Impact of in-utero exposure to HIV and latent TB on infant humoral responses.

Introduction: Latent tuberculosis infection (LTBI) is a common coinfection in people living with HIV (PWH). How LTBI and HIV exposure in utero influence the development of infant humoral immunity is not well characterized. To address this question, we assessed the relationship between maternal humoral responses in pregnant women with HIV or with HIV/LTBI on humoral responses in infants to BCG vaccination and TB acquisition. Methods: Plasma samples were obtained from mother infant pairs during pregnancy (14-34 wks gestation) and in infants at 12 and 44 wks of age from the IMPAACT P1078 clinical trial. LTBI was established by Interferon gamma release assay (IGRA). Progression to active TB (ATB) disease was observed in 5 women at various times after giving birth. All infants were BCG vaccinated at birth and tested for IGRA at 44 weeks. Mtb (PPD, ESAT6/CFP10, Ag85A, LAM), HIV (GP120), and Influenza (HA) specific IgG, IgM, and IgA were measured in plasma samples using a bead based Luminex assay with Flexmap 3D. Results: In maternal plasma there were no differences in Mtb-specific antibodies or viral antibodies in relation to maternal IGRA status. ATB progressors showed increases in Mtb-specific antibodies at diagnosis compared to study entry. However, when compared to the non-progressors at entry, progressors had higher levels of Ag85A IgG and reduced ESAT6/CFP10 IgG and LAM IgG, IgM, and IgA1. All infants showed a decrease in IgG to viral antigens (HIV GP120 and HA) from 12 to 44 weeks attributed to waning of maternally transferred antibody titers. However, Mtb-specific (PPD, ESAT6/CFP10, Ag85A, and LAM) IgG and IgM increased from 12 to 44 weeks. HIV and HA IgG levels in maternal and 12-week infant plasma were highly correlated, and ESAT6/CFP10 IgG and LAM IgG showed a relationship between maternal and infant Abs. Finally, in the subset of infants that tested IGRA positive at 44 weeks, we observed a trend for lower LAM IgM compared to IGRA- infants at 44 weeks. Discussion: The results from our study raise the possibility that antibodies to LAM are associated with protection from progression to ATB and support further research into the development of humoral immunity against TB through infection or vaccination.

Immune reactivity of two biological models to vaccination with inactivated vaccine QazVac against coronavirus infection COVID-19.

INTRODUCTION: Specific prevention of a number of infectious diseases has been introduced into the vaccination schedule. The production of immunoprophylactic drugs, in order to establish standard properties, including safety and specific effectiveness, requires strict adherence to manufacturing regulations, and the reliability of the results obtained requires monitoring of these parameters. The specific effectiveness of vaccine preparations is standardized according to the indicators of stimulation of specific antibody response formed in the body of vaccinated model biological objects. OBJECTIVE: Determination of the immune reactivity of white mice to vaccination with the QazVac vaccine to establish the possibility of using them as a biological model in assessing the immunogenicity of the vaccine instead of Syrian hamsters. MATERIALS AND METHODS: The immune reactivity of model animals was assessed by the seroconversion rate, dynamics of antibody titers to the SARS-CoV-2 virus formed in the body after vaccination with the test vaccine. In the case of seropositivity of animals before administration of vaccine or placebo, the level of immune reactivity was calculated by the difference in antibody titers between control and vaccinated animals or by the difference in antibody titers before and after immunization. Specific antibodies were detected and their titer was determined using a neutralization reaction. RESULTS: The research results showed that the tested biological models had approximately the same immune reactivity to the administration of the QazVac vaccine, confirmed by the level and dynamics of antibody titers. When analyzing the fold increase in antibody titers in comparison to those of control animals, Syrian hamsters were more reactive compared to mice. But SPF white mice were standardized in their lack of the immune reactivity to SARS-CoV-2 virus before the immunization. CONCLUSION: The data obtained indicate that the immune reactivity of white mice to the administration of the QazVac vaccine in terms of the rate and dynamics of the formation of virus-neutralizing antibodies is approximately equivalent to the immune reactivity of Syrian hamsters. Before immunization with the vaccine, SPF white mice, in contrast to Syrian hamsters, do not have humoral immunity specific to the SARS-CoV-2 virus. The immune reactivity equivalent to that observed of Syrian hamsters and the absence of antibodies to the SARS-CoV-2 virus at a baseline indicate the superiority of the use of white mice in assessing the immunogenicity of vaccines against COVID-19 and/or obtaining specific factors of humoral immunity.

A synthetic TLR4 agonist significantly increases humoral immune responses and the protective ability of an MDCK-cell-derived inactivated H7N9 vaccine in mice.

Antigenically divergent H7N9 viruses pose a potential threat to public health, with the poor immunogenicity of candidate H7N9 vaccines demonstrated in clinical trials underscoring the urgent need for more-effective H7N9 vaccines. In the present study, mice were immunized with various doses of a suspended-MDCK-cell-derived inactivated H7N9 vaccine, which was based on a low-pathogenic H7N9 virus, to assess cross-reactive immunity and cross-protection against antigenically divergent H7N9 viruses. We found that the CRX-527 adjuvant, a synthetic TLR4 agonist, significantly enhanced the humoral immune responses of the suspended-MDCK-cell-derived H7N9 vaccine, with significant antigen-sparing and immune-enhancing effects, including robust virus-specific IgG, hemagglutination-inhibiting (HI), neuraminidase-inhibiting (NI), and virus-neutralizing (VN) antibody responses, which are crucial for protection against influenza virus infection. Moreover, the CRX-527-adjuvanted H7N9 vaccine also elicited cross-protective immunity and cross-protection against a highly pathogenic H7N9 virus with a single vaccination. Notably, NI and VN antibodies might play an important role in cross-protection against lethal influenza virus infections. This study showed that a synthetic TLR4 agonist adjuvant has a potent immunopotentiating effect, which might be considered worth further development as a means of increasing vaccine effectiveness.

[Fusion expression and immunogenicity of receptor-binding domains of porcine deltacoronavirus and porcine epidemic diarrhea virus].

This study aims to develop an effective bivalent subunit vaccine that is promising to prevent both porcine deltacoronavirus (PDCoV) and porcine epidemic diarrhea virus (PEDV). The receptor-binding domains (RBDs) of PDCoV and PEDV were fused and cloned into the eukaryotic expression vector pCDNA3.1(+). The fusion protein PDCoV-RBD-PEDV-RBD (pdRBD-peRBD) was expressed by the ExpiCHOTM expression system and purified. Mice were immunized with the fusion protein at three different doses (10, 20, and 30 µg). The humoral immune response and cellular immune response induced by the fusion protein were evaluated by ELISA and flow cytometry. The neutralization titers of the serum of immunized mice against PDCoV and PEDV were determined by the microneutralization test. The results showed that high levels of IgG antibodies were induced in the three different dose groups after booster immunization, and there was no significant difference in the antibody level between different dose groups, indicating that the immunization dose of 10 µg could achieve the fine immune effect. The results of flow cytometry showed that the immunization groups demonstrated increased proportion of CD3+CD4+ T cells and decreased proportion of CD3+CD8+ T cells, which was consistent with the expectation about the humoral immune response induced by the subunit vaccine. At the same time, the levels of interleukin (IL)-2, IL-4, and interferon (IFN)-γ in the serum were determined. The results showed that the fusion protein induced both humoral immune effect and cellular immune response. The results of the neutralization test showed that the antibody induced by 10 µg fusion protein neutralized both PDCoV and PEDV in vitro, with the titers of 1:179.25 and 1:141.21, respectively. The above results suggested that the pdRBD-peRBD could induce a high level of humoral immune response at a dose of 10 µg, and the induced antibody could neutralize both PDCoV and PEDV. Therefore, the fusion protein pdRBD-peRBD is expected to be an effective subunit vaccine that can simultaneously prevent PDCoV and PEDV.

Shrimp hemocyanin elicits a potent humoral response in mammals and is favorable to hapten conjugation.

Conjugation to a carrier protein is essential to give rise to the antigenicity of hapten. Three carrier proteins e.g. KLH (Keyhole Limpet hemocyanin), BSA (bovine serum albumin), and OVA (Ovalbumin) were used mostly. KLH is advantageous to the others, majorly owing to its strong immunogenicity and limited usage in other biological assays. However, the cost of obtaining Keyhole Limpet is high and the solubility of KLH is not as well as the other carriers, especially after hapten conjugation. Here, we extracted the shrimp hemocyanin (SHC) from Litopenaeus vannamei (L. vannamei), which is a commonly sea product worldwide. The high pure SHC could be acquired by two-step purification, with a production yield of > 1 g proteins (98% pure) per 1 kg shrimp. Compared to KLH, the peptide-SHC conjugates exhibit higher solubility after hapten conjugation. Meanwhile, compared with KLH, SHC induces comparable antibody production efficiency in mammals, with or without conjugation. Furthermore, rabbit polyclonal antibodies or mouse monoclonal antibodies were generated by immunizing SHC-peptide conjugates, and the subsequent antibodies were confirmed to be used in western blot, immunofluorescence and immunohistochemistry. Therefore, we demonstrated that SHC may be used as a substitute for KLH in future antibody and vaccine development.

Pretransplant Screening for Prevention of Hyperacute Graft Loss in Pig-to-primate Kidney Xenotransplantation.

BACKGROUND: Xenotransplantation using pig organs is now a clinical reality. However, the process for xenograft recipient screening lacks clarity and scientific rigor: no established thresholds exist to determine which levels of preformed antipig natural antibodies (Nabs) will be safe for clinical xenograft transplantation, and hyperacute rejection (HAR) or acute humoral xenograft rejection (AHXR), which still impacts pig-to-primate kidney xenograft survivals, may impede broader application of pig-to-human clinical xenograft transplantation. METHODS: We retrospectively examined 28 cases of pig-to-baboon kidney xenotransplantation using GalTKO±human complement regulatory protein (hCRP)-transgenic (Tg) pig donors, as well as 6 cases of triple-KO multi-Tg (10GE) pig donors, and developed screening algorithms to predict risk of HAR/AHXR based on recipient antipig Nab levels. Preformed Nabs were evaluated using both complement-dependent cytotoxicity and antibody (IgM and IgG) binding flow-cytometry assays. RESULTS: High complement-dependent cytotoxicity was associated with HAR/AHXR as expected. However, we also found that high levels of IgG were independently associated with HAR/AHXR, and we developed 2 indices to interpret and predict the risk of IgG-mediated HAR/AHXR. CONCLUSIONS: Based on the data in this study, we have established a new 2-step screening, which will be used for future clinical kidney xenotransplantation trials.

Evaluation of vaccine candidates against Rhodococcus equi in BALB/c mice infection model: cellular and humoral immune responses.

Rhodococcus equi (R. equi) is a zoonotic opportunistic pathogen that mainly causes fatal lung and extrapulmonary abscesses in foals and immunocompromised individuals. To date, no commercial vaccine against R. equi exists. We previously screened all potential vaccine candidates from the complete genome of R. equi using a reverse vaccinology approach. Five of these candidates, namely ABC transporter substrate-binding protein (ABC transporter), penicillin-binding protein 2 (PBD2), NlpC/P60 family protein (NlpC/P60), esterase family protein (Esterase), and M23 family metallopeptidase (M23) were selected for the evaluation of immunogenicity and immunoprotective effects in BALB/c mice model challenged with R. equi. The results showed that all five vaccine candidate-immunized mice experienced a significant increase in spleen antigen-specific IFN-γ- and TNF-α-positive CD4 + and CD8 + T lymphocytes and generated robust Th1- and Th2-type immune responses and antibody responses. Two weeks after the R. equi challenge, immunization with the five vaccine candidates reduced the bacterial load in the lungs and improved the pathological damage to the lungs and livers compared with those in the control group. NlpC/P60, Esterase, and M23 were more effective than the ABC transporter and PBD2 in inducing protective immunity against R. equi challenge in mice. In addition, these vaccine candidates have the potential to induce T lymphocyte memory immune responses in mice. In summary, these antigens are effective candidates for the development of protective vaccines against R. equi. The R. equi antigen library has been expanded and provides new ideas for the development of multivalent vaccines.

Immune correlates of protection of the four-segmented Rift Valley fever virus candidate vaccine in mice.

Rift Valley fever (RVF) is a mosquito-borne zoonotic disease caused by RVF virus (RVFV). RVFV infections in humans are usually asymptomatic or associated with mild febrile illness, although more severe cases of haemorrhagic disease and encephalitis with high mortality also occur. Currently, there are no licensed human vaccines available. The safety and efficacy of a genetically engineered four-segmented RVFV variant (hRVFV-4s) as a potential live-attenuated human vaccine has been tested successfully in mice, ruminants, and marmosets though the correlates of protection of this vaccine are still largely unknown. In the present study, we have assessed hRVFV-4s-induced humoral and cellular immunity in a mouse model of RVFV infection. Our results confirm that a single dose of hRVFV-4s is highly efficient in protecting naïve mice from developing severe disease following intraperitoneal challenge with a highly virulent RVFV strain and data show that virus neutralizing (VN) serum antibody titres in a prime-boost regimen are significantly higher compared to the single dose. Subsequently, VN antibodies from prime-boost-vaccinated recipients were shown to be protective when transferred to naïve mice. In addition, hRVFV-4s vaccination induced a significant virus-specific T cell response as shown by IFN-γ ELISpot assay, though these T cells did not provide significant protection upon passive transfer to naïve recipient mice. Collectively, this study highlights hRVFV-4s-induced VN antibodies as a major correlate of protection against lethal RVFV infection.

Specific immunological characteristics and risk factor of XBB variants re-infection in nasopharyngeal carcinoma patients after BA.5 infection.

OBJECTIVES: The specific humoral immune response resulting from inactivated vaccination following by BA.5 infection, and predictors of XBB variants re-infection in BA.5 infection-recovered nasopharyngeal carcinoma (BA.5-RNPC) patients, were explored. METHODS: Serum SARS-CoV-2 specific antibody levels were assessed using enzyme-linked-immunosorbent-assay. Univariate and multivariate binary logistic regression analyses were conducted to identify factors associated with the magnitude of specific humoral immunity and susceptibility to re-infection by XBB variants. RESULTS: Our data demonstrates that SARS-CoV-2 specific antibody levels were comparable between BA.5-RNPC patients and BA.5 infection-recovered-non-cancerous (BA.5-RNC) individuals. Specifically, serum levels of anti-ancestral-S1-IgG, anti-ancestral-nucleocapsid-protein (NP)-IgG, anti-BA.5-receptor binding domain (RBD)-IgG and anti-XBB.1.1.6-RBD-IgG were higher in BA.5-RNPC patients compared to those without a prior infection. Compared to BA.5-RNPC patients without vaccination, individuals who received inactivated vaccination exhibited significantly higher levels of anti-ancestral-S1-IgG and anti-XBB.1.16-RBD-IgG. Multivariate logistic regression analysis revealed that inactivated vaccination was the most significant predictor of all tested SARS-CoV-2 specific antibodies response. Subsequent analysis indicated that a low globulin level is an independent risk factor for XBB re-infection in BA.5-RNPC patients. CONCLUSIONS: The SARS-CoV-2 specific antibodies have been improved in vaccinated BA.5-RNPC patients. However, the baseline immunity status biomarker IgG is an indicators of XBB variant re-infection risk in BA.5-RNPC patients.

Antibody Response to Symptomatic Infection With SARS-CoV-2 Omicron Variant Viruses, December 2021-June 2022.

We describe humoral immune responses in 105 ambulatory patients with laboratory-confirmed SARS-CoV-2 Omicron variant infection. In dried blood spot (DBS) collected within 5 days of illness onset and during convalescence, we measured binding antibody (bAb) against ancestral spike protein receptor binding domain (RBD) and nucleocapsid (N) protein using a commercial multiplex bead assay. Geometric mean bAb concentrations against RBD increased by a factor of 2.5 from 1258 to 3189 units/mL and by a factor of 47 against N protein from 5.5 to 259 units/mL between acute illness and convalescence; lower concentrations were associated with greater geometric mean ratios. Paired DBS specimens may be used to evaluate humoral response to SARS-CoV-2 infection.

Antibody modulation of B cell responses-Incorporating positive and negative feedback.

Antibodies are powerful modulators of ongoing and future B cell responses. While the concept of antibody feedback has been appreciated for over a century, the topic has seen a surge in interest due to the evidence that the broadening of antibody responses to SARS-CoV-2 after a third mRNA vaccination is a consequence of antibody feedback. Moreover, the discovery that slow antigen delivery can lead to more robust humoral immunity has put a spotlight on the capacity for early antibodies to augment B cell responses. Here, we review the mechanisms whereby antibody feedback shapes B cell responses, integrating findings in humans and in mouse models. We consider the major influence of epitope masking and the diverse actions of complement and Fc receptors and provide a framework for conceptualizing the ways antigen-specific antibodies may influence B cell responses to any form of antigen, in conditions as diverse as infectious disease, autoimmunity, and cancer.

[The efficacy and safety of protein A immunoadsorption combined with rituximab treatment for highly sensitized patients undergoing haplo-hematopoietic stem cell transplantation].

Objective: To investigate the efficacy and safety of protein A immunoadsorption (PAIA) combined with rituximab (RTX) in highly sensitized patients who underwent haplo-hematopoietic stem cell transplantation (haplo-HSCT) . Methods: The clinical data of 56 highly sensitized patients treated with PAIA and RTX before haplo-HSCT at the First Affiliated Hospital of Soochow University and Soochow Hopes Hematonosis Hospital between March 2021 and June 2023 were retrospectively analyzed. The number of human leukocyte antigen (HLA) antibody types and the mean fluorescence intensity (MFI), humoral immunity, adverse reactions during adsorption, and survival within 100 days before and after adsorption were measured. Results: After receiving the PAIA treatment, the median MFI of patients containing only HLA Ⅰ antibodies decreased from 7 859 (3 209-12 444) to 3 719 (0-8 275) (P<0.001), and the median MFI of HLA Ⅰ+Ⅱ antibodies decreased from 5 476 (1 977-12 382) to 3 714 (0-11 074) (P=0.035). The median MFI of patients with positive anti-donor-specific antibodies decreased from 8 779 (2 697-18 659) to 4 524 (0-15 989) (P<0.001). The number of HLA-A, B, C, DR, and DQ antibodies in all patients decreased after the PAIA treatment, and the differences were statistically significant (A, B, C, DR: P<0.001, DQ: P<0.01). The humoral immune monitoring before and after the PAIA treatment showed a significant decrease in the number of IgG and complement C3 (P<0.001 and P=0.002, respectively). Forty-four patients underwent HLA antibody monitoring after transplantation, and the overall MFI and number of antibody types decreased. However, five patients developed new antibodies with low MFI, and nine patients continued to have high MFI. The overall survival, disease-free survival, non-recurrent mortality, and cumulative recurrence rates at 100 days post-transplantation were 83.8%, 80.2%, 16.1%, and 4.5%, respectively. Conclusions: The combination of PAIA and RTX has a certain therapeutic effect and good safety in the desensitization treatment of highly sensitive patients before haplo-HSCT.

Prophylactic antibodies inhibit spike-specific T and B cell responses after COVID-19 vaccination.

Active and passive immunization is used in high-risk patients to prevent severe courses of COVID-19, but the impact of prophylactic neutralizing antibodies on the immune reaction to the mRNA vaccines has remained enigmatic. Here we show that CD4 T and B cell responses to Spikevax booster immunization are suppressed by the therapeutic antibodies Casirivimab and Imdevimab. B cell and T cell responses were significantly induced in controls but not in antibody-treated patients. The data indicates that humoral immunity, i. e. high levels of antibodies, negatively impacts reactive immunity, resulting in blunted cellular responses upon boosting. This argues for temporal separation of vaccination efforts; with active vaccination preferably applied before prophylactic therapeutic antibody treatment.

Immunostimulant effect of dates (Phoenix dactylifera) on humoral and cellular immunity cells and their functions.

The study aimed to assess the immunomodulatory effects of Phoenix dactylifera (dates) fruit, a traditional remedy used by Moroccans to enhance immunity against pathogens. This research sought to evaluate the impacts of this fruit on immune cells and their functions. To achieve this, we conducted tests using date extracts on splenocytes, thymocytes, and macrophages, focusing on their functions: antibody production, phagocytosis, and T-lymphocyte toxicity. The results obtained demonstrated that the aqueous extract of P. dactylifera fruit exhibited significant immunostimulatory effects on humoral immunity. It achieved this by enhancing complement activity and increasing splenocyte (including B-lymphocytes) proliferation by 142.5% compared to control cells. Similarly, in the same conditions, there was notable stimulation of cellular immunity through thymocyte activity, resulting in a remarkable increase in cell proliferation (225%) and a boost in thymocyte function (245.9%), which plays a role in safeguarding against cancer. Moreover, the date extract demonstrated anti-inflammatory properties. This was evident in the increased phagocytosis activity mediated by macrophages under the ethyl acetate extract, effectively eliminating pathogens. Assessing the cosmetic potential of date extracts showed that the ethyl acetate extract possesses both anti-inflammatory and strong antioxidant effects, exhibited high photo absorption of ultraviolet-B rays. Based on these findings, we propose to study the utilization of this extract for sun protection as a sunscreen. Furthermore, the Fourier-transform infrared spectroscopy analysis indicated that the most active compounds present were flavonoids. These outcomes substantiate the traditional usage of this fruit for reinforcing immunity.

[Humoral Immunity Abnormalities in Advanced Maternal-Age Women With Recurrent Spontaneous Abortion: A Single Center Study]. / é«˜é¾„å¤å‘æ€§æµäº§æ‚£è€ ä½“æ¶²å ç–«å¼‚å¸¸çš„å•ä¸­å¿ƒç ”ç©¶.

Objective: To determine the humoral immunity in advanced maternal-age women with recurrent spontaneous abortion (RSA). Methods: A retrospective study was performed between January 2022 and October 2023 in the Department of Reproductive Immunity of Shanghai First Maternity and Infant Hospital. Women with RSA were recruited and multiple autoantibodies were tested. Multivariate logistic regression was performed to compare the associations between different age groups (20 to 34 years old in the low maternal-age group and 35 to 45 years in the advanced maternal-age group) and multiple autoantibodies, while controlling for three confounding factors, including body mass index (BMI), previous history of live birth, and the number of spontaneous abortions. Then, we investigated the differences in the humoral immunity of advanced maternal-age RSA women and low maternal-age RSA women. Result: A total of 4009 women with RSA were covered in the study. Among them, 1158 women were in the advanced maternal-age group and 2851 women were in the low maternal-age group. The prevalence of antiphospholipid syndrome, systemic lupus erythematosus, Sjogren's syndrome, rheumatoid arthritis, and undifferentiated connective tissue disease was 15.6% and 14.1%, 0.0% and 0.1%, 0.9% and 0.9%, 0.3% and 0.0%, and 23.7% and 22.6% in the advanced maternal-age group and low maternal-age group, respectively, showing no statistical difference between the two groups. The positive rates of antiphospholipid antibodies (aPLs), antinuclear antibody (ANA), extractable nuclear antigen (ENA) antibody, anti-double stranded DNA (dsDNA) antibody, anti single-stranded DNA (ssDAN) antibody, antibodies against alpha-fodrin (AAA), and thyroid autoimmunity (TAI) were 19.1% and 19.5%, 6.6% and 6.6%, 9.2% and 10.5%, 2.0% and 2.0%, 2.2% and 1.2%, 5.1% and 4.9%, and 17.8% and 16.8%, respectively. No differences were observed between the two groups. 1.6% of the women in the advanced maternal-age group tested positive for lupus anticoagulant (LA), while 2.7% of the women in the low maternal-age group were LA positive, with the differences being statistically significant (odds ratio=0.36, 95% confidence interval: 0.17-0.78). In the 4008 RSA patients, the cumulative cases tested positive for the three antibodies of the aPLs spectrum were 778, of which 520 cases were positive for anti-ß2 glycoprotein Ⅰ antibodies (ß2GPⅠ Ab)-IgG/IgM, 58 were positive for aCL-IgG/IgM, 73 were positive for LA, 105 were positive for both ß2GPⅠ Ab-IgG/IgM and aCL-IgG/IgM, 17 were positive for both ß2GPⅠ Ab-IgG/IgM and LA, 2 were positive for both aCL-IgG/IgM and LA, and 3 were positive for all three antibodies. Conclusion: Our study did not find a difference in humoral immunity between RSA women of advanced maternal age and those of low maternal age.

Essential role of pre-existing humoral immunity in TLR9-mediated type I IFN response to recombinant AAV vectors in human whole blood.

Recombinant adeno-associated virus (AAV) vectors have emerged as the preferred platform for gene therapy of rare human diseases. Despite the clinical promise, host immune responses to AAV vectors and transgene remain a major barrier to the development of successful AAV-based human gene therapies. Here, we assessed the human innate immune response to AAV9, the preferred serotype for AAV-mediated gene therapy of the CNS. We showed that AAV9 induced type I interferon (IFN) and IL-6 responses in human blood from healthy donors. This innate response was replicated with AAV6, required full viral particles, but was not observed in every donor. Depleting CpG motifs from the AAV transgene or inhibiting TLR9 signaling reduced type I IFN response to AAV9 in responding donors, highlighting the importance of TLR9-mediated DNA sensing for the innate response to AAV9. Remarkably, we further demonstrated that only seropositive donors with preexisting antibodies to AAV9 capsid mounted an innate immune response to AAV9 in human whole blood and that anti-AAV9 antibodies were necessary and sufficient to promote type I IFN release and plasmacytoid dendritic (pDC) cell activation in response to AAV9. Thus, our study reveals a previously unidentified requirement for AAV preexisting antibodies for TLR9-mediated type I IFN response to AAV9 in human blood.

Chimeric lipoproteins for leptospirosis vaccine: immunogenicity and protective potential.

Leptospirosis, a neglected zoonotic disease, is caused by pathogenic spirochetes belonging to the genus Leptospira and has one of the highest morbidity and mortality rates worldwide. Vaccination stands out as one of the most effective preventive measures for susceptible populations. Within the outer membrane of Leptospira spp., we find the LIC12287, LIC11711, and LIC13259 lipoproteins. These are of interest due to their surface location and potential immunogenicity. Thorough examination revealed the conservation of these proteins among pathogenic Leptospira spp.; we mapped the distribution of T- and B-cell epitopes along their sequences and assessed the 3D structures of each protein. This information aided in selecting immunodominant regions for the development of a chimeric protein. Through gene synthesis, we successfully constructed a chimeric protein, which was subsequently expressed, purified, and characterized. Hamsters were immunized with the chimeric lipoprotein, formulated with adjuvants aluminum hydroxide, EMULSIGEN®-D, Sigma Adjuvant System®, and Montanide™ ISA206VG. Another group was vaccinated with an inactivated Escherichia coli bacterin expressing the chimeric protein. Following vaccination, hamsters were challenged with a virulent L. interrogans strain. Our evaluation of the humoral immune response revealed the production of IgG antibodies, detectable 28 days after the second dose, in contrast to pre-immune samples and control groups. This demonstrates the potential of the chimeric protein to elicit a robust humoral immune response; however, no protection against challenge was achieved. While this study provides valuable insights into the subject, further research is warranted to identify protective antigens that could be utilized in the development of a leptospirosis vaccine. KEY POINTS: • Several T- and B-cell epitopes were identified in all the three proteins. • Four different adjuvants were used in vaccine formulations. • Immunization stimulated significant levels of IgG2/3 in vaccinated animals.

COVID-19 point-of-care tests can identify low-antibody individuals: In-depth immunoanalysis of boosting benefits in a healthy cohort.

The recommended COVID-19 booster vaccine uptake is low. At-home lateral flow assay (LFA) antigen tests are widely accepted for detecting infection during the pandemic. Here, we present the feasibility and potential benefits of using LFA-based antibody tests as a means for individuals to detect inadequate immunity and make informed decisions about COVID-19 booster immunization. In a health care provider cohort, we investigated the changes in the breadth and depth of humoral and T cell immune responses following mRNA vaccination and boosting in LFA-positive and LFA-negative antibody groups. We show that negative LFA antibody tests closely reflect the lack of functional humoral immunity observed in a battery of sophisticated immune assays, while positive results do not necessarily reflect adequate immunity. After booster vaccination, both groups gain depth and breadth of systemic antibodies against evolving SARS-CoV-2 and related viruses. Our findings show that LFA-based antibody tests can alert individuals about inadequate immunity against COVID-19, thereby increasing booster shots and promoting herd immunity.