Sex differences in vaccine-induced humoral immunity

Immunogenicity of the 9-valent human papillomavirus vaccine: Post hoc analysis from five phase 3 studies

Post hoc analyses of 9-valent human papillomavirus (9vHPV) vaccine immunogenicity were conducted in five Phase 3 studies that enrolled males. Month 7 antibody geometric mean titers (GMTs) after three 9vHPV vaccine doses were analyzed in 10,024 males/females aged 16-26 years from studies 001 (NCT00543543), 002 (NCT00943722), 003 (NCT01651949), and 020 (NCT02114385). Covariates considered were age, gender, sexual orientation, region of residence, and race. GMTs among 2599 males/females aged 9-15 years (studies 002 and 010 [NCT01984697]) were assessed 6 months after one, two, and three 9vHPV vaccine doses. 9vHPV vaccine immunogenicity was robust across populations. Month 7 GMTs were generally higher in participants aged 16-21 versus 22-26 years. Region and race minimally impacted immunogenicity. Adjusted integrated analysis showed lower immunogenicity in men who have sex with men (MSM) versus heterosexual men (HM) for nine HPV types, and higher immunogenicity in HM versus females for seven HPV types. Among 9-15-year-olds, trends toward higher GMTs in males versus females post-Dose 3, similar GMTs post-Dose 2, and lower post-Dose 1 were observed. In conclusion, 9vHPV vaccine immunogenicity was robust in males aged 16-26 years across a range of baseline characteristics. GMT ratios for males versus females aged 9-15 years tended to increase with more doses.

A natural experiment on the effect of herpes zoster vaccination on dementia

Neurotropic herpesviruses may be implicated in the development of dementia1-5. Moreover, vaccines may have important off-target immunological effects6-9. Here we aim to determine the effect of live-attenuated herpes zoster vaccination on the occurrence of dementia diagnoses. To provide causal as opposed to correlational evidence, we take advantage of the fact that, in Wales, eligibility for the zoster vaccine was determined on the basis of an individual's exact date of birth. Those born before 2 September 1933 were ineligible and remained ineligible for life, whereas those born on or after 2 September 1933 were eligible for at least 1 year to receive the vaccine. Using large-scale electronic health record data, we first show that the percentage of adults who received the vaccine increased from 0.01% among patients who were merely 1 week too old to be eligible, to 47.2% among those who were just 1 week younger. Apart from this large difference in the probability of ever receiving the zoster vaccine, individuals born just 1 week before 2 September 1933 are unlikely to differ systematically from those born 1 week later. Using these comparison groups in a regression discontinuity design, we show that receiving the zoster vaccine reduced the probability of a new dementia diagnosis over a follow-up period of 7 years by 3.5 percentage points (95% confidence interval (CI) = 0.6-7.1, P = 0.019), corresponding to a 20.0% (95% CI = 6.5-33.4) relative reduction. This protective effect was stronger among women than men. We successfully confirm our findings in a different population (England and Wales's combined population), with a different type of data (death certificates) and using an outcome (deaths with dementia as primary cause) that is closely related to dementia, but less reliant on a timely diagnosis of dementia by the healthcare system10. Through the use of a unique natural experiment, this study provides evidence of a dementia-preventing or dementia-delaying effect from zoster vaccination that is less vulnerable to confounding and bias than the existing associational evidence.

Development of a messenger RNA vaccine using pH-responsive dipeptide-conjugated lipids exhibiting reduced inflammatory properties

Lipid nanoparticles (LNPs) are used to encapsulate messenger ribonucleic acids (mRNAs) and enhance mRNA vaccine efficacy by producing inflammatory mediators. However, the overproduction of inflammatory mediators via LNP injection causes severe side effects, presenting a potential limitation. To resolve this issue, we developed pH-responsive dipeptide-conjugated lipid (DPL)-based LNPs (DPL-LNPs) for efficient small interfering RNA delivery with excellent biocompatibility. In detail, we optimized the dipeptide sequence and lipid-tail length of DPL, the helper-lipid compositions, and the molecular weight and lipid-tail length of the polyethylene glycol (PEG)-lipid to achieve highly efficient and safe mRNA delivery. Our results revealed that the LNPs prepared using glutamic acid (E)- and arginine (R)-conjugated DPL (DPL-ER) displayed higher protein-expression efficacy than DPL-threonine-R- and DPL-aspartic acid-R-based LNPs. Additionally, the lipid-tail length of the C22-bearing DPL-ER (DPL-ER-C22)-based LNPs displayed higher protein-expression efficacies than their C18 (DPL-ER-C18)- and C24 (DPL-ER-C24)-based LNPs. Moreover, the DPL-ER-C22-based LNPs incorporating low-lipid-tail-length phospholipids and PEG-lipids exhibited efficient protein expression. Most importantly, the injection of optimized DPL-LNPs exhibited comparable antigen-specific antibody production levels, with significantly lower inflammatory-mediator production compared with those of the commercially available LNPs. These results indicate that DPL-based LNPs (DPL-LNPs) can be deployed as highly efficient, safe carriers for mRNA delivery for developing mRNA vaccine formulations.

Neutralizing antibody responses after a two-dose regimen with BNT162b2, CoronaVac or ChAdOx1-S in Brazil: Differential neutralization of SARS-CoV-2 omicron variants

The emergence of SARS-CoV-2 variants has reduced antibody effectiveness, affecting vaccine protection. This study evaluated neutralizing antibodies against Wuhan strain and several variants, including Alpha, Beta, Gamma, Delta, and Omicron, in Brazilians vaccinated twice with CoronaVac, ChAdOx1-S, or BNT162b2 before Delta and Omicron emerged. After the booster, strong antibody responses to the Wuhan strain were seen in all groups, but BNT162b2 resulted in higher anti-Spike and anti-RBD IgG levels. While all vaccines showed some cross-neutralization against Alpha, Beta, Gamma, and Delta, only BNT162b2 was effective against Omicron BA.2 and BA.4/5 subvariants. Furthermore, BNT162b2 vaccination showed a positive correlation between Wuhan RBD-specific IgG and Omicron neutralizing antibodies. This group demonstrated distinct clustering patterns of neutralizing antibodies against all variants, unlike those from CoronaVac and ChAdOx1-S. The findings suggest BNT162b2 offers broader neutralization capability, highlighting the benefit of booster shots with bivalent mRNA vaccines to enhance immune responses against emerging variants.

Seroprevalence of SARS-CoV-2 antibodies in patients with hematological and oncological diseases in early 2024

INTRODUCTION

COVID-19 remains a major threat to immunocompromised individuals. The determination of circulating SARS-CoV-2 antibodies in patients at high risk for severe course of SARS-CoV-2 infection is important for estimating the vaccine-induced humoral immune response. Therefore, we assessed the status quo after winter to analyze the need for booster vaccinations.

METHODS

Anti-spike IgG levels of 46 hospitalized patients with hematological and oncological diseases, measured between 21th December 2023 and 8th February 2024, were compared between subgroups of patients. Demographic data, underlying diseases, antineoplastic treatment, and the number of positive SARS-CoV-2 tests at the University Hospital Cologne were collected.

RESULTS

Patients with different diseases showed varying SARS-CoV-2 spike antibody levels. The highest levels were found in patients with diffuse large cell B-cell lymphoma (DLBCL) and acute leukemia who had not received specific treatment or had just initiated treatment, whereas the lowest levels were found in patients with DLBCL, acute leukemia, and multiple myeloma who had received at least one line of treatment. The geometric mean antibody titers were higher in female patients than in male patients and were highest in patients aged 41-50 years while lowest in those aged 61-70 years.

CONCLUSION

The data presented confirm broad variations in SARS-CoV-2 anti-spike IgG levels across patients with different hematological and oncological diseases and highlight the complex interference of cancer biology, immune dysfunction, and treatment-related factors in shaping immune responses. Further research is needed to elucidate the mechanisms underlying these variations in antibody levels. We emphasize the need for regular booster vaccinations in this patient group.

COVID-19 booster doses reduce sex disparities in antibody responses among nursing home residents

BACKGROUND

Data suggest that antibody responses following COVID-19 vaccines are a correlate of protection. Some studies, including the clinical trials of COVID-19 mRNA vaccines, did not stratify and evaluate whether antibody responses to COVID-19 vaccines differed between the sexes or with aging. This gap in research is particularly relevant for older populations such as nursing home residents (NHR). We hypothesized that sex differences in vaccine-induced antibody responses may intersect with age and be diminished among older adults residing in nursing homes.

METHODS

We analyzed serum samples from 638 NHRs collected serially after the primary two-dose series and three subsequent booster doses of mRNA SARS-CoV-2 vaccinations. We analyzed anti-Spike IgG and neutralizing antibody titers to the Wuhan and Omicron BA.4/5 variant strains. Mixed-effects models predicting log-transformed titers were estimated to compare responses across vaccine doses, focusing on sex-differential responses. For detected post-dose sex differences, additional sample times were analyzed to assess the duration of the difference.

RESULTS

Following the primary series, female NHRs with a prior history of SARS-CoV-2 infection had significantly higher Wuhan anti-Spike antibodies and neutralizing antibody titers than male NHRs with differences persisting up to nine months post-vaccination. Subsequent monovalent booster doses and a bivalent booster dose eliminated this disparity. We did not detect any differential response to the Omicron BA.4/5 variant.

CONCLUSIONS

The blunting of sex differences in antibody response observed following the primary series by the 1st booster dose underscores the importance of booster vaccination in this population.

Cutaneous Adverse Events Following COVID-19 Vaccination in Japan: A Questionnaire Survey

We conducted a nationwide survey in Japan to clarify the clinical spectrum of these events. An initial questionnaire was sent to 126 dermatology facilities, and responses were obtained from 66 (52.4%). Among these responding facilities, the most commonly identified cutaneous adverse events after COVID-19 vaccination were urticaria (49 (74.2%)), delayed local reactions (37 (56.1%)), erythema multiforme (31 (47.0%)), and alopecia (30 (45.5%)). In the detailed survey, the primary adverse events were EM (19 (20.9%)), bullous pemphigoid (7 (7.7%)), and alopecia (6 (6.6%)). The mean latency from vaccination to onset was 13.1 days, and the mean duration of symptoms was 74.2 days. Although this study cannot establish a direct causal relationship between vaccination and adverse events, it highlights the need for dermatologists to recognize potential cutaneous reactions and provide appropriate care.

Examining vaccination-related adverse events in frequent neurodegenerative diseases

This study investigates adverse events following vaccination in patients with four neurodegenerative diseases: Amyotrophic Lateral Sclerosis (ALS), Alzheimer's disease, Multiple Sclerosis (MS), and Parkinson's disease. We applied advanced data processing techniques to analyze symptom patterns and severity scores across these disease groups. Patients were identified through filtering, and symptom clusters were extracted to group similar symptoms into distinct clusters, and severity scores were computed based on hospitalization and death reports. A chi-squared test was performed to assess the statistical significance of adverse event distributions among the diseases for different vaccines. The results reveal that ALS patients exhibit severe respiratory symptoms post-vaccination, while Alzheimer's patients report significant respiratory and gastrointestinal issues. MS patients commonly experience general symptoms such as fatigue, while Parkinson's patients face exacerbated motor symptoms. Notably, our analysis showed no significant difference in adverse event reporting rates between COVID-19 and pneumococcal vaccines across these disease groups. This research provides new insights into disease-specific responses to vaccines, emphasizing the importance of personalized monitoring and treatment strategies to mitigate risks and improve clinical outcomes in these vulnerable populations.

Impact of administration routes and dose frequency on the toxicology of SARS-CoV-2 mRNA vaccines in mice model

The increasing use of SARS-CoV-2 mRNA vaccines has raised concerns about their potential toxicological effects, necessitating further investigation to ensure their safety. To address this issue, we aimed to evaluate the toxicological effects of SARS-CoV-2 mRNA vaccine candidates formulated with four different types of lipid nanoparticles in ICR mice, focusing on repeated doses and administration routes. We conducted an extensive analysis in which mice received the mRNA vaccine candidates intramuscularly (50 μg/head) twice at 2-week intervals, followed by necropsy at 2 and 14 dpsi (days post-secondary injection). In addition, we performed a repeated dose toxicity test involving three, four, or five doses and compared the toxicological outcomes between intravenous and intramuscular routes. Our findings revealed that all vaccine candidates significantly induced SARS-CoV-2 spike protein-specific IgG and T cell responses. However, at 2 dpsi, there was a notable temporary decrease in lymphocyte and reticulocyte counts, anemia-related parameters, and significant increases in cardiac damage markers, troponin-I and NT-proBNP. Histopathological analysis revealed severe inflammation and necrosis at the injection site, decreased erythroid cells in bone marrow, cortical atrophy of the thymus, and increased spleen cellularity. While most toxicological changes observed at 2 dpsi had resolved by 14 dpsi, spleen enlargement and injection site damage persisted. Furthermore, repeated doses led to the accumulation of toxicity, and different administration routes resulted in distinct toxicological phenotypes. These findings highlight the potential toxicological risks associated with mRNA vaccines, emphasizing the necessity to carefully consider administration routes and dosage regimens in vaccine safety evaluations, particularly given the presence of bone marrow and immune organ toxicity, which, though eventually reversible, remains a serious concern.

Nationwide representative serosurvey of third-grade school children to evaluate the hepatitis B vaccination impact in Kyrgyzstan, 2022

BACKGROUND

Kyrgyzstan introduced universal hepatitis B childhood vaccination in 1999 to reduce the burden of hepatitis B. In 2016, aligned with the goal of controlling hepatitis B in the WHO European Region, a regional target of 0.5% was set for seroprevalence of hepatitis B surface antigen (HBsAg) among targeted birth cohorts. We conducted a representative nationwide serosurvey to assess the HBsAg prevalence among third-grade school children in Kyrgyzstan in 2022.

METHODS

We sampled numbers of children proportional to the population size and stratified the sample by region and urbanization level (urban/rural). We applied multistage cluster sampling with school classes as clusters. Identified participants in the survey were tested for HBsAg, using Enzyme-linked Immunosorbent Assay (ELISA), and positive samples confirmed with neutralization tests. Data on vaccination coverage for hepatitis B birth dose (HepB BD), including timing, and three doses of hepatitis B vaccine (HepB3) were collected from medical vaccination records. We calculated crude and weighted proportions for HBsAg seroprevalence and HepB BD and HepB3 coverage.

RESULTS

From the target sample size of 3,352 children, a total of 3,183 children (95%) participated in the survey. The majority of children were 9 or 10 years old (2,964; 93%) with almost equal numbers of girls and boys (1,606; 50% boys) and rural and urban participants (1,624; 51% urban). Five participants tested positive for HBsAg in confirmatory tests. The weighted HBsAg seroprevalence was 0.12% (95% CI 0.04-0.35%). Weighted coverage for HepB BD was 88% (95% CI 86-90%) and for HepB3 90% (95% CI 86-93%). Results from crude and weighted analysis did not differ statistically.

CONCLUSIONS

Our study demonstrates the impact of a successfully implemented hepatitis B vaccination programme in Kyrgyzstan. High hepatitis B vaccination coverage has resulted in very low HBsAg seroprevalence among vaccinated birth cohorts, paving the way towards the achievement of regional hepatitis B control targets. Maintaining high vaccination uptake plus additional measures like screening of pregnant women and treatment of those infected will be key to achieve elimination of vertical transmission of hepatitis B in Kyrgyzstan.

Sex differences in response to HBV vaccination in a cohort of health care workers

Globally, healthcare workers (HCWs) are at greater risk of contracting Hepatitis B virus (HBV) infection than the general population, due to their frequent contact with blood or body fluids. For this reason, WHO underlined the importance of HBV immunization for all HCWs. Although sex is now considered one of the key factors influencing the intensity and duration of the immune response to vaccines, sex-specific analysis of vaccine-induced anti-HBs antibodies is rarely conducted. Our study aimed to evaluate the anti-HBs antibodies' long-lasting protective titers in male and female HCWs to identify sex differences in the humoral response to the HBV vaccine. The study was conducted on 2106 HCWs (1636 females and 470 males) working at the Padova University Hospital, Italy. Our results report significantly higher anti-HBs levels in female HCWs than in males, particularly when considering HCWs for whom the elapsed time since vaccination is greater than 10 years, suggesting a greater persistence of anti-HBs in females. In conclusion, our findings could contribute to understanding differences in the antibody response to the HBV vaccine between male and female subjects and improving vaccination strategies for HCWs.

Sex-based difference in immune responses and efficacy of the pneumococcal conjugate vaccine

Vaccine-mediated protection and susceptibility to Streptococcus pneumoniae (pneumococcus) infections are influenced by biological sex. The incidence of invasive pneumococcal disease remains higher in males compared to females even after the introduction of the pneumococcal conjugate vaccine. However, sex-based differences in the immune response to this conjugate vaccine remain unexplored. To investigate those differences, we vaccinated adult male and female mice with pneumococcal conjugate vaccine and assessed cellular and humoral immune responses. Compared to females, male mice displayed lower levels of T follicular helper cells, germinal center B cells, and plasmablasts, which are all required for antibody production following vaccination. This was linked to lower IgG and IgM levels against pneumococci and lower isotype switching to IgG3 in vaccinated males. Due to lower antibody levels, sera of vaccinated male mice had lower efficacy in several anti-pneumococcal functions, including neutralization of bacterial binding to pulmonary epithelial cells as well as direct cytotoxicity against S. pneumoniae. Importantly, while the vaccine was highly protective in females, vaccinated males succumbed to infection more readily and were more susceptible to both lung-localized infection and systemic spread following S. pneumoniae challenge. These findings identify sex-based differences in immune responses to pneumococcal conjugate vaccine that can inform future vaccine strategies.

Salivary Antibody Responses to Potentially Waterborne and Environmentally Transmitted Infections Among Two Tribal Nations in the Southwest United States

PURPOSE

Tribal Nations disproportionately lack access to safe drinking water and can be adversely affected by other water quality and environmental concerns. Such conditions could lead to an increase in the transmission of waterborne, environmental and hygiene related infections. We collected saliva samples from attendees at two Tribal Nation annual festivals and tested them for salivary immunoglobulin G (IgG) responses to selected common infections using an in-house multiplex immunoassay. Antibody responses were compared to responses from a previously conducted study in the midwestern United States.

METHODS

We collected and tested 531 samples from Tribal Nation sites and used data on 453 previously analyzed samples from the Midwest site. Logistic and linear regression models were used to model a binary classification of seropositivity and the intensity of the antibody response, respectively.

RESULTS

Seroprevalence of chronic infections (Helicobacter pylori and Toxoplasma gondii) were generally consistent with estimates from population-based studies. Compared to the Midwest site, one of the Tribal Nation sites had consistently higher median antibody responses to several noroviruses. The Tribal Nation sites had a lower seroprevalence of hepatitis E virus antibodies. At the Tribal Nation sites, farm residents had higher antibody responses to Cryptosporidium spp., bottled water consumption was associated with lower responses to Cryptosporidium spp., animal contact was associated with T. gondii seropositivity, and recent diarrhea was associated with higher norovirus antibody responses. Helicobacter pylori seropositivity was associated with reduced odds of reporting allergies.

CONCLUSION

This study demonstrated the application of a multiplex salivary immunoassay in Tribal Nations to provide insights regarding selected common pathogens which are transmitted through different transmission pathways including person-to-person contacts, contaminated food, soil and drinking water.

Comparative study of anti-SARS-CoV-2 receptor-binding domain total antibody titer before and after heterologous booster with mRNA-based COVID-19 vaccine

The waning immunity following the COVID-19 vaccination become a significant concern and the immunological dynamics of vaccine-induced antibodies after vaccination need to be explored. The aim of this study was to compare anti-SARS-CoV-2 receptor-binding domain (RBD) antibody levels before and after a booster dose with heterologous COVID-19 vaccine and to identify factors influencing the levels after receiving the booster dose. A cross-sectional study was conducted in which individuals who received primary doses of CoronaVac and a booster dose with an mRNA-based vaccine were recruited using a purposive sampling technique. The titers of anti-SARS-CoV-2 RBD antibodies were measured using an enzyme-linked immunosorbent assay (ELISA), and plausible associated factors were collected using a questionnaire-assisted face-to-face interview. The Wilcoxon test was used to compare the titers before and after the booster dose, while the Kruskal-Wallis and Mann-Whitney tests, followed by multivariate linear regression, were used to assess the factors associated with RBD total antibody titers. The results showed that there was a significant increase of anti-SARS-CoV-2 RBD total antibody titers before and after receiving the booster dose (1,558.7 binding antibody units (BAU)/mL vs 140.6 BAU/mL, p<0.001). The analysis revealed that age (p=0.555), sex (p=0.254), type of vaccine (p=0.914), presence of hypertension (p=0.541), diabetes (p=0.975), chronic obstructive pulmonary disease (COPD, p=0.620), and gout (p=0.364) were not associated with anti-SARS-CoV-2 RBD total antibody titers. However, the titers of anti-SARS-CoV-2 RBD total antibody were significantly different between those with and without hyperlipidemia (p=0.021). This study suggests that a booster dose with a heterologous COVID-19 vaccine could significantly enhance immune responses against COVID-19, and therefore, this strategy may be recommended as part of preventive measures to strengthen immunity against COVID-19.

Assessing humoral immunity in daily practice: A retrospective study in a pediatric tertiary center

The evaluation of humoral immunity is usually performed through the assessment of serum immunoglobulin levels, vaccine titer responses, and B-cell enumeration and phenotyping. We performed a retrospective study assessing humoral immunity in 469 pediatric patients referred at the Sainte-Justine University Hospital Center. Almost half of the patients had at least one abnormal humoral immunological parameter at their evaluation, with low vaccine response titer to protein antigen being the most frequent. Fifteen patients (3.2 %) had a proven monogenic IEI, and 21 patients (4.5 %) required Ig replacement. Besides the infectious burden, hypoIgG remains the only parameter associated with Ig replacement therapy after the age of 6 years. Low antibody titers against conjugate vaccines had low sensitivity and positive predictive values for starting Ig replacement. Our study highlights the challenge of evaluating the humoral function in the pediatric population with suspected IEI with significant age and sex-dependent variability between parameters.

Sex differences in response to COVID-19 mRNA vaccines in Italian population

Since the beginning of mass vaccination campaign for COVID-19 in Italy (December 2020) and following the rapidly increasing vaccine administration, sex differences have been emphasized. Nevertheless, incomplete and frequently incoherent sex-disaggregated data for COVID-19 vaccinations are currently available, and vaccines clinical studies generally do not include sex-specific analyses for safety and efficacy. We looked at sex variations in the COVID-19 vaccine's effectiveness against infection and severe disease outcomes. We conducted a nationwide retrospective cohort study on Italian population, linking information on COVID-19 vaccine administrations obtained through the Italian National Vaccination Registry, with the COVID-19 integrated surveillance system, held by the Istituto Superiore di Sanità. The results showed that, in all age groups, vaccine effectiveness (VE) was higher in the time-interval ≤120 days post-vaccination. In terms of the sex difference in vaccination effectiveness, men and women were protected against serious illness by vaccination in a comparable way, while men were protected against infection to a somewhat greater extent than women. To fully understand the mechanisms underlying the sex difference in vaccine response and its consequences for vaccine effectiveness and development, further research is required. The sex-related analysis of vaccine response may contribute to adjust vaccination strategies, improving overall public health programmes.

Rational design of uncleaved prefusion-closed trimer vaccines for human respiratory syncytial virus and metapneumovirus

Respiratory syncytial virus (RSV) and human metapneumovirus (hMPV) cause human respiratory diseases and are major targets for vaccine development. In this study, we design uncleaved prefusion-closed (UFC) trimers for the fusion protein (F) of both viruses by examining mutations critical to F metastability. For RSV, we assess four previous prefusion F designs, including the first and second generations of DS-Cav1, SC-TM, and 847A. We then identify key mutations that can maintain prefusion F in a native-like, closed trimeric form (up to 76%) without introducing any interprotomer disulfide bond. For hMPV, we develop a stable UFC trimer with a truncated F2-F1 linkage and an interprotomer disulfide bond. Dozens of UFC constructs are characterized by negative-stain electron microscopy (nsEM), x-ray crystallography (11 RSV-F structures and one hMPV-F structure), and antigenic profiling. Using an optimized RSV-F UFC trimer as bait, we identify three potent RSV neutralizing antibodies (NAbs) from a phage-displayed human antibody library, with a public NAb lineage targeting sites Ø and V and two cross-pneumovirus NAbs recognizing site III. In mouse immunization, rationally designed RSV-F and hMPV-F UFC trimers induce robust antibody responses with high neutralizing titers. Our study provides a foundation for future prefusion F-based RSV and hMPV vaccine development.

Exploring the relationship between genetic instability and health outcomes in acute and chronic post-COVID syndrome

The COVID-19 pandemic has led to the emergence of acute and chronic post-COVID syndromes, which present diverse clinical manifestations. The underlying pathophysiology of these conditions is not yet fully understood, but genetic instability has been proposed as a potential contributing factor. This study aimed to explore the differential impact of physical and psychological health factors on genetic instability in individuals with acute and chronic post-COVID syndromes. In this study, three groups of subjects were analyzed: a control group, an acute post-COVID group, and a chronic post-COVID group, with a total of 231 participants. The participants were assessed using a questionnaire for long-COVID-19COVID, and female participants reported more symptoms than male participants in areas related to fatigue, memory, mental health, and well-being during the chronic phase. Genetic instability was assessed using the comet assay, and participants' physical and psychological profiles were evaluated. The overall results showed no significant differences in DNA damage, as measured by the comet assay, among the three groups, suggesting that genetic instability, as assessed by this method, may not be a primary driver of the distinct clinical presentations observed in post-COVID syndromes. However, when gender was considered, male participants in the acute long COVID group exhibited higher levels of genetic instability compared to females. Multiple linear regression analysis revealed that gender, age, and waist circumference were significant predictors of DNA damage. Among females in the acute group, sexual health, and eye-related symptoms significantly influenced the increase in DNA damage. These findings indicate the need for further investigation on the gender-specific differences in genetic instability and their potential implications for the pathophysiology of post-COVID syndromes. Exploring alternative markers of genetic instability and the interplay between genetic, inflammatory, and cellular processes could provide valuable insights for the management of these debilitating post-viral sequelae.

Anti-A and anti-B titers in A, B and O whole blood donors: Beyond "dangerous O"

BACKGROUND AND OBJECTIVES

Hemolytic transfusion reactions (HTRs) pose significant risks in transfused patients, with anti-A and anti-B antibodies in donor plasma being potential contributing factors. Despite advancements in component preparation, HTRs remain a concern, particularly with apheresis-derived platelets. This study aimed to determine the prevalence of high anti-A and anti-B titers among A, B, and O blood group donors and to explore factors associated with high titers.

MATERIALS AND METHODS

A cross-sectional observational study was conducted over 18 months, enrolling 978 participants from a tertiary care teaching hospital in Western India. Anti-A and anti-B titers were determined using the Conventional Tube Technique (CTT). Statistical analysis assessed correlations between high titers and demographic factors.

RESULTS

The majority of participants were young males (98.8%). Prevalence of high titers for IgM anti-A was 12.2% and IgG anti-A was 2.5%. For anti-B, IgM titers were 2.3% and IgG titers were 0.2%. The prevalence of dangerous O was found to be 14.1%, while 3.52% and 10.5% of A and B blood group donors were found to have high titers, respectively. Factors associated with high titers included female gender, vegetarian diet, age <30 years, and O blood group.

CONCLUSION

The study sheds additional light and provides supplementary information regarding the prevalence and correlation of high anti-A and anti-B titers among O, A and B blood donors. Understanding these factors is crucial for optimizing transfusion safety protocols, including selective screening of platelet units and tailored transfusion strategies based on donor characteristics.

Evolving understanding of autoimmune mechanisms and new therapeutic strategies of autoimmune disorders

Autoimmune disorders are characterized by aberrant T cell and B cell reactivity to the body's own components, resulting in tissue destruction and organ dysfunction. Autoimmune diseases affect a wide range of people in many parts of the world and have become one of the major concerns in public health. In recent years, there have been substantial progress in our understanding of the epidemiology, risk factors, pathogenesis and mechanisms of autoimmune diseases. Current approved therapeutic interventions for autoimmune diseases are mainly non-specific immunomodulators and may cause broad immunosuppression that leads to serious adverse effects. To overcome the limitations of immunosuppressive drugs in treating autoimmune diseases, precise and target-specific strategies are urgently needed. To date, significant advances have been made in our understanding of the mechanisms of immune tolerance, offering a new avenue for developing antigen-specific immunotherapies for autoimmune diseases. These antigen-specific approaches have shown great potential in various preclinical animal models and recently been evaluated in clinical trials. This review describes the common epidemiology, clinical manifestation and mechanisms of autoimmune diseases, with a focus on typical autoimmune diseases including multiple sclerosis, type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, and sjögren's syndrome. We discuss the current therapeutics developed in this field, highlight the recent advances in the use of nanomaterials and mRNA vaccine techniques to induce antigen-specific immune tolerance.

Mechanisms of long COVID and the path toward therapeutics

Long COVID, a type of post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PASC) defined by medically unexplained symptoms following infection with SARS-CoV-2, is a newly recognized infection-associated chronic condition that causes disability in some people. Substantial progress has been made in defining its epidemiology, biology, and pathophysiology. However, there is no cure for the tens of millions of people believed to be experiencing long COVID, and industry engagement in developing therapeutics has been limited. Here, we review the current state of knowledge regarding the biology and pathophysiology of long COVID, focusing on how the proposed mechanisms explain the physiology of the syndrome and how they provide a rationale for the implementation of a broad experimental medicine and clinical trials agenda. Progress toward preventing and curing long COVID and other infection-associated chronic conditions will require deep and sustained investment by funders and industry.

Divergent humoral responses between males and females against 24 kDa excretory-secretory protein of Haemonchus contortus and influence of ovine β-globin polymorphism

Lambs harboring the Hb-AA β-globin haplotype present improved cell-mediated responses and increased resistance against Haemonchus contortus infection. The aim of the present study was to compare the effect of sex and β-globin haplotypes on specific humoral responses and phenotypes of resistance during H. contortus infection in Morada Nova sheep. As expected, females displayed stronger resistance during the first and second experimental challenges. Differential systemic humoral immune responses were observed comparing sex groups, in which higher levels of specific antibodies targeting 24 kDa excretory-secretory (ES24) protein of H. contortus of IgG and IgM antibodies were respectively observed as predominant isotypes in males and females. The IgM levels were significantly correlated with phenotypes of resistance, evaluated by packed cell volume and fecal egg counts. To our knowledge this is the first study reporting divergent humoral responses profiles to H. contortus infection between male and female sheep. The impact of β-globin haplotypes was less pronounced in females compared to males. Notably, only males showed significant weight differences across haplotypes, with Hb-AA lambs being the heaviest. Additionally, Hb-AA males had significantly higher PCV (indicating better red blood cell health) and lower FEC (indicating lower parasite burden). These findings suggest a more pronounced effect of β-globin polymorphisms on H. contortus infection in males, potentially due to their generally weaker resistance compared to females. This study highlights the importance of sex and β-globin haplotypes in shaping immune responses to H. contortus infection. Specifically, IgM antibodies targeting the ES24 protein appear to play a crucial role in host-parasite interactions and may hold promise for therapeutic development.

How does geographical diversity shape vaccine efficacy?

Vaccination is a cornerstone of public health, saving millions of lives each year by preventing a variety of infectious diseases. Yet, despite global vaccination efforts, emerging research highlights significant geographical disparities in vaccine efficacy and immunogenicity. These variations underscore the critical interplay between immunological factors and environmental, genetic, and nutritional elements across different populations. Our review article aimed to explore the multifactorial reasons behind geographical variations in vaccine efficacy. Also, this study has shown how important host factors like age, obesity, gender, and genetic diversity, especially within the major histocompatibility complex, are in determining how well a vaccine works. Nutritional status, namely deficiencies in micronutrients such as vitamins and zinc, and lifestyle factors including stress, sleep, alcohol consumption, and physical activity are also shown to have profound effects on vaccine-induced immunity. Importantly, our paper also brought to light the influence of microbial and ecological factors, such as the gut microbiome and environmental pollutants, on the immune system's response to vaccination. The findings emphasize the importance of tailoring vaccination strategies to accommodate the unique immunological landscapes shaped by geographical and societal factors. This tailored approach could enhance vaccine efficacy, reduce disparities in vaccine response, and ultimately contribute to the global fight against infectious diseases.

Melanoma and sex hormones: Pathogenesis, progressive disease and response to treatments

Cutaneous melanoma represents the fifth tumor in terms of incidence in young adults, with a major involvement of males than females. Despite the significant changes in available effective treatments for cutaneous melanoma, there is still a proportion of patients that do not benefit long-term disease control with immune checkpoint inhibitors and/or BRAF/MEK inhibitors, and eventually develop progressive disease. In addition to the emerging biomarkers under investigation to understand resistance to treatments, recent studies resumed the role of sex hormones (estrogens, progesterone and androgens) in melanoma patients. In the last decades, the impact of sex hormones has been considered controversial in melanoma patients, but actual growing preclinical and clinical evidence underline the potential influence on melanoma cells' growth, tumor microenvironment, the immune system and consequently on the course of disease.This review will provide available insights on the role of sex hormones in melanoma pathogenesis, disease progression and response/resistance to systemic treatments. We will also offer an overview on the recent studies on the theme, describing the hormonal contribution to disease response and the interaction with targeted therapies and immune-checkpoint inhibitors in cutaneous melanoma patients, illustrating an insight into future research in this field.

The roles of CD4+ T cell help, sex, and dose in the induction of protective CD8+ T cells against a lethal poxvirus by mRNA-LNP vaccines

The role of CD4+ T cells in the induction of protective CD8+ T cells by mRNA lipid nanoparticle (LNP) vaccines is unknown. We used B6 or Tlr9 -/- mice depleted or not of CD4+ T cells and LNP vaccines loaded with mRNAs encoding the ectromelia virus (ECTV) MHC class I H-2 Kb-restricted immunodominant CD8+ T cell epitope TSYKFESV (TSYKFESV mRNA-LNPs) or the ECTV EVM158 protein, which contains TSYKFESV (EVM-158 mRNA-LNPs). Following prime and boost with 10 μg of either vaccine, Kb-TSYKFESV-specific CD8+ T cells fully protected male and female mice from ECTV at 29 (both mRNA-LNPs) or 90 days (EVM158 mRNA-LNPs) post boost (dpb) independently of CD4+ T cells. However, at 29 dpb with 1 μg mRNA-LNPs, males had lower frequencies of Kb-TSYKFESV-specific CD8+ T cells and were much less well protected than females from ECTV, also independently of CD4+ T cells. At 90 dpb with 1 μg EVM158 mRNA-LNPs, the frequencies of Kb-TSYKFESV-specific CD8+ T cells in males and females were similar, and both were similarly partially protected from ECTV, independently of CD4+ T cells. Therefore, at optimal or suboptimal doses of mRNA-LNP vaccines, CD4+ T cell help is unnecessary to induce protective anti-poxvirus CD8+ T cells specific to a dominant epitope. At suboptimal doses, protection of males requires more time to develop.

Sex differences in CD8+ T cell responses during adaptive immunity

Biological sex is an important variable that influences the immune system's susceptibility to infectious and non-infectious diseases and their outcomes. Sex dimorphic features in innate and adaptive immune cells and their activities may help to explain sex differences in immune responses. T lymphocytes in the adaptive immune system are essential to providing protection against infectious and chronic inflammatory diseases. In this review, T cell responses are discussed with focus on the current knowledge of biological sex differences in CD8+ T cell mediated adaptive immune responses in infectious and chronic inflammatory diseases. Future directions aimed at investigating the molecular and cellular mechanisms underlying sex differences in diverse T cell responses will continue to underscore the significance of understanding sex differences in protective immunity at the cellular level, to induce appropriate T cell-based immune responses in infection, autoimmunity, and cancer. This article is categorized under: Immune System Diseases > Molecular and Cellular Physiology Infectious Diseases > Molecular and Cellular Physiology.

A humanized mouse that mounts mature class-switched, hypermutated and neutralizing antibody responses

Humanized mice are limited in terms of modeling human immunity, particularly with regards to antibody responses. Here we constructed a humanized (THX) mouse by grafting non-γ-irradiated, genetically myeloablated KitW-41J mutant immunodeficient pups with human cord blood CD34+ cells, followed by 17β-estradiol conditioning to promote immune cell differentiation. THX mice reconstitute a human lymphoid and myeloid immune system, including marginal zone B cells, germinal center B cells, follicular helper T cells and neutrophils, and develop well-formed lymph nodes and intestinal lymphoid tissue, including Peyer's patches, and human thymic epithelial cells. These mice have diverse human B cell and T cell antigen receptor repertoires and can mount mature T cell-dependent and T cell-independent antibody responses, entailing somatic hypermutation, class-switch recombination, and plasma cell and memory B cell differentiation. Upon flagellin or a Pfizer-BioNTech coronavirus disease 2019 (COVID-19) mRNA vaccination, THX mice mount neutralizing antibody responses to Salmonella or severe acute respiratory syndrome coronavirus 2 Spike S1 receptor-binding domain, with blood incretion of human cytokines, including APRIL, BAFF, TGF-β, IL-4 and IFN-γ, all at physiological levels. These mice can also develop lupus autoimmunity after pristane injection. By leveraging estrogen activity to support human immune cell differentiation and maturation of antibody responses, THX mice provide a platform to study the human immune system and to develop human vaccines and therapeutics.

Increased risk of chronic fatigue syndrome following pneumonia: A population-based Cohort study

BACKGROUND

Chronic fatigue syndrome (CFS) has been linked to several conditions, including infections, immune system changes, or emotional stress. Our study aimed to assess the risk of CFS after a pneumonia diagnosis using data from National Health Insurance Research Database of Taiwan.

METHODS

In this nested case-control study, we identified 2,000,000 adult patients from a nationwide population-based health insurance claims database spanning from January 1, 2000, to December 31, 2017. Each case diagnosed with a pathogenic infection was matched with a corresponding control using propensity scores. We excluded individuals under 20 years of age, those with a history of pathogenic infections before the index date, or those with more than one potential pathogen. To estimate hazard ratios (HR) and the adjusted hazard ratio (aHR) with their respective 95 % confidence intervals (CI), we applied univariable and multivariable Cox proportional hazard models. The multivariable analysis incorporated adjustments for age, sex, and comorbidity-related confounders.

RESULTS

The relationship between infection and the subsequent risk of CFS was assessed using Cox proportional hazards regression analysis. The incidence density rates were 6.13 and 8.70 per 1000 person-years among the non-pulmonary infection and pulmonary infection populations, respectively (adjusted hazard ratio [HR] = 1.4, 95 % confidence interval [CI] 1.32-1.5). Patients infected with Pseudomonas, Klebsiella pneumoniae, Haemophilus influenzae, Streptococcus pneumoniae, and influenza virus exhibited a significantly higher risk of CFS than those without these pathogens (p < 0.05). Additionally, patients with pneumonia had a significantly increased risk of thromboembolism compare with control group (p < 0.05).

Influence of adiposity and sex on SARS-CoV-2 antibody response in vaccinated university students: A cross-sectional ESFUERSO study

Prior studies have identified various determinants of differential immune responses to COVID-19. This study focused on the Ig-G anti-RBD marker, analyzing its potential correlations with sex, vaccine type, body fat percentage, metabolic risk, perceived stress, and previous COVID-19 exposure. In this study, data (available in S1 Data) were obtained from 108 participants from the ESFUERSO cohort, who completed questionnaires detailing their COVID-19 experiences and stress levels assessed through the SISCO scale. IgG anti-RBD concentrations were quantified using an ELISA assay developed by UNAM. Multiple regression analysis was employed to control for covariates, including sex, age, body fat percentage, body mass index (BMI), and perceived stress. This sample comprised young individuals (average age of 21.4 years), primarily consisting of females (70%), with a substantial proportion reporting a family history of diabetes, hypertension, or obesity. Most students had received the Moderna or Pfizer vaccines, and 91% displayed a positive anti-RBD response. A noteworthy finding was the interaction between body fat percentage and sex. In males, increased adiposity was associated with decreased Ig-G anti-RBD concentration; in females, the response increased. Importantly, this pattern remained consistent regardless of the vaccine received. No significant associations were observed for dietary habits or perceived stress variables. This research reports the impact of sex and body fat percentage on the immune response through Ig-G anti-RBD levels to COVID-19 vaccines. The implications of these findings offer a foundation for educational initiatives and the formulation of preventive policies aimed at mitigating health disparities.

A Cross-Sectional Study of Measles-Specific Antibody Levels in Australian Blood Donors-Implications for Measles Post-Elimination Countries

Passive immunisation with normal human immunoglobulin (NHIG) is recommended as post-exposure prophylaxis (PEP) for higher-risk measles contacts where vaccination is contraindicated. However, the concentration of measles-specific antibodies in NHIG depends on antibody levels within pooled donor plasma. There are concerns that measles immunity in the Australian population may be declining over time and that blood donors' levels will progressively decrease, impacting levels required to produce effective NHIG for measles PEP. A cross-sectional study of Australian plasmapheresis donors was performed using an age-stratified, random sample of recovered serum specimens, collected between October and November 2019 (n = 1199). Measles-specific IgG antibodies were quantified by ELISA (Enzygnost anti-measles virus IgG, Siemens), and negative and equivocal specimens (n = 149) also underwent plaque reduction neutralisation testing (PRNT). Mean antibody levels (optical density values) progressively decreased from older to younger birth cohorts, from 2.09 [±0.09, 95% CI] to 0.58 [±0.04, 95% CI] in donors born in 1940-1959 and 1990-2001, respectively (p < 0.0001). This study shows that mean measles-specific IgG levels are significantly lower in younger Australian donors. While current NHIG selection policies target older donors, as younger birth cohorts become an increasingly larger proportion of contributing donors, measles-specific antibody concentrations of NHIG will progressively reduce. We therefore recommend monitoring measles-specific antibody levels in future donors and NHIG products in Australia and other countries that eliminated measles before the birth of their youngest blood donors.

The conneXion between sex and immune responses

There are notable sex-based differences in immune responses to pathogens and self-antigens, with female individuals exhibiting increased susceptibility to various autoimmune diseases, and male individuals displaying preferential susceptibility to some viral, bacterial, parasitic and fungal infections. Although sex hormones clearly contribute to sex differences in immune cell composition and function, the presence of two X chromosomes in female individuals suggests that differential gene expression of numerous X chromosome-linked immune-related genes may also influence sex-biased innate and adaptive immune cell function in health and disease. Here, we review the sex differences in immune system composition and function, examining how hormones and genetics influence the immune system. We focus on the genetic and epigenetic contributions responsible for altered X chromosome-linked gene expression, and how this impacts sex-biased immune responses in the context of pathogen infection and systemic autoimmunity.

Immunoengineering Biomaterials for Musculoskeletal Tissue Repair across Lifespan

Musculoskeletal diseases and injuries are among the leading causes of pain and morbidity worldwide. Broad efforts have focused on developing pro-regenerative biomaterials to treat musculoskeletal conditions; however, these approaches have yet to make a significant clinical impact. Recent studies have demonstrated that the immune system is central in orchestrating tissue repair and that targeting pro-regenerative immune responses can improve biomaterial therapeutic outcomes. However, aging is a critical factor negatively affecting musculoskeletal tissue repair and immune function. Hence, understanding how age affects the response to biomaterials is essential for improving musculoskeletal biomaterial therapies. This review focuses on the intersection of the immune system and aging in response to biomaterials for musculoskeletal tissue repair. The article introduces the general impacts of aging on tissue physiology, the immune system, and the response to biomaterials. Then, it explains how the adaptive immune system guides the response to injury and biomaterial implants in cartilage, muscle, and bone and discusses how aging impacts these processes in each tissue type. The review concludes by highlighting future directions for the development and translation of personalized immunomodulatory biomaterials for musculoskeletal tissue repair.

A prospective cohort-based artificial intelligence evaluation system for the protective efficacy and immune response of SARS-CoV-2 inactivated vaccines

BACKGROUND

Novel coronaviruses constitute a significant health threat, prompting the adoption of vaccination as the primary preventive measure. However, current evaluations of immune response and vaccine efficacy are deemed inadequate.

OBJECTIVES

The study sought to explore the evolving dynamics of immune response at various vaccination time points and during breakthrough infections. It aimed to elucidate the synergistic effects of epidemiological factors, humoral immunity, and cellular immunity. Additionally, regression curves were used to determine the correlation between the protective efficacy of the vaccine and the stimulated immune response.

METHODS

Employing LASSO for high-dimensional data analysis, the study utilised four machine learning algorithms-logistical regression, random forest, LGBM classifier, and AdaBoost classifier-to comprehensively assess the immune response following booster vaccination.

RESULTS

Neutralising antibody levels exhibited a rapid surge post-booster, escalating to 102.38 AU/mL at one week and peaking at 298.02 AU/mL at two weeks. Influential factors such as sex, age, disease history, and smoking status significantly impacted post-booster antibody levels. The study further constructed regression curves for neutralising antibodies, non-switched memory B cells, CD4+T cells, and CD8+T cells using LASSO combined with the random forest algorithm.

CONCLUSION

The establishment of an artificial intelligence evaluation system emerges as pivotal for predicting breakthrough infection prognosis after the COVID-19 booster vaccination. This research underscores the intricate interplay between various components of immunity and external factors, elucidating key insights to enhance vaccine effectiveness. 3D modelling discerned distinctive interactions between humoral and cellular immunity within prognostic groups (Class 0-2). This underscores the critical role of the synergistic effect of humoral immunity, cellular immunity, and epidemiological factors in determining the protective efficacy of COVID-19 vaccines post-booster administration.

Sex differences in immune protection in mice conferred by heterologous vaccines for pneumonic plague

Background

Yersinia pestis is the etiological agent of plague, which can manifest as bubonic, septicemic, and/or pneumonic disease. Plague is a severe and rapidly progressing illness that can only be successfully treated with antibiotics initiated early after infection. There are no FDA-approved vaccines for plague, and some vaccine candidates may be less effective against pneumonic plague than bubonic plague. Y. pestis is not known to impact males and females differently in mechanisms of pathogenesis or severity of infection. However, one previous study reported sex-biased vaccine effectiveness after intranasal Y. pestis challenge. As part of developing a safe and effective vaccine, it is essential that potential sex differences are characterized.

Methods

In this study we evaluated novel vaccines in male and female BALB/c mice using a heterologous prime-boost approach and monitored survival, bacterial load in organs, and immunological correlates. Our vaccine strategy consisted of two subcutaneous immunizations, followed by challenge with aerosolized virulent nonencapsulated Y. pestis. Mice were immunized with a combination of live Y. pestis pgm- pPst-Δcaf1, live Y. pestis pgm- pPst-Δcaf1/ΔyopD, or recombinant F1-V (rF1-V) combined with adjuvants.

Results

The most effective vaccine regimen was initial priming with rF1-V, followed by boost with either of the live attenuated strains. However, this and other strategies were more protective in female mice. Males had higher bacterial burden and differing patterns of cytokine expression and serum antibody titers. Male mice did not demonstrate synergy between vaccination and antibiotic treatment as repeatedly observed in female mice.

Conclusions

This study provides new knowledge about heterologous vaccine strategies, sex differences in plague-vaccine efficacy, and the immunological factors that differ between male and female mice.

An Analysis of Antibody Response to COVID-19 Vaccination Among Medicos in a Predominantly Tribal State in India: A Comparative Study

Introduction Global health is still being impacted by the coronavirus disease 2019 (COVID-19) pandemic. Objectives We evaluated the antibody response in this study in individuals who received two doses of the COVID-19 vaccination, both with and without a history of SARS-CoV-2 infection. Methodology It was a hospital-based cross-sectional study conducted among healthcare personnel at a tertiary institution of a predominantly tribal state in India. Results A total of 187 medical students made up the vaccinee group; the majority (152; 81.3%) were between the ages of 18 and 23; 128 (68.4%) of the students were female; and 104 (55.6%) had received the Covishield (AstraZeneca plc, England, UK) vaccination. Of the subjects, 51 (27.3%) had a history of COVID-19 infection. For those who were infected, the antibody titer peaked after six months, whereas it took twice as long for those who were not. Up to a year later, the antibody titers for Covaxin (Bharat Biotech, Hyderabad, India) and Covishield remained equal; however, Covishield titers drastically decreased while Covaxin stayed constant when an infection history was present. Conclusion The study's findings show that immunization in individuals who have previously contracted COVID-19 induces a higher level of antibody response than immunization in individuals who have not previously contracted the virus.

Sex Differences in the Immunogenicity and Efficacy of Seasonal Influenza Vaccines: A Meta-analysis of Randomized Controlled Trials

Background

Sex impacts individuals' response to vaccination. However, most vaccine studies do not report these differences disaggregated by sex. The aim of this study was to assess sex differences in the immunogenicity and efficacy of influenza vaccine.

Methods

We performed a meta-analysis using phase 3 randomized controlled trial data conducted between 2010 and 2018. Using hemagglutination inhibition antibody titers for each strain, differences in geometric mean ratios (GMRs) were calculated by sex. Risk ratios (RRs) comparing seroconversion proportions were pooled for females and males using random-effects models. Vaccine efficacy (VE) was assessed. Data were analyzed by age group (18-64 vs ≥65 years).

Results

A total of 33 092 healthy adults from 19 studies were included for immunogenicity analysis, and 6740 from 1 study for VE. Whereas no sex differences in immunogenicity were found in adults <65 years old, older females had a significantly greater chance to seroconvert compared to older males for all strains: RRH1N1 = 1.17 [95% confidence interval {CI}, 1.12-1.23]; RRH3N2 = 1.09 [95% CI, 1.05-1.14]; RRVictoria = 1.23 [95% CI, 1.14-1.31]; RRYamagata = 1.22 [95% CI, 1.14-1.30]. GMRs were also higher in older females for all strains compared to older males. VE in preventing laboratory-confirmed influenza was higher in older females compared to older males with VEs of 27.32% (95% CI, 1.15%-46.56%) and 6.06% (95% CI, -37.68% to 35.90%), respectively.

Conclusions

Our results suggest a higher immunogenicity and VE in females compared to males in older adults. These differences in immunogenicity and VE support the disaggregation of vaccine data by sex in clinical trials and observational studies.

Clinical Trials Registration

CRD42018112260.

Cyclodextrin microneedles for the delivery of a nanoparticle-based peptide antigen vaccine

In recent years, microneedles (MNs) have gained considerable interest in drug formulation due to their non-invasive and patient-friendly nature. Dissolving MNs have emerged as a promising approach to enhance drug delivery across the skin in a painless manner without generating sharp waste and providing the possibility for self-administration. Cyclodextrins, a group of cyclic oligosaccharides, are well-established in pharmaceutical products due to their safety and unique ability to form inclusion complexes with various drug molecules. In this manuscript, we report the development and characterization of dissolving MNs composed of cyclodextrins for intradermal delivery of a cyclodextrin-based nanoparticulate vaccine. Different cyclodextrins were tested and the most promising candidates were fabricated into MNs by micromolding. The MNs' piercing effectiveness and drug permeation across the skin were tested ex vivo. Furthermore, in vivo studies were carried out to assess the skin's tolerance to cyclodextrin-based MNs, and to evaluate the immune response using a model peptide antigen in a mouse model. The data revealed that the MNs were well-tolerated and effective, even leading to dose-sparing effects. This study highlights the potential of cyclodextrin-based dissolving MNs as a versatile platform for intradermal vaccine delivery, providing a compatible matrix for nanoparticulate formulations to enhance immune responses.

SARS-CoV-2 booster vaccine dose significantly extends humoral immune response half-life beyond the primary series

SARS-CoV-2 lipid nanoparticle mRNA vaccines continue to be administered as the predominant prophylactic measure to reduce COVID-19 disease pathogenesis. Quantifying the kinetics of the secondary immune response from subsequent doses beyond the primary series and understanding how dose-dependent immune waning kinetics vary as a function of age, sex, and various comorbidities remains an important question. We study anti-spike IgG waning kinetics in 152 individuals who received an mRNA-based primary series (first two doses) and a subset of 137 individuals who then received an mRNA-based booster dose. We find the booster dose elicits a 71-84% increase in the median Anti-S half life over that of the primary series. We find the Anti-S half life for both primary series and booster doses decreases with age. However, we stress that although chronological age continues to be a good proxy for vaccine-induced humoral waning, immunosenescence is likely not the mechanism, rather, more likely the mechanism is related to the presence of noncommunicable diseases, which also accumulate with age, that affect immune regulation. We are able to independently reproduce recent observations that those with pre-existing asthma exhibit a stronger primary series humoral response to vaccination than compared to those that do not, and further, we find this result is sustained for the booster dose. Finally, via a single-variate Kruskal-Wallis test we find no difference between male and female humoral decay kinetics, however, a multivariate approach utilizing  Least Absolute Shrinkage and Selection Operator (LASSO) regression for feature selection reveals a statistically significant (p < 1 × 10 - 3 ), albeit small, bias in favour of longer-lasting humoral immunity amongst males.

Hormones and B-cell development in health and autoimmunity

The development of B cells into antibody-secreting plasma cells is central to the adaptive immune system as they induce protective and specific antibody responses against invading pathogens. Various studies have shown that, during this process, hormones can play important roles in the lymphopoiesis, activation, proliferation, and differentiation of B cells, and depending on the signal given by the receptor of each hormone, they can have a positive or negative effect. In autoimmune diseases, hormonal deregulation has been reported to be related to the survival, activation and/or differentiation of autoreactive clones of B cells, thus promoting the development of autoimmunity. Clinical manifestations of autoimmune diseases have been associated with estrogens, prolactin (PRL), and growth hormone (GH) levels. However, androgens, such as testosterone and progesterone (P4), could have a protective effect. The objective of this review is to highlight the links between different hormones and the immune response mediated by B cells in the etiopathogenesis of systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and multiple sclerosis (MS). The data collected provide insights into the role of hormones in the cellular, molecular and/or epigenetic mechanisms that modulate the B-cell response in health and disease.

SARS-CoV-2 mRNA Vaccines Induce Greater Complement Activation and Decreased Viremia and Nef Antibodies in Men With HIV-1

BACKGROUND

Immune dysregulation in people with human immunodeficiency virus-1 (PWH) persists despite potent antiretroviral therapy and, consequently, PWH tend to have lower immune responses to licensed vaccines. However, limited information is available about the impact of mRNA vaccines in PWH. This study details the immunologic responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines in PWH and their impact on HIV-1.

METHODS

We quantified anti-S immunoglobulin G (IgG) binding and neutralization of 3 SARS-CoV-2 variants of concern and complement activation in blood from virally suppressed men with HIV-1 (MWH) and men without HIV-1 (MWOH), and the characteristics that may impact the vaccine immune responses. We also studied antibody levels against HIV-1 proteins and HIV-1 plasma RNA.

RESULTS

MWH had lower anti-S IgG binding and neutralizing antibodies against the 3 variants compared to MWOH. MWH also produced anti-S1 antibodies with a 10-fold greater ability to activate complement and exhibited higher C3a blood levels than MWOH. MWH had decreased residual HIV-1 plasma viremia and anti-Nef IgG approximately 100 days after immunization.

CONCLUSIONS

MWH respond to SARS-CoV-2 mRNA vaccines with lower antibody titers and with greater activation of complement, while exhibiting a decrease in HIV-1 viremia and anti-Nef antibodies. These results suggest an important role of complement activation mediating protection in MWH.

NADPH oxidase exerts a B cell-intrinsic contribution to lupus risk by modulating endosomal TLR signals

Genome-wide association studies in systemic lupus erythematosus (SLE) have linked loss-of-function mutations in phagocytic NADPH oxidase complex (NOX2) genes, including NCF1 and NCF2, to disease pathogenesis. The prevailing model holds that reduced NOX2 activity promotes SLE via defective efferocytosis, the immunologically silent clearance of apoptotic cells. Here, we describe a parallel B cell-intrinsic mechanism contributing to breaks in tolerance. In keeping with an important role for B cell Toll-like receptor (TLR) pathways in lupus pathogenesis, NOX2-deficient B cells exhibit enhanced signaling downstream of endosomal TLRs, increased humoral responses to nucleic acid-containing antigens, and the propensity toward humoral autoimmunity. Mechanistically, TLR-dependent NOX2 activation promotes LC3-mediated maturation of TLR-containing endosomes, resulting in signal termination. CRISPR-mediated disruption of NCF1 confirmed a direct role for NOX2 in regulating endosomal TLR signaling in primary human B cells. Together, these data highlight a new B cell-specific mechanism contributing to autoimmune risk in NCF1 and NCF2 variant carriers.

Investigating Nonspecific Effects of the Live-Attenuated Japanese Encephalitis Vaccine on Lower Respiratory Tract Infections in Children Aged 25-35 Months: Retrospective Cohort Study

BACKGROUND

Live attenuated vaccines may be used to prevent nontargeted diseases such as lower respiratory tract infections (LRTIs) due to their nonspecific effects (NSEs).

OBJECTIVE

We aimed to analyze the NSEs of the Japanese encephalitis vaccine on pediatric LRTIs in children aged 25 months to 35 months.

METHODS

A retrospective cohort study was conducted by using a population-based electronic health record database in Zhejiang, China. Enrolled participants were children born from January 1, 2017, to December 31, 2017, and who were inoculated with the live-attenuated Japanese encephalitis vaccine (JE-L) or inactivated Japanese encephalitis vaccine (JE-I) as the most recent vaccine at 24 months of age. The study was carried out between January 1, 2019, and December 31, 2019. All inpatient and outpatient hospital visits for LRTIs among children aged 25 months to 35 months were recorded. The Andersen-Gill model was used to assess the NSEs of JE-L against LRTIs in children and compared with those of JE-I as the most recent vaccine.

RESULTS

A total of 810 children born in 2017 were enrolled, of whom 585 received JE-L (JE-L cohort) and 225 received JE-I (JE-I cohort) as their last vaccine. The JE-L cohort showed a reduced risk of LRTIs (adjusted hazard ratio [aHR] 0.537, 95% CI 0.416-0.693), including pneumonia (aHR 0.501, 95% CI 0.393-0.638) and acute bronchitis (aHR 0.525, 95% CI 0.396-0.698) at 25 months to 35 months of age. The NSEs provided by JE-L were especially pronounced in female children (aHR 0.305, 95% CI 0.198-0.469) and children without chronic diseases (aHR 0.553, 95% CI 0.420-0.729), without siblings (aHR 0.361, 95% CI 0.255-0.511), with more than 30 inpatient and outpatient hospital visits prior to 24 months of age (aHR 0.163, 95% CI 0.091-0.290), or with 5 to 10 inpatient and outpatient hospital visits due to infectious diseases prior to 24 months old (aHR 0.058, 95% CI 0.017-0.202).

CONCLUSIONS

Compared with JE-I, receiving JE-L as the most recent vaccine was associated with lower risk of inpatient and outpatient hospital visits for LRTIs among children aged 25 months to 35 months. The nature of NSEs induced by JE-L should be considered for policymakers and physicians when recommending JE vaccines to those at high risk of infection from the Japanese encephalitis virus.

XX sex chromosome complement modulates immune responses to heat-killed Streptococcus pneumoniae immunization in a microbiome-dependent manner

BACKGROUND

Differences in male vs. female immune responses are well-documented and have significant clinical implications. While the immunomodulatory effects of sex hormones are well established, the contributions of sex chromosome complement (XX vs. XY) and gut microbiome diversity on immune sexual dimorphisms have only recently become appreciated. Here we investigate the individual and collaborative influences of sex chromosome complements and gut microbiota on humoral immune activation.

METHODS

Male and female Four Core Genotype (FCG) mice were immunized with heat-killed Streptococcus pneumoniae (HKSP). Humoral immune responses were assessed, and X-linked immune-related gene expression was evaluated to explain the identified XX-dependent phenotype. The functional role of Kdm6a, an X-linked epigenetic regulatory gene of interest, was evaluated ex vivo using mitogen stimulation of B cells. Additional influences of the gut microbiome on sex chromosome-dependent B cell activation was also evaluated by antibiotically depleting gut microbiota prior to HKSP immunization. Reconstitution of the depleted microbiome with short-chain fatty acid (SCFA)-producing bacteria tested the impact of SCFAs on XX-dependent immune activation.

RESULTS

XX mice exhibited higher HKSP-specific IgM-secreting B cells and plasma cell frequencies than XY mice, regardless of gonadal sex. Although Kdm6a was identified as an X-linked gene overexpressed in XX B cells, inhibition of its enzymatic activity did not affect mitogen-induced plasma cell differentiation or antibody production in a sex chromosome-dependent manner ex vivo. Enhanced humoral responses in XX vs. XY immunized FCG mice were eliminated after microbiome depletion, indicating that the microbiome contributes to the identified XX-dependent immune enhancement. Reconstituting microbiota-depleted mice with select SCFA-producing bacteria enhanced fecal SCFA concentrations and increased humoral responses in XX, but not XY, FCG mice. However, exposure to the SCFA propionate alone did not enhance mitogenic B cell stimulation in ex vivo studies.

CONCLUSIONS

FCG mice have been used to assess sex hormone and sex chromosome complement influences on various sexually dimorphic traits. The current study indicates that the gut microbiome impacts humoral responses in an XX-dependent manner, suggesting that the collaborative influence of gut bacteria and other sex-specific factors should be considered when interpreting data aimed at delineating the mechanisms that promote sexual dimorphism.

Sex- and species-associated differences in complement-mediated immunity in humans and rhesus macaques

The complement system can be viewed as a "moderator" of innate immunity, "instructor" of humoral immunity, and "regulator" of adaptive immunity. While sex is known to affect humoral and cellular immune systems, its impact on complement in humans and rhesus macaques, a commonly used non-human primate model system, has not been well studied. To address this knowledge gap, we analyzed serum samples from 90 humans and 72 rhesus macaques for the abundance and activity of the complement system components. While sequences of cascade proteins were highly conserved, dramatically different levels were observed between species. Whereas the low levels detected in rhesus samples raised questions about the suitability of the test for use with macaque samples, differences in levels of complement proteins were observed in male and female humans. Levels of total and antibody-dependent deposition of C1q and C3b on a glycosylated antigen differed between humans and rhesus, suggesting differential recognition of glycans and balance between classical and alternative activation pathways. Functional differences in complement-mediated lysis of antibody-sensitized cells were observed in multiple assays and showed that human females frequently exhibited higher lytic activity than human males or rhesus macaques, which typically did not exhibit such sex-associated differences. Other differences between species and sexes were observed in more narrow contexts-for only certain antibodies, antigens, or assays. Collectively, these results expand knowledge of sex-associated differences in the complement system in humans, identifying differences absent from rhesus macaques.IMPORTANCEThe complement system is a critical part of host defense to many bacterial, fungal, and viral infections. In parallel, rich epidemiological, clinical, and biomedical research evidence demonstrates that sex is an important biological variable in immunity, and many sex-specific differences in immune system are intimately tied with disease outcomes. This study focuses on the intersection of these two factors to define the impact of sex on complement pathway components and activities. This work expands our knowledge of sex-associated differences in the complement system in humans and also identifies the differences that appear to be absent in rhesus macaques, a popular non-human primate model. Whereas differences between species suggest potential limitations in the ability of macaque model to recapitulate human biology, knowledge of sex-based differences in humans has the potential to inform clinical research and practice.

The Role of Biological Sex in Pre-Clinical (Mouse) mRNA Vaccine Studies

In this study, we consider the influence of biological sex-specific immune responses on the assessment of mRNA vaccines in pre-clinical murine studies. Recognising the established disparities in immune function attributed to genetic and hormonal differences between individuals of different biological sexes, we compared the mRNA expression and immune responses in mice of both biological sexes after intramuscular injection with mRNA incorporated within lipid nanoparticles. Regarding mRNA expression, no significant difference in protein (luciferase) expression at the injection site was observed between female and male mice following intramuscular administration; however, we found that female BALB/c mice exhibit significantly greater total IgG responses across the concentration range of mRNA lipid nanoparticles (LNPs) in comparison to their male counterparts. This study not only contributes to the scientific understanding of mRNA vaccine evaluation but also emphasizes the importance of considering biological sex in vaccine study designs during pre-clinical evaluation in murine studies.

Slowing Alzheimer's disease progression through probiotic supplementation

The lack of affordable and effective therapeutics against cognitive impairment has promoted research toward alternative approaches to the treatment of neurodegeneration. In recent years, a bidirectional pathway that allows the gut to communicate with the central nervous system has been recognized as the gut-brain axis. Alterations in the gut microbiota, a dynamic population of trillions of microorganisms residing in the gastrointestinal tract, have been implicated in a variety of pathological states, including neurodegenerative disorders such as Alzheimer's disease (AD). However, probiotic treatment as an affordable and accessible adjuvant therapy for the correction of dysbiosis in AD has not been thoroughly explored. Here, we sought to correct the dysbiosis in an AD mouse model with probiotic supplementation, with the intent of exploring its effects on disease progression. Transgenic 3xTg-AD mice were fed a control or a probiotic diet (Lactobacillus plantarum KY1032 and Lactobacillus curvatus HY7601) for 12  weeks, with the latter leading to a significant increase in the relative abundance of Bacteroidetes. Cognitive functions were evaluated via Barnes Maze trials and improvements in memory performance were detected in probiotic-fed AD mice. Neural tissue analysis of the entorhinal cortex and hippocampus of 10-month-old 3xTg-AD mice demonstrated that astrocytic and microglial densities were reduced in AD mice supplemented with a probiotic diet, with changes more pronounced in probiotic-fed female mice. In addition, elevated numbers of neurons in the hippocampus of probiotic-fed 3xTg-AD mice suggested neuroprotection induced by probiotic supplementation. Our results suggest that probiotic supplementation could be effective in delaying or mitigating early stages of neurodegeneration in the 3xTg-AD animal model. It is vital to explore new possibilities for palliative care for neurodegeneration, and probiotic supplementation could provide an inexpensive and easily implemented adjuvant clinical treatment for AD.

Analysis of Serum Anti-HBs Levels and HBsAg/HBeAg Markers in Children and Adolescents: A Cross-Sectional Study

Hepatitis B virus (HBV) is a global public health concern, and China continues to face a high burden of HBV cases. Vaccination plays a critical role in controlling and eradicating HBV. However, studies have shown that some individuals may experience waning immunity over time, highlighting the importance of enhanced immunization strategies. This study aimed to investigate the relationship between age, gender, and anti-HBs antibody levels, as well as the prevalence of serum hepatitis B surface antigen (HBsAg)/HBV e antigen (HBeAg) positivity. This retrospective study included 43,609 pediatric patients who visited the outpatient department between January 2013 and December 2022. Serum biomarkers (HBsAg, anti-HBs, HBeAg, anti-HBe, and anti-HBc) were measured using Roche Cobas 8000. There is a significant difference in anti-HBs titer between genders and across different age groups (p < 0.05). The serological markers HBsAg/HBeAg exhibited the highest positivity rate in the age group of 15-18 years. The findings demonstrate a gradual decrease in anti-HBs levels following HBV vaccination. The prevalence of serum markers HBsAg/HBeAg is higher among adolescents aged 15-18 years, which should be a matter of concern and attention.

Evaluating the hepatitis B vaccination impact in the Republic of Moldova: A nationwide representative serosurvey of children born in 2013

Objectives

The WHO European Region set targets for the control of hepatitis B through immunization, including prevalence of hepatitis B surface antigen (HBsAg) at ≤0.5% in vaccinated cohorts. The Republic of Moldova implemented universal hepatitis B vaccination since 1995. We conducted a nationwide representative serosurvey to estimate HBsAg seroprevalence in children born in 2013 to validate hepatitis B control targets.

Methods

We used probability-based sampling and a two-stage cluster design. All children born in 2013 and registered in primary healthcare facilities were eligible for participation. We tested blood samples of all participants for hepatitis B core antibody (anti-HBc), using Enzyme-Linked Immunosorbent Assay (ELISA). Anti-HBc-positive samples were tested for HBsAg and HBsAg-positive samples confirmed, using ELISA. We obtained information on hepatitis B vaccination from vaccination cards.

Results

Of 3352 sampled children, 3064 (91%) participated. Most participating children were 7 years old (n = 3030, 99%), 1426 (48%) were girls. The weighted, national seroprevalence estimate was 3.1% (95% confidence interval = 2.1-4.5) for anti-HBc and 0.21% (95% confidence interval = 0.08-0.53) for HBsAg.

Conclusion

The study demonstrated the impact of hepatitis B vaccination and allowed the Republic of Moldova to validate regional hepatitis B control targets. Other countries with high vaccination coverage could use hepatitis B serosurveys and apply for validation. Sustained efforts in the Republic of Moldova will be crucial on the path to hepatitis B elimination.

Tailoring Tfh profiles enhances antibody persistence to a clade C HIV-1 vaccine in rhesus macaques

CD4 T follicular helper cells (Tfh) are essential for establishing serological memory and have distinct helper attributes that impact both the quantity and quality of the antibody response. Insights into Tfh subsets that promote antibody persistence and functional capacity can critically inform vaccine design. Based on the Tfh profiles evoked by the live attenuated measles virus vaccine, renowned for its ability to establish durable humoral immunity, we investigated the potential of a Tfh1/17 recall response during the boost phase to enhance persistence of HIV-1 Envelope (Env) antibodies in rhesus macaques. Using a DNA-prime encoding gp160 antigen and Tfh polarizing cytokines (interferon protein-10 (IP-10) and interleukin-6 (IL-6)), followed by a gp140 protein boost formulated in a cationic liposome-based adjuvant (CAF01), we successfully generated germinal center (GC) Tfh1/17 cells. In contrast, a similar DNA-prime (including IP-10) followed by gp140 formulated with monophosphoryl lipid A (MPLA) +QS-21 adjuvant predominantly induced GC Tfh1 cells. While the generation of GC Tfh1/17 cells with CAF01 and GC Tfh1 cells with MPLA +QS-21 induced comparable peak Env antibodies, the latter group demonstrated significantly greater antibody concentrations at week 8 after final immunization which persisted up to 30 weeks (gp140 IgG ng/ml- MPLA; 5500; CAF01, 2155; p<0.05). Notably, interferon γ+Env-specific Tfh responses were consistently higher with gp140 in MPLA +QS-21 and positively correlated with Env antibody persistence. These findings suggest that vaccine platforms maximizing GC Tfh1 induction promote persistent Env antibodies, important for protective immunity against HIV.

Oral administration of a recombinant modified RBD antigen of SARS-CoV-2 as a possible immunostimulant for the care of COVID-19

BACKGROUND

Developing effective vaccines against SARS-CoV-2 that consider manufacturing limitations, equitable access, and acceptance is necessary for developing platforms to produce antigens that can be efficiently presented for generating neutralizing antibodies and as a model for new vaccines.

RESULTS

This work presents the development of an applicable technology through the oral administration of the SARS-CoV-2 RBD antigen fused with a peptide to improve its antigenic presentation. We focused on the development and production of the recombinant receptor binding domain (RBD) produced in E. coli modified with the addition of amino acids extension designed to improve antigen presentation. The production was carried out in shake flask and bioreactor cultures, obtaining around 200 mg/L of the antigen. The peptide-fused RBD and peptide-free RBD proteins were characterized and compared using SDS-PAGE gel, high-performance chromatography, and circular dichroism. The peptide-fused RBD was formulated in an oil-in-water emulsion for oral mice immunization. The peptide-fused RBD, compared to RBD, induced robust IgG production in mice, capable of recognizing the recombinant RBD in Enzyme-linked immunosorbent assays. In addition, the peptide-fused RBD generated neutralizing antibodies in the sera of the dosed mice. The formulation showed no reactive episodes and no changes in temperature or vomiting.

CONCLUSIONS

Our study demonstrated the effectiveness of the designed peptide added to the RBD to improve antigen immunostimulation by oral administration.