High Levels Of IgG Antibodies Research Articles

Clinical validation of circulating immune complexes for use as a diagnostic marker of canine leishmaniosis.

Canine leishmaniosis (CanL) is a systemic disease that affects dogs. When multiplication of the parasite cannot be controlled, dogs consistently show high levels of antigen and IgG antibodies, which lead to the formation of circulating immune complexes (CIC). Timely intervention to reduce the parasite load and CIC levels is crucial for preventing irreversible organ damage. However, a diagnostic test to quantify CIC levels is currently lacking. In this real-world study, we aimed to examine the performance of a new ELISA to measure CIC levels in dogs naturally infected with Leishmania infantum. Thirty-four dogs were treated according to their clinical condition and followed for 360 days. Before (day 0) and after treatment (days 30, 90, 180, 270, and 360), all dogs underwent a physical examination, and blood samples were obtained for CBC, biochemical profile, serum protein electrophoresis and IFAT. Serum PEG-precipitated CIC were determined by ELISA. Our results indicate higher CIC levels in dogs in advanced disease stages showing higher antibody titres (p < 0.0001, r = 0.735), anemia (p < 0.0001), dysproteinemia (p < 0.0001), and proteinuria (p = 0.004). Importantly, dogs responding well to treatment exhibited declining CIC levels (p < 0.0001), while in poor responders and those experiencing relapses, CIC were consistently elevated. CIC emerged as a robust discriminator of relapse, with an area under the curve (AUC) of 0.808. The optimal cut-off to accurately identify relapse was an optical density of 1.539. Our findings suggest that declining CIC levels should be expected in dogs showing a favorable treatment response. Conversely, in dogs displaying a poor response and recurrent clinical relapses, CIC levels will be high, emphasizing the need for vigilant monitoring. These findings suggest that CIC could serve as a valuable biomarker for disease progression, treatment efficacy, and relapse detection in CanL. Our study contributes to enhancing diagnostic approaches for CanL and underscores the potential of CIC as a complementary tool in veterinary practice. As we move forward, larger studies will be essential to confirm these findings and establish definitive cut-offs for clinical application.

Long-Term Immunological Alertness and Response to COVID-19 Vaccination-Conditions for Prevention in Early Palliative Oncological Care Patients.

Aside from the general population, the COVID-19 pandemic has also affected a group of patients in palliative oncology care. In this study, long-term immune responses against SARS-CoV-2 after vaccination were monitored in a cohort of patients in palliative oncology care. This non-randomized, prospective, and open-label pilot study recruited patients from the Palliative Oncology Program and included 147 patients, of which 80 were females (54.4%) and 67 males (45.6%). The overall evaluation included current health status, SARS-CoV-2 anti-S IgG titer, and neutralizing antibodies using the SARS-CoV-2 virus neutralization test (VNT). Anti-S IgG antibody analysis revealed high (H) antibody levels in 35.7% (n = 10) and very high (VH) levels in 39.3% (n = 11) of patients after the second vaccination dose. Similarly, after the third dose, H was found in 29.6% (n = 32) and VH in 55.5% (n = 60) of patients. High and very high anti-S IgG antibody levels were consistent with high VNT titers (>2560) and H antibody levels in 17.1% (n = 12) or VH in 82.9% (n = 58) of patients. Patients with two or more doses showed H and VH antibody levels at a median of 451 and 342 days after vaccination, respectively. In this clinical trial, patients showed high and very high levels of anti-S IgG antibodies over a longer period of time. These patients did not show reduced immunological responses to the COVID-19 vaccine challenge. We can assume that prevention through vaccination can reduce the risk of complications or death from COVID-19 in patients in early palliative oncology care.

Analysis of the Presence and Levels of IgG Antibodies Directed against the S1 Protein Receptor Binding Domain and the N Protein of SARS-CoV-2 in Patients with Multiple Sclerosis Treated with Immunomodulatory Therapies.

The coronavirus 2019 disease (COVID-19) course and serological statuses of patients with relapsing-remitting multiple sclerosis (RRMS), treated with disease-modifying therapies (DMTs) are generally parallel that of the general population. Over the pandemic's course, however, a notable increase in the number of RRMS patients who received vaccination against severe acute respiratory coronavirus 2 (SARS-CoV-2) and those who had COVID-19 (symptomatic and asymptomatic) was reported. This virus and/or vaccination likely influenced DMT-treated RRMS patients' serological statuses regarding the presence of SARS-CoV-2 antibodies and their quantitative expression. This investigation assesses the presence and levels of the antibody directed against the S1 protein receptor binding domain (SRBD) and against the N protein of SARS-CoV-2 in 38 DMT-treated RRMS patients. The findings indicate that people vaccinated against SARS-CoV-2 exhibited significantly higher levels of IgG antibodies against S1-RBD at both assessment points. Patients with a prior history of COVID-19 demonstrated statistically significant increases in anti-N antibodies at visit 1, whereas such statistical significance was not observed at visit 2. DMT-treated RRMS patients generated neutralizing antibodies following vaccination and/or COVID-19 infection. Nevertheless, it is noteworthy that antibody levels more accurately reflect the serological status and exhibit a stronger correlation with vaccination than just the presence of antibodies.

A subunit-based influenza/SARS-CoV-2 Omicron combined vaccine induced potent protective immunity in BALB/c mice.

Infection with influenza A virus (IAV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses a significant risk to human life, health, and the global economy. Vaccination is one of the most effective strategies in the fight against infectious viruses. In this study, we, for the first time, have evaluated the immunogenicity and protective effect of an influenza/SARS-CoV-2 Omicron subunit combined vaccine adjuvanted with MF59 and administered to BALB/c mice. Results showed that the combined vaccine induced high levels of IgG, IgG1 , and IgG2a antibodies, as well as influenza A H1N1/California/2009 virus-specific hemagglutination-inhibiting antibodies in BALB/c mice. Moreover, this subunit combined vaccine induced high titers of neutralization antibodies against SARS-CoV-2 Omicron sublineage BA.5 pseudovirus and effectively reduced the viral load of authentic SARS-CoV-2 Omicron sublineage BA.5.2 in the cell culture supernatants. These results suggested that this subunit combined vaccine achieved protective effect against both H1N1 A/California/07/2009 strain and SARS-CoV-2 Omicron BA.5.2 variant. It is therefore expected that this study will establish the scientific foundation for the next-step development of combined vaccines against other strains or variants of IAV and SARS-CoV-2.

Synthesis and evaluation of gold nanoparticles conjugated with five antigenic peptides derived from the spike protein of SARS-CoV-2 for vaccine development

Introduction: The development of innovative anti-COVID-19 vaccines is a need to ensure the population’s immunity worldwide, with broad protection against variants of concern and low cost as the main goals. Gold nanocarriers are potential entities that could aid in the development of innovative vaccines having thermal stability, high immunogenicity, and safety as the main attributes. Moreover, this approach could lead to adjuvant-free formulations, which will reduce the costs of vaccines.Methods: In this study, five peptides (P1, P2, P3, P4, and P5) corresponding to linear epitopes of the SARS-CoV-2 spike (S) protein were chemisorbed on gold nanoparticles (AuNP) of 20 nm, prefunctionalized with heterobifunctional polyethylene glycol, by using glutaraldehyde as crosslinker to generate nanovaccine prototypes.Results and discussion: The surface modification was confirmed by DLS with an increase of 31.7 ± 1.8 nm in the hydrodynamic diameter and an average ζ potential of −8.3 ± 2.2 mV in PBS (as excipient). The coupling concentration achieved was 23.7 ± 7.1 μg of peptide per mg AuNP. These AuNP-based conjugates showed no inherent toxicity in assays performed with HEK293T cells, in which a 100–1,000 μg/mL concentration range only led to a temporary decrease of up to 30% in cell viability after 48 h of treatment with restoration by 72 h. The immunogenicity of the conjugates produced was assessed in test mice subjected to three subcutaneous doses at 2-week intervals. Significant levels of IgM against each target peptide were observed at an early stage of the immunization scheme in all groups, reaching maximum levels after the second dose, whereas the IgG response increased after the third dose. The AuNP-P2, AuNP-P3, and AuNP-P5 conjugates induced the highest levels of IgG antibodies, lasting for at least 2 months after the last boost, with a predominance of the IgG1 subclass. Although the magnitude of the response induced by the gold conjugates was comparable to that with alum as adjuvant, these nanoconjugates induced a longer response. Our data support the use of AuNP as carriers in innovative vaccines against SARS-CoV-2.

Post Covid-19 Effect on Avascular Necrosis of Hip Joint

Background and objectives: The exact course of Severe acute respiratory syndrome (SARS) -2(COVID-19) and itscomplications on multiorgan system are complex and still under studies. Musculoskeletal system has also beenaffected post covid in various forms. This study was taken up to analyse the effects of covid-19 disease on the hipbone and join tissue.Materials and Methods: Retrospective analysis of ten patients was done who had been hospitalised with covid-19infection and later complained of hip pain . They underwent MR imaging and were found to have degenerativechanges characterizing with avascular necrosis (AVN) of head of femur .One of them had history of previoussurgery of femur with PFN, doing well but developed AVN after COVID .Results: Observation of this group showed a clear correlation among the history of COVID-19 disease in thepatients, moderately severe symptoms, high levels of IgG antibodies, and the time of occurrence of joint changes.No other risk factors for AVN or autoimmune or degenerative diseases were found in the study group. The groupof patients responded well to empirical treatment with anti-inflammatory drugs ans supportive therapy, whichsubsided acute inflammatory symptoms and pain in the joints.Conclusions: It is concluded that there have been obvious musculoskeletal complications in covid patientsincluding AVN which could be attributed to the high use steroids and microembolism leading to bone necrosis.Hence more studies and long follow-up is suggested.

Post Covid-19 Effect on Avascular Necrosis of Hip Joint

Background and objectives: The exact course of Severe acute respiratory syndrome (SARS) -2(COVID-19) and itscomplications on multiorgan system are complex and still under studies. Musculoskeletal system has also beenaffected post covid in various forms. This study was taken up to analyse the effects of covid-19 disease on the hipbone and join tissue.Materials and Methods: Retrospective analysis of ten patients was done who had been hospitalised with covid-19infection and later complained of hip pain . They underwent MR imaging and were found to have degenerativechanges characterizing with avascular necrosis (AVN) of head of femur .One of them had history of previoussurgery of femur with PFN, doing well but developed AVN after COVID .Results: Observation of this group showed a clear correlation among the history of COVID-19 disease in thepatients, moderately severe symptoms, high levels of IgG antibodies, and the time of occurrence of joint changes.No other risk factors for AVN or autoimmune or degenerative diseases were found in the study group. The groupof patients responded well to empirical treatment with anti-inflammatory drugs ans supportive therapy, whichsubsided acute inflammatory symptoms and pain in the joints.Conclusions: It is concluded that there have been obvious musculoskeletal complications in covid patientsincluding AVN which could be attributed to the high use steroids and microembolism leading to bone necrosis.Hence more studies and long follow-up is suggested.

Development of an RBD-Fc fusion vaccine for COVID-19

Although the global pandemic of SARS-CoV-2 has passed, there are still regional outbreaks that continue to jeopardize human health. Hence, there is still a great deal of interest in developing an efficient vaccine that can quickly and effectively prevent reemerging outbreaks of SARS-CoV-2. Delta variant was once a dominant strain in the world in 2021, and we first constructed a recombinant RBDdelta-Fc fusion vaccine by coupling the RBD of Delta variant with the human Fc fragment. This Fc fusion strategy increases the immunogenicity of the recombinant RBD vaccine, with a long-lasting high level of IgG antibodies and neutralizing antibodies induced by RBDdelta-Fc vaccine. This RBDdelta-Fc vaccine, as well as the RBD-Fc vaccine prepared in our previously study, could trigger a durable immune effect by the heterologous boosting immunity, and the RBD-Fc induced a quicker humoral immune response than the homologous immunization with inactivated vaccines. In conclusion, the Fc fusion strategy has a significant role in enhancing the immunogenicity of recombinant protein vaccines, thus promising the development of a safe and efficient vaccine for the heterologous boosting against SARS-CoV-2.

Enhancing Protective Antibodies against Opioids through Antigen Display on Virus-like Particles.

Opioid use disorder (OUD) has become a public health crisis, with recent significant increases in the number of deaths due to overdose. Vaccination can provide an attractive complementary strategy to combat OUD. A key for high vaccine efficacy is the induction of high levels of antibodies specific to the drug of abuse. Herein, a powerful immunogenic carrier, virus-like particle mutant bacteriophage Qβ (mQβ), has been investigated as a carrier of a small molecule hapten 6-AmHap mimicking heroin. The mQβ-6-AmHap conjugate was able to induce significantly higher levels of IgG antibodies against 6-AmHap than mice immunized with the corresponding tetanus toxoid-6-AmHap conjugate in head-to-head comparison studies in multiple strains of mice. The IgG antibody responses were persistent with high anti-6-AmHap titers 600 days after being immunized with mQβ-6-AmHap. The antibodies induced exhibited strong binding toward multiple heroin/morphine derivatives that have the potential to be abused, while binding weakly to medications used for OUD treatment and pain relief. Furthermore, vaccination effectively reduced the impacts of morphine on mice in both ambulation and antinociception assays, highlighting the translational potential of the mQβ-6-AmHap conjugate to mitigate the harmful effects of drugs of abuse.

Characteristics of innate, humoral and cellular immunity in children with non-severe SARS-CoV-2 infection

The symptoms of children infected with SARS-CoV-2 are mainly asymptomatic, mild, moderate, and a few severe cases. To understand the immune response characteristics of children infected with SARS-COV-2 who do not develop severe cases, 82 children infected with the SARS-CoV-2 delta strain were recruited in this study. Our results showed that high levels of IgG, IgM, and neutralization antibodies appeared in children infected with SARS-CoV-2. SARS-CoV-2 induced upregulation of both pro-inflammatory factors including TNF-α and anti-inflammatory factors including IL-4 and IL-13 in the children, even IL-10. The expression of INF-α in infected children also showed a significant increase compared to healthy children. However, IL-6, one of the important inflammatory factors, did not show an increase in infected children. It is worth noting that a large number of chemokines reduced in the SARS-CoV-2-infected children. Subsequently, TCR Repertoire, TCRβ bias, and preferential usage were analyzed on data of TCR next-generation sequencing from 8 SARS-CoV-2-infected children and 8 healthy controls. We found a significant decrease in TCR clonal diversity and a significant increase in TCR clonal expansion in SARS-CoV-2-infected children compared to healthy children. The most frequent V and J genes in SARS-CoV-2 children were TRBV28 and TRBJ2-1. The most frequently VβJ gene pairing in SARS-CoV-2 infected children was TRBV20-1-TRBJ2-1. The strong antiviral antibody levels, low expression of key pro-inflammatory factors, significant elevation of anti-inflammatory factors, and downregulation of many chemokines jointly determine that SARS-CoV-2-infected children rarely develop severe cases. Overall, our findings shed a light on the immune response of non-severe children infected with SARS-CoV-2.

Evaluation of the immunoprotective effects of porcine deltacoronavirus subunit vaccines

Porcine deltacoronavirus (PDCoV), a new porcine enteric coronavirus, has seriously endangered the pig breeding industry and caused great economic losses. However, a PDCoV vaccine is not commercially available. Therefore, new and efficient PDCoV vaccines must be developed without delay. In this study, we used the ExpiCHO eukaryotic expression system to express and purify the following 3 structural proteins of PDCoV: S, N and M. Subsequently, the level of humoral and cellular immunity induced by the S protein (immunization with the S protein alone) and a protein mixture (immunization with a mixture of S, N and M proteins) were evaluated in mice and piglets, respectively, and the performances of the 2 immunizations in a challenge protection test were assessed in piglets. The results showed that both the S protein and the protein mixture induced the production of high levels of specific IgG antibodies and neutralizing antibodies and effectively neutralized PDCoV-infected LLC-PK cells in vitro. Furthermore, compared with the S protein, the N and M proteins in the protein mixture promoted the expression of CD8+ T cells and IFN-γ, induced a stronger cellular immune response, and effectively protected 4/5 of the piglets from PDCoV infection. In conclusion, the results of this study showed that the N and M proteins play important roles in inducing an immunoprotective response. Using N and M antigens as effective antigenic components in the development of PDCoV vaccines in the future will effectively increase the immune efficacy of the vaccines.

Antibodies elicited by Newcastle disease virus-vectored H7N9 avian influenza vaccine are functional in activating the complement system

H7N9 subtype avian influenza virus poses a great challenge for poultry industry. Newcastle disease virus (NDV)-vectored H7N9 avian influenza vaccines (NDVvecH7N9) are effective in disease control because they are protective and allow mass administration. Of note, these vaccines elicit undetectable H7N9-specific hemagglutination-inhibition (HI) but high IgG antibodies in chickens. However, the molecular basis and protective mechanism underlying this particular antibody immunity remain unclear. Herein, immunization with an NDVvecH7N9 induced low anti-H7N9 HI and virus neutralization titers but high levels of HA-binding IgG antibodies in chickens. Three residues (S150, G151 and S152) in the hemagglutinin (HA) of H7N9 virus were identified as the dominant epitopes recognized by the NDVvecH7N9 immune serum. Passively transferred NDVvecH7N9 immune serum conferred complete protection against H7N9 virus infection in chickens. The NDVvecH7N9 immune serum can mediate a potent lysis of HA-expressing and H7N9 virus-infected cells and significantly suppress H7N9 virus infectivity. These activities of the serum were significantly impaired after heat-inactivation or treatment with complement inhibitor, suggesting the engagement of the complement system. Moreover, mutations in the 150-SGS-152 sites in HA resulted in significant reductions in cell lysis and virus neutralization mediated by the NDVvecH7N9 immune serum, indicating the requirement of antibody-antigen binding for complement activity. Therefore, antibodies induced by the NDVvecH7N9 can activate antibody-dependent complement-mediated lysis of H7N9 virus-infected cells and complement-mediated neutralization of H7N9 virus. Our findings unveiled a novel role of the complement in protection conferred by the NDVvecH7N9, highlighting a potential benefit of engaging the complement system in H7N9 vaccine design.

Safety and immunogenicity of varied doses of R21/Matrix-M™ vaccine at three years follow-up: A phase 1b age de-escalation, dose-escalation trial in adults, children, and infants in Kilifi-Kenya

Background: Falciparum malaria remains a global health problem. Two vaccines, based on the circumsporozoite antigen, are available. RTS, S/AS01 was recommended for use in 2021 following the advice of the World Health Organisation (WHO) Strategic Advisory Group of Experts (SAGE) on Immunization and WHO Malaria Policy Advisory Group (MPAG). It has since been pre-qualified in 2022 by the WHO. R21 is similar to RTS, S/AS01, and recently licensed in Nigeria, Ghana and Burkina Faso following Phase 3 trial results. Methods: We conducted a Phase 1b age de-escalation, dose escalation bridging study after a change in the manufacturing process for R21. We recruited healthy adults and children and used a three dose primary vaccination series with a booster dose at 1–2 years. Variable doses of R21 and adjuvant (Matrix-M ™) were administered at 10µgR21/50 µg Matrix-M™, 5µgR21/25µg Matrix-M™ and 5µgR21/50µg Matrix-M™ to 20 adults, 20 children, and 51 infants. Results: Self-limiting adverse events were reported relating to the injection site and mild systemic symptoms. Two serious adverse events were reported, neither linked to vaccination. High levels of IgG antibodies to the circumsporozoite antigen were induced, and geometric mean titres in infants, the target group, were 1.1 (0.9 to 1.3) EU/mL at day 0, 10175 (7724 to 13404) EU/mL at day 84 and (following a booster dose at day 421) 6792 (5310 to 8687) EU/mL at day 456. Conclusions: R21/Matrix-M™ is safe, and immunogenic when given at varied doses with the peak immune response seen in infants 28 days after a three dose primary vaccination series given four weeks apart. Antibody responses were restored 28 days after a 4th dose given one year post a three dose primary series in the young children and infants. Registration: Clinicaltrials.gov (NCT03580824; 9th of July 2018; Pan African Clinical Trials Registry (PACTR202105682956280; 17th May 2021).

Serological analysis reveals differential antibody responses between TB patients and latently infected individuals from the TB endemic country of Mozambique.

Serological antibody profiling of tuberculosis (TB) patients and household contacts with latent TB infection (LTBI) could identify risk indicators of disease progression, and potentially also serve as an easily accessible diagnostic tool to discriminate between these two stages of Mycobacterium tuberculosis (Mtb) infection. Yet, despite significant efforts over many decades, neither application has yet fully materialised, and this is at least in part due to inconsistent and varying antibody profiles from different TB endemic regions. In this study, we conducted a retrospective exploratory analysis of serum antibodies in a cohort of active TB patients (ATB) and their interferon-gamma release assay (IGRA) positive household contacts (LTBI), as well as healthy controls (HC) from Mozambique, a country with a high TB burden from the Sub-Saharan region. Using several Mtb antigens as well as crude preparations of culture filtrate proteins (CFP) from Mtb and Bacille Calmette Guérin (BCG), we report that the most discriminatory response for TB and LTBI was observed for serum IgA antibodies to the MPT64 antigen, followed by IgG antibodies to Ag85B and CFP, with ATB patients having significantly higher levels than LTBI or BCG-vaccinated healthy controls. Conversely, sera from LTBI individuals had higher levels of IgG antibodies to the HBHA antigen than ATB. While our sample size (n = 21 for ATB, 18 for LTBI and 17 for HC) was too small to fully evaluate the diagnostic potential of these differing serological profiles, our study however preliminarily indicated high level of sensitivity (95%) and specificity (97%) of an ELISA MPT64-IgA test for discriminating TB from LTBI and healthy controls, supporting the notion that it alone, or possibly in combination with other antigens such as Ag85B or CFP could lead to development of an easily accessible diagnostic tool for TB.

Live attenuated influenza vaccine induces broadly cross-reactive mucosal antibody responses to different influenza strains in tonsils

Intranasal live attenuated influenza vaccine (LAIV) was used to stimulate tonsillar monocular cells (MNCs) following isolation. Haemagglutinin (HA) proteins of several influenza strains were used for the detection of HA-specific IgG, IgM and IgA antibodies using ELISA. Significant anti-sH1N1 HA IgG IgA and IgM antibody titres were detected in cell culture supernatants after stimulation (mean ± SE: 0.43 ± 0.09, mean ± SE: 0.23 ± 0.04 and mean ± SE: 0.47 ± 0.05 respectively, p < 0.01). LAIV stimulation of tonsillar MNCs induced significant IgG, IgA and IgM antibodies to the pH1N1 HA (mean ± SE:1.35 ± 0.12), (mean ± SE: 0.35 ± 0.06) and (mean ± SE: 0.58 ± 0.10) respectively, p < 0.01. Surprisingly, LAIV was shown to induce cross-reactive anti-aH5N1 HA antibodies (mean ± SE: 0.84 ± 0.20, p < 0.01) to avian influenza virus (aH5N1). Anti-H2N2 HA IgG antibody was also detected in the cell culture supernatants in a significant level after LAIV stimulation (mean ± SE: 0.93 ± 0.23, p < 0.01). High levels of anti-sH3N2 HA IgG antibody was discovered after LAIV stimulation of tonsillar MNCs, (mean ± SE: 1.2 ± 0.23p < 0.01). The current model of human nasal-associated lymphoid tissue (NALT) to evaluate B cells responses to LAIV was evident that it is a successful model to study future intranasal vaccines.

Elevated Levels of Cytotoxicity, Cytokines, and Anti-SARS-CoV-2 Antibodies in Mild Cases of COVID-19.

Current evidence shows higher production of cytokines and antibodies against severe acute respiratory coronavirus 2 (SARS-CoV-2) in severe and critical cases of Coronavirus Disease 2019 (COVID-19) in comparison with patients with moderate or mild disease. A recent hypothesis proposes an important role of genotoxicity and cytotoxicity in the induction of the cytokine storm observed in some patients at later stages of the disease. Interestingly, in this study, we report significantly higher levels of interleukin (IL)-1β, IL-6, MCP-1, and IL-4 cytokines in mild COVID-19 patients versus severe cases, as well as a high frequency of karyorrhexis (median [Me] = 364 vs. 20 cells) and karyolysis (Me = 266 vs. 52 cells) in the mucosal epithelial cells of both groups of patients compared with uninfected individuals. Although we observed higher levels of anti-SARS-CoV-2 IgM and IgG antibodies in COVID-19 patients, IgM antibodies were significantly higher only in mild cases, for the N and the S viral antigens. High levels of IgG antibodies were observed in both mild and severe cases. Our results showed elevated concentrations of proinflammatory and anti-inflammatory cytokines in mild cases, which may reflect an active innate immune response and could be related to the higher IgM and IgG antibody levels found in those patients. In addition, we found that SARS-CoV-2 infection induces cytotoxic damage in the oral mucosa, highlighting the importance of studying the genotoxic and cytotoxic events induced by infection and its role in the pathophysiology of COVID-19.

A chimeric protein-based vaccine elicits a strong IgG antibody response and confers partial protection against Shiga toxin-producing Escherichia coli in mice.

Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen that causes gastrointestinal infections, ranging from acute diarrhea and dysentery to life-threatening diseases such as Hemolytic Uremic Syndrome. Currently, a vaccine to prevent STEC infection is an unmet medical need. We developed a chimeric protein-based vaccine targeting seven virulence factors of STEC, including the Stx2B subunit, Tir, Intimin, EspA, Cah, OmpT, and AggA proteins. Immunization of mice with this vaccine candidate elicited significant humoral and cellular immune responses against STEC. High levels of specific IgG antibodies were found in the serum and feces of immunized mice. However, specific IgA antibodies were not detected in either serum or feces. Furthermore, a significantly higher percentage of antigen-specific CD4+ T cells producing IFN-γ, IL-4, and IL-17 was observed in the spleens of immunized mice. Notably, the immunized mice showed decreased shedding of STEC O157:H7 and STEC O91:H21 strains and were protected against weight loss during experimental infection. Additionally, infection with the STEC O91:H21 strain resulted in kidney damage in control unimmunized mice; however, the extent of damage was slightly lower in immunized mice. Our findings suggest that IgG antibodies induced by this vaccine candidate may have a role in inhibiting bacterial adhesion and complement-mediated killing. This study provides evidence that IgG responses are involved in the host defense against STEC. However, our results do not rule out that other classes of antibodies also participate in the protection against this pathogen. Additional work is needed to improve the protection conferred by our vaccine candidate and to elucidate the relevant immune responses that lead to complete protection against this pathogen.

Membrane vesicles derived from Listeria monocytogenes might be a potential antigen delivery vector

Membrane vesicles (MVs) derived from Listeria monocytogenes (LM) have a natural nanoscale size and contain a variety of bacterial components. We speculated that LM MVs may be a novel delivery vector, but it is necessary to evaluate the safety and immunogenicity of LM MVs in vivo. Here, we isolated LM MVs and tested their safety and immunogenicity both in vitro and in vivo. The results showed that LM MVs stimulated RAW264.7 cells and DC2.4 cells to secrete the inflammatory cytokines IL-1β, TNF-α, IL-6 and IL-10. Intraperitoneal injection of LM MVs at 80 μg per C57BL/6 mouse did not cause lethal effects or irreversible pathological changes in major organs, indicating that LM MVs were safe. Intraperitoneal immunization of C57BL/6 mice twice with LM MVs mainly induced a high level of LM MV-specific IgG antibodies. In addition, we subcutaneously injected C57BL/6 mice with a mixture of ovalbumin and LM MVs and found that LM MVs exhibited a humoral immune adjuvant effect equal to that of the same amount of alum. The results of this study indicated that LM MVs have good safety and effective immunogenicity and may act as humoral immune adjuvants. Therefore, LM MVs are a potential new choice for antigen and drug delivery vectors.

Assessment of the level of immune layer to SARS-CoV-2 in children under conditions of novel coronavirus infection COVID-19

Introduction. Asymptomatic transmission of the coronavirus poses a significant threat to efforts to reduce the incidence of COVID-19. A specific humoral immune response against SARS-CoV-2 can be induced in most symptomatic cases and in asymptomatic carriers. Determining the pattern of antibody response to SARS-CoV-2 infection in children can provide important information for improving screening and targeted protection of population that continue to suffer from this pandemic. Aim. To determine the level of antibodies to SARS-CoV-2 in children during the COVID19 epidemic. Materials and methods. Serum samples from 254 clinic patients from 1 to 17 years old, with an average age of 9.7±0.3 years, were studied by random selection. The analysis was carried out in 2 groups of patients: patients who underwent COVID-19 in the period from January 2021 to March 2022 with a positive SARS-CoV-2 PCR result (n=36) and a control group of children who deny the disease (n=218). IgM and IgG were determined in blood serum samples by means of ELISA using the SARS CoV-2-IgM and SARS CoV-2-IgG quantitative diagnostic kits (Vector-Best, Novosibirsk, Russia). Results. In the group of children who did not have COVID-19, negative results were detected in 25.2% of cases. IgG antibodies specific to SARS-CoV-2 were detected in 74.8% of patients, of which a low level of virus-neutralizing activity was found in 15.6% of patients, an average level in 20.2% of cases, and a high level in 39.0% of cases. In the group of children who had the disease, a low level of virus-neutralizing activity was detected in 29.4%, an average level in 32.4%, and a high level of IgG antibodies to SARS-CoV-2 was detected in 38.2% of cases. In the group of children who underwent COVID-19, 77.8% of the disease proceeded with symptoms of acute respiratory viral infections, 22.2% had CT signs of pneumonia, and there were no significant differences in the levels of specific antibodies. In the group of children who underwent COVID-19, 77.8% of the disease proceeded with symptoms of acute respiratory viral infections, 22.2% had CT signs of pneumonia, and there were no significant differences in the levels of specific antibodies. Analysis of seroprevalence in dynamics after the disease showed that the highest level of antibodies persisted for 2-4 months. after an illness. Conclusion. The proportion of asymptomatic forms of infection among children and adolescents is quite high. These undocumented infections often go unrecognized due to mild or absence of symptoms and, depending on their contagiousness and number of contacts, may play a significant role in the transmission of SARS-CoV-2. The findings raise important questions that should be explored in further studies regarding the role of serological tests in assessing the true extent of SARS-CoV-2 exposure in pediatric populations, as well as monitoring the response and duration of SARS-CoV2 antibody-mediated immunity.

Avascular Necrosis of the Hip after the COVID-19 Pandemic.

It is clear that COVID-19 can have a wide range of effects on the body, and the musculoskeletal system is no exception. Studies are ongoing to better understand how the virus may impact the hip bone and joint tissue. However, it is known that COVID-19 can cause inflammation and damage to various parts of the body, including the bones and joints, which could lead to pain, stiffness, and other symptoms. A retrospective analysis is done with ten patients admitted to the hospital due to COVID-19 and later complained of hip pain. Magnetic resonance imaging (MRI) was performed on the patients, and it was found that they had degenerative changes characterized by avascular necrosis (AVN) of the head of the femur. One of the patients had a history of previous surgery on the femur with a plate and screws and was doing well but developed AVN after contracting COVID-19. Observation among these groups shows a strong association between the history of COVID-19, high levels of IgG antibodies, the presence of joint abnormalities, and moderately severe symptoms. There is no evidence of identifying autoimmune, degenerative, or AVN diseases. This set of patients responded positively to supportive therapy and anti-inflammatory drugs used in empirical treatment, which subsided joint pain and acute inflammatory symptoms. It has been determined that there are significant musculoskeletal complications in COVID-19 patients, including AVN, which may be caused by the high use of steroids and microembolism leading to bone necrosis. Therefore, further studies and long-term follow-up are recommended.