Typhoid Conjugate Vaccine: A Boon for Endemic Regions.

Typhoid fever has the highest disease burden in countries in low- and middle-income countries, primarily located in Asia and Sub-Saharan Africa. Previous typhoid vaccines such as the live attenuated typhoid (Ty21a) vaccine and Vi (virulence) capsular polysaccharide vaccine had the limitation that they could not be administered with other standard childhood immunizations and were ineffective in children under two years of age. To address these shortcomings of the previous vaccines, typhoid conjugate vaccines (TCVs) were developed and prequalified by the World Health Organization. Cross-reacting material and tetanus toxoid are widely used as carrier proteins in TCVs. According to various studies, TCV has higher efficacy, has a more extended protection period, and is safe and immunogenic in infants as young as six months. This review article aims to comprehensively appraise the data available on TCVs' efficacy, duration of protection, safety, and immunogenicity in endemic regions.

Potential Protectivity of a Conjugated COVID-19 Vaccine against Tetanus.

PastoCovac is a subunit protein vaccine against COVID-19 which contains the tetanus toxoid as a carrier conjugated to SARS-CoV-2 RBD. The primary goal of the tetanus application was to elicit a stronger specific response in the individuals. However, conjugate vaccines have the potency to generate anticarrier antibodies in addition to the target antigen. Therefore, the present study aimed to evaluate the PastoCovac vaccine in the humoral immune induction against tetanus. Six groups of individuals, including those who received one, two, or three doses of the PastoCovac vaccine, Td vaccine, and also the controls who received other COVID-19 vaccines (except PastoCovac), were investigated. The anti-tetanus IgG was assessed by an ELISA assay in all vaccinated groups. The antibody persistency against tetanus in the group who received one dose of the PastoCovac vaccine was also assessed on day 60, 90, and 180 after the last injection. The anti-tetanus antibody titer in the three groups of PastoCovac recipients was positive, though additional doses of the vaccine led to a significant antibody rise (p = 0.003). Notably, the comparison of the mean antibody titer between the Td recipients and those who received one/two doses of PastoCovac showed that the mean rise in the antibody titer before and after the injection was not significant. Although the antibody titer on day 180 decreased to a lower level than on day 21, it was still estimated to be highly positive against tetanus. Eventually, none of the PastoCovac recipients presented vaccine side-effects during the follow-up. The current data indicate that the tetanus conjugate vaccine against COVID-19, PastoCovac, could induce immune responses against tetanus, which can persist for at least 6 months. Combination vaccine formulae containing TT and DT as carriers for conjugate vaccines could be considered instead of TT and/or DT boosters in adults if they are indicated.

Detection of tetanus toxoid with iron magnetic nanobioprobe.

Diagnosis of diseases with low facilities, speed, accuracy and sensitivity is an important matter in treatment. Bioprobes based on iron oxide nanoparticles are a good candidate for early detection of deadly and infectious diseases such as tetanus due to their high reactivity, biocompatibility, low production cost and sample separation under a magnetic field. In this study, silane groups were coated on surface of iron oxide nanoparticles using tetraethoxysilane (TEOS) hydrolysis. Also, NH2 groups were generated on the surface of silanized nanoparticles using 3-aminopropyl triethoxy silane (APTES). Antibody was immobilized on the surface of silanized nanoparticles using TCT trichlorothriazine as activator. Silanization and stabilized antibody were investigated by using of FT-IR, EDX, VSM, SRB technique. UV/vis spectroscopy, fluorescence, agglutination test and ELISA were used for biosensor performance and specificity. The results of FT-IR spectroscopy showed that Si-O-Si and Si-O-Fe bonds and TCT chlorine and amine groups of tetanus anti-toxoid antibodies were formed on the surface of iron oxide nanoparticles. The presence of Si, N and C elements in EDX analysis confirms the silanization of iron oxide nanoparticles. VSM results showed that the amount of magnetic nanoparticles after conjugation is sufficient for biological applications. Antibody stabilization on nanoparticles increased the adsorption intensity in the uv / vis spectrometer. The fluorescence intensity of nano bioprobe increased in the presence of 10 ng / ml. Nanobio probes were observed as agglomerates in the presence of tetanus toxoid antigen. The presence of tetanus antigen caused the formation of antigen-nanobioprobe antigen complex. Identification of this complex by HRP-bound antibody confirmed the specificity of nanobioprobe. Tetanus magnetic nanobioprobe with a diagnostic limit of 10 ng / ml of tetanus antigen in a short time can be a good tool in LOC devices and microfluidic chips.

Protective doses of tetanus toxoid immunization and its associated factors among mothers in southern Ethiopia.

The World Health Organization recommends tetanus toxoid immunization before or during pregnancy for all women of childbearing age. The goal is to reduce maternal and neonatal mortality due to tetanus. According to the 2016 Ethiopia Demographic and Health Survey (EDHS) report, more than half (51%) of women did not receive protective doses of tetanus immunization. To the best of our knowledge, this study uniquely tried to assess the level of protective doses of tetanus toxoid immunization in southern Ethiopia. A community-based cross-sectional study was conducted among 580 randomly selected participants. Variable with p-value of less than .25 in the bivariate analysis were included in the multivariable logistic regression analysis. Finally, statistical significance was declared at a p-value of less than .05. The proportion of protective doses of tetanus toxoid immunization uptake in the area was found to be 41.9% (95% CI: 38-46%). Being enrolled in formal education [AOR = 6.55, 95% CI: 3.23-9.01], having at least two postnatal care visits [AOR = 3.82; 95% CI: 1.78-6.40], having at least four antenatal care visits [AOR = 2.56; 95% CI: 1.41-4.34], and being visited by Health Extension Workers [AOR = 2.66; 95% CI: 1.42-4.01] were found to be factors enhancing the uptake of protective doses of tetanus toxoid immunization. Generally, the uptake or prevalence of the protective doses of tetanus toxoid immunization in the area was lower than the World Health Organization's target. Therefore, all responsible bodies, including healthcare providers, need to strengthen counseling mothers to enhance the uptake of tetanus toxoid immunization.

Craniocervical Tetanus: A Practical Consideration During Work-up of Acute-Onset Trismus.

This clinical record revisits the classical and pathognomonic features of craniocervical tetanus in a 65-year-old farmer who presented with acute-onset trismus, multiple cranial nerve pareses (III, IX, and X), risus sardonicus, and spasm of the head-neck musculature. This paper explores the relevant literature and presents a brief pictorial analysis of the global epidemiologic data. With most countries successfully adopting the maternal and neonatal tetanus elimination (MNTE) program, the incidence and mortality of tetanus across age groups have sharply reduced in high-income and most middle-income nations. In adults, tetanus is now encountered in specialized situations like waning immunity and incomplete vaccination, in the resource-poor and low-income nations, in countries achieving MNTE recently, and as cluster cases in the aftermath of natural disasters involving human settlements. Therefore, present-day practicing otolaryngologists and residents who have limited exposure to the tell-tale clinical features of craniocervical tetanus should consider it during work-up of acute-onset trismus in adults in susceptible situations and with a conducive background. The clinical spectrum of craniocervical tetanus as depicted in this report, including the demonstration of the pathognomonic positive spatula test, provides valuable learning points for otolaryngologists in this regard.

Longitudinal gut microbiota composition of South African and Nigerian infants in relation to tetanus vaccine responses.

Infants who are exposed to HIV but uninfected (iHEU) have higher risk of infectious morbidity than infants who are HIV-unexposed and uninfected (iHUU), possibly due to altered immunity. As infant gut microbiota may influence immune development, we evaluated the effects of HIV exposure on infant gut microbiota and its association with tetanus toxoid vaccine responses. We evaluated the gut microbiota of 82 South African (61 iHEU and 21 iHUU) and 196 Nigerian (141 iHEU and 55 iHUU) infants at <1 and 15 weeks of life by 16S rRNA gene sequencing. Anti-tetanus antibodies were measured by enzyme-linked immunosorbent assay at matched time points. Gut microbiota in the 278 included infants and its succession were more strongly influenced by geographical location and age than by HIV exposure. Microbiota of Nigerian infants, who were exclusively breastfed, drastically changed over 15 weeks, becoming dominated by Bifidobacterium longum subspecies infantis. This change was not observed among South African infants, even when limiting the analysis to exclusively breastfed infants. The Least Absolute Shrinkage and Selection Operator regression suggested that HIV exposure and gut microbiota were independently associated with tetanus titers at week 15, and that high passively transferred antibody levels, as seen in the Nigerian cohort, may mitigate these effects. In conclusion, in two African cohorts, HIV exposure minimally altered the infant gut microbiota compared to age and setting, but both specific gut microbes and HIV exposure independently predicted humoral tetanus vaccine responses.IMPORTANCEGut microbiota plays an essential role in immune system development. Since infants HIV-exposed and uninfected (iHEU) are more vulnerable to infectious diseases than unexposed infants, we explored the impact of HIV exposure on gut microbiota and its association with vaccine responses. This study was conducted in two African countries with rapidly increasing numbers of iHEU. Infant HIV exposure did not substantially affect gut microbial succession, but geographic location had a strong effect. However, both the relative abundance of specific gut microbes and HIV exposure were independently associated with tetanus titers, which were also influenced by baseline tetanus titers (maternal transfer). Our findings provide insight into the effect of HIV exposure, passive maternal antibody, and gut microbiota on infant humoral vaccine responses.

Testing a Recombinant Form of Tetanus Toxoid as a Carrier Protein for Glycoconjugate Vaccines.

Glycoconjugate vaccines play a major role in the prevention of infectious diseases worldwide, with significant impact on global health, enabling the polysaccharides to induce immunogenicity in infants and immunological memory. Tetanus toxoid (TT), a chemically detoxified bacterial toxin, is among the few carrier proteins used in licensed glycoconjugate vaccines. The recombinant full-length 8MTT was engineered in E. coli with eight individual amino acid mutations to inactivate three toxin functions. Previous studies in mice showed that 8MTT elicits a strong IgG response, confers protection, and can be used as a carrier protein. Here, we compared 8MTT to traditional carrier proteins TT and cross-reactive material 197 (CRM197), using different polysaccharides as models: Group A Streptococcus cell-wall carbohydrate (GAC), Salmonella Typhi Vi, and Neisseria meningitidis serogroups A, C, W, and Y. The persistency of the antibodies induced, the ability of the glycoconjugates to elicit booster response after re-injection at a later time point, the eventual carrier-induced epitopic suppression, and immune interference in multicomponent formulations were also evaluated. Overall, immunogenicity responses obtained with 8MTT glycoconjugates were compared to those obtained with corresponding TT and, in some cases, were higher than those induced by CRM197 glycoconjugates. Our results support the use of 8MTT as a good alternative carrier protein for glycoconjugate vaccines, with advantages in terms of manufacturability compared to TT.

Retrospective study of tetanus in 18 dogs-Causes, management, complications, and immunological status.

Objective: Tetanus is a severe neurologic disease caused by Clostridium tetani, resulting in spastic paralysis. Canine tetanus is associated with serious complications such as aspiration and a high mortality rate of up to 50%. Materials and methods: Medical records of all dogs diagnosed with tetanus over 8 years (2014-2022) were analyzed for severity grade, treatment protocols, nutritional management, and complications, as well as outcome, vaccination, and antibody production in some dogs. No medical records were excluded. Normality was analyzed by the D'Agostino-Pearson test. Parametric, normally distributed data were presented as mean ± standard deviation. Non-parametric, non-normally distributed data were presented as median (m) and range (minimum-maximum). The association between tetanus grade, progression of diseases, and duration of hospitalization was analyzed using the t-test, Mann-Whitney U test, and Kruskal-Wallis test. A P ≤ 0.05 was considered significant. Results: Eighteen dogs were identified. Most affected dogs were classified into severity grade II (66.7%, 12 of 18). Clinical signs deteriorated in 55.6% of dogs (10 of 18). A source was identified in 88.9% of dogs (16 of 18). Nine dogs required surgical wound revision. A percutaneous endoscopic gastropexy tube was placed in 83.3% of dogs (15 of 18) for nutritional support. Medical treatment included metronidazole, methocarbamol, and combinations of different sedatives adapted to the patient's requirements. Tetanus antitoxin was used in 72.2% of dogs (13 of 18) without reported adverse events. The survival rate was 88.9% (16 of 18). Complications, such as hypertension, aspiration pneumonia, and laryngeal spasm occurred in 12 of 18 dogs. Median hospitalization time (8 days; range 0-16 days) was associated with the maximum tetanus severity grade (p = 0.022). Rapid eye movement behavior disorder was observed in 72.2% of dogs (13 of 18). In 5 dogs, antibodies were measured after recovery, and in 4 of 5 dogs, no antibodies were detectable despite generalized tetanus disease. Vaccination with tetanus toxoid was performed in five dogs following the disease. Conclusion: In the present study, the mortality rate was lower than previously reported. Tetanus is still a life-threatening disease, but the prognosis may be good if adequate management and monitoring can be ensured.

Prevalence and determinants of two or more doses of tetanus toxoid-containing vaccine immunization among pregnant women in sub-Saharan Africa: Evidence from recent demographic and health survey data.

INTRODUCTION: Tetanus is a major public health problem in low and middle income countries including in sub-Saharan Africa. Tetanus toxoid vaccine immunization during pregnancy is a global strategy against mortality due to maternal and neonatal tetanus. Recent data on tetanus toxoid-containing vaccination during pregnancy provides insight to policymakers for better implementation of the vaccine. Hence, this study aimed to determine prevalence and determinants of immunization with tetanus toxoid containing vaccine among pregnant women in sub-Saharan Africa. METHODS: Secondary analysis of the recent demographic and health survey data was done using a sample of 173,032 pregnant women. Stata 14 statistical software was used for analysis and multilevel logistic regression model was applied to determine associated factors of two or more tetanus toxoid-containing vaccine immunization. P-value less than 0.05 for adjusted odds ratio was used to identify factors significantly associated with the outcome. RESULT: The prevalence of immunization with two and more doses of tetanus toxoid-containing vaccine in sub-Saharan Africa was found to be 49.8 %. Women's age 36-49, women's education, poor household wealth index, unwanted pregnancy, women's occupation, husband education, and community illiteracy were significantly associated with two or more doses of tetanus toxoid-containing vaccine immunization in sub-Saharan Africa. CONCLUSION: In sub-Saharan Africa, less than half of pregnant women were immunized with two or more doses of tetanus toxoid-containing vaccine. Women's education and women's employment positively affected immunization with two or more doses of tetanus toxoid-containing vaccine. Women's age group of 36-49 years, unwanted pregnancy, poor household wealth index, husbands having no formal education, and community illiteracy negatively affected receipt of two or more doses of tetanus toxoid-containing vaccine. Therefore, policymakers should take into account the determinants of tetanus toxoid immunization throughout its implementation so as to boost the coverage of tetanus toxoid immunization in sub-Saharan Africa.

Spatial distribution and determinants of tetanus toxoid immunization among pregnant women in Ethiopia using data from Ethiopian demographic and health survey 2016.

INTRODUCTION: Tetanus is a major public health problem caused by clostridium tetani. Although it is vaccine-preventable, the case fatality rate among neonates in areas with poor immunization coverage and limited access to clean deliveries reaches 80-100%. Vaccination of pregnant mothers with the tetanus toxoid (TT) vaccine is the most effective way to protect against neonatal tetanus. This study aimed to examine the spatial distribution and determinants of tetanus toxoid immunization among pregnant mothers using the 2016 EDHS data. METHOD: Secondary analysis of the Ethiopia Demographic and Health Survey 2016 was done to assess the spatial distribution and determinants of tetanus toxoid vaccine among pregnant women in Ethiopia. Spatial autocorrelation analysis and hot spot analysis were used to detect spatial dependency and spatial clustering of the tetanus toxoid vaccine in Ethiopia. Spatial interpolation was used to predict the tetanus toxoid vaccine coverage in unsampled areas. The multilevel binary logistic regression model was fitted to identify factors associated with tetanus toxoid vaccination. An adjusted odds ratio with 95% CI was calculated and used as the measure of association and a p-value less than 0.05 were considered statistically significant. RESULT: From the total of 7043 pregnant women, 42.4% of them have taken at least two doses of tetanus toxoid immunization. Spatial clustering of TT immunization was observed in the Northern, Southwestern and Southwestern parts of Ethiopia. Whereas, low TT coverage was observed in the Eastern and Western parts of the country. Increased ANC visits and the richest economic status favored TT immunization, whereas living in Addis Ababa and Dire Dewa cities decreased the TT immunization coverage. CONCLUSION: The finding of this study reveals that TT immunization had spatial dependency, with the highest immunization coverage observed in the Northern, Southwestern and Southeastern parts of the Country. Thus, geographically targeted interventions should be implemented particularly in the eastern and western parts of the country.

Assessing the impact of the 2018 tetanus guidelines on knowledge and practices of emergency physicians in trauma patients: a national survey study.

Background: Tetanus remains a significant public health issue in China, with the approach of anti-tetanus prophylaxis in the emergency department resulting in both overuse, particularly of human tetanus immune globulin (TIG), and underuse with the tetanus vaccine. This is largely due to the absence of updated guidelines on tetanus prophylaxis before 2018. Our study aimed to evaluate the effects of the 2018 Chinese tetanus guidelines on the knowledge and practices of emergency physicians about tetanus prevention in trauma patients. Methods: From November 2019 to April 2020, we conducted a web-based survey involving 499 emergency physicians. The survey included a questionnaire covering knowledge, attitudes, and practices related to tetanus. We assessed the influence of the 2018 tetanus guidelines on the knowledge and practices of emergency physicians related to tetanus prevention for patients with trauma using multiple regression analysis. Results: The survey results showed that only 45.3% of the participants had received formal training on tetanus immunization, despite 53.3% reporting the availability of tetanus vaccines at their institutions. Physicians typically prescribed tetanus antitoxin or human TIG instead of tetanus toxoid (TT) to treat injuries, regardless of the patient's TT vaccination history. Among the respondents, those who were aware of the 2018 tetanus guidelines had higher mean scores on the general knowledge, risk knowledge, and treatment knowledge scales, with increases of 6%, 13%, and 9%, respectively, compared to those who were unaware of the guidelines. Awareness of the 2018 tetanus guidelines was associated with a high level of knowledge, as indicated by the general knowledge score, recommendation knowledge score, and total knowledge score, after adjusting for the effects of all variables on the knowledge, attitudes, and practices of the participants. A high level of education was also associated with a high level of knowledge indicated by the recommendation knowledge score and total knowledge score. Conclusions: Our study highlights a substantial gap in the attitudes, knowledge, and practices of emergency physicians in China regarding tetanus immunization. The results suggest an urgent need to promote the Chinese Expert Consensus Guidelines on tetanus to improve emergency physicians' knowledge and competence in tetanus prophylaxis. The findings underscore the importance of enhancing physicians' awareness of the latest guidelines to ensure appropriate and effective treatment for patients with tetanus-prone injuries.

Spatial distribution and associated factors of poor tetanus toxoid immunization among pregnant women in Ethiopia: spatial and multilevel analysis.

Background: Neonatal mortality from tetanus can be reduced by 94% when pregnant women receive at least two doses of tetanus toxoid. In Ethiopia, immunization programs are suboptimal despite their importance. Therefore, the aim of this study was to examine the geographic distribution and associated factors of poor tetanus toxoid (TT) immunization among pregnant women in Ethiopia. Methods: Secondary data analysis was used using the 2016 Ethiopian Demographic and Health Survey (EDHS). ArcGIS version 10.8 statistical software was used to explore the spatial distribution of poor TT immunization and SaTScan version 9.6 software was used to identify significant hotspot areas of poor TT immunization. For associated factors, a multilevel binary logistic regression model was fitted using STATA version 14 software. In the multivariable multilevel analysis, adjusted OR (AOR) with 95% CI was reported to reveal significantly associated factors of poor TT immunization. Result: In Ethiopia, the spatial distribution of poor tetanus toxoid immunization was clustered with Global Moran's I = 0.59 at p-value of <0.0001. The highest poor TT immunization clusters were observed in the East and South Tigray, the central part of Amhara, West Afar, East Somali, and West Gambella. Pregnant women with no Antenatal care (ANC) visits [Adjusted Odds Ratio (aOR) = 10.46, 95% CI: (8.82, 12.41))], pregnant women with 1-3 ANC visits [aOR = 1.51, 95% CI: (1.31, 1.73)], media exposure [aOR = 1.45, 95% CI: (1.26, 1.67)], poor wealth index [aOR = 1.22; 95% CI: (1.03, 1.45)], middle wealth index [aOR = 1.23; 95% CI: (1.03, 1.47)], family planning use [aOR = 1.28; 95% CI: (1.11, 1.57)] and community level education [aOR = 1.43, 95% CI: (1.14, 1.80)] were significantly associated with poor tetanus toxoid immunization. Conclusion: Poor tetanus toxoid immunization among pregnant women varies in Ethiopia. It was highest in East and South Tigray, the central part of Amhara, West Afar, East Somali, and West Gambella. Therefore, public health programs should design targeted interventions in identified hot spots to improve tetanus toxoid immunization. Health programmers should be promoting optimal ANC visits, women's education, and family planning use.

Collaborative study for the calibration of a replacement International Standard for tetanus toxoid for use in flocculation test.

Here we report the results of a study to establish a replacement WHO International Standard (IS) for tetanus toxoid for use in flocculation test. The standard was calibrated in flocculation units (Lf) against the 2nd IS using the Ramon flocculation method. At its 70th meeting in October 2019, WHO ECBS established the material (coded 16/302) as the 3rd WHO IS, with an assigned value of 970 Lf/ampoule from the results of seventeen laboratories across ten different countries. The study also provided an opportunity to assess the use of alternative methods for measuring Lf. Participants were asked to use an in-house Enzyme Linked Immunosorbent Assay (ELISA) developed at NIBSC, or other suitable in-house methods, to determine ELISA-specific Lf values (Lf-eq units are specific only for pre-calibration of antitoxin in the flocculation test) of 16/302 to compare to those of the flocculation test. Nine laboratories participated by performing the NIBSC ELISA, one laboratory performed flocculation by laser light-scattering following an in-house protocol, and three laboratories performed ELISA following in-house protocols. The results intimate that these alternative methods could be useful for monitoring consistency of production at different stages of vaccine manufacturing.

Predictors of Tetanus Vaccine Uptake among Pregnant Women in Khartoum State, Sudan: A Hospital-Based Cross-Sectional Study.

Tetanus toxoid (TT) vaccination during pregnancy has been proven as an effective preventative measure to reduce the incidence of maternal and neonatal morbidity and mortality worldwide. This study aimed to assess the determinants of TT vaccine uptake among pregnant women at two public maternity specialized hospitals in Sudan. A hospital-based cross-sectional study was conducted at two public hospitals, Omdurman Maternity Hospital and Al Saudi Hospital in Omdurman, Khartoum State, in Sudan from February to April 2020. Logistic regression analysis was carried out to identify factors associated with receiving three or more doses of the TT vaccine among pregnant women, presented as odds ratios, with p-values < 0.05 considered significant (at a 95% confidence interval). The study recruited 350 pregnant women, with 313 participants included in the analysis. This study found that only 40% of the pregnant women had received three doses or more of the TT vaccine. Pregnant women who attended Al Saudi Hospital were less likely to be vaccinated with the recommended dose of the TT vaccine in districts at high risk (received ≥3 doses) compared to those who attended Omdurman Hospital [OR = 0.49 (95% C.I. 0.29-0.82), p-value < 0.05]. Furthermore, the number of children at home was a significant predictor of the mothers' immunization status as those with five children or more were ten times more likely to be vaccinated with three doses or more [OR = 10.54 (95% C.I. 4.30-25.86), p-value < 0.05]. We conclude that this low rate of TT vaccine uptake found in this study among pregnant women increases the number of newborn babies susceptible to contracting neonatal tetanus. The findings of this study should be considered in the development of communication strategies targeting and prioritizing at-risk groups to increase TT vaccine uptake among pregnant women in Sudan.

Longitudinal gut microbiota composition of South African and Nigerian infants in relation to tetanus vaccine responses.

Introduction: Infants who are exposed to HIV but uninfected (iHEU) have higher risk of infectious morbidity than infants who are HIV-unexposed and uninfected (iHUU), possibly due to altered immunity. As infant gut microbiota may influence immune development, we evaluated the effects of HIV exposure on infant gut microbiota and its association with tetanus toxoid (TT) vaccine responses. Methods: We evaluated gut microbiota by 16S rRNA gene sequencing in 278 South African and Nigerian infants during the first and at 15 weeks of life and measured antibodies against TT vaccine by enzyme-linked immunosorbent assay (ELISA) at matched time points. Results: Infant gut microbiota and its succession were more strongly influenced by geographical location and age than by HIV exposure. Microbiota of Nigerian infants drastically changed over 15 weeks, becoming dominated by Bifidobacterium longum subspecies infantis. This change was not observed among EBF South African infants. Lasso regression suggested that HIV exposure and gut microbiota were independently associated with TT vaccine responses at week 15, and that high passive antibody levels may mitigate these effects. Conclusion: In two African cohorts, HIV exposure minimally altered the infant gut microbiota compared to age and country, but both specific gut microbes and HIV exposure independently predicted humoral vaccine responses.

Annual two-dose tetanus toxoid vaccination induces protective humoral immunity to all age groups of rhesus macaques.

A tetanus outbreak occurred during 2014-2015 in the rhesus macaques reared in an open enclosure in our facility. As the soil of the facility was suspected to be contaminated with Clostridium tetani spores, there was a risk of further tetanus occurring among the macaques. To protect them from tetanus, a tetanus toxoid vaccination was recommended; however, the vaccinated elderly animals might not be effectively protected due to insufficient humoral immune responses. Hence, we evaluated the dynamics of antibody responses among rhesus macaques of all age groups vaccinated with two-dose tetanus toxoid at a 1-year interval during a 3-year follow-up study. The vaccination developed anti-tetanus toxin-specific antibodies in animals of all age groups, the antibody levels peaked 1 year after the second vaccination, and the peak levels decreased with age. However, the levels among elderly individuals (aged ≥13 years) were still higher than the threshold level, which was supposed to protect them from tetanus development. Although the rhesus macaques in our facility had a risk of occasional exposure to the spores due to the outbreak, no incidence of tetanus has ever occurred to date. These results indicate that the vaccination protocol is effective in protecting not only younger but also older animals from tetanus.

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.

An ELISA system for tetanus toxoid potency tests: An alternative to lethal challenge.

For a long time, a widely used method for tetanus toxoid (Ttd) potency has been the challenge test, in which animals are immunized and then challenged with tetanus toxin in lethal or non-lethal way. In the context of animal welfare, an alternative is desired because the method causes unsustainable distress to animals. We aimed to replace the system for describing test results, in which scores are assigned to symptoms exhibited by challenged animals, with scores assigned to antibody ELISA titers in immunized mouse sera. The potency values and confidence intervals calculated by the absorbance score system were equivalent to those calculated by the symptom score system. We also attempted to utilize the raw ELISA absorbance instead of the assigned absorbance score and obtained similar results. ELISA may serve as an alternative to the lethal challenge for Ttd potency tests, not only in Japan but also in other countries in which mouse challenge tests are employed.

Field investigation of high reported non-neonatal tetanus burden in Uganda, 2016-2017.

BACKGROUND: Despite providing tetanus-toxoid-containing vaccine (TTCV) to infants and reproductive-age women, Uganda reports one of the highest incidences of non-neonatal tetanus (non-NT). Prompted by unusual epidemiologic trends among reported non-NT cases, we conducted a retrospective record review to see whether these data reflected true disease burden. METHODS: We analysed nationally reported non-NT cases during 2012-2017. We visited 26 facilities (14 hospitals, 12 health centres) reporting high numbers of non-NT cases (n = 20) or zero cases (n = 6). We identified non-NT cases in facility registers during 1 January 2016-30 June 2017; the identified case records were abstracted. RESULTS: During 2012-2017, a total of 24 518 non-NT cases were reported and 74% were ≥5 years old. The average annual incidence was 3.43 per 100 000 population based on inpatient admissions. Among 482 non-NT inpatient cases reported during 1 January 2016-30 June 2017 from hospitals visited, 342 (71%) were identified in facility registers, despite missing register data (21%). Males comprised 283 (83%) of identified cases and 60% were ≥15 years old. Of 145 cases with detailed records, 134 (92%) were clinically confirmed tetanus; among these, the case-fatality ratio (CFR) was 54%. Fourteen cases were identified at two hospitals reporting zero cases. Among >4000 outpatient cases reported from health centres visited, only 3 cases were identified; the remainder were data errors. CONCLUSIONS: A substantial number of non-NT cases and deaths occur in Uganda. The high CFR and high non-NT burden among men and older children indicate the need for TTCV booster doses across the life course to all individuals as well as improved coverage with the TTCV primary series. The observed data errors indicate the need for data quality improvement activities.

Preparation and characterization of a neutralizing murine monoclonal antibody against tetanus toxin.

After Clostridium tetani infects the human body, it propagates under anaerobic conditions and produces tetanus neurotoxin (TeNT). TeNT can affect the central nervous system, inhibit the release of neurotransmitters, and result in respiratory failure, which are the root causes of death in tetanus patients. Identifying monoclonal antibodies (mAbs) targeting TeNT with neutralizing activity is urgently needed for the prevention and treatment of tetanus infection. In this study, through immunizing BALB/c mice with tetanus toxoid (TT), we obtained six positive hybridoma cell lines (1A7, 2C7, 3A7, 3H4, 4C1, and 4E12). Antibody isotyping showed that the antibodies are all of the IgG1/κ subclass. Ascites fluid was prepared by allogeneic ascites induction and the antibodies were purified through protein G affinity chromatography columns. Purities of the produced murine mAbs were all greater than 95%. All six antibodies bound to linear epitopes, among which 3A7 bound to the TeNT/L domain and the other five antibodies bound to the TeNT/Hc domain. Moreover, the affinity constants of these six antibodies against the antigen were all in the nanomolar range, and the affinity of 4E12 antibody reached the picomolar range. Results from toxin-neutralization assays in mice showed that 2C7 antibody delayed animal death, while 1A7, 3A7, 3H4, and 4E12 antibodies conferred partial protection. Additionally, 4C1 antibody offered complete protection, as 200 µg of 4C1 antibody fully protected against toxin challenge with 10 LD50 of TeNT and had a window period of 1 h. Antibody epitope grouping results revealed that the binding epitopes of 4C1 antibody were different from those of the other five antibodies. When 4C1 antibody was used in combination with another antibody, the neutralizing activities of antibodies were all evidently enhanced. Specifically, 4C1 combined with 3A7 antibody led to the greatest improvement in neutralizing activities, and 20 µg antibodies total (10 + 10 µg) fully protected against toxin challenge with 10 LD50. When 4E12, 3A7, and 4C1 antibodies were used in combination, 18 µg antibodies total (6 + 6 + 6 µg) completely neutralized 10 LD50 toxin. The present study derived murine mAbs with neutralizing activities and laid the foundation for follow-up therapeutic drug development for TeNT poisoning as well as establishment of TeNT detection methods.