Differences In Antibody Levels Research Articles

The Role of Sex, Ethnicity, Age, and Nutritional Status in the Seropositivity of the Measles Vaccine

AIM: This study investigates the relationship between sex, ethnicity, age, nutritional status with the seropositivity of the Edmonston-Zagreb vaccine in children. METHODS: A cross sectional, observational study was conducted. A total of 45 children were differentiated based on sex, ethnicity, age, and nutritional status when they received the Edmonston-Zagreb measle vaccine for the first time. Flow cytometry was used to look at differences in antibody status as well as populations of CD-4 and CD-8 cells that release IFN- γ. RESULTS: We found no significant differences in antibody levels or CD-4 and CD-8 cell populations that secrete IFN- γ between boys and girls (p > 0.05). Besides, similar results were also confirmed in comparisons between Javanese and Sundanese ethnic groups, 9 months versus more than 9 months of age, or normal versus low body mass index (p > 0.05). CONCLUSIONS: We conclude that sex, race, age, and nutritional status had no effect on immune response to vaccination. As a result, there was no barrier to seroconversion and optimal immunological performance in the children in this trial who received the Edmonston-Zagreb measles vaccination.

Real-World Serologic Responses to Extended-Interval and Heterologous COVID-19 mRNA Vaccination in Frail Elderly - Interim Report from a Prospective Observational Cohort Study

Background: The Coronavirus disease 2019 (Covid-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has prompted accelerated vaccines development. Their use was prioritized to protect the most vulnerable, notably, the elderly. Because of fluctuations in vaccine availability, strategies such as delayed second dose and heterologous prime-boost have been employed. The effectiveness of these strategies in the frail elderly are unknown. Methods: In this real-world vaccination study, under a government-decreed rationing strategy, elderly adults residing in long-term care facilities, with or without previously-documented SARS-CoV-2 infection, were administered homologous or heterologous mRNA vaccines, with an extended 16-week interval between doses. Clinical data and blood were serially collected during and after this interval period. Sera were tested for SARS-CoV-2-specific IgG antibodies (to trimeric S; RBD; nucleocapsid) by automated chemiluminescent ELISA. Findings: After a significant increase 4 weeks post-prime dose, there was a significant decline in anti-RBD and anti-S IgG levels until the boost dose, followed by an increase 4 weeks later. Previously uninfected individuals exhibited lower antibody responses up to 16 weeks post-prime dose, but achieved comparable levels to previously infected counterparts by 4 weeks post-second dose. Individuals primed with BNT162b2 exhibited larger decrease in anti-RBD and anti-S IgG levels with 16-week interval between doses, compared to those who received mRNA-1273. No differences in antibody levels 4 weeks after the second dose were noted between the two vaccines, in either homologous or heterologous combinations. Interpretations: These interim results of this ongoing longitudinal study show that, among frail elderly, neither age, sex, nor comorbidity affect antigenicity of mRNA-based COVID vaccines, but previous SARS-CoV-2 infection and type of mRNA vaccine influenced antibody responses when used with a 16-week interval between doses. Homologous/heterologous use of mRNA vaccines was not associated with significant differences in antibody responses 4 weeks following second dose, supporting their interchangeability.Funding: This project was supported by funding from the Public Health Agency of Canada, through the Vaccine Surveillance Reference group and the COVID-19 Immunity Task Force (CITF).Declaration of Interest: None to declare.Ethical Approval: This study was conducted in 12 LTC facilities of the Montréal Centre-Sud – Integrated University Health and Social Services Centre (CIUSSS du Centre-Sud-de-l'Île-de-Montréal) and was approved by its research ethics board (Comité d'éthique de la rechercheVieillissement-Neuroimagerie, protocol number 20-21-36 MP).

Immunologic memory to SARS-CoV-2 in convalescent COVID-19 patients at 1 year postinfection

BackgroundUnderstanding the complexities of immune memory to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is key to gain insights into the durability of protective immunity against reinfection.ObjectiveWe sought to evaluate the immune memory to SARS-CoV-2 in convalescent patients with longer follow-up time.MethodsSARS-CoV-2–specific humoral and cellular responses were assessed in convalescent patients with coronavirus disease 2019 (COVID-19) at 1 year postinfection.ResultsA total of 78 convalescent patients with COVID-19 (26 moderate, 43 severe, and 9 critical) were recruited after 1 year of recovery. The positive rates of both anti–receptor-binding domain and antinucleocapsid antibodies were 100%, whereas we did not observe a statistical difference in antibody levels among different severity groups. Accordingly, the prevalence of neutralizing antibodies (nAbs) reached 93.59% in convalescent patients. Although nAb titers displayed an increasing trend in convalescent patients with increased severity, the difference failed to achieve statistical significance. Notably, there was a significant correlation between nAb titers and anti–receptor-binding domain levels. Interestingly, SARS-CoV-2–specific T cells could be robustly maintained in convalescent patients, and their number was positively correlated with both nAb titers and anti–receptor-binding domain levels. Amplified SARS-CoV-2–specific CD4+ T cells mainly produced a single cytokine, accompanying with increased expression of exhaustion markers including PD-1, Tim-3, TIGIT, CTLA-4, and CD39, while the proportion of multifunctional cells was low.ConclusionsRobust SARS-CoV-2–specific humoral and cellular responses are maintained in convalescent patients with COVID-19 at 1 year postinfection. However, the dysfunction of SARS-CoV-2–specific CD4+ T cells supports the notion that vaccination is needed in convalescent patients for preventing reinfection.

Evaluation of Three Anti-SARS-CoV-2 Serologic Immunoassays for Post-Vaccine Response.

BackgroundIn North America, both messenger RNA (mRNA) vaccines, Pfizer-BioNTech BNT162b2, and Moderna mRNA-1273, each utilizing a 2-dose regimen, have started to be administered to individuals.MethodsWe evaluated the quantitative serologic antibody response following administration of either a single dose or both doses of an mRNA severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine in a cohort of 98 participants (88 healthcare workers [HCW] and 10 solid organ transplant [SOT] recipients). Antibody levels were compared across 3 immunoassays: Elecsys Anti-SARS-CoV-2 S (Roche Diagnostics), SARS-CoV-2 TrimericS IgG (DiaSorin), and SARS-CoV-2 IgG II Quant (Abbott).ResultsAmong HCW, sensitivity ranged from 100% (Roche), 99% (Abbott) and 98% (DiaSorin). The SARS-CoV-2 IgG II Quant and SARS-CoV-2 TrimericS IgG assays showed good agreement with a Pearson correlation coefficient of R = 0.95. Pearson correlation coefficients of R = 0.82 and 0.83 were obtained for Elecsys Anti-SARS-CoV-2 S vs SARS-CoV-2 TrimericS IgG and SARS-CoV-2 IgG II Quant vs Elecsys Anti-SARS-CoV-2 S, respectively. Significant differences in antibody levels between HCW and SOT recipients were observed. A decrease in antibody levels from time of vaccine administration to blood draw was evident. Among those with a second dose, an increase in antibody levels with increased time between administration of the first and second dose was observed.ConclusionsThe absolute values generated from each of the assay platforms are not interchangeable. Antibody levels differed with increased time between vaccine administration and with increased time between administration of the first and second dose. Further, significant differences in antibody levels between HCW and SOT recipients were observed.

Eleven years of Toxoplasma gondii serological follow-up in a goat herd and association of toxoplasmosis with reproductive losses.

Toxoplasmosis is considered one of the most important causes of abortion in small ruminants. The aim of this study was to evaluate the relationship between Toxoplasma gondii antibody titres and reproductive losses over an 11year period in a goat farm located in Buenos Aires province, Argentina. Blood samples were obtained from 85 goats, representing three breeds, during the last third of gestation (n=165 gestations), in consecutive pregnancies (2008-2019), and from 51 goats during kidding to analyze seroconversion. Serum was evaluated by IFAT with T. gondii antigen, using 1:100 dilution as the cut-off titre and processed to end titre. An overall reproductive loss of 31% (51/165) was detected, including 16.4% (27/165) abortions and 14.6% (24/165) perinatal deaths. The seropositivity to T. gondii was 100% (85/85) with all animals positive in successive samplings and, therefore, considered chronically infected. Antibody titres showed average values greater than 1100 in each year and breed group. Differences in antibody levels were associated with breed and were lower in those that were predominately Creole and higher in those that were predominately Saanen. Seroconversion was detected in 16.2% (6/37) and 57.1% (8/14) of goats from the Creole and Sannen breed groups, respectively. There were no significant differences in the antibody titre average between goats with reproductive losses and those with healthy kids, although the goats with perinatal deaths had a significantly higher titre average. These results suggest reinfection or reactivation, although no association with reproductive losses was observed. Higher antibody titres were associated with perinatal deaths. The high T. gondii antibody titres in a farm with 100% seroprevalence did not allow for association with reproductive losses, particularly abortion, to be assessed.

Investigation of the baseline tetanus antibody level and its persistence in a military unit

ObjectivesTo determine tetanus antibody levels in army recruits and evaluate the persistence of immunity following tetanus booster immunization in adults. MethodsA total of 680 recruits were selected for observation of their tetanus antibody levels. From 2005 to 2015, 691 peacekeepers with tetanus vaccination were included in the questionnaire-based and serological survey based on cluster stratification. The tetanus antibody-positive rate, geometric mean concentration (GMC), and their respective changes over time were analyzed in different age groups, regions, and years after tetanus booster immunization. ResultsThe positivity rates of tetanus antibodies in the recruits and peacekeepers were 74.85% and 99.86%, respectively (χ2 = 193.00, P < 0.05) and the antibody GMCs were 0.05 and 0.70 IU/mL (t = 15.73, P < 0.05). The antibody positivity rates of recruits from 12 provinces ranged from 47.62% (Hubei) to 100% (Inner Mongolia) (χ2 = 37.24, P < 0.05) and the antibody GMCs ranged from 0.02 (Hubei) to 0.09 IU/mL (Heilongjiang) (F = 5.19, P < 0.01). Among the 691 peacekeepers, no statistically significant difference in antibody positivity rate was detected between men and women. After administration of one booster dose of the tetanus vaccine, a protective antibody level was calculated to persist up to 22 years; a significant difference in antibody levels was observed within 10 years between one and two or more booster doses. ConclusionThe rate at which recruits tested positive for tetanus antibodies was low. Thus, it is necessary to screen for tetanus antibodies during military recruitment and implement a precision-based booster immunization protocol for tetanus vaccine. Moreover, one dose of the tetanus vaccine booster has been calculated to maintain a protective antibody level up to 22 years, without the need for repeated reinforcements during this period.

MO439NATURAL IMMUNISATION AGAINST ATHEROSCLEROSIS IN BEARS DURING HIBERNATION*

Abstract Background and Aims Brown bears (Ursus arctos) hibernate for 5-6 months during winter, but in spite of kidney insufficiency, dyslipidemia, insulin resistance and inactivity they do not seem to develop atherosclerosis or cardiovascular disease (CVD). Antibodies against phosphorylcholine (anti-PC) are associated with protection in atherosclerosis, CVD and uremia. Potential underlying protective mechanisms include anti-inflammatory effects, inhibition of cell death, promotion of T regulatory cells, clearance of dead cells and inhibition of oxidized Low density lipoprotein (OxLDL)-uptake in macrophages in atherosclerotic plaques. PC is an important antigen on nematodes, parasites, some bacteria, dead and dying cells and OxLDL. Method Paired serum from 12 brown bears sampled during winter and summer were analyzed for metabolic parameters and for IgM, IgG, IgG1/2 and IgA anti-PC by enzyme linked immunosorbent assay (ELISA). Differences in antibody levels between winter and summer were determined by paired Student´s t test or Wilcoxon´s signed rank test (when not normally distributed). Results As expected, marked differences in metabolic parameters were found comparing median summer vs winter values; Cholesterol 5.9 vs 11.3 mmol/L; p&amp;lt;0.001, triglycerides 1.9 vs 3.7 mmol/L; p&amp;lt;0.001, glucose 5.4 vs 7.7 mmol/L; p&amp;lt;0.05, S-creatinine 76 vs 203 µmol/L; p&amp;lt;0.001, urea 12.1 vs 2.9 mmol/L; p&amp;lt;0.002. When determined as arbitrary units (AU; median set at 100 at summer), marked and significant differences were observed between summer and winter. Conclusion Anti-PC (strikingly so for IgA and IgG1) are significantly raised during hibernation as compared to levels during summer. We hypothesize that these changes contribute to the protection of arteries, but also kidneys and other organs, during the metabolic vulnerable hibernation period. Our observation may represent a natural immunization with microorganisms, preventing atherosclerosis during a period of severe kidney insufficiency and could have therapeutic implications for patients with chronic kidney disease.

Serum IgG levels in children 6 months after SARS-CoV-2 infection and comparison with adults

Since the outbreak of SARS-CoV-2 among the population has occurred quite recently, there is a lack of evidence on the long-term duration of antibody response, especially in children. It is therefore crucial to clarify this aspect, considering its implications in the development of successful surveillance strategies, therapies, and vaccinations. The aim of this study was to assess the antibody response in a children group after SARS-CoV-2 infection, and to compare it with that of their parents affected by SARS-CoV-2 infection. We enrolled 12 children and their parents, both groups being affected by COVID-19 in April 2020. In the children’s group, we collected real-time RT-PCR cycle threshold (Ct) values and gene characterization of first nasal-throat swab at the time of diagnosis (T0); 30 days after the diagnosis (T30), we performed blood tests to detect anti-SARS-CoV-2 IgM and IgG. Finally, 180 days after the diagnosis (T180), we measured anti-SARS-CoV-2 IgG in both children and parents. In children, antibody levels declined significantly at 180 days (T180) after first measurement (T30). There were no significant differences in IgG level related to age, sex, and clinical manifestations. We found a significant correlation between IgG titers at T30 and Ct value of gene N. Children showed a lower level of antibodies against SARS-CoV-2 at T180 compared to their parents.Conclusion: Antibody responses in children waned 180 days after SARS-CoV-2 infection, and at the same time, their parents showed a different antibody response to the virus. These results highlight that serological tests should be used with caution in surveillance strategies among the general population.What is known:• Currently is not known how long antibody response will be maintained or if it protects from reinfection.• Recent reports in adults suggest that antibodies to SARS-CoV-2 declined several months after infection, but data are missing in pediatric age.What is new:• We showed that antibody responses to SARS-CoV-2 wane several months after infection also in children with quantitative differences in antibody levels between children and adults.• In this context, serological tests should be used with caution in surveillance strategies.

Diagnostic performance of an automated chemiluminescence immunoassay for SARS-CoV-2 IgG and IgM antibodies detection: A real life experience

BackgroundRecently many serological assays for detection of antibodies to SARS-COV-2 virus were introduced on the market. Aim of this study was to assess the diagnostic performance of an automated CLIA for quantitative detection of anti-SARS-CoV-2 IgM and IgG antibodies. MethodsA total of 354 sera, 89 from consecutive patients diagnosed with COVID-19 (43 mild, 32 severe and 13 critical) and 265 from asymptomatic and negative on rRT-PCR testing healthcare workers, were evaluated for IgM and IgG anti-SARS-CoV-2 antibodies with MAGLUMI immunoassay. ResultsThe overall sensitivity and specificity were 86.5% (95%CI: 77.6–92.8) and 98.5% (95%CI:96.2–99.6), respectively. PPV, PPN, LR+, LR- and OR were 95.1 (95%CI: 87.8–98.6), 95.6 (95%CI: 92.4–97.7), 57.3 (95%CI: 21.6–152.1), 7.3 (95%CI: 4.31–12.4) and 418.6 (95%CI: 131.2–1335.2), respectively. The levels of SARS-CoV-2 IgM and IgG antibodies were 1.22 ​± ​1.2 AU/mL and 15.86 ​± ​24.83 AU/mL, 2.86 ​± ​2.4 AU/mL and 69.3 ​± ​55.5 AU/mL, 2.47 ​± ​1.33 AU/mL and 83.9 ​± ​83.9 AU/mL in mild, severe and critical COVID-19 groups, respectively. A significant difference in antibody levels between mild and severe/critical subjects has been shown. ConclusionsThe CLIA assay showed good diagnostic performance and a significant association between antibody levels and severity of the disease was found.

Topical Imiquimod Does Not Provide an Adjuvant Effect When Administered With Inactivated Influenza A/H5N1 Vaccine in Healthy Young Adults.

Safe, effective, and easy to deploy adjuvants are needed for influenza prepandemic preparedness. Based on recent reports, we hypothesized that preapplication of topical imiquimod followed by intradermal (ID) vaccination with monovalent inactivated influenza A/H5N1 vaccine (MIV A/H5N1) results in improved serologic responses. We randomized 50 healthy adults in a 1:1 ratio to receive topical imiquimod (group 1) or control cream (group 2) followed by ID injection of 9 µg of the hemagglutinin MIV A/H5N1 in 2 doses, 21 days apart. Subjects were followed for safety and serologic responses as measured by the hemagglutination inhibition (HAI) and microneutralization (MN) assays. Solicited and unsolicited adverse events were comparable between groups 1 and 2, and were mostly mild to moderate in severity. At 21 days after dose 2, the geometric mean titers (GMTs) of HAI antibodies against the vaccine strain were 16.2 and 24.3 in groups 1 and 2, respectively. The MN antibody GMTs were 9.3 and 10.7 in groups 1 and 2, respectively. There were no significant differences in antibody levels between groups at study time points. Topical imiquimod administration combined with ID MIV A/H5N1 was safe but did not result in improved serologic responses to the vaccine.Clinical Trials Registration. NCT03472976.

Survey of antibody levels of pertussis, diphtheria and tetanus in 495 pregnant women in Nanshan District of 2019, Shenzhen

Objective: The purpose of this study was to investigate the IgG antibody levels of whooping cough, diphtheria, and tetanus in pregnant women in Nanshan District. Methods: From January to March 2019, 495 pregnant women who met the inclusion criteria in a hospital in Nanshan District, Shenzhen were selected as the survey subjects. The enzyme-linked immunosorbent assay was used to detect serum levels of pertussis, diphtheria, and tetanus IgG antibodies and we compared the differences in antibody levels of pregnant women with different characteristics. Results: The maternal age was (29.23±4.08) years old. The geometric mean concentration of pertussis antibody was 2.589 (1.172-4.953) IU/ml, 1.01% (5 cases) of pregnant women had pertussis antibody concentration ≥ 40 IU/ml, and 75.15% (372 cases) of pregnant women had pertussis antibody concentration<5 IU/ml. The GMC value and antibody positive rate of diphtheria in pregnant women were 0.024(0.009-0.065) IU/ml and 72.53% (359 cases), respectively. The GMC value and antibody positive rate of tetanus in pregnant women were 0.014 (0.006-0.034) IU/ml and 53.74% (266 cases), respectively. There was no statistical difference in the antibody level and antibody positive rate among pregnant women of diphtheria and tetanus, respectively. Conclusion: The concentration of antibodies against pertussis, diphtheria, and tetanus in pregnant women are all at a low level, which is not enough to protect themselves from disease infection.

Serological Levels of Anti-clathrin Antibodies Are Decreased in Patients With Pseudoexfoliation Glaucoma.

Evidence for immunologic contribution to glaucoma pathophysiology is steadily increasing in ophthalmic research. Particularly, an altered abundance of circulating autoantibodies to ocular antigens is frequently observed. Here, we report an analysis of autoantibody abundancies to selected antigens in sera of open-angle glaucoma patients, subdivided into normal-tension glaucoma (N = 31), primary open-angle glaucoma (N = 43) and pseudoexfoliation glaucoma (N = 45), vs. a non-glaucomatous control group (N = 46). Serum samples were analyzed by protein microarray, including 38 antigens. Differences in antibody levels were assessed by ANOVA. Five serological antibodies showed significantly altered levels among the four groups (P < 0.05), which can be used to cluster the subjects in groups consisting mainly of PEXG or POAG/NTG samples. Among the altered autoantibodies, anti-Clathrin antibodies were identified as most important subgroup predictors, enhancing prospective glaucoma subtype prediction. As a second aim, we wanted to gain further insights into the characteristics of previously identified glaucoma-related antigens and their role in glaucoma pathogenesis. To this end, we used the bioinformatics toolset of Metascape to construct protein-protein interaction networks and GO enrichment analysis. Glaucoma-related antigens were significantly enriched in 13 biological processes, including mRNA metabolism, protein folding, blood coagulation and apoptosis, proposing a link of glaucoma-associated pathways to changes in the autoantibody repertoire. In conclusion, our study provides new aspects of the involvement of natural autoimmunity in glaucoma pathomechanisms and promotes advanced opportunities toward new diagnostic approaches.

Altered Antibody Responses in Persons Infected with HIV-1 While Using Preexposure Prophylaxis.

Preexposure prophylaxis (PrEP) is an effective HIV prevention tool, although effectiveness is dependent upon adherence. It is important to characterize the impact of PrEP on HIV antibody responses in people who experience breakthrough infections to understand the potential impact on timely diagnosis and treatment. Longitudinal HIV-1-specific antibody responses were evaluated in 42 people who inject drugs (PWID) from the Bangkok Tenofovir Study (BTS) (placebo = 28; PrEP = 14) who acquired HIV while receiving PrEP. HIV-1 antibody levels and avidity to three envelope proteins (gp41, gp160, and gp120) were measured in the plasma using a customized Bio-Plex (Bio-Rad Laboratories, Hercules, CA) assay. A time-to-event analysis was performed for each biomarker to compare the distribution of times at which study subjects exceeded the recent/long-term assay threshold, comparing PrEP and placebo treatment groups. We fit mixed-effects models to identify longitudinal differences in antibody levels and avidity between groups. Overall, longitudinal antibody levels and avidity were notably lower in the PrEP breakthrough group compared to the placebo group. Time-to-event analyses demonstrated a difference in time to antibody reactivity between treatment groups for all Bio-Plex biomarkers. Longitudinal gp120 antibody levels within the PrEP breakthrough group were decreased compared to the placebo group. When accounting for PrEP adherence, both gp120 and gp160 antibody levels were lower in the PrEP breakthrough group compared to the placebo group. We demonstrate hindered envelope antibody maturation in PWID who became infected while receiving PrEP in the BTS, which has significant implications for HIV diagnosis. Delayed maturation of the antibody response to HIV may increase the time to detection for antibody-based tests. Clinical Trial Registration Number, NCT00119106.

Associations between animal and herd management factors, serological response to three respiratory pathogens and pluck lesions in finisher pigs on a farrow-to-finish farm

BackgroundSerological screening is a common method to monitor antibody response to pathogen exposure, but results could vary due to several factors. This study aimed to quantify animal and management related factors associated with variation in antibody levels in finisher pigs at slaughter, in an Irish farrow-to-finish farm endemically infected with Actinobacillus pleuropneumonia (App), Mycoplasma hyopneumoniae (Mhyo) and swine influenza virus (SIV). A second objective was to estimate differences in antibody levels in pigs presenting pluck lesions. This was an observational study whereby pigs were managed as per routine farm practice. Data on sow parity, number of born alive (NBA) pigs per litter, cross-fostering status, birth and weaning body weight were recorded from 1016 pigs born from one farrowing batch. At slaughter, blood samples were collected for serological analysis and pigs were inspected for presence of enzootic pneumonia (EP)-like lesions, pleurisy, pericarditis and heart condemnations. Pigs were retrospectively classified into three production flows, depending on time spent in each production stage: flow 1 (F1; pigs followed the normal production flow); flow 2 (F2; pigs which were delayed by 1 week from advancing forward); and flow 3 (F3; pigs delayed by > 1 week from advancing forward). A nested case-control design was applied by matching pigs from each flow by sow parity, birth weight and NBA.ResultsPigs born from primiparous sows had higher antibody levels for App than those born to parity ≥5 sows (P < 0.05) and there was no association between any of the pathogens investigated and other early life indicators (P > 0.05). Pigs in F1 had lower antibody levels for App but higher antibody levels for SIV than F2 and F3 pigs (P < 0.05). There was no association between pluck lesions and respiratory pathogens (P > 0.05), except for increased antibody levels for Mhyo when EP-like lesions were present (P = 0.006).ConclusionResults indicate that offspring from primiparous sows develop higher antibody levels for App IV toxin when exposed to this disease and that enforcement of a strict all-in/all-out production system would reduce on-farm disease circulation. A high percentage of pigs were affected with EP-like lesions which were associated with higher antibody levels for Mhyo.

The immunoglobulin G antibody response to malaria merozoite antigens in asymptomatic children co-infected with malaria and intestinal parasites.

Co-infection with malaria and intestinal parasites is common in children in Africa and may affect their immune response to a malaria parasite infection. Prior studies suggest that co-infections may lead to increased susceptibility to malaria infection and disease severity; however, other studies have shown the reverse. Knowledge on how co-morbidities specifically affect the immune response to malaria antigens is limited. Therefore, this study sought to determine the prevalence of co-infection of malaria and intestinal parasites and its association with antibody levels to malaria merozoite antigens. A cross sectional study was carried out in two villages with high transmission of malaria in Cameroon (Ngali II and Mfou) where mass drug administration (MDA) had been administered at ~6-month intervals (generally with albendazole or mebendazole). Children aged 1-15 years were enrolled after obtaining parental consent. A malaria rapid diagnostic test was used on site. Four (4) ml of peripheral blood was collected from each participant to determine Plasmodium falciparum infections by microscopy, haemoglobin levels and serology. Fresh stool samples were collected and examined by wet mount, Kato-Katz method and modified Ritchie concentration techniques. A Multiplex Analyte Platform assay was used to measure antibody levels. A total of 320 children were enrolled. The prevalence of malaria by blood smear was 76.3% (244/320) and prevalence of malaria and intestinal parasites was 16.9% (54/320). Malaria prevalence was highest in young children; whereas, intestinal parasites (IP+) were not present until after 3 years of age. All children positive for malaria had antibodies to MSP142, MSP2, MSP3 and EBA175. No difference in antibody levels in children with malaria-co infections compared to malaria alone were found, except for antibody levels to EBA-175 were higher in children co-infected with intestinal protozoa (p = 0.018), especially those with Entamoeba histolytica infections (p = 0.0026). Antibody levels to EBA175 were significantly higher in children co-infected with malaria and E. histolytica compared to children infected with malaria alone. It is important to further investigate why and how the presence of these protozoans might modulate the immune response to malaria antigens.

Evaluation of selected parameters of immune response to rubella virus, hepatitis B virus and varicella-zoster virus infections in children born to mothers after kidney or liver transplantation

Background The immune status of children exposed prenatally to immunosuppressants is not fully understood. Material and methods A single-center study evaluated possible differences in antibody levels between children prenatally exposed to immunosuppressants born to mothers after hepatic or kidney transplantation (study group) compared to children without prenatal exposure to immunosuppressants (control group). Children from the study and control group were age-matched at the time of the examination and gestational age-matched, so as to obtain similar stages of the vaccination schedule and to enable reliable comparison of the results. The selection of children was made in a 1:1 ratio. The study population, a total of 138 children, was divided according to the age of the children at the time of the study into three age groups: newborns, infants (from 29 days to 1 year) and children aged >1 year. Immunoenzymatic tests were used to analyze the titers of the chickenpox virus (VZV-IgG), rubella (RuV-IgG) and hepatitis B virus (HBV, HBsAb). The studied differences were compared depending on the age group and the immunosuppressive regimen used by the pregnant mother. Results In neonates born to mothers after liver transplantation, significant differences were found in HBsAb levels (>250 mIU/ml) compared to newborns without prenatal exposure to immunosuppressants taken by pregnant mothers (11/16, 69% vs. 4/14, 29%, respectively; p = .028). A similar difference in the level of HbsAb was no longer noted at later stages of children’s lives. In infants, these values were 80% (4/5) vs. 33% (2/6), and in children over 1 year of age 15% (7/48) vs. 12% (6/49), respectively. No other significant differences were noted when compared the distribution of measured parameters of VZV and RuV in both analyzed groups (children of mothers after kidney or liver transplantation chronically treated with immunosuppression and children without prenatal exposure to immunosuppression). Conclusions Prenatal exposure to immunosuppressive therapy does not appear to affect VZV, RuV and HBV antibody levels in children of mothers who have had a kidney or liver transplant. Initially elevated HBSAb levels in newborns of mothers after liver transplantation are not observed in later stages of life.

The Promotion of Peony Seed Proteolysis Product to the Immune Efficacy Induced by ptfA Gene DNA Vaccine of Avian Pasteurella multocida

Background: Avian Pasteurella multocida is one of the pathogens that affect the health of poultry. The protective efficacy of traditional attenuated vaccine is not ideal. In previous study, we prepared ptfA gene DNA vaccine of avian P. multocida. However, the protective effect of ptfA gene DNA vaccine was inferior to the attenuated vaccine. Therefore, it is necessary to improve the immune efficacy of avian P. multocida DNA vaccine, such as screening for novel adjuvant. Methods: In this study, the peony seed proteolysis product was gavaged to chickens before DNA vaccination or was added to the ptfA gene DNA vaccine as adjuvant. These vaccines were administered to chickens and the serum antibody, lymphocyte proliferation levels, IFN-g, IL-2, IL-4 and IL-6 concentrations secreted by peripheral blood lymphocytes were determined. After challenging with virulent avian P. multocida, survival time and protective efficacy was evaluated. Result: Following vaccination, no significant differences in antibody levels and concentrations of IL-4 among the DNA vaccine group, adjuvant-DNA vaccine group and gavaged group were observed. The stimulation index (SI) values, concentrations of IFN-g, IL-2 and IL-6 in adjuvant-DNA vaccine group and gavaged group were significantly higher than those in the DNA vaccine group. The protective efficacy of live attenuated vaccine group, DNA vaccine group, adjuvant-DNA vaccine group and gavaged group were 92%, 52%, 72% and 60%, respectively. This study has laid a foundation for the design and application of future DNA vaccines of P. multocida and DNA vaccine adjuvant.

Presence of Antibodies Against Haemophilus influenzae Serotype a in Alaska Before and After the Emergence of Invasive Infections.

Haemophilus influenzae bacteria can cause asymptomatic carriage and invasive disease. Haemophilus influenzae serotype a (Hia) is an emerging cause of invasive disease in Alaska, with greatest burden occurring among rural Alaska Native (AN) children. The first case of invasive Hia (iHia) in Alaska was reported in 2002; however, it is unclear how long the pathogen has been in Alaska. We quantified immunoglobulin G antibodies against Hia (anti-Hia) in 839 banked serum samples from Alaska residents, comparing antibody concentrations in samples drawn in the decades before (1980s and 1990s) and after (2000s) the emergence of iHia. We also assessed serum antibody concentration by age group, region of residence, and race. The anti-Hia was >0.1 µg/mL in 88.1% (348 of 395) and 91.0% (404 of 444) of samples from the decades prior and after the emergence of Hia, respectively (P = .17). No significant differences in antibody levels were detected between people from rural and urban regions (1.55 vs 2.08 µg/mL, P = .91 for age ≥5) or between AN and non-AN people (2.50 vs 2.60 µg/mL, P = .26). Our results are consistent with widespread Hia exposure in Alaska predating the first iHia case. No difference in Hia antibody prevalence was detected between populations with differing levels of invasive disease.

Infant antibody levels following 10-valent pneumococcal-protein D conjugate and DTaP-Hib vaccinations in the first year of life after maternal Tdap vaccination: An open-label, parallel, randomised controlled trial

BackgroundMaternal antibody levels after Tdap vaccination during pregnancy may affect infant primary antibody responses to pertussis, Tetanus toxoid (TT), Diphtheria toxoid (DT) vaccinations and pneumococcal vaccines with diphtheria toxin mutants like CRM197 as carrier protein. MethodsMothers were recruited in an open label randomised parallel controlled trial in 2014–2016 through midwifes. They received Tdap [Boostrix] at 30–32 weeks of pregnancy (n = 58) or within 48 h after delivery (n = 60). Infants received DTaP-IPV-Hib-HepB [Infanrix Hexa] and 10-valent protein D conjugated pneumococcal conjugate vaccine (PHiD-CV10 [Synflorix]) at age 3, 5 and 11 months. We now report on infant specific IgG levels towards DT, TT, Haemophilus influenzae type b polyribosylribitol phosphate (Hib PRP) and PHiD-CV10 before and after primary- and booster vaccination as secondary study endpoints; pertussis antibodies were the primary endpoint of the study. This trial is registered in clinicaltrialsregister.eu (EudraCT 2012–004006-9) and trialregister.nl (NTR number NTR4314). FindingsPost primary vaccinations, antibody levels to DT, but not TT, were significantly lower after Tdap vaccination during pregnancy compared to controls (GMC ratio 0.4, 95% CI 0.3–0.6 and 0.9, 95% CI 0.6–1.2, respectively). Antibodies to serotype 19F were significantly lower in the maternal Tdap group, whereas there were no differences in antibody levels to Hib PRP and the other 9 pneumococcal serotypes. Post booster vaccinations, no significant differences were observed, except for DT. InterpretationMaternal Tdap vaccination results in significant interference with infants responses not only to DT but also to conjugated pneumococcal vaccines containing DT mutants as carrier proteins. These interactions after maternal Tdap vaccination need to be taken into account when designing infants’ national immunization schedules and choice of vaccines. FundingThe Dutch Ministry of Health, Welfare and Sport.

Viral RNA level, serum antibody responses, and transmission risk in recovered COVID-19 patients with recurrent positive SARS-CoV-2 RNA test results: a population-based observational cohort study

ABSTRACT Managing recovered COVID-19 patients with recurrent-positive SARS-CoV-2 RNA test results is challenging. We performed a population-based observational study to characterize the viral RNA level and serum antibody responses in recurrent-positive patients and evaluate their viral transmission risk. Of 479 recovered COVID-19 patients, 93 (19%) recurrent-positive patients were identified, characterized by younger age, with a median discharge-to-recurrent-positive length of 8 days. After readmission, recurrent-positive patients exhibited mild (28%) or absent (72%) symptoms, with no disease progression. The viral RNA level in recurrent-positive patients ranged from 1.8 to 5.7 log10 copies/mL (median: 3.2), which was significantly lower than the corresponding values at disease onset. There are generally no significant differences in antibody levels between recurrent-positive and non-recurrent-positive patients, or in recurrent-positive patients over time (before, during, or after recurrent-positive detection). Virus isolation of nine representative specimens returned negative results. Whole genome sequencing of six specimens yielded only genomic fragments. 96 close contacts and 1,200 candidate contacts of 23 recurrent-positive patients showed no clinical symptoms; their viral RNA (1,296/1,296) and antibody (20/20) tests were negative. After full recovery (no longer/never recurrent-positive), 60% (98/162) patients had neutralizing antibody titers of ≥1:32. Our findings suggested that an intermittent, non-stable excretion of low-level viral RNA may result in recurrent-positive occurrence, rather than re-infection. Recurrent-positive patients pose a low transmission risk, a relatively relaxed management of recovered COVID-19 patients is recommended.