Development of novel Streptococcus equi vaccines with an assessment of their immunizing potentials and protective efficacies.

Strangles is a highly contagious disease of the equine upper respiratory tract caused by Streptococcus equi subspecies. Streptococcus equi subsp. equi (S. equi) and Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) was isolated, as local, hot, and field strains, from horses clinically suffering from respiratory distress. The isolated Streptococci were identified using bacteriological and molecular techniques. Four formulations of inactivated S. equi vaccines were developed and evaluated. The first formulation was prepared using the S. equi isolates, adjuvanted with MONTANIDE GEL adjuvant, while the second formulation was adjuvanted with MONTANIDE ISA-70 adjuvant. The other 2 formulations were inactivated combined vaccines prepared from both S. equi and S. zooepidemicus isolates. The 3rd formulation was the combined isolates adjuvanted with MONTANIDE GEL while the 4th formulation was the combined isolates adjuvanted with MONTANIDE ISA-70. The developed vaccines' physical properties, purity, sterility, safety, and potency were ensured. The immunizing efficacy was determined in isogenic BALB/c mice and white New Zealand rabbits using the passive hemagglutination test. Also, the antibodies' titer of the combined S. equi and S. zooepidemicus vaccine adjuvanted with MONTANIDE ISA-70 in foals was tracked using an indirect enzyme-linked immunosorbent assay. The protective efficacy of the developed vaccines was determined using a challenge test in both laboratory and field animal models, where a 75% protection rate was achieved. The combined vaccine proved to be more efficacious than the monovalent vaccine. Also, the MONTANIDE ISA-70 adjuvant provided significant protective efficacy than the MONTANIDE GEL. The current work is introducing a very promising mitigative and strategic controlling solution for strangles.

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.

Performance Assessment of Treponemal and Nontreponemal Tests for the Diagnosis of Acquired Syphilis.

There are a variety of nontreponemal test (NTT) and treponemal test (TT) kits for the serologic diagnosis of syphilis. Because of the complexity of the infection (multiple clinical stages) and the different antigens used in these kits, a systematic evaluation of the accuracy of the currently available commercial tests is warranted. Our objective was to evaluate the performance of commercially available tests for the diagnosis of syphilis infection. In this study, we analyzed one NTT (Venereal Disease Research Laboratory [VDRL] test, Wiener Laboratories, Rosario, Argentina) and two TTs (fluorescent treponemal antibody absorption [FTA-ABS] test, Euroimmun, Lübeck, Germany, and syphilis recombinant ELISA v. 4.0 test [ELISA], Wiener Laboratories, Rosario, Argentina) using a panel of 187 samples, including serum samples from 31 individuals with primary syphilis, 77 with secondary syphilis, and 79 with latent syphilis. An additional 192 samples from uninfected individuals and 323 serum samples from individuals with other diseases were included. The sensitivities of the VDRL, ELISA, and FTA-ABS tests were 97.9%, 100%, and 96.3%, respectively. The VDRL and ELISA tests showed a specificity of 100%, and the FTA-ABS test showed a specificity of 99.5%. Accuracy was 98.9% for the VDRL test, 100% for the ELISA, and 97.9% for the FTA-ABS test. For primary, secondary, and latent syphilis, the ELISA achieved a diagnostic performance of 100%, whereas the sensitivity for the VDRL and FTA-ABS tests ranged from 96.8% to 98.7% and 93.7% to 98.7%, respectively. No difference was observed when the tests were used as traditional or reverse algorithms. In general, all three tests are able to discriminate positive and negative samples for syphilis, regardless of the diagnostic algorithm.

External quality assessment to support the WHO ProSPeRo study for the evaluation of two dual HIV/syphilis point-of-care tests in seven countries.

BACKGROUND: Sexually transmitted infections (STIs) such as syphilis and HIV remain to be a significant public health issue worldwide. Dual rapid point-of-care tests (POCTs) have shown promise for detecting antibodies to HIV and syphilis but have not been fully evaluated in the field. Our study supported the WHO ProSPeRo study on Sexually Transmitted Infection Point-of-Care Testing (STI POCT) by providing external quality assessment (EQA) for HIV and syphilis testing in reference laboratories and their associated clinical sites in seven countries. METHODS: HIV/syphilis serum liquid and dried tube specimen (DTS) panels were prepared by CDC. Liquid panels were distributed to the reference laboratories for three rounds of testing using commercially and locally available laboratory-based serological tests. DTS panels were sent to the clinical testing sites for 8 rounds of POC testing using the Abbott SD BIOLINE HIV/Syphilis Duo test (hereafter referred to as SD BIOLINE) and the Chembio Dual Path Platform (DPP) HIV-Syphilis assay. EQA panels were tested at CDC using the Rapid Plasma Reagin (RPR) test and the Treponema pallidum Particle Agglutination assay (TP-PA) for syphilis antibodies. Genetic Systems HIV-1/HIV-2 Plus O EIA, Geenius HIV Supplemental Assay and the Oraquick Advance HIV test were used to detect HIV antibodies in the EQA panels. Results from the reference laboratories and POCT sites were compared to those obtained at the CDC and a percentage agreement was calculated. RESULTS: Qualitative RPR and TP-PA performed at the reference laboratories demonstrated 95.4-100% agreement with CDC results while quantitative RPR and TP-PA tests demonstrated 87.7% and 89.2% agreement, respectively. A 93.8% concordance rate was observed for qualitative HIV testing in laboratories. EQA testing at clinical sites using dual tests showed 98.7% and 99.1% agreement for detection of HIV antibodies and eight out of 10 sites had > 95.8% agreement for syphilis testing. However, two clinical sites showed only 65.0-66.7% agreement for SD BIOLINE and 84.0-86.7% for DPP, respectively, for syphilis testing. CONCLUSIONS: Overall, laboratories demonstrated high EQA performance in this study. Both HIV/syphilis POCTs gave expected results in the clinic-based evaluations using DTS. However, testing errors were identified in a few testing sites suggesting the necessity for continuous training and monitoring the quality of POC testing.

Randomized controlled trial comparing the costs of gastric cancer screening systems between serological risk-based upper gastrointestinal endoscopy and the existing barium photofluorography: gastric cancer screening labeled by serum examination in place of aged gastric cancer organized screening systems (GALAPAGOS study).

BACKGROUND: Although the risk of gastric cancer can be stratified according to Helicobacter pylori (H. pylori) IgG antibody titer and pepsinogen levels (ABC classification), a population-based gastric cancer screening system combining serological tests and endoscopy has not been introduced. This study aimed to compare the total testing cost per participant between the ABC classification method and the existing protocol. METHODS: Using the minimization method with sex and age as allocation factors, 1206 participants were randomly assigned to the following two methods for a 5-year intervention: barium photofluorography as primary examination followed by detailed examination with upper gastrointestinal endoscopy (Ba-Endo) and risk-based upper gastrointestinal endoscopy by ABC classification (ABC-Endo). The primary endpoint was the total testing cost per participant over a 5-year period. The secondary endpoint was the expense required to detect one gastric cancer. RESULTS: The total testing cost per participant was 39,711 yen in Ba-Endo (604 participants) and 45,227 yen in ABC-Endo (602 participants), with the latter being significantly higher (p < 0.001). During the intervention period, gastric cancer was found in 11 and eight participants in Ba-Endo and ABC-Endo, respectively. The expenses required to detect one gastric cancer were 2,240,931 yen in Ba-Endo and 3,486,662 yen in ABC-Endo. CONCLUSIONS: The testing cost per participant turned out to be higher in the ABC-Endo group than in the Ba-Endo group. This superiority trial, based on the hypothesis that the cost of testing is lower for ABC-Endo than for Ba-Endo, was rejected.

Design, development, and assessment of a novel multi-peptide vaccine targeting PspC, PsaA, and PhtD proteins of Streptococcus pneumoniae.

Pneumococcus is the top cause of diseases such as pneumonia/meningitis, and of secondary infections after viral respiratory diseases like COVID-19/flu. Pneumococcal protein-based vaccines consisting of proteins with various functions in virulence might provide a qualified alternative for present vaccines. In this project, PspC, PsaA, and PhtD proteins were considered to anticipate B/T-cell epitopes using immunoinformatics to develop 4 multi-peptide constructs (C, A, and D individual constructs, and a fusion construct CAD). We tested whether vaccination with CAD is able to elicit more efficient protective responses against infection than vaccination with the individual constructs or combination of C + A + D. Based on the in silico results, the constructs were predicted to be antigenic, soluble, non-toxic, and stable, and also be able to provoke humoral/cellular immune reactions. When mice were immunized with the fusion protein, significantly higher levels of IgG and cytokines were induced in serum. The IgG in the fusion group had an effective bioactivity for pneumococcus clearance utilizing the complement pathway. The mice immunized with fusion protein were the most protected from challenge. This report for the first time presents a novel multi-peptide vaccine composed of immunodominant peptides of PspC, PsaA, and PhtD. In general, the experimental results supported the immunoinformatics predictions.

Stability assessment of anti-bacterial antibodies in immunoglobulin G-depleted serum with validated immunoassays.

Aim: To investigate the stability of the anti-pneumococcal (PCP) and anti-haemophilus type B (Hib) immunoglobulins (IgGs) in human IgG-depleted serum samples frozen at -20°C. Materials & methods: Modified commercially available immunoassays (ELISAs) were bioanalytically validated. These ELISAs were used to measure levels of the two anti-bacterial IgG in samples kept at -20°C for up to 15 months. Human IgG-depleted serum was spiked with GAMMAGARD Liquid to obtain those samples. Results: Both ELISAs passed the validation test. Anti-PCP IgG and anti-Hib IgG were shown to be stable for at least 15 months at -20°C. Conclusion: These data confirm the stability of anti-bacterial IgG in human IgG-depleted serum and support the common practice of testing frozen samples.

Immunodeficiency disorders can prevent your body from fighting infections. These disorders make it easier to catch viruses and bacterial infections caused by so-called pathogens. Patients suffering from immunodeficiencies are treated throughout their lives with antibodies purified from human plasma. This immunoglobulin replacement therapy, which helps to avoid infections, provides specific antibodies directed against these pathogens. An antibody is a protein produced by the body's immune system to detect (bind) antigens and to help eliminating harmful substances. Little is known about the stability of such specific antibodies in samples taken from patients during clinical studies carried out to improve the replacement therapy. We investigated the stability of two such antibodies using a standard technique for their measurement. In a process termed validation, these methods were demonstrated to deliver accurate and precise results. For the stability study, we prepared human serum (= the liquid part of human blood) samples with specific antibodies levels expected in samples from patients on replacement therapy. These samples were kept frozen at -20°C for up to 15 months. The data obtained on analysis of the frozen samples showed the adequate stability of both antibodies directed against important pathogen. This stability confirms a common testing practice applied for samples obtained in clinical studies where usually such samples are not tested immediately but are stored frozen and tested in batches. In particular, the data for the two anti-bacterial antibodies support the storage of such samples for at least 15 months at -20°C before testing.

Assessment of tetanus revaccination regimens in horses not vaccinated in the previous year.

A two-dose revaccination against tetanus is recommended for horses over 2 years old in Japan with no history of vaccination in the previous year. Here, the need for two-dose revaccination was evaluated in terms of antibody titers for each vaccine type, namely monovalent or multivalent. There was no difference in antibody titers between one- and two-dose regimens for up to 1 year, except at 8 weeks with the multivalent vaccine, and all horses had sufficient antibody titers for 1 year of tetanus prophylaxis. These results suggest that one-dose revaccination, regardless of the vaccine type, is as effective as two-dose in preventing tetanus for at least 1 year in horses not vaccinated in the previous year.

Formulation Studies to Develop Low-Cost, Orally-Delivered Secretory IgA Monoclonal Antibodies for Passive Immunization Against Enterotoxigenic Escherichia coli.

Enterotoxigenic Escherichia coli (ETEC) is a common cause for diarrheal infections in children in low- and middle-income countries (LMICs). To date, no ETEC vaccine candidates have been approved. Passive immunization with low-cost, oral formulations of secretory IgA (sIgA) against ETEC is an alternative approach to protect high-risk populations in LMICs. Using a model sIgA monoclonal antibody (anti-LT sIgA2-mAb), the stability profiles of different formulations were assessed during storage and in in vitro digestion models (mimicking in vivo oral delivery). First, by employing various physicochemical techniques and a LT-antigen binding assay, three formulations with varying acid-neutralizing capacity (ANC) were evaluated to stabilize sIgA2-mAb during stress studies (freeze-thaw, agitation, elevated temperature) and during exposure to gastric phase digestion. Next, a low-volume, in vitro intestinal digestion model was developed to screen various additives to stabilize sIgA2-mAb in the intestinal phase. Finally, combinations of high ANC buffers and decoy proteins were assessed to collectively protect sIgA2-mAb during in vitro sequential (stomach to intestine) digestion. Based on the results, we demonstrate the feasibility of low-cost, 'single-vial', liquid formulations of sIgA-mAbs delivered orally after infant feeding for passive immunization, and we suggest future work based on a combination of in vitro and in vivo stability considerations.

Assessment of the influence of ABO blood groups on oral cholera vaccine immunogenicity in a cholera endemic area in Zambia.

BACKGROUND: Histo-blood group antigens (HBGAs) which include the ABO and Lewis antigen systems have been known for determining predisposition to infections. For instance, blood group O individuals have a higher risk of severe illness due to V. cholerae compared to those with non-blood group O antigens. We set out to determine the influence that these HBGAs have on oral cholera vaccine immunogenicity and seroconversion in individuals residing within a cholera endemic area in Zambia. METHODOLOGY: We conducted a longitudinal study nested under a clinical trial in which samples from a cohort of 223 adults who were vaccinated with two doses of Shanchol™ and followed up over 4 years were used. We measured serum vibriocidal geometric mean titers (GMTs) at Baseline, Day 28, Months 6, 12, 24, 30, 36 and 48 in response to the vaccine. Saliva obtained at 1 year post vaccination was tested for HBGA phenotypes and secretor status using an enzyme-linked immunosorbent assay (ELISA). RESULTS: Of the 133/223 participants included in the final analysis, the majority were above 34 years old (58%) and of these, 90% were males. Seroconversion rates to V. cholerae O1 Inaba with non-O (23%) and O (30%) blood types were comparable. The same pattern was observed against O1 Ogawa serotype between non-O (25%) and O (35%). This trend continued over the four-year follow-up period. Similarly, no significant differences were observed in seroconversion rates between the non-secretors (26%) and secretors (36%) against V. cholerae O1 Inaba. The same was observed for O1 Ogawa in non-secretors (22%) and the secretors (36%). CONCLUSION: Our results do not support the idea that ABO blood grouping influence vaccine uptake and responses against cholera.

Assessment of the Possible Correlation between the Presence of Helicobacter Pylori Infection and Hairy Tongue Lesion in a Group of Patients in Syria: A Cross-Sectional and Pilot Study.

BACKGROUND: This study aimed to evaluate the correlation between the presence of hairy tongue and H. pylori infection in patients referring to their blood test based on the serum levels of anti-H pylori IgG antibodies. METHODS: This cross-sectional study was conducted in the Department of Oral Medicine, University of Damascus Dental School, between February 2021 and January 2022. The sample size of 40 patients (23 males, 17 females), whose ages ranged from 20-79 years with a mean age of 41.5 ± 12 years, was calculated using the G*power 3.1.3, with a statistical power of 80% and a significance level of 0.05. The hairy tongue index was assessed by a visual method based on observing the dorsum tongue appearance. Then, a blood test was performed to detect the presence of H. pylori by Immulite 2000 XPi. Statistical analysis was performed using SPSS software 22.0, Chi-square. RESULTS: The prevalence of hairy tongue was higher among males (75%) as compared to females (25%) and was found to be statistically significant (p = 0.026). The hairy tongue lesions were found to be least in the 20-39 age group and most prevalent in the 40-59 age group, without statistically significant correlation. H. pylori infection was detected positive in 70% and negative in 30% of hairy tongue patients, compared to the control group, where the rates were 15% and 85%, respectively, with a statistically significant correlation between infection with H. pylori and hairy tongue (p = 0.001). CONCLUSION: Our results strongly suggest that the hairy tongue might be considered an indicator of H. pylori infection.

Seroprevalence of human leptospirosis in a rural community from Tandil, Argentina. Assessment of risk factors and spatial analysis.

Leptospirosis is a neglected zoonosis that is widely distributed in the world. Although it is endemic in Argentina, prevalence remains unknown. The aims of the study were: (i) to determine the prevalence of leptospirosis in humans from a rural community in Tandil Argentina, (ii) to identify infecting Leptospira spp. serogroups, (iii) to identify factors associated with the infection, (iv) to estimate the population attributable fraction (PAF) of the risk factors and (v) to determine the spatial patterns of disease presentation and related risk factors. Blood samples from 202 participants were collected. A survey was conducted to obtain clinical and epidemiological data. Serological testing was performed by the microscopic agglutination test (MAT). Univariate and multivariate methods were applied to evaluate associations. Spatial clusters were investigated for seroprevalence and risk factors. Antibodies were found in 32.2% of participants (95% CI: 25.8-39.1). The most prevalent serogroup was Hebdomadis followed by Sejroe; Icterohaemorrhagiae; Tarassovi and Canicola. Living at lower altitudes (OR: 13.04; 95% CI: 2.60-65.32); not having access to water supply network (OR: 2.95; 95% CI: 1.30-6.69); living close to flooded streets (OR: 2.94; 95% CI: 1.14-7.69) and practicing water sports (OR: 3.12; 95% CI: 1.12-8.33) were associated with seropositivity. Factors related with housing characteristics, services and infrastructure had the higher PAF (from 17% to 81%). A spatial cluster with higher rates of positivity and of the main risk factors was determined. This work contributes useful data for specific preventive measures that should be implemented for the control of the disease.

Development and evaluation of polyclonal antibody-based antigen detection ELISA and dot blot assays as a less costly diagnostic alternative for pathogenic Leptospira infection.

Leptospirosis is an infectious, zoonotic disease of worldwide distribution, the cause of which is infection by pathogenic Leptospira. In Chile, dairy cattle are recognized a significant source in the maintenance and transmission of this infection, which causes economic losses and represents an infection threat to workers in the dairy industry. The infection is underestimated in cattle, due to the lack of clinical, pathognomonic signs, as well as the low efficiency of current diagnostic techniques. In this study, we developed antigen ELISA and dot blot assays, based on polyclonal antibodies, to detect pathogenic Leptospira in the urine samples of dairy cattle. The proposed tests showed an acceptable diagnostic accuracy, based on an analytical sensitivity of 1·104 Leptospira per mL for ELISA, and 3.2·103 for dot blot. These results corresponded with those obtained by qPCR, and the use of urine samples allowed us to propose new diagnostic alternatives for pathogenic Leptospira infection at a low cost, which can provide information on active infection status, which is a key element in control programs both at individual and herd level.

Application of vaccine response in the evaluation of patients with suspected B-cell immunodeficiency: Assessment of responses and challenges with interpretation.

Diagnostic vaccination is an integral component in the evaluation of patients suspected to have a B cell or humoral deficiency. Evaluation of antibody production in response to both protein- and polysaccharide-based vaccines aids in distinguishing between specific categories of humoral deficiency. Although assessment of pneumococcal polysaccharide responses is widely available and included in diagnostic guidelines, significant variability still exists in the measurement and interpretation of these responses. Interpretation can also be complicated by age, vaccination history and treatment with immunoglobulin replacement therapy. Despite the challenges and limitations of evaluating pneumococcal polysaccharide vaccine responses, it can provide valuable diagnostic and prognostic information to guide therapeutic intervention. Future efforts are needed to further standardize measurement and interpretation of pneumococcal antibody responses to vaccination and to identify and establish other methods and/or vaccines as alternatives to pneumococcal vaccination to address the challenges in certain patient populations.

Development of a cell line-based in vitro assay for assessment of Diphtheria, Tetanus and acellular Pertussis (DTaP)-induced inflammasome activation.

Safety and potency assessment for batch release testing of established vaccines still relies partly on animal tests. An important avenue to move to batch release without animal testing is the consistency approach. This approach is based on thorough characterization of the vaccine to identify critical quality attributes that inform the use of a comprehensive set of non-animal tests to release the vaccine, together with the principle that the quality of subsequent batches follows from their consistent production. Many vaccine antigens are by themselves not able to induce a protective immune response. The antigens are therefore administered together with adjuvant, most often by adsorption to aluminium salts. Adjuvant function is an important component of vaccine potency, and an important quality attribute of the final product. Aluminium adjuvants are capable of inducing NLRP3 inflammasome activation. The aim of this study was to develop and evaluate an in vitro assay for NLRP3 inflammasome activation by aluminium-adjuvanted vaccines. We evaluated the effects of Diphtheria-Tetanus-acellular Pertussis combination vaccines from two manufacturers and their respective adjuvants, aluminium phosphate (AP) and aluminium hydroxide (AH), in an in vitro assay for NLRP3 inflammasome activation. All vaccines and adjuvants tested showed a dose-dependent increase in IL-1ß production and a concomitant decrease in cell viability, suggesting NLRP3 inflammasome activation. The results were analysed by benchmark dose modelling, showing a similar 50% effective dose (ED50) for the two vaccine batches and corresponding adjuvant of manufacturer A (AP), and a similar ED50 for the two vaccine batches and corresponding adjuvant of manufacturer B (AH). This suggests that NLRP3 inflammasome activation is determined by the adjuvant only. Repeated freeze-thaw cycles reduced the adjuvant biological activity of AH, but not AP. Inflammasome activation may be used to measure adjuvant biological activity as an important quality attribute for control or characterization of the adjuvant.

Assessment of recombinant antigens Tp0100 and Tp1016 of Treponema pallidum for serological diagnosis of syphilis.

OBJECTIVE: To discover novel serodiagnostic candidates for the serological diagnosis of syphilis. METHODS: Two recombinant Treponema pallidum proteins Tp0100 and Tp1016 were expressed, purified, and identified by Western Blotting. A total of 600 clinical serum samples were tested with the Tp0100-based ELISA, the Tp1016-based ELISA, and the commercial LICA Syphilis TP kit (ChIVD, Beijing, China). The sensitivities were determined by testing 340 samples from individuals with clinically diagnosed primary, secondary, latent, and tertiary syphilis. The specificities were determined by screening 260 samples from healthy controls and individuals with potentially cross-reactive infections, including leptospirosis, Lyme disease, hepatitis B, tuberculosis, rheumatoid arthritis, systemic lupus erythematosus. Kappa (κ) values were applied to compare the agreement between clinical syphilis diagnosis and the Tp0100-based ELISA, the Tp1016-based ELISA, or the LICA Syphilis TP test. RESULTS: Using clinical syphilis diagnosis as the gold standard, Tp0100 exhibited an overall sensitivity of 95.6% and specificity of 98.1% for testing IgG antibody while Tp1016 demonstrated only an overall sensitivity of 75.0% and specificity of 79.6%. In contrast, the LICA Syphilis TP test revealed an overall sensitivity of 97.6% and specificity of 96.2%. In addition, the overall percent agreement and corresponding κ values were 96.7% (95% CI 95.6%-97.8%) and 0.93 for the Tp0100-based ELISA, 77.0% (95% CI 74.3%-79.7%) and 0.54 for the Tp1016-based ELISA, and 97.0% (95% CI 96.0%-98.0%) and 0.94 for the LICA Syphilis TP test, respectively. CONCLUSION: The recombinant T. pallidum protein Tp0100 shows promise as a novel diagnostic antigen in the serological tests for syphilis.

Immunogenicity of a single 4CMenB vaccine booster in adolescents 11 years after childhood immunisation.

The clinical development of the meningococcal vaccine, 4CMenB, included 2 doses in vaccine-naïve adolescents, which was considered unlikely to be cost-effective for implementation. Theoretically, priming with 4CMenB in early childhood might drive strong immune responses after only a single booster dose in adolescents and reduce programmatic costs. To address this question, children over 11 years old who took part in previous trials involving the administration of 3-5 doses of 4CMenB at infant/preschool age from 2006 were recruited into a post licensure single-centre trial, and were divided into two groups: those who received their last dose at 12 months old (infant group) and those who received their last dose at 3 years old (infant + preschool group). Naïve age-matched controls were randomised to receive one (adolescent 1 group) or two doses at days 0 and 28 (adolescent 2 group) of 4CMenB. Serum bactericidal antibody (SBA) assays using human complement were performed against three reference strains prior to vaccination, and at 1, 6 and 12 months. Previous vaccination was associated with a higher response to a single booster dose at 11 years of age, one-month post-vaccination, when compared with a single dose in naïve age-matched controls. At day 180, the highest responses were observed in participants in the infant + preschool group against strain 5/99 (GMT 316.1 [CI 158.4 to 630.8]), as compared with naïve adolescents who received two doses (GMTs 84.5 [CI 57.7 to 123.6]). When the last dose was received at 12-months of age, responses to a single adolescent dose were not as robust (GMT 61.1 [CI 14.8 to 252.4] to strain 5/99). This descriptive study indicates that the highest SBA responses after a single dose in adolescence were observed in participants who received a preschool dose, suggesting that B cell memory responses are not sufficiently primed at less than 12 months of age. Trial registration EudraCT 2017-004732-11, ISRCTN16774163.

Analytical technology development to monitor the stability of Polysaccharide-Protein conjugate vaccines.

The covalent attachment of a bacterial-derived capsular polysaccharide to protein is of critical importance in transforming the polysaccharide from an antigen with limited immunogenicity in infants and older adults to an antigen that can prevent potentially fatal disease. For a polysaccharide-protein conjugate vaccine (PCV) candidate to be successful, it must be sufficiently stable. Chemical breakage of carbohydrate bonds in the polysaccharide may result in the reduction of "conjugate dose" and could negatively impact immunogenicity and the ability of the vaccine to prime for memory responses. Therefore, development of analytical tools to monitor the integrity of a polysaccharide-protein conjugate (glycoconjugate) vaccine is of practical significance. In this work, reducing SDS-PAGE, Intrinsic Protein Fluorescence Spectroscopy (IPFS), Differential Scanning Fluorimetry (DSF) were evaluated methods to study the impact of time, temperature, and formulation composition on the stability of a glycoconjugate vaccine prepared by multisite coupling of polysaccharide to a carrier protein. In addition, an automated capillary Western system was also evaluated to study the impact of storage on glycoconjugate vaccine stability. Two streptococcus pneumoniae polysaccharide-protein conjugates (serotype 3 and serotype 19A) were chosen to examine their physicochemical stability when formulated as a single antigen vaccine. While all methods require only a small amount of test article and can test multiple samples per assay run, automated capillary Western has the additional advantage of being highly sensitive even at low concentrations in complex vaccine formulations that contain aluminum adjuvant and multiple antigens. Results suggest that automated capillary Western is stability-indicating and may be an effective analytical technology tool for the formulation development of a multivalent glycoconjugate vaccine.

Introduction of IgM testing for the diagnosis of acute Lyme borreliosis: a study of the benefits, limitations and costs.

Testing for IgM antibodies to Borrelia burgdorferi in Scottish patients with suspected Lyme borreliosis was introduced in 2018 to supplement the IgG testing already in situ. Results from 2018 to 2020 were assessed alongside available clinical data to evaluate the utility of IgM testing in serum. An estimated false positive rate of 25.5% was observed with IgM immunoblot vs 80.1% for IgM chemiluminescent immunoassay (CLIA). IgM testing can aid earlier diagnoses if used within a selective two-tier testing protocol: only patients with acute onset of symptoms should be tested for IgM CLIA but confirmation by immunoblot and consideration of clinical picture is necessary.

Pertussis Immunization During Pregnancy: Assessment of the Role of Maternal Antibodies on Immune Responses in Term and Preterm-Born Infants.

BACKGROUND: Limited data exist on the impact of maternal tetanus, diphtheria, acellular pertussis (Tdap) vaccination for preterm born infants. We report its effect at birth and on antibody-mediated immune responses to a DTaP-IPV-HB-PRP~T vaccine in preterm compared with term infants. METHODS: Women delivering at term or prematurely were either vaccinated with a Tdap vaccine (Boostrix; GSK) during pregnancy or not vaccinated in the last 5 years. Cord and maternal blood were collected at delivery. Infants were vaccinated with DTaP-IPV-HB-PRP~T vaccine (Hexyon; Sanofi Pasteur) and blood collected before and 1 month after primary (8-12-16 weeks) and before and 1 month after booster vaccination (13 or 15 months for preterm and term, respectively). Immunoglobulin G antibodies against all antigens included in DTaP-IPV-HB-PRP~T vaccine were measured (NCT02511327). RESULTS: Cord blood geometric mean concentrations (GMCs) in preterm infants from Tdap-vaccinated women were significantly higher than in term and preterm infants from unvaccinated women. A longer time interval between maternal vaccination and delivery resulted in higher cord blood GMCs in preterm infants. Equal GMCs in term and preterm infants from Tdap-vaccinated women were observed after primary vaccination. After boosting, significantly lower GMCs were seen for pertussis toxin, filamentous hemagglutinin, and tetanus toxoid in preterm compared with term infants from Tdap-vaccinated women, yet still comparable to GMCs in both term and preterm infants from unvaccinated women. CONCLUSIONS: Preterm infants profit from maternal Tdap vaccination. Prematurity did not influence primary immune responses in the presence of maternal antibodies but was associated with a lower booster immune response.