Francisella tularensis-specific antibody levels in sera from Swedish patients with suspected tularemia during a 13-year period.

Introduction: For a majority of tularemia patients, serology is the basis for the diagnosis. The aim of this study was to perform an analysis of the samples analyzed at a Swedish reference laboratory for the presence of Francisella tularensis-specific antibody levels in sera from individuals with suspected tularemia. Annual and monthly variations of the total number of samples and proportions of positive samples were analyzed, as well as the influence of age and gender. Methods: We performed a retrospective analysis of the presence of F. tularensis-specific antibodies in serological samples from patients with suspected tularemia analyzed during the period 2010 - 2022 at the University Hospital of Umeå in Sweden, a national reference laboratory, by use of various statistical methods. In total, some 15,100 serum samples had been analyzed for the presence of IgG and IgM antibodies by ELISA during the 13-year period. Results: Overall, there were higher number of samples with IgG positive or borderline titers, 2,522 and 921, respectively, than with IgM positive or borderline titers, 1,802 and 409, respectively. Repeated samples were obtained from some 1,930 individuals and approximately a third of the cases, which were initially seronegative, had seroconverted when resampled. Peak number of monthly samples were recorded in August and September, > 3,000. Annual numbers varied greatly and peak numbers were observed in 2015 and 2019, 1,832 and 2,250, respectively, whereas some other years the numbers were 700 - 800. There was also much variation in the annual and monthly percentages of positive samples and they varied between less than 10% to greater than 20%. The highest percentages of positive samples were recorded in September and October. IgG and IgM titers declined with age and these differences were highly significant for IgG titers, with decreasing average titers for each 20-year interval. Discussion: Collectively, the data demonstrate the marked annual and seasonal variations in tularemia sampling occurring in Sweden. Also, the proportion of positive samples increased during months and years with peak number of samples. Another notable finding was that average antibody titers decreased with increased age.

Seroprevalence of Helicobacter pylori infection among schoolchildren in southern Taiwan-A 20-year longitudinal follow-up.

BACKGROUND: Helicobacter pylori infection is primarily acquired in childhood and can lead to peptic ulcer diseases and gastric cancer. The prevalence of H. pylori infection varies widely in different countries. The aim of this study was to explore the change of pediatric H. pylori seroprevalence in the past two decades and to investigate the risk factors for pediatric H. pylori seropositivity in southern Taiwan. MATERIALS AND METHODS: This study enrolled children aged 7-12 years in Tainan City in 2018 and compared the result with our previous data in 1998, 2005, and 2010. Parents of the participants were invited to fill out questionnaires, including information of personal history, family history of peptic ulcer diseases, annual household income, and source of drinking water. Blood samples were analyzed for anti-H. pylori IgG by enzyme-linked immunosorbent assay. RESULTS: A total of 391, 629, 618, and 488 elementary school students in Tainan City were enrolled in 1998, 2005, 2010, and 2018, respectively. There was a significant decline in H. pylori seroprevalence from 9.2% in 1998, 7.8% in 2005, 6.2% in 2010 to 4.7% in 2018 (p < 0.001). Neither gender difference nor age difference was found in H. pylori seropositivity in each year of enrollment. Low household income was significantly associated with pediatric H. pylori seropositivity. CONCLUSIONS: The seroprevalence of H. pylori infection among elementary schoolchildren has remarkably declined in southern Taiwan in the past two decades. Low household income was a risk factor for pediatric H. pylori seropositivity.

Production of a new tetravalent vaccine targeting fimbriae and enterotoxin of enterotoxigenic Escherichia coli.

Enterotoxigenic Escherichia coli (ETEC) is an important type of pathogenic bacteria that causes diarrhea in pigs. The objective of this study was to prepare a novel tetravalent vaccine to effectively prevent piglet diarrhea caused by E. coli. In order to realize the production of K88ac-K99-ST1-LTB tetravalent inactivated vaccine, the biological characteristics, stability, preservation conditions, and safety of the recombinant strain BL21(DE3) (pXKKSL4) were studied, and the vaccine efficacy and minimum immune dose were measured. The results indicated that the biological characteristics, target protein expression, and immunogenicity of the 1st to 10th generations of the strain were stable. Therefore, the basic seed generation was preliminarily set as the 1st to 10th generations. The results of the efficacy tests showed that the immune protection rate could reach 90% with 1 minimum lethal dose (MLD) virulent strain attack in mice. The immunogenicity was stable, and the minimum immune dose was 0.1 mL per mouse. Our research showed that the genetically engineered vaccine developed in this way could prevent piglet diarrhea caused by enterotoxigenic E. coli through adhesin and enterotoxin. In order to realize industrial production of the vaccine as soon as possible, we conducted immunological tests and production process research on the constructed K88ac-K99-ST1-LTB tetravalent inactivated vaccine. The results of this study provide scientific experimental data for the commercial production of vaccines and lay a solid foundation for their industrial production.

Escherichia coli entérotoxinogènes (ETEC) est un type important de bactéries pathogènes qui cause de la diarrhée chez les porcs. L'objectif de l'étude était de préparer un nouveau vaccin tétravalent pour prévenir efficacement la diarrhée causée par E. coli chez les porcelets. Afin de réaliser la production du vaccin tétravalent inactivé K88ac-K99-ST1-LTB, les caractéristiques biologiques, la stabilité, les conditions de conservation, et la sécurité de la souche recombinante (BL21(DE3)(pXKKSL4) ont été étudiées et l'efficacité du vaccin et la dose immunitaire minimum ont été mesurées. Les résultats indiquent que les caractéristiques biologiques, l'expression des protéines cibles, et l'immunogénicité de la 1ère à la 10e génération de la souche étaient stables. Ainsi, la génération germinale de base a été établie de manière préliminaire comme étant de la 1ère à la 10e générations. Les résultats des tests d'efficacité ont démontré que le taux de protection immunitaire pouvait atteindre 90 % avec une attaque au moyen de 1 dose léthale minimale (MLD) d'une souche virulente chez les souris. L'immunogénicité était stable et la dose immunitaire minimum était de 0,1 mL par souris. Nos travaux ont démontré que le vaccin génétiquement élaboré développé de cette façon pourrait prévenir la diarrhée chez les porcelets causée par des E. coli entérotoxigénique via les adhésines et les entérotoxines. Afin d'atteindre la production industrielle de ce vaccin aussitôt que possible, nous avons mené des tests immunologiques et de la recherche sur le processus de production du vaccin tétravalent inactivé K88ac-K99-ST1-LTB. Les résultats de la présente étude fournissent des données scientifiques expérimentales pour la production commerciale de vaccins et jettent une base solide pour leur production industrielle.(Traduit par Docteur Serge Messier).

State of pneumococcal vaccine immunity.

Like the other invasive encapsulated bacteria, Streptococcus pneumoniae is also covered with a polysaccharide structure. Infants and elderly are most vulnerable to the invasive and noninvasive diseases caused by S. pneumoniae. Although antibodies against polysaccharide capsule are efficient in eliminating S. pneumoniae, the T cell independent nature of the immune response against polysaccharide vaccines renders them weakly antigenic. The introduction of protein conjugated capsular polysaccharide vaccines helped overcome the weak immunogenicity of pneumococcal polysaccharides and decreased the incidence of pneumococcal diseases, especially in pediatric population. Conjugate vaccines elicit T cell dependent response which involve the interaction of specialized CD4+ T cells, called follicular helper T cells (Tfh) with germinal center B cells in secondary lymphoid organs. Despite their improved immunogenicity, conjugate vaccines still need to be administered three to four times in infants during the first 15 month of their life because they mount poor Tfh response. Recent studies revealed fundamental differences in the generation of Tfh cells between neonates and adults. As the portfolio of pneumococcal conjugate vaccines continues to increase, better understanding of the mechanisms of antibody development in different age groups will help in the development of pneumococcal vaccines tailored for different ages.

Novel method for production and purification of untagged pneumococcal surface protein A from clade 1.

Streptococcus pneumoniae can cause diseases with high mortality and morbidity. The licensed vaccines are based on capsular polysaccharides and induce antibodies with low cross reactivity, leading to restricted coverage of serotypes. For surpassing this limitation, new pneumococcal vaccines are needed for induction of broader protection. One important candidate is the pneumococcal surface protein A (PspA), which can be classified in 6 clades and 3 families. We have reported an efficient process for production and purification of untagged recombinant PspA from clade 4 (PspA4Pro). We now aim to obtain a highly pure recombinant PspA from clade 1 (PspA1) to be included, together with PspA4Pro, in a vaccine formulation to broaden response against pneumococci. The vector pET28a-pspA1 was constructed and used to transform Escherichia coli BL21(DE3) strain. One clone with high production of PspA1 was selected and adapted to high-density fermentation (HDF) medium. After biomass production in 6 L HDF using a bioreactor, the purification was defined after testing 3 protocols. During the batch bioreactor cultivation, plasmid stability remained above 90% and acetate formation was not detected. The final protein purification process included treatment with a cationic detergent after lysis, anion exchange chromatography, cryoprecipitation, cation exchange chromatography, and multimodal chromatography. The final purification process showed PspA1 purity of 93% with low endotoxin content and an overall recovery above 20%. The novel established process can be easily scaled-up and proved to be efficient to obtain a highly pure untagged PspA1 for inclusion in vaccine formulations. KEY POINTS: • Purification strategy for recombinant PspA1 from Streptococcus pneumoniae • Downstream processing for untagged protein antigens, the case of PspA1 • Purification strategy for PspA variants relies on buried amino acids in their sequences.

Chitosan-LeoA-DNA Nanoparticles Promoted the Efficacy of Novel LeoA-DNA Vaccination on Mice Against Helicobacter pylori.

More than half of the world's population is infected with Helicobacter pylori (H. pylori), which may lead to chronic gastritis, peptic ulcers, and stomach cancer. LeoA, a conserved antigen of H. pylori, aids in preventing this infection by triggering specific CD3+ T-cell responses. In this study, recombinant plasmids containing the LeoA gene of H. pylori are created and conjugated with chitosan nanoparticle (CSNP) to immunize BALB/c mice against the H. pylori infection. We used the online Vaxign tool to analyze the genomes of five distinct strains of H. pylori, and we chose the outer membrane as a prospective vaccine candidate. Afterward, the proteins' immunogenicity was evaluated. The DNA vaccine was constructed and then encapsulated in CSNPs. The effectiveness of the vaccine's immunoprotective effects was evaluated in BALB/c mice. Purified activated splenic CD3+ T cells are used to test the anticancer effects in vitro. Nanovaccines had apparent spherical forms, were small (mean size, 150-250 nm), and positively charged (41.3 ± 3.11 mV). A consistently delayed release pattern and an entrapment efficiency (73.35 ± 3.48%) could be established. Compared to the non-encapsulated DNA vaccine, vaccinated BALB/c mice produced higher amounts of LeoA-specific IgG in plasma and TNF-α in splenocyte lysate. Moreover, BALB/c mice inoculated with nanovaccine demonstrated considerable immunity (87.5%) against the H. pylori challenge and reduced stomach injury and bacterial burdens in the stomach. The immunological state in individuals with GC with chronic infection with H. pylori is mimicked by the H. pylori DNA nanovaccines by inducing a shift from Th1 to Th2 in the response. In vitro human GC cell development is inhibited by activated CD3+ T lymphocytes. According to our findings, the H. pylori vaccine-activated CD3+ has potential immunotherapeutic benefits.

Poor association between 13-valent pneumococcal conjugate vaccine-induced serum and mucosal antibody responses with experimental Streptococcus pneumoniae serotype 6B colonisation.

BACKGROUND: Pneumococcal carriage is the primary reservoir for transmissionand a prerequisite for invasive pneumococcal disease. Pneumococcal Conjugate Vaccine 13 (PCV13) showed a 62% efficacy in protection against experimental Streptococcus pneumoniae serotype 6B (Spn6B) carriage in a controlled human infection model (CHIM) of healthy Malawian adults. We, therefore, measured humoral responses to experimental challenge and PCV-13 vaccination and determined the association with protection against pneumococcal carriage. METHODS: We vaccinated 204 young, healthy Malawian adults with PCV13 or placebo and nasally inoculated them with Spn6B at least four weeks post-vaccination to establish carriage. We collected peripheral blood and nasal lining fluid at baseline, 4 weeks post-vaccination (7 days pre-inoculation), 2, 7, 14 and > 1 year post-inoculation. We measured the concentration of anti-serotype 6B Capsular Polysaccharide (CPS) Immunoglobulin G (IgG) and IgA antibodies in serum and nasal lining fluid using the World Health Organization (WHO) standardised enzyme-linked immunosorbent assay (ELISA). RESULTS: PCV13-vaccinated adults had higher serum IgG and nasal IgG/IgA anti-Spn6B CPS-specific binding antibodies than placebo recipients 4 to 6 weeks post-vaccination, which persisted for at least a year after vaccination. Nasal challenge with Spn6B did not significantly alter serum or nasal anti-CPS IgG binding antibody titers with or without experimental pneumococcal carriage. Pre-challenge titers of PCV13-induced serum IgG and nasal IgG/IgA anti-Spn6B CPS binding antibodies did not significantly differ between those that got experimentally colonised by Spn6B compared to those that did not. CONCLUSION: This study demonstrates that despite high PCV13 efficacy against experimental Spn6B carriage in young, healthy Malawian adults, robust vaccine-induced systemic and mucosal anti-Spn6B CPS binding antibodies did not directly relate to protection.

Immunogenicity and safety of adsorbed diphtheria-purified pertussis-tetanus-inactivated polio (Sabin strain)-Haemophilus type b conjugate combined vaccine (DPT-IPV-Hib) in healthy Japanese Infants ≥ 2 and < 43 months of Age: A phase III, multicenter, active controlled, assessor-blinded, randomized, parallel-group study.

OBJECTIVE: This study investigated the immunogenicity and safety of a pentavalent vaccine Gobik (DPT-IPV-Haemophilus influenzae type b [Hib]) in healthy Japanese infants aged ≥ 2 and < 43 months using a concomitant vaccination with ActHIB® (Hib) and Tetrabik (DPT-IPV) as a comparator. METHODS: This study was conducted as a phase 3, multicenter, active controlled, assessor-blinded, randomized, parallel-group study. Participants received a total of 4 subcutaneous doses (3 primary immunization doses and a booster dose) of either the experimental drug (DPT-IPV-Hib) or the active comparator (Hib + DPT-IPV). The primary endpoints were the anti-PRP antibody prevalence rate with ≥ 1 µg/mL, and the antibody prevalence rates against pertussis, diphtheria toxin, tetanus toxin, and attenuated poliovirus after the primary immunization. RESULTS: In 267 randomized participants (133 in the DPT-IPV-Hib group and 134 in the Hib + DPT-IPV group), the antibody prevalence rates after the primary immunization in both groups were 100.0 % and 88.7 % for anti-PRP antibody with ≥ 1 µg/mL, 99.2 % and 98.5 % against diphtheria toxin, and 100.0 % and 99.2 % against tetanus toxin, respectively. The antibody prevalence rates against pertussis and attenuated poliovirus were 100.0 % in both groups. The non-inferiority of the DPT-IPV-Hib group to the Hib + DPT-IPV group was verified for all measured antibodies. In both groups, all the GMTs of antibodies after the primary immunization were higher than those before the first dose, and those after the booster dose were higher than those after the primary immunization. No safety issues were identified. CONCLUSION: A single-agent Gobik, the first DPT-IPV-Hib pentavalent vaccine approved in Japan, was confirmed to simultaneously provide primary and booster immunizations against Hib infection, pertussis, diphtheria, tetanus, and poliomyelitis and to have a preventive effect and safety comparable to concomitant vaccination with Hib (ActHIB®) and DPT-IPV quadrivalent vaccine (Tetrabik).

Assessment of the effect of long-term serum storage for retrospective serologic diagnosis of canine monocytic ehrlichiosis (Ehrlichia canis).

There is currently sparse information on the possible effect of long-term storage of serum specimens for the retrospective serodiagnosis of canine monocytic ehrlichiosis (CME). The aim of this study was to assess the agreement between the original serologic outcome and the results of a repeat indirect fluorescent antibody (IFA) assay for the detection of IgG antibodies against E. canis. A secondary aim was to compare the diagnostic performance of two commercially available point-of-care (POC) immunochromatographic (IC) assays. Archived serum samples originally tested as positive (n=66) or negative (n=19) for E. canis IgG antibodies and kept frozen at -20°C for a median of 22 years, were retrospectively examined by IFA and by two POC IC assays. Cohen's Kappa coefficient (0.748, p < 0.0001), indicated a substantial agreement between the original and repeat serologic testing results. An almost identical high sensitivity and moderate specificity were established for the two POC IC assays. Canine serum specimens on long-term storage may still be of value for seroepidemiologic surveys investigating the exposure to E. canis.

Causal associations between Helicobacter pylori infection and pregnancy and neonatal outcomes: a two-sample Mendelian randomization study.

Background: Observational studies have reported that Helicobacter pylori (H. pylori) infection is associated with a series of pregnancy and neonatal outcomes. However, the results have been inconsistent, and the causal effect is unknown. Methods: A two-sample Mendelian randomization (MR) study was performed using summary-level statistics for anti-H. pylori IgG levels from the Avon Longitudinal Study of Parents and Children Cohort. Outcome data for pregnancy (miscarriage, preeclampsia-eclampsia, gestational diabetes mellitus, placental abruption, premature rupture of membranes, postpartum hemorrhage) and neonates (birthweight, gestational age, and preterm birth) were sourced from genome-wide association meta-analysis as well as the FinnGen and Early Growth Genetics Consortium. Causal estimates were calculated by five methods including inverse variance weighted (IVW). The heterogeneity of instrumental variables was quantified by Cochran's Q test, while sensitivity analyses were performed via MR-Egger, MR-PRESSO, and leave-one-out tests. Results: IVW estimates suggested that genetically predicted anti-H. pylori IgG levels were significantly associated with increased risks of preeclampsia-eclampsia (odds ratio [OR] = 1.12, 95% confidence interval [CI] 1.01-1.24, P = 0.026) and premature rupture of membranes (OR = 1.17, 95% CI 1.05-1.30, P = 0.004). Similar results were obtained for preeclampsia-eclampsia from the MR-Egger method (OR = 1.32, 95% CI 1.06-1.64, P = 0.027) and for premature rupture of membranes from the weighted median method (OR = 1.22, 95% CI 1.06-1.41, P = 0.006). No significant causal effects were found for other outcomes. There was no obvious heterogeneity and horizontal pleiotropy across the MR analysis. Conclusion: Our two-sample MR study demonstrated a causal relationship of H. pylori infection with preeclampsia-eclampsia and premature rupture of membranes. The findings confirm the epidemiological evidence on the adverse impact of H. pylori in pregnancy. Further studies are needed to elucidate the pathophysiological mechanisms and assess the effectiveness of pre-pregnancy screening and preventive eradication.

Humoral and cellular immune responses induced by serogroup W135 meningococcal conjugate and polysaccharide vaccines.

Investigating the mechanisms by which W135 meningococcal conjugate (PSW135-TT) activates adaptive immune responses in mice can provide a comprehensive understanding of the immune mechanisms of bacterial polysaccharide conjugate vaccines. We compared B-cell and T-cell immune responses immunized with W135 meningococcal capsular polysaccharides (PSW135), tetanus toxoid (TT) and PSW135-TT in mice. The results showed that PSW135-TT could induce higher PSW135-specific and TT-specific IgG antibodies with a significant enhancement after two doses. All serum antibodies immunized with PSW135- TT had strong bactericidal activity, whereas none of the serum antibodies immunized with PSW135 had bactericidal activity. Besides, IgM and IgG antibodies immunized with PSW135-TT after two doses were positively correlated with the titer of bactericidal antibodies. We also found Th cells favored Th2 humoral immune responses in PSW135-TT, PSW135, and TT-immunized mice, especially peripheral blood lymphocytes. Furthermore, PSW135-TT and TT could effectively activate bone marrow derived dendritic cells (BMDCs) and promote BMDCs to highly express major histocompatibility complex Ⅱ (MHCⅡ), CD86 and CD40 molecules in mice, whereas PSW135 couldn't. These data verified the typical characteristics of PSW135-TT and TT as T cell dependent antigen (TD-Ag) and PSW135 as T cell independent antigen (TI-Ag), which will be very helpful for further exploration of the immune mechanism of polysaccharide-protein conjugate vaccines and improvement of the quality of bacterial polysaccharide conjugate vaccines in future.

A randomized, blind, parallel controlled phase I clinical trial to evaluate the safety and preliminary immunogenicity of 23-valent pneumococcal polysaccharide vaccine in healthy people aged 2 years and older.

BACKGROUND: Despite some progress in pneumococcal immunization, the global burden of pneumococcal infection remains high, and pneumococcal disease remains a public health concern. Studies in China and abroad have found that 23-valent pneumococcal polysaccharide vaccine (PPV23) vaccination can effectively prevent invasive pneumococcal disease. This phase Ⅰ clinical study assessed the safety and immunogenicity of a PPV23 vaccine candidate. METHODS: All subjects were randomly assigned to receive one dose intramuscular injection of experimental vaccine or control vaccine at a ratio of 1:1. The incidence of any adverse events was observed within 30 min, 0-7 days and 8-28 days post vaccination and the incidence of abnormal blood biochemical and blood routine indicators were tested on the 4th day post vaccination, the incidence of serious adverse events (SAEs) at 6 months post vaccination was recorded. Blood samples were collected prior to vaccination and on the 28th day post vaccination, and serum antibodies were detected by enzyme linked immunosorbent assay (ELISA). RESULTS: The most common adverse reaction was pain at the injection site, followed by erythema. There was no significant difference of the incidence of systemic adverse reactions between the two vaccine groups. The adverse reactions observed in the trial were all common vaccination-related reactions, and no serious adverse reactions were observed. Compared to pre-vaccination, the (geometric mean concentrations) GMCs of IgG (immunoglobulin G) specific antibody against each serotype were all increased in the experimental group and the control group, there were statistical differences in seroconversion rates of serotypes 4 and 20 between the two vaccine groups. CONCLUSION: This clinical study showed good safety of the PPV23 vaccine candidate produced by Ab&b Biotechnology Co., Ltd.JS had good safety after vaccination in people aged 2 years and older. At the same time, good immunogenicity was also demonstrated.

Diagnostic value of IgG antibody and stool antigen tests for chronic Helicobacter pylori infections in Ibb Governorate, Yemen.

The stool antigen test (SAT) and the serum Helicobacter pylori (H. pylori) IgG antibody assays exhibit significant utility in the clinical diagnosis of H. pylori infection and in distinguishing between acute and chronic infections. The main objective of the current study was to identify the diagnostic value of serum H. pylori IgG antibody and SAT in the detection of H. pylori infections among chronic H. pylori-infected patients residing in Ibb Governorate, Yemen. 200 patients with H. pylori infection, confirmed through positive results in the serum immunochromatographic antibody test, were selected for H. pylori infection confirmation using serum H. pylori IgG antibodies and SAT across diverse hospitals, gastroenterology, and Hepatology clinics in Ibb Governorate. After the selection of patients, blood and stool specimens were obtained from all participants and underwent analysis via the Statistical Package for the Social Sciences (SPSS). The prevalence of H. pylori infection demonstrated variability based on the confirmatory tests, with rates of 54% for SAT and 78.5% for serum H. pylori IgG antibody, contrasting with a 100% prevalence observed in the screening serum immunochromatographic antibody test. Clinically, the study categorized H. pylori infections into four stages, whereby a significant proportion of patients (40.5%) exhibited positivity for both serum H. pylori IgG antibody and SAT, indicative of active chronic infections. The majority of positive cases only manifested serum H. pylori IgG antibody presence (chronic infections) at 38%, whereas 13.5% exclusively tested positive for SAT, corresponding to acute infections. Moreover, 88% of patients did not have either serum H. pylori IgG antibody or SAT (absence of infections) during confirmatory tests. Noteworthy is the study's approach employing multiple tests for H. pylori infection detection, focusing predominantly on chronic infections-prevailing types caused by H. pylori. The results revealed a significant association between serum levels of H. pylori IgG antibody and SAT results with the presence of diverse gastrointestinal symptoms among patients, which increased with long H. pylori infection durations.

Sero-prevalence and risk factors associated with occurrence of anti-Brucella antibodies among slaughterhouse workers in Uganda.

INTRODUCTION: Brucellosis is a febrile zoonosis occurring among high-risk groups such as livestock keepers and abattoir workers and is a public health priority in Uganda. The technical complexities of bacteriological and molecular methods make serological approaches the cornerstone of diagnosis of human brucellosis in resource limited settings. Therefore, proper application and interpretation of serological tests is central to achieve a correct diagnosis. MATERIALS AND METHODS: We conducted a cross-sectional study to estimate the seroprevalence and factors associated with anti-Brucella antibodies among slaughterhouse workers processing ruminants and pigs in three regions of the country with serial testing using a combination of the Rose Bengal Test (RBT) and the BrucellaCapt test. An authorized clinician collected 543 blood samples from consenting abattoir workers as well as attribute medical and social demographic data. Univariable and multivariable logistic regression were used to determine factors associated with anti-Brucella sero-positivity. RESULTS AND DISCUSSION: The sero-prevalence among ruminant slaughterhouse workers ranged from 7.3% (95% CI: 4.8-10.7) using BrucellaCapt to 9.0% (95% CI: 6.3-12.7) using RBT. Slaughterhouse workers from the Eastern regions (AOR = 9.84, 95%CI 2.27-69.2, p = 0.006) and those who graze animals for alternative income (AOR = 2.36, 95% CI: 1.91-6.63, p = 0.040) were at a higher risk of exposure to Brucella. Similarly, those who wore Personal Protective Equipment (AOR = 4.83, 95%CI:1.63-18.0, p = 0.009) and those who slaughter cattle (AOR = 2.12, 95%CI: 1.25-6.0, p = 0.006) were at a higher risk of exposure to Brucella. Those who slaughter small ruminants (AOR = 1.54, 95%CI: 1.32-4.01, p = 0.048) were also at a higher risk of exposure to Brucella. CONCLUSIONS AND RECOMMENDATIONS: Our study demonstrates the combined practical application of the RBT and BrucellaCapt in the diagnosis of human brucellosis in endemic settings. Both pharmaceutical (e.g., routine testing and timely therapeutic intervention), and non-pharmaceutical (e.g., higher index of suspicion of brucellosis when investigating fevers of unknown origin and observation of strict abattoir hygiene) countermeasures should be considered for control of the disease in high-risk groups.

Seroprevalence of Infection by Borrelia Species Responsible for Lyme Disease in the French Alps: Analysis of 27,360 Serology Tests, 2015-2020.

Objectives: Lyme borreliosis incidence is increasing in several areas; moreover, it has recently gained the public's attention. Apart from erythema migrans, Lyme disease diagnosis relies (among others) on serology test; however, the prevalence of positive enzyme-linked immunosorbent assay (ELISA) and western blot (WB) assay has been poorly studied in the general population. We aimed to approach the seroprevalence of infection by Borrelia species responsible for Lyme disease in the French Isere department using city laboratories data. Patients and Methods: We retrieved all serological tests for Borrelia species responsible for Lyme disease performed in the two main networks of city laboratories between 2015 and 2020. All patients with both ELISA and WB IgG were considered seropositive. Results: We analyzed 27,360 tests (ELISA/ELISA+WB). Mean age was 50.9 ± 20.3 years (ranges: 0-101), with 57.1% females. Overall, 11.7% had IgG detected by ELISA, and 4.7% had IgG detected by both ELISA and WB assay. Seropositive status was more frequent in males (7.0% vs. 2.9%, p < 0.001). Seropositivity rate increased with age after a first peak in childhood; men aged 61-70 years had the highest seropositivity rate (10.3%). In addition, seropositivity rate was higher in persons from a rural area. In multivariate analysis, older age, male gender and living in a rural area were independently associated with seropositivity. Seropositivity rate was stable on the 2017-2020 period. Conclusion: The seroprevalence of infection by Borrelia species responsible for Lyme disease is high in Isere; this probably reduces the predictive positive value for Lyme disease of ELISA and WB IgG, suggesting that this serological test should not be performed for nonspecific symptoms.

Antibodies from chlamydia-infected individuals facilitate phagocytosis via Fc receptors.

Non-neutralizing functions of antibodies, including phagocytosis, may play a role in Chlamydia trachomatis (CT) infection, but these functions have not been studied and assays are lacking. We utilized a flow-cytometry-based assay to determine whether serum samples from a well-characterized cohort of CT-infected and naïve control individuals enhanced phagocytosis via Fc-receptor-expressing THP-1 cells, and whether this activity correlated with antibody titers. Fc-receptor-mediated phagocytosis was detected only in CT+ donors. Phagocytosis generally did not correlate well with antibody titer. In addition, we found that complement from both CT+ and negative individuals enhanced phagocytosis of CT into primary neutrophils. These results suggest that anti-CT antibodies can have functions that are not reflected by titer. This method could be used to quantitively measure Fc-receptor-mediated function of anti-CT antibodies or complement activity and could reveal new immune correlates of protection.

Single-domain antibodies reveal unique borrelicidal epitopes on the Lyme disease vaccine antigen, outer surface protein A (OspA).

Camelid-derived, single-domain antibodies (VHHs) have proven to be extremely powerful tools in defining the antigenic landscape of immunologically heterogeneous surface proteins. In this report, we generated a phage-displayed VHH library directed against the candidate Lyme disease vaccine antigen, outer surface protein A (OspA). Two alpacas were immunized with recombinant OspA serotype 1 from Borrelia burgdorferi sensu stricto strain B31, in combination with the canine vaccine RECOMBITEK Lyme containing lipidated OspA. The phage library was subjected to two rounds of affinity enrichment ("panning") against recombinant OspA, yielding 21 unique VHHs within two epitope bins, as determined through competition enzyme linked immunosorbent assays (ELISAs) with a panel of OspA-specific human monoclonal antibodies. Epitope refinement was conducted by hydrogen exchange-mass spectrometry. Six of the monovalent VHHs were expressed as human IgG1-Fc fusion proteins and shown to have functional properties associated with protective human monoclonal antibodies, including B. burgdorferi agglutination, outer membrane damage, and complement-dependent borreliacidal activity. The VHHs displayed unique reactivity profiles with the seven OspA serotypes associated with B. burgdorferi genospecies in the United States and Europe consistent with there being unique epitopes across OspA serotypes that should be considered when designing and evaluating multivalent Lyme disease vaccines.

A case of transfusion-transmission Anaplasma phagocytophilum from leukoreduced red blood cells.

BACKGROUND: Anaplasma phagocytophilum is a tick-borne bacterium and the cause of human granulocytic anaplasmosis (HGA). Here, we report a case of transfusion-transmitted (TT)-HGA involving a leukoreduced (LR) red blood cell (RBC) unit. CASE REPORT: A 64-year-old woman with gastric adenocarcinoma and multiple myeloma who received weekly blood transfusions developed persistent fevers, hypotension, and shortness of breath 1 week after receiving an RBC transfusion. Persistent fevers, new thrombocytopenia, and transaminitis suggested a tick-borne infection. RESULTS: The absence of blood parasites on thick and thin blood smears suggested that malaria and Babesia infection were not present, and the recipient tested negative for antibodies to Borrelia burgdorferi. Blood testing by polymerase chain reaction (PCR) for Ehrlichia and Anaplasma species identified A. phagocytophilum. Treatment with doxycycline resolved the infection; however, the recipient expired due to complications of her known malignancies. The recipient lived in a nursing home and did not have pets or spend time outdoors. The donor was a female in her 70s from Maine who was diagnosed with HGA 3 weeks after donating blood and whose LR-RBCs from the donation were transfused to the recipient 9 days following collection. CONCLUSION: This is a confirmed case of TT-HGA. Although rare, TT-HGA has been reported with LR-RBCs and platelets. In endemic areas, testing for tick-borne associated infections should be considered when investigating post-transfusion complications.

Suppression of host humoral immunity by Borrelia burgdorferi varies over the course of infection.

Borrelia burgdorferi, the spirochetal agent of Lyme disease, utilizes a variety of strategies to evade and suppress the host immune response, which enables it to chronically persist in the host. The resulting immune response is characterized by unusually strong IgM production and a lack of long-term protective immunity. Previous studies in mice have shown that infection with B. burgdorferi also broadly suppresses host antibody responses against unrelated antigens. Here, we show that mice infected with B. burgdorferi and concomitantly immunized with recombinant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein had an abrogated antibody response to the immunization. To further define how long this humoral immune suppression lasts, mice were immunized at 2, 4, and 6 weeks post-infection. Suppression of host antibody production against the SARS-CoV-2 spike protein peaked at 2 weeks post-infection but continued for all timepoints measured. Antibody responses against the SARS-CoV-2 spike protein were also assessed following antibiotic treatment to determine whether this immune suppression persists or resolves following clearance of B. burgdorferi. Host antibody production against the SARS-CoV-2 spike protein returned to baseline following antibiotic treatment; however, anti-SARS-CoV-2 IgM remained high, comparable to levels found in B. burgdorferi-infected but untreated mice. Thus, our data demonstrate restored IgG responses following antibiotic treatment but persistently elevated IgM levels, indicating lingering effects of B. burgdorferi infection on the immune system following treatment.