher than male children; however, additional investigations using of serological as well as molecular assays are of great importance to demonstrate the extent of infection and to define the full spectrum of EBV-associated diseases.

A-309 Challeging Diagnostic of Neurosyphilis: Use of CXCL13 Concentration in Cerebrospinal Fluid

Abstract Background Previous retrospective has been demonstrated the concentration of chemokine ligand CXCL13 in cerebrospinal fluid (CSF-CXCL13) is a promising biomarker in the diagnosis of neurosyphilis (NS) and monitoring of therapeutic efficacy. The goal of this study was to measure CXCL13 concentrations in CSF of NS suspected patients and compare with patients with syphilis non-NS and patients with treated syphilis. Methods One hundred and eleven NS-suspected participants from Rio de Janeiro (Brazil) were investigated for the detection of IgG antibodies against Treponema pallidum, using ELISA and Indirect Immunofluorescence tests (EUROIMMUN, Lübeck, Germany). CSF-CXCL13 concentration was prospectively performed by ELISA (EUROIMMUN, Lübeck, Germany) assay in all participants at baseline and in participants diagnosed with NS in follow-up visits at 3, 6, and 12 months after therapy. Results CSF-CXCL13 concentrations were significantly higher in patients with established NS presenting a median concentration of 207.4 pg/mL (IQR 69.3–1515.5 pg/mL) than in patients with syphilis non-NS with a median of 1.0 pg/mL (IQR 0.1–11.0 pg/mL, P &amp;lt; 0.001) or patients with treated syphilis with a median of 0.1 pg/mL (IQR 0.1–7.1 pg/mL, P &amp;lt; 0.001). The CSF-CXCL13 concentrations decreased after 3, 6 and 12 months of therapy compared to baseline in all cases of NS. The added concentration of CSF-CXCL13 above 62.8 pg/mL plus CSF-FTA-ABS reactivity agreed with diagnosis of NS in 88.9% of People Living with HIV (PLWHs) and plus CSF-TPHA reactivity agreed with the diagnosis of NS in 100% of HIV-uninfected patients. Conclusion The study suggests that the clinical use of CSF-CXCL13 is useful for supplementary biomarker for NS and as monitoring the effectiveness of NS therapy, especially in PLWHs with nonreactive CSF-VDRL, excluded other neurologic diseases.

A-235 Results and Interpretation: Serology Testing Platforms and Assays Compatibility Assessment for MASTM SARS-CoV-2 IgG Quality Controls

Abstract Background Serology testing of antibodies against SARS-CoV-2 viruses serves many purposes: disease diagnosis, on-going and surveillance, epidemiologic and vaccine studies, etc. There was a critical need to provide standardized quality control materials for development and harmonization across different test methods and IVD platforms. The MAS™ SARS-CoV-2 IgG Controls are human plasma-based materials containing IgG antibodies against SARS-CoV-2. The control offers commutability by mimicking patient samples and is intended to be used for monitoring serological assays, providing confidence in routine test results, test methods troubleshooting and system errors identification. We report here the compatibility assessment of MAS™ SARS-CoV-2 Controls testing on different assays and platforms. Methods The platforms and assays compatibility was assessed for the MAS™ SARS-CoV-2 IgG Positive and Negative Controls across all 11 assays and platforms listed as below. These serology assays target either total antibodies (IgA, IgM, IgG), IgM/IgG, or IgG against either the SARS-CoV-2 nucleocapsid (N), RBD or spike (S) proteins. Replicated samples were tested on each instrument for statistical confidence. Results All results demonstrated conclusively the comparable performance of MAS™ SARS-CoV-2 IgG controls across different clinical diagnostic assays and platforms manufactured by Abbott, Roche, Ortho, DiaSorin, Beckman Coulter and bioMérieux. The positive control showed 100% expected reactive results (IgG Positive) and Negative control at 82% non-reactive results, respectively. Furthermore, both controls were compatible towards assays detecting IgG antibodies targeting specific regions (N, S or RBD). Conclusion SARS-CoV-2 serology testing remains unstandardized with numerous assays and platforms receiving FDA EUA. While tested on multiple commonly used assays and platforms, MAS™ SARS-CoV-2 IgG Positive and Negative Controls were found to be platform agnostic. To conclude, MAS Controls will contribute to the harmonization of the SARS-CoV-2 Serology assay offerings, monitor the clinical laboratory analytical performance, streamline the workflow on test method development, validation and verification, and routine assessment.