Ab ELISA Research Articles

Seroprevalence of Maedi-Visna Infection in Sheep in the Central Black Sea Region of Türkiye

Maedi-Visna is a slowly progressive infection of sheep that affects the respiratory and nervous systems and causes significant yield losses worldwide. This study was conducted to assess the seroprevalence of Maedi-Visna infection in sheep across several provinces in the Central Black Sea region of Türkiye, namely Samsun, Sinop, Ordu, Giresun, Amasya and Tokat. A total of 476 sheep serum samples were collected for further analysis. The presence of antibodies in the sera was determined by Ab ELISA. As a result of the study, 263 (55.25%) blood serum samples were positive for the presence of MVV antibodies. Seropositivity rates by province were as follows: Samsun 45%, Sinop 80%, Ordu 58.75%, Giresun 35%, Amasya 38.75%, Tokat 75%. Notably, our findings suggest a significantly high seroprevalence of Maedi-Visna infection in this region compared to other studies conducted in different parts of Türkiye This information is pivotal for understanding the extent of the infection in the sheep population of the Central Black Sea region and can contribute to the development of strategies for disease management and control.

STAT3 single-nucleotide variants in autoimmune thyroid disease in the Pakhtun population of Khyber Pakhtunkhwa, Pakistan

The current study was conducted to assess the relationship between the STAT3 gene variants rs744166 and rs2293152 and autoimmune thyroid disorder in the Pakhtun population of the province, of Khyber Pakhtunkhwa, Pakistan. Blood was collected from 100 healthy individuals and 400 thyroid-disordered patients. Of these, one hundred were diagnosed with Hashimoto's thyroiditis (HT), while 32 were confirmed as Grave's disease (GD) patients. T3, T4, and TSH serum levels were checked to diagnose thyroid disorders. The blood was analyzed for anti-thyroid peroxidase antibodies (Anti-TPOAb) (AESKULISA- ATPO - elisa kit), (Germany), and thyroid stimulating hormone receptor antibodies (TSHRAb), TSHR Ab elisa kit (Diametra Italy), respectively. PCR was used to amplify the targeted STAT3 gene polymorphisms from rs744166 (301 bp) and rs2293152 (365 bp) sequences and then digested by specific restriction endonucleases (AluI) and AciI respectively. The disease displayed a female predominance. The genotype TC and CC of rs744166 showed a significant relationship with Grave's disease (p = 0.002, OR = 0.28, 95 % CI = 0.11–0.77) in patients. The C allele contributed significantly to the disease in GD patients. The SNP rs2293152 significantly differed between GD patients and control (p = 0.032, OR = 0.29, 95 % CI = 0.09–0.86). Similarly, the G and C alleles showed a significant (p = 0.02) difference between GD patients and the control. No significant association was found for both SNPs in Hashimoto's thyroiditis disease. It is concluded that the STAT3 gene (rs744166 and rs2293152) was found to have a potential role in autoimmunity in GD patients. Still, it needs further studies with larger sample sizes in the Pakhtun population to understand this relationship.

Correlation of Robust Immune Response against SARS-CoV-2 Vaccine among Diabetic and Non-Diabetic Participants

Correlation of Robust Immune Response against SARS-CoV-2 Vaccine among Diabetic and Non-Diabetic Participants

The Elecsys® Anti-SARS-CoV-2 and Elecsys® Anti-SARS-CoV-2 S antibody assays: Differentiating between vaccination and infection, and assessing long-term performance.

Serological surveillance is useful for assessing SARS-CoV-2 immunity in populations. To effectively study the presence and persistence of antibodies, it is necessary to distinguish between persons with past infection, and persons who only received vaccination. Knowledge of the duration of antibody persistence is essential for correct interpretation of surveillance results. Starting in April 2020, waning of SARS-CoV-2 antibodies was studied in a longitudinal cohort study of 495 SARS-CoV-2 antibody-positive Dutch blood donors, not pre-selected by PCR testing or disease severity. Additionally, in May 2021, a sample of donors representative for the Dutch population was tested for antibodies against the SARS-CoV-2 spike (S) protein, using the Wantai Ab ELISA and the Elecsys® Anti-SARS-CoV-2 S assay; and for antibodies against the nucleocapsid protein, which indicate past infection, using the Elecsys® Anti-SARS-CoV-2 assay. The anti-S response in donors that were infected in April or May 2020 remained positive in 100% of donors in the Elecsys® Anti-SARS-CoV-2 S assay one year after infection, after which follow up of waning was no longer possible because of large scale vaccination. The anti-nucleocapsid response results were still positive in approximately 80% of donors two years after infection. In May 2021, 51% of the donors showed anti-S reactivity and 16.8% tested positive for anti-nucleocapsid antibodies. Infection with SARS-CoV-2 resulted in spike and nucleocapsid antibody levels still detectable in the majority of donors 1-2 years after infection. In May 2021, 51% of donors were vaccinated and 16.8% had had an infection. Thus, both Elecsys® SARS-CoV-2 antibody assays can be used to reliably assess the vaccination and infection status of individuals.

Seroprevalence of SARS-CoV-2 infection in the general population of Nepal during the first and second generalized waves of the COVID-19 pandemic-2020-2021.

Few seroprevalence studies have been conducted on coronavirus disease (COVID-19) in Nepal. Here, we aimed to estimate seroprevalence and assess risk factors for infection in the general population of Nepal by conducting two rounds of sampling. The first round was in October 2020, at the peak of the first generalized wave of COVID-19, and the second round in July-August 2021, following the peak of the wave caused by the delta variant of SARS-CoV-2. We used cross-sectional probability-to-size (PPS)-based multistage cluster sampling to estimate the seroprevalence in the general population of Nepal at the national and provincial levels. We tested for anti-SARS-CoV-2 total antibody using the WANTAI SARS-CoV-2 Ab ELISA kit. In Round 1, the overall national seroprevalence was 14.4%, with provincial estimates ranging from 5.3% in Sudurpaschim to 27.3% in Madhesh Province. In Round 2, the estimated national seroprevalence was 70.7%, with the highest in the Madhesh Province (84.8%) and the lowest in the Gandaki Province (62.9%). Seroprevalence was comparable between males and females (Round 1, 15.8% vs. 12.2% and Round 2, 72.3% vs. 68.7%). The seroprevalence in the ecozones-Terai, hills, and mountains-was 76.3%, 65.3%, and 60.5% in Round 2 and 17.7%, 11.7%, and 4.6% in Round 1, respectively. In Nepal, COVID-19 vaccination was introduced in January 2021. At the peak of the first generalized wave of COVID-19, most of the population of Nepal remained unexposed to SARS-CoV-2. Towards the end of the second generalized wave in April 2021, two thirds of the population was exposed.

Incidence rate and predictors of COVID-19 in the two largest cities of Burkina Faso - prospective cohort study in 2021 (ANRS-COV13)

BackgroundEarly data on COVID-19 (based primarily on PCR testing) indicated a low burden in Sub-Saharan Africa. To better understand this, this study aimed to estimate the incidence rate and identify predictors of SARS-CoV-2 seroconversion in the two largest cities of Burkina Faso. This study is part of the EmulCOVID-19 project (ANRS-COV13).MethodsOur study utilized the WHO Unity protocol for cohort sero-epidemiological studies of COVID-19 in general population. We conducted random sampling stratified by age group and sex. Individuals aged 10 years and older in the cities of Ouagadougou and Bobo-Dioulasso, Burkina Faso were included and surveyed at 4 time points, each 21 days apart, from March 3 to May 15, 2021. WANTAI SARS-CoV-2 Ab ELISA serological tests were used to detect total antibodies (IgM, IgG) in serum. Predictors were investigated using Cox proportional hazards regression.ResultsWe analyzed the data from 1399 participants (1051 in Ouagadougou, 348 in Bobo-Dioulasso) who were SARS-CoV-2 seronegative at baseline and had at least one follow-up visit. The incidence rate of SARS-CoV-2 seroconversion was 14.3 cases [95%CI 13.3–15.4] per 100 person-weeks. The incidence rate was almost three times higher in Ouagadougou than in Bobo-Dioulasso (Incidence rate ratio: IRR = 2.7 [2.2–3.2], p < 0.001). The highest incidence rate was reported among women aged 19–59 years in Ouagadougou (22.8 cases [19.6–26.4] per 100 person-weeks) and the lowest among participants aged 60 years and over in Bobo-Dioulasso, 6.3 cases [4.6–8.6] per 100 person-weeks. Multivariable analysis showed that participants aged 19 years and older were almost twice as likely to seroconvert during the study period compared with those aged 10 to 18 years (Hazard ratio: HR = 1.7 [1.3–2.3], p < 0.001). Those aged 10–18 years exhibited more asymptomatic forms than those aged 19 years and older, among those who achieved seroconversion (72.9% vs. 40.4%, p < 0.001).ConclusionThe spread of COVID-19 is more rapid in adults and in large cities. Strategies to control this pandemic in Burkina Faso, must take this into account. Adults living in large cities should be the priority targets for vaccination efforts against COVID-19.

Sero-prevalence of anti-SARS-CoV-2 antibodies among communities between July and August 2022 in Bangui, Central African Republic.

Large-scale population-based seroprevalence studies of SARS-CoV-2 are essential to characterize the cumulative incidence of SARS-CoV-2 infection and to extrapolate the prevalence of presumptive immunity at the population level. Objective. The objective of our survey was to estimate the cumulative population immunity for COVID-19 and to identify individual characteristics associated with positive serostatus. This was a clustered cross-sectional study conducted from July 12 to August 20, 2021, in households in the city of Bangui, the capital of the Central African Republic. Information regarding demographic characteristics (age, gender, and place of residence), and comorbidities (chronic diseases) was collected. A venous blood sample was obtained from each participant to determine the level of total anti-SARS-CoV-2 antibodies using a WANTAI SARS-CoV-2 Ab ELISA kit. All up, 799 participants were surveyed. The average age was 27 years, and 45.8% of the respondents were male (sex ratio: 0.8). The overall proportion of respondents with positive serostatus was 74.1%. Participants over 20 years of age were twice as likely to have positive serostatus, with an OR of 2.2 [95% CI: (1.6, 3.1)]. The results of this survey revealed a high cumulative level of immunity in Bangui, thus indicating a significant degree of spread of SARS-CoV-2 in the population. The public health implications of this immunity to SARS-CoV-2 such as the post-vaccination total antibody kinetics remain to be determined.

Поширеність антитіл до SARS-CoV-2 у дітей та підлітків: одноцентрове дослідження

Despite the fact that children with COVID-19 are usually asymptomatic or mild, infection with SARS-CoV-2 is more likely to lead to the development of an antibody response. Understanding humoral immunity to SARS-CoV-2, including in children, is critical for future public health and vaccination strategies. Children with chronic diseases deserve special attention. Purpose - to study the prevalence of positive antibodies to SARS-CoV-2 in children and adolescents who were in paediatric hospital without signs of viral disease to develop future healthcare strategies. Materials and methods. In 32 children aged 6-17 years (14 (43.8%) boys and 16 (56.2%) girls) quantitative determination of IgG antibodies to SARS-CoV-2 in blood serum was carried out by enzyme immunoassay using commercial SARS-CoV-2 S1\RBD IgG Ab ELISA (TECAN, IBL International GmbH, Germany). Results. The majority (n=27, 84.4%) of children had a positive level of class G antibodies to SARS-CoV-2. 7 (25.9%) children had a positive PCR test in their anamnesis, 6 (18.8%) persons provided information about the infection transmitted by family members. Clinical manifestations characteristic of SARS-CoV-19 were present in 2 (7.4%) children. Parents of 18 (66.7%) children claimed that their children had no symptoms of COVID-19, while family members of 6 (33.3%) children had cases of the disease. All children (n=6, 18.8%) who were vaccinated with two doses of Comirnaty® vaccine had positive IgG antibodies to SARS-CoV-2. Antibodies to SARS-CoV-2 were absent in 5 (15.4%) people, all of them were patients with type 1 diabetes. Conclusions. The study of the prevalence of antibodies to SARS-CoV-2 provides important information about circulating antibodies against SARS-CoV-2 in children and adolescents, in particular those with chronic diseases. The obtained results showed the predominant seropositivity of children, which is formed regardless of the clinical manifestations of the disease. A high level of antibodies under the conditions of revaccination confirms the benefit of revaccination of children to strengthen memory formation. The research was carried out in accordance with the principles of the Helsinki Declaration. The study protocol was approved by the Local Ethics Committee of the participating institution. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.

High Prevalence of Occult Hepatitis B Virus Infection among Iranian Hemodialysis Patients.

Considering the potential risks associated with occult hepatitis B virus (HBV) infection, this study was designed to investigate the magnitude and genotypic pattern of occult HBV infection among hemodialysis patients. All patients on regular hemodialysis attending the dialysis centers located in southern Iran and 277 nonhemodialysis controls were invited to participate in this study. Serum samples were tested for detection of hepatitis B core antibody (HBcAb) and hepatitis B surface antigen (HBsAg) by competitive enzyme immunoassay and sandwich ELISA, respectively. The molecular evaluation of HBV infection was conducted by two nested polymerase chain reaction (PCR) assays, targeting S, X, and precore regions of HBV genome, and sequencing by Sanger dideoxy sequencing technology. Moreover, HBV viremic samples were tested for hepatitis C virus (HCV) coinfection by HCV Ab ELISA and seminested reverse transcriptase PCR. Of 279 hemodialysis patients, five (1.8%) were positive for HBsAg, 66 (23.7%) were positive for HBcAb, and 32 (11.5%) had HBV viremia with HBV genotype D, sub-genotype D3 and subtype ayw2. Moreover, 90.6% of the hemodialysis patients with HBV viremia had occult HBV infection. Hemodialysis patients (11.5%) had significantly higher prevalence of HBV viremia than nonhemodialysis controls (1.08%; P = 0.0001). The prevalence of HBV viremia among hemodialysis patients was not statistically associated with duration of hemodialysis, age and gender distribution. In contrast, HBV viremia was significantly associated with place of residency and ethnicity, with residents of Dashtestan and Arab having had significantly higher prevalence of HBV viremia compared with the residents of other cities and Fars patients. Notably, 27.6% and 6.9% of hemodialysis patients infected with occult HBV infection were also positive for anti-HCV antibodies and HCV viremia, respectively. High prevalence of occult HBV infection was detected in hemodialysis patients, whereas 62% of patients with occult HBV infection were negative for HBcAb. Therefore, screening of all hemodialysis patients by sensitive molecular tests, regardless of the pattern of HBV serological markers, is recommended to increase the diagnosis rate of HBV infection.

Evaluation of ten (10) SARS-CoV-2 rapid serological tests in comparison with WANTAI SARS-CoV-2 ab ELISA in Burkina Faso, West Africa

BackgroundThe aim of this study was to evaluate the performance of ten (10) SARS-CoV-2 serological rapid diagnostic tests in comparison with the WANTAI SARS-CoV-2 Ab ELISA test in a laboratory setting.Materials and methodsTen (10) SARS-CoV-2 serological rapid diagnostic tests (RDTs) for SARS-CoV-2 IgG/IgM were evaluated with two (2) groups of plasma tested positive for one and negative for the other with the WANTAI SARS-CoV-2 Ab ELISA. The diagnostic performance of the SARS-CoV-2 serological RDTs and their agreement with the reference test were calculated with their 95% confidence intervals.ResultsThe sensitivity of serological RDTs ranged from 27.39 to 61.67% and the specificity from 93.33 to 100% compared to WANTAI SARS-CoV-2 Ab ELISA test. Of all the tests, two tests (STANDARD Q COVID-19 IgM/IgG Combo SD BIOSENSOR and COVID-19 IgG/IgM Rapid Test (Zhejiang Orient Gene Biotech Co., Ltd)) had a sensitivity greater than 50%. In addition, all ten tests had specificity greater than or equal to 93.33% each. The concordance between RDTs and WANTAI SARS-CoV-2 Ab ELISA test ranged from 0.25 to 0.61.ConclusionThe SARS-CoV-2 serological RDTs evaluated show low and variable sensitivities compared to the WANTAI SARS-CoV-2 Ab ELISA test, with however a good specificity. These finding may have implications for the interpretation and comparison of COVID-19 seroprevalence studies depending on the type of test used.

Analysis of Robust Immune Response among Diabetic and Non-Diabetic Individuals against SARS-CoV-2 Vaccination

The pandemic on SARS-CoV-2 infection has adversely impacted mankind all over the globe and more importantly, amidst individuals having Type-2 diabetic mellitus (T2DM) as well as among those who produce SARS-CoV-2 intricacies. Humoral and T cell-mediated immunity are adaptive immunity has a pivotal role to play in removing pathogens, comprising SARS-CoV-2. The infected cells are being eliminated by the primarily cytotoxic CD8+ T cells as well as certain antibodies in opposition to SARS-CoV-2 among humoral immunological responses possess the capacity for neutralizing this virus or by eliminating the infected cells with the support of cytotoxic in order to manage the progression of the disease. This cross-sectional study was carried out between January 2022 to December 2022. The serum samples were used to analyze SARS-CoV-2 total Ab among individuals having and not having T2DM and several metabolic risk factors like hypertension using WANTAI SARS-CoV-2 Total Ab ELISA Kit. There were 354 individuals, of which 141 (39.8%) had T2DM and 213 (60.2%) were nondiabetic patients. T2DM showed reduced antibody levels (average 5 AU/ml) than those without diabetes (average 12 AU/ml). SARS-CoV2 total antibody levels are considerably lower in hypertension patients (8 AU/ml) over those who are normotensive (14 AU/ml). The present study implies that the continuous monitoring of the total antibody profile of SARS-CoV-2 that may be a practical strategy to help individuals with T2DM and hypertension to determine their need of precautionary doses for sustaining SARS-CoV-2 vaccines by producing immunity for protection against infections.

Performance of the SureScreen Diagnostics COVID-19 antibody rapid test in comparison with three automated immunoassays

Lateral flow immunoassays (LFIA) for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies are used for population surveillance and potentially individual risk assessment. The performance of the SureScreen Diagnostics LFIA targeting the spike protein was evaluated in comparison with 3 automated assays (Abbott Alinity-i SARS-CoV-2 IgG, DiaSorin Liaison® SARS-CoV-2 S1/S2 IgG, Wantai SARS-CoV-2 Ab ELISA). We assessed sensitivity using 110 serum samples from PCR confirmed COVID-19 infected patients. Specificity was evaluated using 120 prepandemic samples, including potential cross-reactive antibodies samples. Sensitivity ranged between 93.3% and 98.7% on samples collected >14 days postsymptom onset. All assays achieved a specificity >98%. Moreover, its performance seems not to be affected by Alpha, Beta or Delta variants over a wide range of antibody titers. The latter showed a very good agreement with the Wantai and the Abbott assays and a substantial agreement with the DiaSorin assay. Our data demonstrate the good clinical performance of the SureScreen Diagnostics LFIA for SARS-CoV-2 seroprevalence screening.

Laboratory Based Preliminary Study on Anti-SARS-CoV-2 Antibody Response among State Sector Healthcare Workers in a Single District in Sri Lanka

Background: Severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) is responsible for the current COVID-19 pandemic. Healthcare workers are one of the risk groups due to their strategic role in patient management. Presence of antiSARS-CoV-2antibodies in serum following seroconversion could be determined through antibody ELISA assay. Objectives: This study was to analyze the laboratory identified viral markers of Anti SARS-CoV-2 antibody in blood samples of health care workers to demonstrate the seroconversion to SARS-CoV-2 virus following exposures, natural infection or vaccination and to describe the sociodemographic, and clinical parameters among them. Study design: This laboratory based retrospective study was conducted at the National Virus Reference Laboratory (NVRL), at the Medical Research Institute (MRI). The study retrospectively analyzed 235 blood samples received to the NVRL, for testing of anti-SARS-CoV-2 antibody among health care workers in a one month period. All samples requested for anti-SARSCoV-2 antibody were tested with SARS-CoV-2 spike protein specific IgG antibody, and with SARS-CoV-2 Total Ab ELISA. The socio-demographic data were gathered through the request forms were also analyzed. Results: Total 235blood samples were tested for anti-SARS-CoV-2 antibody and 234(99.6%) were confirmed to have spike protein specific IgG antibody while 2% were confirmed to have Nucleo-capsid protein targeting antibodies of the positives, 100% were vaccinated with two doses of vaccine and 1% had positive PCR. Conclusion: The current study encounters a significantly high prevalence of vaccine induces SARS-CoV-2 antibody carriers among the healthcare workers in the study community.

Immunization and SARS-CoV-2 Antibody Seroprevalence in a Country with High Vaccination Coverage: Lessons from Chile.

Chile is among the most successful nations worldwide in terms of its COVID-19 vaccine rollout. By 31 December 2021, 84.1% of the population was fully vaccinated, and 56.1% received booster doses using different COVID-19 vaccines. In this context, we aimed to estimate the prevalence of anti-SARS-CoV-2 antibodies following the infection and vaccination campaign. Using a three-stage stratified sampling, we performed a population-based cross-sectional serosurvey based on a representative sample of three Chilean cities. Selected participants were blood-sampled on-site and answered a short COVID-19 and vaccination history questionnaire using Wantai SARS-CoV-2 Ab ELISA to determine seroprevalence. We recruited 2198 individuals aged 7–93 between 5 October and 25 November 2021; 2132 individuals received COVID-19 vaccinations (97%), 67 (3.1%) received one dose, 2065 (93.9%) received two doses, and 936 received the booster jab (42.6%). Antibody seroprevalence reached 97.3%, ranging from 40.9% among those not vaccinated to 99.8% in those with booster doses (OR = 674.6, 154.8–2938.5). SARS-CoV-2 antibodies were associated with vaccination, previous COVID-19 diagnosis, age group, and city of residence. In contrast, we found no significant differences in the type of vaccine used, education, nationality, or type of health insurance. We found a seroprevalence close to 100%, primarily due to the successful vaccination program, which strongly emphasizes universal access.

Prevalence, genotype distribution and mutations of hepatitis B virus and the associated risk factors among pregnant women residing in the northern shores of Persian Gulf, Iran.

Considering perinatal transmission and the high rate of chronic hepatitis B virus (HBV) infection in infants, diagnosis of HBV infection during pregnancy and timely interventions are of great importance. Therefore, this study was performed to investigate the prevalence and genotype distribution of HBV infection and the associated risk factors among pregnant women in the northern shores of the Persian Gulf, South of Iran. Serum samples of 1425 pregnant women were tested for the presence of HBsAg and HBcAb by ELISA (HBsAg one-Version ULTRA and HBc Ab ELISA kits, DIA.PRO, Milan, Italy). The seropositive samples were tested for the presence of HBV DNA by nested PCR, targeting S, X, pre-core (pre-C), and basal core promoter (BCP) regions of the HBV genome. The amplified fragments were sequenced by Sanger dideoxy sequencing technology to evaluate the genotype distribution and mutations of HBV infection by using the MEGA 7 software. The HBV seropositive pregnant women were tested for HCV and HIV coinfections by ELISA (HCV Ab and HIV Ab/Ag ELISA kits, DIA.PRO, Milan, Italy). Of 1425 participants, 15 pregnant women (1.05%, 95% CI: 0.64%-1.73%) were positive for HBsAg, 41 women (2.88%, 95% CI: 2.10%-3.88%) were positive for HBcAb, and 5 women (0.35%, 95% CI: 0.15% -0.82%) had HBV viremia with genotype D, sub-genotype D3 and subtype ayw2. One of the viremic samples was positive for HBcAb but negative for HBsAg, which is indicative of an occult HBV infection. HBsAg seroprevalence was higher among pregnant women aged 20 to 29 years, women in the third trimester of pregnancy, residents of Khormuj city, Afghan immigrants, illiterate women, and pregnant women with a history of tattoo and HBV vaccination. The highest rate of HBcAb seroprevalence was observed in residents of Borazjan city, Turk ethnicity, the age group >39 years, and those women with more parities and a history of abortion. Nevertheless, HBV seroprevalence among pregnant women was not statistically associated with these variables. In contrast, HBcAb seropositivity was significantly associated with the history of tattoo (P = 0.018). According to mutations analyses, seven amino acid substitutions in the HBsAg, one point mutation in the pre-C region, and five points mutations in the BCP region were detected. Besides, the BCP mutations caused amino acid substitutions in the X protein. Of note, the conversion of Ala → Val at amino acid 168 (A168V) and Thr → Pro at amino acid 127 (T127P) were detected in HBsAg of the occult HBV strain. These results indicate a relatively low prevalence of HBV infection among pregnant women in the South of Iran, while tattooing is a risk factor for exposure to HBV infection. Moreover, all of the HBV-positive pregnant women were asymptomatic and unaware of their infection. Therefore, routine screening for HBV markers during pregnancy, appropriate treatment of HBV-infected women, and HBV vaccination are recommended to decrease mother-to-child transmission of HBV.

Seroprevalence of SARS-CoV-2 antibodies and knowledge, attitude and practice toward COVID-19 in the Republic of Srpska-Bosnia & Herzegovina: A population-based study.

The aim of the study was to assess the seroprevalence of SARS-CoV-2 in the Republic of Srpska, Bosnia and Herzegovina, and to analyse the knowledge, attitudes and practices of the population toward COVID-19. This population-based study was conducted in a group of 1,855 randomly selected individuals from all municipalities from 1 December 2020 to 15 January 2021. All individuals were asked to sign a consent form and to fill in a questionnaire, following which a blood samples were collected. Total anti-SARS-CoV-2 antibodies were determined in serum specimens using the total Ab ELISA assay. The overall seroprevalence rate was 40.3%. Subjects aged <65 years were 2.06 times more likely to be seropositive than those aged ≥65, and 30% of seropositive individuals presented no COVID-19 symptoms. The household members of seropositive individuals were 2.24 times more likely to develop COVID-19 symptoms than the household members of seronegative individuals. More than 95% of respondents believe that preventive measures are very important to control the infection transmission. Majority of respondents wear the masks properly, maintain the required physical distance whenever possible and wash hands with soap. Nearly 50% of individuals were of the opinion that the vaccine could prevent the infection. This study showed that an overall SARS-CoV-2 seropositivity rate by the middle of January 2021 was very high. Attitudes and practices regarding the COVID-19 indicate that additional efforts should be taken in order to improve the health education with a focus on preventive measures and vaccination.

Evaluation of loop-mediated isothermal amplification assay and enzyme-linked immunosorbent assay in detecting Schistosoma japonicum in Siargao Island, Surigao del Norte, the Philippines

ObjectivesThis study aimed to describe the prevalence and seroprevalence of schistosomiasis in Siargao Island, Surigao del Norte and to compare the performance of enzyme-linked immunosorbent assay antibody test (ELISA Ab) and loop-mediated isothermal amplification assay (LAMP) for diagnosis of schistosomiasis. MethodsThe study was conducted in selected barangays (villages) in five municipalities in Siargao Island, Surigao del Norte and included school-age children (SAC) who submitted stool and blood samples. Stool samples were examined using the Kato-Katz technique. Blood samples were collected through venipuncture. The stool samples and the blood samples collected were tested using LAMP assay and polymerase chain reaction (PCR). The blood samples were examined using ELISA Ab. Diagnostic performance of LAMP assay using stool specimen was evaluated using Kato-Katz technique and PCR assay as the composite reference standard, while PCR assay was used as the reference standard to evaluate LAMP assay and ELISA Ab using blood specimens. ResultsA total of 417 stool samples from SAC were examined. The prevalence of schistosomiasis and moderate-heavy intensity (MHI) schistosomiasis were 3.8% and 1.4%, respectively. Schistosomiasis and soil-transmitted helminthiases (STH) coinfection prevalence were 2.6%. A total of 425 blood samples were examined using ELISA Ab. Seroprevalence was 61.6%. The municipality of San Isidro had the highest seroprevalence at 84.8%, while Burgos had the lowest seroprevalence at 48.5%.LAMP assay had higher sensitivity and positive predictive value but lower specificity when using stool than when using blood samples. Its negative predictive value was similar regardless of the specimen used. ELISA Ab has higher sensitivity and negative predictive value than LAMP assay although it has lower specificity and positive predictive value. This may be due to ELISA Ab measuring Schistosoma exposure and is thus unable to distinguish past from active infection. ConclusionsSchistosomiasis remains a public health concern in Siargao Island, Surigao del Norte. The locally developed LAMP assay offers a simpler diagnostic test for schistosomiasis compared with PCR, while minimizing the risk of misdiagnosis compared with Kato-Katz technique. It could serve as a point of care diagnostics for schistosomiasis. ELISA Ab is more useful in surveillance particularly in low-endemicity areas where determination of exposure is more important than differentiating past from active infection. ELISA Ab may be helpful in the clinical setting when coupled with the expertise of a physician who is familiar with schistosomiasis.

Establishment of a peptide-based enzyme-linked immunosorbent assay for detecting antibodies against PRRSV M protein

BackgroundPorcine reproductive and respiratory syndrome (PRRS) is one of the most economically devastating diseases affecting the swine industry globally. Evaluation of antibody responses and neutralizing antibody titers is the most effective method for vaccine evaluation. In this study, the B cell line epitopes of PRRSV M protein were predicted, and two peptide ELISA assays were established (M-A110-129 ELISA, M-A148-174 ELISA) to detect antibodies against PRRSV M protein. Field serum samples collected from pig farms were used to validate the peptide ELISA and compare it with an indirect immunofluorescence assay.ResultsThe sensitivity and specificity of M-A110-129 ELISA and M-A148-174 ELISA were (111/125) 88.80%, (69/70) 98.57% and (122/125) 97.60%, (70/70) 100%, relative to indirect immunofluorescence assay. This peptide ELISA could detect antibodies against different genotypes of PRRSV including type 1 PRRSV, classical PRRSV, HP-PRRSV, and NADC30 like PRRSV, but not antibodies against other common swine viruses. The results of ROC analysis showed that the area under the curve (AUC) of the M-A110-129 ELISA and M-A148-174 ELISA were 0.967 and 0.996, respectively. Compared the concordance of results using two peptide ELISA assays, the IDEXX PRRSV X3 Ab ELISA and a virus neutralization test, were assessed using a series of 147 sera from pigs vaccinated with the NADC30-like PRRSV inactivated vaccine. The M-A148-174 ELISA had the best consistency, with a Cohen’s kappa coefficient of 0.8772. The concordance rates of the Hipra PRRSV ELISA kit, M-A110-129 ELISA and M-A148-174 ELISA in the field seropositive detection results were 91.08, 86.32 and 95.35%, relative to indirect immunofluorescence assay.ConclusionsIn summary, compared with M-A110-129 ELISA, the PRRSV M-A148-174 ELISA is of value for detecting antibodies against PRRSV and the evaluation of the NADC30-like PRRSV inactivated vaccine, but the advantage is insufficient in serological early diagnosis.

Development and Optimization of an Enzyme Immunoassay to Detect Serum Antibodies against the Hepatitis E Virus in Pigs, Using Plant-Derived ORF2 Recombinant Protein.

Hepatitis E is an emerging global disease, mainly transmitted via the fecal–oral route in developing countries, and in a zoonotic manner in the developed world. Pigs and wild boar constitute the primary Hepatitis E virus (HEV) zoonotic reservoir. Consumption of undercooked animal meat or direct contact with infected animals is the most common source of HEV infection in European countries. The purpose of this study is to develop an enzyme immunoassay (EIA) for the detection of anti-hepatitis E virus IgG in pig serum, using plant-produced recombinant HEV-3 ORF2 as an antigenic coating protein, and also to evaluate the sensitivity and specificity of this assay. A recombinant HEV-3 ORF2 110-610_6his capsid protein, transiently expressed by pEff vector in Nicotiana benthamiana plants was used to develop an in-house HEV EIA. The plant-derived HEV-3 ORF2 110-610_6his protein proved to be antigenically similar to the HEV ORF2 capsid protein and it can self-assemble into heterogeneous particulate structures. The optimal conditions for the in-house EIA (iEIA) were determined as follows: HEV-3 ORF2 110-610_6his antigen concentration (4 µg/mL), serum dilution (1:50), 3% BSA as a blocking agent, and secondary antibody dilution (1:20 000). The iEIA developed for this study showed a sensitivity of 97.1% (95% Cl: 89.9–99.65) and a specificity of 98.6% (95% Cl: 92.5–99.96) with a Youden index of 0.9571. A comparison between our iEIA and a commercial assay (PrioCHECK™ Porcine HEV Ab ELISA Kit, ThermoFisher Scientific, MA, USA) showed 97.8% agreement with a kappa index of 0.9399. The plant-based HEV-3 ORF2 iEIA assay was able to detect anti-HEV IgG in pig serum with a very good agreement compared to the commercially available kit.

Seroprevalence of pestivirus infections is low in Belgian small ruminant flocks and is significantly associated with the presence of cattle

A study was implemented to estimate the pestivirus seroprevalence in sheep and goats in Belgium, to identify circulating species and to check for a potential association between seropositivity of small ruminants and presence of cattle in the same farm. It was based on the testing of serum samples and bulk tank milk samples (BTM) collected in sheep and goat flocks in 2018–2019 all over the country. 7460 serum samples collected from 410 flocks were tested by a commercial ELISA able to detect antibodies (Ab) against Border Disease Virus (BDV), and Bovine Viral Diarrhea Virus (BVDV). BTM samples (n = 144) were collected from dairy flocks in November 2019 and tested with the same Ab ELISA. ELISA positive serum samples were also tested by virus neutralization test (VNT) for neutralizing antibodies against BDV, BVDV-type1 and BVDV-type2. Virological tests (RT-PCR) were performed on pools of serum samples from pestivirus-exposed flocks with at least two seropositive animals and on all Antibody-positive BTM samples. Information about serum and milk samples (identification, test results, farm of origin and location, presence of cattle) were gathered in animal-level and farm-level databases.Based on this study, the apparent animal seroprevalence for pestiviruses in small ruminant flocks in Belgium in 2018 was estimated to be 0.87 % (95 % C.I. [0.68 %–1.11 %]). The prevalence of flocks exposed to pestivirus (i.e. with at least one seropositive animal) was estimated to be 8.5 % (95 % C.I. [6.4 % - 11.6 %]). In exposed flocks, the average within-flock seroprevalence was 9.9 %. In dairy sheep and goats, the estimated proportion of exposed flocks in 2019, based on the detection of pestivirus antibodies in the bulk tank milk, was 9.7 % [5.9 %–15.7 %]. All PCR tests were negative, indicating the likely absence of active pestivirus circulation in these flocks. Although the observed pestivirus seroprevalence was found to be low in Belgian small ruminants, this study also showed, based on VNT results, that they are exposed to several pestivirus species: BDV, BVDV-1 and BVDV-2. 22.4 % of the farms included in the serological survey were holding both a small ruminant flock and a cattle herd, hence with a potential risk of contact between the two species. There was a significant positive association between pestivirus seropositivity in the sheep/goat flocks and the presence of a cattle herd in the same farm (OR = 2.42 (95 %C.I. [1.18–4.94]) but this association was not found for Ab-positive BTM in dairy flocks.