Levels Of Specific IgG Antibodies Research Articles

Enhancement of SARS-CoV-2 mRNA Vaccine Efficacy through the Application of TMSB10 UTR for Superior Antigen Presentation and Immune Activation.

The development of effective vaccines against SARS-CoV-2 remains a critical challenge amidst the ongoing global pandemic. This study introduces a novel approach to enhancing mRNA vaccine efficacy by leveraging the untranslated region (UTR) of TMSB10, a gene identified for its significant mRNA abundance in antigen-presenting cells. Utilizing the GEO database, we identified TMSB10 among nine genes, with the highest mRNA abundance in dendritic cell subtypes. Subsequent experiments revealed that TMSB10's UTR significantly enhances the expression of a reporter gene in both antigen-presenting and 293T cells, surpassing other candidates and a previously optimized natural UTR. A comparative analysis demonstrated that TMSB10 UTR not only facilitated a higher reporter gene expression in vitro but also showed marked superiority in vivo, leading to enhanced specific humoral and cellular immune responses against the SARS-CoV-2 Delta variant RBD antigen. Specifically, vaccines incorporating TMSB10 UTR induced significantly higher levels of specific IgG antibodies and promoted a robust T-cell immune response, characterized by the increased secretion of IFN-γ and IL-4 and the proliferation of CD4+ and CD8+ T cells. These findings underscore the potential of TMSB10 UTR as a strategic component in mRNA vaccine design, offering a promising avenue to bolster vaccine-induced immunity against SARS-CoV-2 and, potentially, other pathogens.

Preparation and adjuvanticity against PCV2 of Viola philippica polysaccharide loaded in Chitosan-Gold nanoparticle

The present Porcine circovirus type 2 virus (PCV2) vaccine adjuvants suffer from numerous limitations, such as adverse effects, deficient cell-mediated immune responses, and inadequate antibody production. In this study, we explored the potential of a novel nanoparticle (CS-Au NPs) based on gold nanoparticles (Au NPs) and chitosan (CS) that modified Viola philippica polysaccharide (VPP) as efficient adjuvants for PCV2 vaccine. The characterization demonstrated that CS-Au-VPP NPs had a mean particle size of 507.42 nm and a zeta potential value of −21.93 mV. CS-Au-VPP NPs also exhibited good dispersion and a stable structure, which did not alter the polysaccharide properties. Additionally, the CS-Au-VPP NPs showed easy absorption and utilization by the organism. To investigate their immune-enhancing potential, mice were immunized with a mixture of CS-Au-VPP NPs and PCV2 vaccine. The evaluation of relevant immunological indicators, including specific IgG antibodies and their subclasses, cytokines, and T cell subpopulations, confirmed their immune-boosting effects. The in vivo experiments revealed that the medium-dose CS-Au-VPP NPs significantly elevated the levels of specific IgG antibodies and their subclasses, cytokines, and T cell subpopulations in PCV2-immunized mice. These findings suggest that CS-Au-VPP NPs can serve as a promising vaccine adjuvant due to their stable structure and immunoenhancement capabilities.

Lycium barbarum polysaccharide promotes the immunoprotective effects of a recombinant Lactobacillus plantarum vaccine expressing the Trichinella spiralis cathepsin F-like protease 1 gene

Trichinellosis caused by Trichinella spiralis (T. spiralis) is a zoonotic disease that poses a substantial risk to human health. At present, vaccines used to prevent trichinellosis are effective, but the production of antibody levels and immunogenicity are low. Adjuvants can increase antibody levels and vaccine immunogenicity. As a result, it is critical to develop an effective adjuvant for the T. spiralis vaccine. Recent research has shown that traditional Chinese medicine polysaccharides with low-toxicity and biodegradability can act as adjuvants in vaccines. In this study, BALB/c mice were orally inoculated with a recombinant Lactobacillus plantarum (L. plantarum) vaccine expressing the T. spiralis cathepsin F-like protease 1 gene (rTs-CPF1), which was given three times at 10-day intervals. Lycium barbarum polysaccharide (LBP) was administered orally for 37 days. At 37 days after the first immunization, mice were infected with 350 T. spiralis muscle larvae (ML). Specific IgG and sIgA antibody levels against the T. spiralis CPF1 protein were increased in mice immunized with rTs-CPF1+LBP compared to those immunized with rTs-CPF1 alone. Furthermore, LBP increased IFN-γ and IL-4 expression levels, and the number of intestinal and intramuscular worms was significantly reduced in the rTs-CPF1+LBP group compared to that in the rTs-CPF1 group. In the rTs-CPF1+LBP group, the reduction rates of adult worms and muscle larvae were 47.31 % and 68.88 %, respectively. To summarize, LBP promotes the immunoprotective effects of the T. spiralis vaccine and may be considered as a novel adjuvant in parasitic vaccines.

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.

ApoB-specific CD4+ T cells circulate in human blood and formation of a memory population is driven by coronary artery disease and an elevated cardiovascular risk profile

Abstract Aim Atherosclerosis is a chronic inflammatory disease involving an autoimmune response against Apolioprotein B (ApoB), the core protein of low-density lipoprotein (LDL) cholesterol. Using a translational bench-to-bedside approach, we linked the presence and immuno-phenotype of ApoB-specific CD4+ T cells to clinical risk profiles for cardiovascular disease in humans. Methods Peripheral blood mononuclear cells (PBMCs) from 230 patients that underwent coronary angiography were co-incubated in vitro with a pool of immunodominant peptides from human ApoB for 6h. Reactive ApoB-specific T cells (ApoB+) were defined in flow cytometry by expression of the activation marker CD40L. Partition of ApoBpos into naïve and memory T cells was achieved by extracellular fluorochrome-based staining of CD45RO, CCR7 and CD45RA. Cytokine expression of ApoBpos was determined by intracellular staining. Results We found that a median of 0.69±0.1% of circulating CD4+ T cells were reactive to Apolipoprotein B. We found detectable concentrations of auto reactive ApoB+ T cells in 86,44% of all healthy individuals. However, overall frequencies of ApoB reactive T cells did not correlate with diagnosed coronary artery disease (CAD). Compared to ApoBneg. T cells, we detected a higher fraction of memory T cells in ApoBpos (p<0,0001), suggesting a previously occurred ApoB directed immune response. Accordingly, elevated serum levels of ApoB specific IgG Antibodies associated with high proportions of ApoB specific memory cells. Patients diagnosed with coronary artery disease presented higher percentages of central memory T cells among ApoBpos compared to healthy individuals. Correspondingly, these observations applied to patients with an elevated 10-year risk for cardiovascular events estimated by the ESC-SCORE2. These effects largely grounded on strong associations with the clinical diagnosis of arterial hypertension, elevated levels of Lp(a) and obesity. Interestingly, systolic blood pressure and LDL-serum levels correlated with elevated proportions of memory-status ApoBpos T cells in patients without statin intake, although this was not the case for patients with LDL-lowering medication. Analysis of cytokine expression in ApoBpos CD4+ T cells showed significantly increased expression of anti-inflammatory Il-2 and IL-10 in addition to pro-inflammatory IFNγ. Cytokine secretion was mainly driven by memory-status ApoBpos when compared to naïve ApoBpos T cells. Interestingly, a significant number of patients showed a mixed TH1/Treg phenotype among ApoBpos with simultaneous expression of IL-10 and IFN-γ. Conclusions Our data show for the first time that ApoB-reactive T cells exist even in healthy individuals. Cardiovascular risk factors and clinically relevant atherosclerotic disease drive memory formation and activation of ApoB+ T cells. ApoB+ Memory T cells are prone to secrete pro- and anti-inflammatory cytokines and may modulate systemic inflammation in atherosclerosis.

Raman spectroscopic analysis of human serum samples of convalescing COVID-19 positive patients

Rapid screening, detection and monitoring of viral infection is of critical importance, as exemplified by the rapid spread of SARS-CoV-2, leading to the worldwide pandemic of COVID-19. This is equally the case for the stages of patient convalescence as for the initial stages of infection, to understand the medium and long terms effects, as well as the efficacy of therapeutic interventions. Optical spectroscopic techniques potentially offer an alternative to currently employed techniques of screening for the presence, or the response to infection. In this study, the ability of Raman spectroscopy to distinguish between samples of the serum of convalescent COVID-19 positive patients and COVID-19 negative serum samples, and to further analyse and quantify systemic responses, was explored. The study included serum samples of patients who had been tested for SARS-CoV-2 specific IgG and IgM responses between 25 and 134 days after the infection was identified. Both COVID-19 positive and negative groups included males and females who ranged in age from 21 to 81 years old. No correlation was apparent between the specified SARS-CoV-2 specific IgG and IgM immunoglobulin levels of the positive group, their sex, or age. Raman spectroscopic measurements were performed at 785 nm, in liquid serum, thawed from frozen, and spectra were pre-processed to remove the contribution of water, normalising to the water content. Principal components analysis of the spectral dataset over the range 400–1800 cm-1 provided no clear indication of a difference between normal serum and SARS-CoV-2 positive serum. A selection of 5 of the samples, which were available in sufficient volume, were fractionated by centrifugal filtration, and the 100 kDa, 50 kDa, 30 kDa, and 10 kDa concentrates similarly analysed by Raman spectroscopy. Partial least squares regression analysis revealed a negative correlation between the spectral profile of the 30 kDa fractions and SARS-CoV-2 specific IgG antibody levels, potentially indicating an association with depleted glutathione levels. The study supports a potential role of Raman screening of blood serum for monitoring of SARS-CoV-2 infection, but also in longitudinal studies of disease progression, long term effects, and therapeutic interventions.

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.

Testing Efficacy of a Conserved Polypeptide from the Bm86 Protein against Rhipicephalus microplus in the Mexican Tropics.

Rhipicephalus microplus economically impacts cattle production in tropical and subtropical countries. Application of acaricides constitutes the major control method; however, inadequate use has increased resistant tick populations, resulting in environmental and cattle product contamination. Anti-tick vaccines based on the Bm86 antigen are an environmentally friendly, safe, and economically sustainable alternative for controlling R. microplus infestations. Nevertheless, variable efficacy has been experienced against different geographic tick strains. Herein, we evaluated the efficacy of a conserved polypeptide Bm86 derived from a Mexican R. microplus strain previously characterized. Twelve cows were assigned to three experimental groups and immunized with three doses of the polypeptide Bm86 (pBm86), adjuvant/saline alone, and Bm86 antigen (control +), respectively. Specific IgG antibody levels were measured by ELISA and confirmed by Western blot. In addition, the reproductive performance of naturally infested R. microplus was also determined. The more affected parameter was the adult female tick number, with a reduction of 44% by the pBm86 compared to the controls (p < 0.05), showing a vaccine efficacy of 58%. Anti-pBm86 IgG antibodies were immunogenic and capable of recognizing the native Bm86 protein in the eggs, larvae, and guts of R. microplus. The negative correlation between antibody levels and the reduction of naturally tick-infested cattle suggested that the effect of the polypeptide Bm86 was attributed to the antibody response in immunized cattle. In conclusion, the polypeptide Bm86 showed a specific immune response in cattle and conferred protection against R. microplus in a Mexican tropical region. These findings support further experiments with this antigen to demonstrate its effectiveness as a regional vaccine.

The role of interleukin-21 in COVID-19 vaccine–induced B cell–mediated immune responses in patients with kidney disease and kidney transplant recipients

T-cell–mediated help to B cells is required for the development of humoral responses, in which the cytokine interleukin (IL)-21 is key. Here, we studied the mRNA-1273 vaccine–induced SARS-CoV-2–specific memory T-cell IL-21 response, memory B cell response, and immunoglobulin (Ig)G antibody levels in peripheral blood at 28 days after the second vaccination by ELISpot and the fluorescent bead–based multiplex immunoassay, respectively. We included 40 patients with chronic kidney disease (CKD), 34 patients on dialysis, 63 kidney transplant recipients (KTR), and 47 controls. We found that KTR, but not patients with CKD and those receiving dialysis, showed a significantly lower number of SARS-CoV-2–specific IL-21 producing T cells than controls (P < .001). KTR and patients with CKD showed lower numbers of SARS-CoV-2–specific IgG–producing memory B cells when compared with controls (P < .001 and P = .01, respectively). The T-cell IL-21 response was positively associated with the SARS-CoV-2–specific B cell response and the SARS-CoV-2 spike S1–specific IgG antibody levels (both Pearson r = 0.5; P < .001). In addition, SARS-CoV-2–specific B cell responses were shown to be IL-21 dependent. Taken together, we show that IL-21 signaling is important in eliciting robust B cell–mediated immune responses in patients with kidney disease and KTR.

SARS-COV-2 IgG specific antibodies persistence in recovered COVID-19 individuals and its association with severity and time of illness

In order to accurately interpret the immune response to COVID-19, it is critical to know how long serum antibodies to COVID-2 persist. This study aimed to describe the serum IgG responses to SARS-CoV-2 in patients with mild, moderate, and severe COVID-19 infection in Birjand, South Khorasan province, Iran. The study was performed on individuals whose COVID-19 disease was confirmed by RT-PCR and recovered from the disease. After completing the questionnaire, blood samples were collected from 4 different groups based on the time of the test at two, four, six, and eight months' post-recovery. Then, SARS-COV-2 virus-specific IgG nucleocapsid antibody level in patients was measured using the enzyme-linked immunosorbent assay (ELISA). In total, 206 patients (mean age 44.19 ​± ​14.9, 51% man) were included in the survey. Serum prevalence of specific IgG antibodies in patients with mild, moderate, and severe COVID-19 disease was 51.5%, 64% and 78.9%, respectively. Furthermore, serum prevalence of COVID-19 specific IgG antibody level in two, four, six, and eight months after recovery were 80.8, 69.1, 43.2 and 41.8%, respectively (p ​< ​0.05). The multiple logistic regression model showed that the variables of age and the time elapsed after recovery had a significant relationship with the positive antibody test of recovered COVID-19 patients (P ​< ​0.05). But other variables had no significant relationship with the result of antibody test (P ​> ​0.05). In the present report, we attempted to characterize the antibody response against SARS-CoV-2 in patients with mild, moderate, and severe COVID-19, with the aim of better elucidating the humoral immune response after recovery from SARS-CoV-2 infection.

Genetically engineered bacterial‐like particles induced specific cellular and humoral immunity as effective tick‐borne encephalitis virus vaccine

AbstractTick‐borne encephalitis (TBE) is a natural focal disease with fatal encephalitis induced by tick‐borne encephalitis virus (TBEV), seriously threatening human and public health. Protection of TBE depends on vaccination with inactivated vaccine, which requires high cost and multiple immunizations. Here, we construct genetically engineered bacterial‐like particles (BLPs) as an effective TBEV vaccine with simplified immunizations and improved immune efficacy. The TBEV BLPs involve the combination of the gram‐positive enhancer matrix from Lactococcus lactis, and TBEV envelope (E) protein expressed by genetically engineered recombinant baculovirus. The prepared TBEV BLPs can effectively stimulate the activation of dendritic cells to present the TBEV E proteins to T and B cells, leading to strong and durable cellular and humoral immune responses in mice. Surprisingly, the serum levels of specific IgG antibodies in mice remain about 106 at 6 months after the secondary immunization. Overall, the TBEV BLPs can be used as a potent vaccine candidate, laying the foundation for developing novel TBEV genetically engineered vaccines.

Comparative analysis of the effectiveness of vaccines against SARS-CoV-2 3 months after revaccination

Since 2021, Turkmenistan has been vaccinating the population against COVID-19. The aim of the work is a comparative analisis of the effectiveness of vaccines against SARS–CoV-2 used in mass vaccination of the population in the development of population immunity.Research materials. The blood serum of 960 people vaccinated with “Sputnik-lite” or “BIOvac” was used in the work.Conclusion. 3 months after revaccination, 100 % of vaccinated patients have a high level of specific IgG antibodies in their blood serum. A comparative analysis of the effectiveness of two vaccines “Sputnik-lite” and “BIOvac”, showed that a longer immune response persists after the introduction of the vaccine “Sputnik-lite”.

Enhancement of immune responses by vaccine potential of three antigens, including ROP18, MIC4, and SAG1 against acute toxoplasmosis in mice

Toxoplasma gondii (T. gondii) causes considerable financial losses in the livestock industry and can present serious threats to pregnant women, as well as immunocompromised patients. Therefore, it is required to design and produce an efficient vaccine for controlling toxoplasmosis. The present study aimed to evaluate the protective immunity induced by RMS protein (ROP18, MIC4, and SAG1) with Freund adjuvant, calcium phosphate nanoparticles (CaPNs), and chitosan nanoparticles (CNs) in BALB/c mice. The RMS protein was expressed in Escherichia coli (E. coli) and purified using a HisTrap HP column. Thereafter, cellular and humoral immunity was assessed by injecting RMS protein on days 0, 21, and 35 into four groups [RMS, RMS-chitosan nanoparticles (RMS-CNs), RMS-calcium phosphate nanoparticles (RMS-CaPNs), and RMS-Freund]. Phosphate buffered saline (PBS), CNs, CaPNs, and Freund served as the four control groups. The results displayed that vaccination with RMS protein and adjuvants significantly elicited the levels of specific IgG antibodies and cytokines against toxoplasmosis. There were high levels of total IgG, IgG2a, and IFN-γ in vaccinated mice, compared to those in the control groups, especially in the RMS-Freund, indicating a Th-1 type response. The vaccinated and control mice were challenged intraperitoneally with 1 × 103 tachyzoites of the T. gondii RH strain four weeks after the last injection, and in RMS-Freund and RMS-CaPNs groups, the highest increase in survival time was observed (15 days). The RMS can significantly increase Th1 and Th2 responses; moreover, multi-epitope vaccines with adjuvants can be a promising strategy for the production of a vaccine against toxoplasmosis.

Safety of the Salmonella enterica serotype Dublin strain Sdu189-derived live attenuated vaccine-A pilot study.

Salmonella enterica serovar Dublin (S. Dublin) is an important zoonotic pathogen with high invasiveness. In the prevention and control of the Salmonella epidemic, the live attenuated vaccine plays a very important role. To prevent and control the epidemic of S. Dublin in cattle farms, the development of more effective vaccines is necessary. In this study, we constructed two gene deletion mutants, Sdu189ΔspiC and Sdu189ΔspiCΔaroA, with the parental strain S. Dublin Sdu189. The immunogenicity and protective efficacy were evaluated in the mice model. First, both mutant strains were much less virulent than the parental strain, as determined by the 50% lethal dose (LD50) for specific pathogen-free (SPF) 6-week-old female BALB/c mice. Second, the specific IgG antibody level and the expression level of cytokine TNF-α, IFN-γ, IL-4, and IL-18 were increased significantly in the vaccinated mice compared to the control group. In addition, the deletion strains were cleared rapidly from organs of immunized mice within 14 d after immunization, while the parental strain could still be detected in the spleen and liver after 21 d of infection. Compared with the parental strain infected group, no obvious lesions were detected in the liver, spleen, and cecum of the deletion strain vaccinated groups of mice. Immunization with Sdu189ΔspiC and Sdu189ΔspiCΔaroA both provided 100% protection against subsequent challenges with the wild-type Sdu189 strain. These results demonstrated that these two deletion strains showed the potential as live attenuated vaccines against S. Dublin infection. The present study established a foundation for screening a suitable live attenuated Salmonella vaccine.

Towards the development of an epitope-focused vaccine for SARS-CoV-2

The rapid spread of COVID-19 on all continents and the mortality induced by SARS-CoV-2 virus, the cause of the pandemic coronavirus disease 2019 (COVID-19) has motivated an unprecedented effort for vaccine development. Inactivated viruses as well as vaccines focused on the partial or total sequence of the Spike protein using different novel platforms such us RNA, DNA, proteins, and non-replicating viral vectors have been developed. The high global need for vaccines, now and in the future, and the emergence of new variants of concern still requires development of accessible vaccines that can be adapted according to the most prevalent variants in the respective regions.Here, we describe the immunogenic properties of a group of theoretically predicted RBD peptides to be used as the first step towards the development of an effective, safe and low-cost epitope-focused vaccine. One of the tested peptides named P5, proved to be safe and immunogenic. Subcutaneous administration of the peptide, formulated with alumina, induced high levels of specific IgG antibodies in mice and hamsters, as well as an increase of IFN-γ expression by CD8+ T cells in C57 and BALB/c mice upon in vitro stimulation with P5. Neutralizing titers of anti-P5 antibodies, however, were disappointingly low, a deficiency that we will attempt to resolve by the inclusion of additional immunogenic epitopes to P5. The safety and immunogenicity data reported in this study support the use of this peptide as a starting point for the design of an epitope restricted vaccine.

Estimate of anti-SARS-CoV-2 spike IgG antibodies prevalence among Iranian population based on blood donations: A serial cross-sectional study during the third wave of the pandemic.

ObjectivesIran is one of the countries that have been confronted with the SARS-CoV-2 epidemic since February 2020. This study aimed to determine the levels of specific IgG antibodies against SARS-CoV-2 among healthy blood donors to estimate the burden of the epidemic.Material and methodsA serial cross-sectional study was conducted on blood donors who referred to 31 main blood donation centers in different provinces during the third weeks of September, October, and November 2020. A questionnaire was filled out to collect socio-demographic characteristics, history of contact with COVID-19 patients, and history of COVID-19. A blood sample was collected from each participant to assess the antibodies against SARS-CoV-2 using the ELISA method. The crude prevalence of anti-SARS-CoV-2 IgG was calculated. Then it was weighted based on the gender and age groups of the general population in each province and adjusted for test sensitivity and specificity.ResultsDuring three time points of the study, 3840, 3697, and 3152 participants enrolled. The seroprevalence of SARS-CoV-2 IgG antibodies was 19.59% (17.18–22.00), 22.67% (20.70–24.65), and 32.63% (29.93–35.33) over the three rounds of the study.We found an association between the seropositivity and the highest educational level; AOR 0.76 (0.63–0.93), history of close contact with COVID-19 patients; AOR 1.69 (1.35–2.11), and history of confirmed SARS-CoV-2 infection; AOR 8.86 (5.38–14.60).ConclusionThis study showed that about one-third of the population had been infected with COVID-19. Furthermore, a significant upward trend in seroprevalence was observed. The predisposing factors indicate the importance of public health.

Low quantity and quality of anti-spike humoral response is linked to CD4 T-cell apoptosis in COVID-19 patients

In addition to an inflammatory reaction, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)-infected patients present lymphopenia, which we recently reported as being related to abnormal programmed cell death. As an efficient humoral response requires CD4 T-cell help, we hypothesized that the propensity of CD4 T cells to die may impact the quantity and quality of the humoral response in acutely infected individuals. In addition to specific immunoglobulins (Ig)A, IgM, and IgG against SARS-CoV-2 nucleocapsid (N), membrane (M), and spike (S1) proteins, we assessed the quality of IgG response by measuring the avidity index. Because the S protein represents the main target for neutralization and antibody-dependent cellular cytotoxicity responses, we also analyzed anti-S-specific IgG using S-transfected cells (S-Flow). Our results demonstrated that most COVID-19 patients have a predominant IgA anti-N humoral response during the early phase of infection. This specific humoral response preceded the anti-S1 in time and magnitude. The avidity index of anti-S1 IgG was low in acutely infected individuals compared to convalescent patients. We showed that the percentage of apoptotic CD4 T cells is inversely correlated with the levels of specific IgG antibodies. These lower levels were also correlated positively with plasma levels of CXCL10, a marker of disease severity, and soluble Fas ligand that contributes to T-cell death. Finally, we found lower S-Flow responses in patients with higher CD4 T-cell apoptosis. Altogether, these results demonstrate that individuals with high levels of CD4 T-cell apoptosis and CXCL10 have a poor ability to build an efficient anti-S response. Consequently, preventing CD4 T-cell death might be a strategy for improving humoral response during the acute phase, thereby reducing COVID-19 pathogenicity.

Synthesis and immunological study of a glycosylated wall teichoic acid-based vaccine against Staphylococcus aureus

Staphylococcus aureus wall teichoic acids (WTAs) are attractive targets for antibacterial vaccine development. In this study, three core glycosylated WTA structure, including α-1,4-GlcNAc, β-1,4-GlcNAc and β-1,3-GlcNAc modified ribitol phosphates containing a linker are chemically synthesized and conjugated with tetanus toxin (TT) carrier protein as vaccine candidates. In vivo immunological studies demonstrate that the synthesized glycosylated WTAs display high immunogenicity and all conjugates provoke strong immune responses and elicit high levels of specific IgG antibodies against the GlcNAc-modified WTA. Furthermore, antibodies elicited by the vaccine candidates remain the capability to recognize S. aureus cells and display significant opsonophagocytic activity to clear S. aureus. This study demonstrates that the core structure of glycosylated WTAs are effective antigens for constructing anti-S. aureus vaccines to prevent and control S. aureus infections.

α-Gal antigen-deficient rabbits with GGTA1 gene disruption via CRISPR/Cas9

BackgroundPrevious studies have identified the carbohydrate epitope Galα1–3Galβ1–4GlcNAc-R (termed the α-galactosyl epitope), known as the α-Gal antigen as the primary xenoantigen recognized by the human immune system. The α-Gal antigen is regulated by galactosyltransferase (GGTA1), and α-Gal antigen-deficient mice have been widely used in xenoimmunological studies, as well as for the immunogenic risk evaluation of animal-derived medical devices. The objective of this study was to develop α-Gal antigen-deficient rabbits by GGTA1 gene editing with the CRISPR/Cas9 system.ResultsThe mutation efficiency of GGTA1 gene-editing in rabbits was as high as 92.3% in F0 pups. Phenotype analysis showed that the α-Gal antigen expression in the major organs of F0 rabbits was decreased by more than 99.96% compared with that in wild-type (WT) rabbits, and the specific anti-Gal IgG and IgM antibody levels in F1 rabbits increased with increasing age, peaking at approximately 5 or 6 months. Further study showed that GGTA1 gene expression in F2-edited rabbits was dramatically reduced compared to that in WT rabbits.Conclusionsα-Gal antigen-deficient rabbits were successfully generated by GGTA1 gene editing via the CRISPR/Cas9 system in this study. The feasibility of using these α-Gal antigen-deficient rabbits for the in situ implantation and residual immunogenic risk evaluation of animal tissue-derived medical devices was also preliminarily confirmed.

An Eimeria maxima Antigen: Its Functions on Stimulating Th1 Cytokines and Protective Efficacy Against Coccidiosis

A consensus is that the Th1 immune response plays a predominant role against avian coccidiosis. Therefore, an antigen with the ability to induce Th1 cytokine responses is an ideal candidate for the development of coccidiosis vaccines. In our previous study, EmARM-β, a Th1 cytokines-stimulating antigen, was screened from the cDNA expression library of Eimeria maxima (E. maxima). Herein, we verified its stimulative effects on Th1 cytokine productions and evaluated its protective efficacy against E. maxima infection. Recombinant EmARM-β protein was expressed, and eukaryotic expression plasmid pVAX1-EmARM-β was also constructed for the immunization of birds. An immunofluorescence assay was performed to detect the native form of EmARM-β protein in the stage of sporozoites. Expressions of specific transcription factors and cytokines in immunized chickens were measured using qPCR and ELISA to verify its stimulating function on Th1 cytokines. Specific IgG antibody levels and T lymphocyte subpopulation in the immunized chickens were detected using ELISA and indirect flow cytometry to determine induced immune responses. The results showed that EmARM-β native protein is massively expressed in the sporozoites stage of E. maxima. Effective stimulation from the EmARM-β antigen to T-bet and Th1 cytokines (IL-2 and IFN-γ) was observed in vivo. After being immunized with rEmARM-β or pVAX1-EmARM-β, significant promotion to the proportion of CD4+ and CD8+ T cells and the level of antigen-specific IgG antibodies in immunized chickens was also observed. Furthermore, vaccination with rEmARM-β antigen or pVAX1-EmARM-β resulted in alleviated weight loss and enteric lesion, reduced oocyst output, and higher anticoccidial index (ACI) in challenged birds. These results indicate that EmARM-β antigen can effectively stimulate the expression of Th1 cytokines and initiate host immune responses, providing moderate protective efficacy against E. maxima. Notably, EmARM-β protein is a promising candidate for developing a novel anticoccidial vaccine.