Comparison of Adverse Events and Antibody Responses Among Different COVID-19 Vaccination Schedules.

Global investment in developing COVID-19 vaccines has been substantial, but vaccine hesitancy has emerged due to misinformation. Concerns about adverse events, vaccine shortages, dosing confusion, mixing vaccines, and access issues contribute to hesitancy. Initially, the WHO recommended homologous vaccination (same vaccine for both doses), but evolving factors led to consideration of heterologous vaccination (different vaccines). The study compared reactogenicity and antibody response for both viral protein spike (S) and nucleocapsid (N) in 205 participants who received three vaccination regimens: same vaccine for all doses (Pfizer), two initial doses of the same vaccine (CoronaVac or AstraZeneca), and a Pfizer booster. ChAdOx1 and BNT162b2 vaccines were the most reactogenic vaccines, while CoronaVac vaccine was the least. ChAdOx1 and BNT162b2 achieved 100% of S-IgG seropositivity with one dose, while CoronaVac required two doses, emphasizing the importance of the second dose in achieving complete immunization across the population with different vaccine regimes. Pfizer recipients showed the highest S-IgG antibody titers, followed by AstraZeneca recipients, both after the first and second doses. A third vaccine dose was essential to boost the S-IgG antibodies and equalize the antibody levels among the different vaccine schedules. CoronaVac induced N-IgG antibodies, while in the Pfizer and AstraZeneca groups, they were induced by a natural infection, reinforcing the role of N protein as a biomarker of infection.

New highly antigenic linear B cell epitope peptides from PvAMA-1 as potential vaccine candidates.

Peptide-based vaccines have demonstrated to be an important way to induce long-lived immune responses and, therefore, a promising strategy in the rational of vaccine development. As to malaria, among the classic vaccine targets, the Apical membrane antigen (AMA-1) was proven to have important B cell epitopes that can induce specific immune response and, hence, became key players for a vaccine approach. The peptides selection was carried out using a bioinformatic approach based on Hidden Markov Models profiles of known antigens and propensity scale methods based on hydrophilicity and secondary structure prediction. The antigenicity of the selected B-cell peptides was assessed by multiple serological assays using sera from acute P.vivax infected subjects. The synthetic peptides were recognized by 45.5%, 48.7% and 32.2% of infected subjects for peptides I, II and III respectively. Moreover, when synthetized together (tripeptide), the reactivity increases up to 62%, which is comparable to the reactivity found against the whole protein PvAMA-1 (57%). Furthermore, IgG reactivity against the tripeptide after depletion was reduced by 42%, indicating that these epitopes may be responsible for a considerable part of the protein immunogenicity. These results represent an excellent perspective regarding future chimeric vaccine constructions that may come to contemplate several targets with the potential to generate the robust and protective immune response that a vivax malaria vaccine needs to succeed.

Better Response to Influenza Virus Vaccination in Physically Trained Older Adults Is Associated With Reductions of Cytomegalovirus-Specific Immunoglobulins as Well as Improvements in the Inflammatory and CD8+ T-Cell Profiles.

Chronic cytomegalovirus (CMV) infection is a trigger factor for the development of immunosenescence and negatively impacts the immune response to influenza virus vaccination (IVV) in older adults. However, the role of physical exercise training in this context is unknown. Thus, the aim of this study was to investigate whether the regular practice of combined exercise training can improve the specific antibody response to IVV in CMV-seropositive older adults. Eighty older adults were distributed into two groups-non-practitioners (NP, n = 31, age = 74.06 ± 6.4 years) and practitioners of combined exercise training (CET, n = 49, age = 71.7 ± 5.8 years)-for at least 12 months. Both volunteer groups were submitted to IVV and blood samples were collected before (pre) and 30 days after (post) the vaccination. Concerning the specific antibody response to IVV, higher serum levels of specific immunoglobulin A (IgA) were found in the CET group post- than pre-vaccination (p < 0.01), whereas higher levels of specific immunoglobulin M (IgM) were observed both in the NP (p < 0.05) and CET (p < 0.001) groups post-vaccination as compared to the pre-vaccination values. Serum levels of specific immunoglobulin G (IgG) for IVV and CMV, as well as interleukin 6 (IL-6) and IL-10, were similar between the time points evaluated. However, the IL-10/IL-6 ratio post-vaccination was higher (p < 0.05) in the CET group than that before vaccination. Negative correlations were observed between the specific IgG levels for IVV and CMV only in the CET group, both pre- and post-vaccination. In addition, negative correlations were found between IL-10 and specific IgG for CMV in all volunteer groups pre- and post-vaccination, whereas a positive correlation between IL-10 and specific-IgG for IVV pre- and post-vaccination was observed in the CET group. In addition, with the hemagglutination inhibition (HAI) assay, it was found that 32.2% of the NP group and 32.6% of the CET group were responders to IVV and displayed reductions in the CMV serostatus (p < 0.05 and p < 0.001, respectively) and increases in naive and effector CD8+ T cells post-vaccination (p < 0.01). However, only the responders from the CET group showed significant reductions in the ratio of effector to naive CD8+ T cells (p < 0.05) and increased IL-10 levels post-vaccination (p < 0.001). In summary, this study demonstrates that the improvement in the response to IVV in CMV-seropositive older adults was related to an anti-inflammatory status and enhancement of naive CD8+ T cells, particularly associated with regular practice of CET.

SARS-CoV-2 RBD-Tetanus Toxoid Conjugate Vaccine Induces a Strong Neutralizing Immunity in Preclinical Studies.

Controlling the global COVID-19 pandemic depends, among other measures, on developing preventive vaccines at an unprecedented pace. Vaccines approved for use and those in development intend to elicit neutralizing antibodies to block viral sites binding to the host's cellular receptors. Virus infection is mediated by the spike glycoprotein trimer on the virion surface via its receptor binding domain (RBD). Antibody response to this domain is an important outcome of immunization and correlates well with viral neutralization. Here, we show that macromolecular constructs with recombinant RBD conjugated to tetanus toxoid (TT) induce a potent immune response in laboratory animals. Some advantages of immunization with RBD-TT conjugates include a predominant IgG immune response due to affinity maturation and long-term specific B-memory cells. These result demonstrate the potential of the conjugate COVID-19 vaccine candidates and enable their advance to clinical evaluation under the name SOBERANA02, paving the way for other antiviral conjugate vaccines.

PD-L1 Blockade During Allergen Sensitization Inhibits the Synthesis of Specific Antibodies and Decreases Mast Cell Activation in a Murine Model of Active Cutaneous Anaphylaxis.

Programmed cell death ligand 1(PDL-1) is known for its inhibitory effect on the cellular immune response. Even though it is expressed on the surface of mast cells, its role in allergic diseases is unknown. We analyzed the effects of PD-L1 blockade in a murine model of active cutaneous anaphylaxis (ACA). C57BL/6 mice were sensitized and challenged with ovalbumin (OVA). Blood samples were collected to measure specific immunoglobulins. The mice were divided into six groups that underwent the active cutaneous anaphylaxis procedure. Group 1 (negative control) received 50 µl of phosphate-buffered saline (PBS) subcutaneously, and the other five groups were sensitized with 50 µg of OVA subcutaneously. Group 2 was the positive control, and the others received the anti-PD-L1 antibody or its isotype during sensitization (groups 3 and 4) or during the challenge (groups 5 and 6). All animals that underwent ACA on the ears with OVA and PBS were sacrificed, and the reaction was evaluated by extravasation of Evans blue (measured by spectrophotometry) and histological analysis of the collected fragments. Anti-PD-L1 blockade during the sensitization phase led to a reduction in specific IgE and IgG1 levels, allergic reaction intensity at the ACA site, and mast cell degranulation in the tissue. There was no significant biological effect of anti-PD-L1 administration on the challenge phase. PD-L1 blockade during allergen sensitization inhibited the synthesis of specific IgE and IgG1 and decreased mast cell activation in this murine model of anaphylaxis.

Variation in genes implicated in B-cell development and antibody production affects susceptibility to pemphigus.

Pemphigus foliaceus (PF) is an autoimmune blistering skin disease characterized by the presence of pathogenic autoantibodies against desmoglein 1, a component of intercellular desmosome junctions. PF occurs sporadically across the globe and is endemic in some Brazilian regions. Because PF is a B-cell-mediated disease, we aimed to study the impact of variants within genes encoding molecules involved in the different steps of B-cell development and antibody production on the susceptibility of endemic PF. We analysed 3,336 single nucleotide polymorphisms (SNPs) from 167 candidate genes genotyped with Illumina microarray in a cohort of 227 PF patients and 193 controls. After quality control and exclusion of non-informative and redundant SNPs, 607 variants in 149 genes remained in the logistic regression analysis, in which sex and ancestry were included as covariates. Our results revealed 10 SNPs within or nearby 11 genes that were associated with susceptibility to endemic PF (OR >1.56; p < 0.005): rs6657275*G (TGFB2); rs1818545*A (RAG1/RAG2/IFTAP);rs10781530*A (PAXX), rs10870140*G and rs10781522*A (TRAF2); rs535068*A (TNFRSF1B); rs324011*A (STAT6);rs6432018*C (YWHAQ); rs17149161*C (YWHAG); and rs2070729*C (IRF1). Interestingly, these SNPs have been previously associated with differential gene expression, mostly in peripheral blood, in publicly available databases. For the first time, we show that polymorphisms in genes involved in B-cell development and antibody production confer differential susceptibility to endemic PF, and therefore are candidates for possible functional studies to understand immunoglobulin gene rearrangement and its impact on diseases.

Safety and immunogenicity of two novel type 2 oral poliovirus vaccine candidates compared with a monovalent type 2 oral poliovirus vaccine in children and infants: two clinical trials.

BACKGROUND: Continued emergence and spread of circulating vaccine-derived type 2 polioviruses and vaccine-associated paralytic poliomyelitis from Sabin oral poliovirus vaccines (OPVs) has stimulated development of two novel type 2 OPV candidates (OPV2-c1 and OPV2-c2) designed to have similar immunogenicity, improved genetic stability, and less potential to reacquire neurovirulence. We aimed to assess safety and immunogenicity of the two novel OPV candidates compared with a monovalent Sabin OPV in children and infants. METHODS: We did two single-centre, multi-site, partly-masked, randomised trials in healthy cohorts of children (aged 1-4 years) and infants (aged 18-22 weeks) in Panama: a control phase 4 study with monovalent Sabin OPV2 before global cessation of monovalent OPV2 use, and a phase 2 study with low and high doses of two novel OPV2 candidates. All participants received one OPV2 vaccination and subsets received two doses 28 days apart. Parents reported solicited and unsolicited adverse events. Type 2 poliovirus neutralising antibodies were measured at days 0, 7, 28, and 56, and stool viral shedding was assessed up to 28 days post-vaccination. Primary objectives were to assess safety in all participants and non-inferiority of novel OPV2 day 28 seroprotection versus monovalent OPV2 in infants (non-inferiority margin 10%). These studies were registered with ClinicalTrials.gov, NCT02521974 and NCT03554798. FINDINGS: The control study took place between Oct 23, 2015, and April 29, 2016, and the subsequent phase 2 study between Sept 19, 2018, and Sept 30, 2019. 150 children (50 in the control study and 100 of 129 assessed for eligibility in the novel OPV2 study) and 684 infants (110 of 114 assessed for eligibility in the control study and 574 of 684 assessed for eligibility in the novel OPV2 study) were enrolled and received at least one study vaccination. Vaccinations were safe and well tolerated with no causally associated serious adverse events or important medical events in any group. Solicited and unsolicited adverse events were overwhelmingly mild or moderate irrespective of vaccine or dose. Nearly all children were seroprotected at baseline, indicating high baseline immunity. In children, the seroprotection rate 28 days after one dose was 100% for monovalent OPV2 and both novel OPV2 candidates. In infants at day 28, 91 (94% [95% CI 87-98]) of 97 were seroprotected after receiving monovalent OPV2, 134 (94% [88-97]) of 143 after high-dose novel OPV2-c1, 122 (93% [87-97]) of 131 after low-dose novel OPV2-c1, 138 (95% [90-98]) of 146 after high-dose novel OPV2-c2, and 115 (91% [84-95]) of 127 after low-dose novel OPV2-c2. Non-inferiority was shown for low-dose and high-dose novel OPV2-c1 and high-dose novel OPV2-c2 despite monovalent OPV2 recipients having higher baseline immunity. INTERPRETATION: Both novel OPV2 candidates were safe, well tolerated, and immunogenic in children and infants. Novel OPV2 could be an important addition to our resources against poliovirus given the current epidemiological situation. FUNDING: Fighting Infectious Diseases in Emerging Countries and Bill & Melinda Gates Foundation.

Avaliação da resposta de anticorpos IgG contra diferentes variantes alélicas do Antígeno 1 de Membrana Apical (AMA-1) de Plasmodium vivax em indivíduos de áreas endêmicas de malária / Evaluation of IgG antibody response against different variants of Plasmodium vivax apical membrane antigen 1 (AMA-1) in individuals from malaria endemic areas

O Plasmodium vivax é a espécie com maior distribuição geográfica no mundo e a que predomina nas Américas, incluindo o Brasil. Comparado ao Plasmodium falciparum, poucas vacinas contra o P. vivax encontram-se em fase de testes clínicos. Um dos antígenos de formas sanguíneas de P. vivax candidato a vacina é o Antígeno 1 de Membrana Apical (PvAMA-1). Entretanto, a diversidade antigênica do mesmo na natureza representa um grande desafio para seu uso no desenvolvimento de uma vacina de ampla cobertura. No presente estudo, avaliamos se os polimorfismos de sequências já descritos são capazes de influenciar na eficácia de uma vacina baseada em PvAMA-1. Para isso, geramos 9 proteínas recombinantes a partir da levedura Pichia pastoris, as quais são representativas de diferentes variantes alélicas do antígeno PvAMA-1, a saber: Belem, Chesson I, Sal-1, Indonesia XIX, SK0814, TC103, PNG_05_ESP, PNG_62_MU e PNG_68_MAS. Após expressão e purificação das proteínas selecionadas, avaliamos comparativamente por ELISA a resposta de anticorpos IgG naturalmente adquiridos em indivíduos expostos a malária, procedentes da Região Amazônica. Todas as proteínas foram obtidas com rendimento e pureza apropriados para os estudos propostos. A prevalência total de indivíduos expostos a malária com anticorpos contra PvAMA-1 Belem foi de 53,68%, em 611 amostras de soro testadas. Entre 100 das amostras sorologicamente positivas para PvAMA-1 Belem, os maiores valores de DO492 foram obtidos para as variantes Chesson I, SK0814 e Sal-1, sugerindo que epítopos comuns ou de reatividade cruzada estão sendo reconhecidos nessas variantes. Por outro lado, níveis mais baixos de DO492 foram obtidos para as variantes Indonesia XIX, TC103, PNG_05_ESP, PNG_62_MU e PNG_68_MAS, o que pode significar que essas variantes são menos prevalentes ou não circulam no Brasil. Soros policlonais de camundongos C57BL/6 previamente imunizados com PvAMA-1 Belem foram testados quanto ao reconhecimento das diferentes variantes por ELISA. Nossos resultados demonstraram que as variantes Chesson I, Indonesia XIX, SK0814, Sal-1 e a proteína homóloga foram predominantemente reconhecidas. Por fim, ensaios de competição baseados em ELISA revelaram que as proteínas Chesson I, Indonesia XIX, SK0814 e Sal-1, na fase solúvel, foram capazes de inibir a ligação de anticorpos à variante Belem aderida a placa, sugerindo a presença de epítopos comuns ou de reatividade cruzada entre as mesmas. Nossos dados sugerem que uma vacina baseada na variante PvAMA-1 Belem gera anticorpos variante-transcendentes. Entretanto, para gerar uma vacina universal baseada em PvAMA-1, uma formulação multi-alélica, incluindo variantes da Tailândia e Papua Nova Guiné, deverão ser testadas

Plasmodium vivax has the largest geographical distribution Plasmodium species in the world, and is predominant in the Americas, including Brazil. Fewer P. vivax vaccines than P. falciparum vaccines have successfully reached clinical trials. One of the candidate antigens for a blood-stage P. vivax vaccine is the apical membrane antigen 1 (PvAMA-1). However, the high natural variability found in this antigen presents a major challenge for its development into a wide-range vaccine. In the present study, we evaluated whether sequence polymorphisms would influence a vaccine based on PvAMA-1. To achieve this, we generated 9 recombinant proteins from the yeast Pichia pastoris, representative of different allelic variants of the PvAMA-1 antigen: Belem, Chesson I, Sal-1, Indonesia XIX, SK0814, TC103, PNG_05_ESP, PNG_62_MU, and PNG_68_MAS. After expression and purification of these proteins, we compared, by ELISA and IgG blocking, the natural acquired response from malaria-exposed individuals in the Amazon Region. All proteins selected had the appropriate yield and purity for the proposed studies. The total prevalence of malaria-exposed individuals with reactivity to PvAMA-1 Belem was 53,68%, from 611 serum samples tested. One hundred of these serologically positive samples were further tested against recombinant proteins representing the other allelic variants. The highest OD values resulted from Sal-1, Chesson I and SK0814 variants, suggesting that common epitopes or cross-reactivity exist across the variants. On the other hand, the lowest OD values resulted from the variants Indonesia XIX, TC103, PNG_05_ESP, PNG_62_MU, and PNG_68_MAS, which may mean these variants are less prevalent or do not circulate in Brazil. Polyclonal sera from C57BL/6 mice immunized with PvAMA-1 Belem were tested for recognition of different variants by ELISA. Our results showed that the variants Chesson I, Sal-1, Indonesia XIX, SK0814 and the homologous protein were predominantly recognized. Lastly, ELISA-based competition assays revealed that Chesson I, Sal-1, Indonesia XIX and SK0814 proteins were able to inhibit antibody binding to the Belem variant, suggesting the presence of common epitopes or cross-reactivity between these variants. Our data suggest that a vaccine based on the PvAMA-1 Belem variant displays strain-transcendent antibodies. However, to generate a universal vaccine based on PvAMA-1, a multiallelic formulation including variants from Thailand and Papua New Guinea must be tested

Conventional type 1 dendritic cells induce TH 1, TH 1-like follicular helper T cells and regulatory T cells after antigen boost via DEC205 receptor.

Conventional dendritic cells (cDCs) are specialized in antigen presentation. In the mouse spleen, cDCs are classified in cDC1s and cDC2s, and express DEC205 and DCIR2 endocytic receptors, respectively. Monoclonal antibodies (mAbs) αDEC205 (αDEC) and αDCIR2 have been fused to different antigens to deliver them to cDC1s or cDC2s. We immunized mice with αDEC and αDCIR2 fused to an antigen using Poly(I:C) as adjuvant. The initial immune response was analyzed from days 3 to 6 after the immunization. We also studied the influence of a booster dose. Our results showed that antigen targeting to cDC1s promoted a pro-inflammatory TH 1 cell response. Antigen targeting to cDC2s induced TFH cells, GCs, and plasma cell differentiation. After boost, antigen targeting to cDC1s improved the TH 1 cell response and induced TH 1-like TFH cells that led to an increase in specific antibody titers and IgG class switch. Additionally, a population of regulatory T cells was also observed. Antigen targeting to cDC2s did not improve the specific antibody response after boost. Our results add new information on the immune response induced after the administration of a booster dose with αDEC and αDCIR2 fusion mAbs. These results may be useful for vaccine design using recombinant mAbs.

Susceptibility of the Elderly to SARS-CoV-2 Infection: ACE-2 Overexpression, Shedding, and Antibody-dependent Enhancement (ADE).

The world is currently facing a serious SARS-CoV-2 infection pandemic. This virus is a new isolate of coronavirus, and the current infection crisis has surpassed the SARS and MERS epidemics that occurred in 2002 and 2013, respectively. SARS-CoV-2 has currently infected more than 142,000 people, causing 5,000 deaths and spreading across more than 130 countries worldwide. The spreading capacity of the virus clearly demonstrates the potential threat of respiratory viruses to human health, thereby reiterating to the governments around the world that preventive health policies and scientific research are pivotal to overcoming the crisis. Coronavirus disease (COVID-19) causes flu-like symptoms in most cases. However, approximately 15% of the patients need hospitalization, and 5% require assisted ventilation, depending on the cohorts studied. What is intriguing, however, is the higher susceptibility of the elderly, especially individuals who are older than 60 years of age, and have comorbidities, including hypertension, diabetes, and heart disease. In fact, the death rate in this group may be up to 10-12%. Interestingly, children are somehow less susceptible and are not considered as a risk group. Therefore, in this review, we discuss some possible molecular and cellular mechanisms by virtue of which the elderly subjects may be more susceptible to severe COVID-19. Toward this, we raise two main points, i) increased ACE-2 expression in pulmonary and heart tissues in users of chronic angiotensin 1 receptor (AT1R) blockers; and ii) antibody-dependent enhancement (ADE) after previous exposure to other circulating coronaviruses. We believe that these points are pivotal for a better understanding of the pathogenesis of severe COVID-19, and must be carefully addressed by physicians and scientists in the field.

Susceptibility of the elderly to SARS-COV-2 infection: ace-2 overexpression, shedding, and antibody-dependent enhancement (ADE)

The world is currently facing a serious SARS-CoV-2 infection pandemic. </mac_aq>This virus is a new isolate of coronavirus, and the current infection crisis has surpassed the SARS and MERS epidemics</mac_aq> that occurred in 2002 and 2013, respectively. SARS-CoV-2 has currently infected more than 142,000 people, causing </mac_aq>5,000 deaths and spreading across more than 130 </mac_aq>countries worldwide. The spreading capacity of the virus clearly demonstrates the potential threat </mac_aq>of respiratory viruses to human health, thereby reiterating to the governments around the world that preventive </mac_aq>health policies and scientific research are pivotal to overcoming the crisis. Coronavirus disease (COVID-19) causes flu-like symptoms in most cases. However, approximately 15% of the patients need hospitalization, and 5% require assisted ventilation, depending on the cohorts studied. What is intriguing, however, is the higher susceptibility of the elderly, especially individuals who are older than 60 years of age, and have comorbidities, including hypertension, diabetes, and heart disease. In fact, the death rate in this group may be up to 10-12%. Interestingly, children are somehow less susceptible and are not considered as a risk group. Therefore, in this review, we discuss some possible molecular and cellular mechanisms by virtue of which the elderly subjects may be more susceptible to severe COVID-19. Toward this, we raise two main </mac_aq>points, i) increased ACE-2 expression in pulmonary and heart tissues in users of chronic angiotensin 1 </mac_aq>receptor (AT1R) blockers; and ii) antibody-dependent enhancement (ADE) after previous exposure to other circulating coronaviruses. We believe that these points are pivotal for a better understanding of the pathogenesis of severe COVID-19, and must be carefully addressed by physicians and scientists in the field.

Antibody Responses Against Plasmodium vivax TRAP Recombinant and Synthetic Antigens in Naturally Exposed Individuals From the Brazilian Amazon.

Thrombospondin-related adhesive protein (TRAP) is essential for sporozoite motility and the invasion of mosquitoes' salivary gland and vertebrate's hepatocyte and is, thus, considered a promising pre-erythrocytic vaccine candidate. Despite the existence of a few reports on naturally acquired immune response against Plasmodium vivax TRAP (PvTRAP), it has never been explored so far in the Amazon region, so results are conflicting. Here, we characterized the (IgG and IgG subclass) antibody reactivity against recombinant PvTRAP in a cross-sectional study of 299 individuals exposed to malaria infection in three municipalities (Cruzeiro do Sul, Mâncio Lima and Guajará) from the Acre state of the Brazilian Amazon. In addition, the full PvTRAP sequence was screened for B-cell epitopes using in silico and in vitro approaches. Firstly, we confirmed that PvTRAP is naturally immunogenic in the cohort population since 49% of the individuals were IgG-responders to it. The observed immune responses were mainly driven by cytophilic IgG1 over all other sublcasses and the IgG levels that was corelated with age and time of residence in the studied area (p < 0.05). Interestingly, only the levels of specific anti-TRAP IgG3 seemed to be associated with protection, as IgG3 responders presented a significantly higher time elapse since the last malaria episode than those recorded for IgG3 non-responders. Regarding the B-cell epitope mapping, among the 148 responders to PvTRAP, four predicted epitopes were confirmed by recognition of antibodies (PvTRAPR197-H227; PvTRAPE237-T258; PvTRAPP344-G374; and PvTRAPE439-K454). Nevertheless, the frequency of responders against these peptides were low and did not show a clear correlation with the antibody response against the corresponding antigen. Moreover, none of the linear confirmed epitopes were located in the binding regions of PvTRAP in respect to the host cell ligand. Collectively, our data confirm the PvTRAP immunogenicity among Amazon inhabitants, while suggesting that the main important B-cell epitopes are not linear.

Effect on cellular recruitment and the innate immune response by combining saponin, monophosphoryl lipid-A and Incomplete Freund's Adjuvant with Leishmania (Viannia) braziliensis antigens for a vaccine formulation.

The poor immunogenicity displayed by some antigens has encouraged the development of strategies to improve the immune response and safety of vaccine candidates, resulting in an intense search for substances that potentiate vaccine response. Adjuvants have these properties helping vaccine candidates to induce a strong, durable, and fast immune response. In this study, we evaluated the specific immune response of adjuvants alone, Saponin (SAP), Incomplete Freund's Adjuvant (IFA) and Monophosphoryl lipid-A SE (MPL-SE®) and in combination with total antigen of L. braziliensis (LB): LBSAP, LBIFA and LBMPL. The specific immune response induced by these compositions demonstrated that they were powerfully immunogenic, increasing cellular infiltration in the skin. Draining lymph nodes cultures showed that LBIFA and LBMPL have higher ability to increase the capacity of APCs to present antigens, with increased frequency of CD11c+CD86+ cells. SAP, MPL, LBSAP, LBIFA and LBMPL could activate lymphocytes increasing expression of CD69 and CD25. LBSAP group was an excellent inducer of pro-inflammatory cytokines at 24 h. At 48 h, higher cytokines production was observed in IFA, LBIFA, MPL and LBMPL groups. Our data demonstrate that LBSAP and LBMPL are potential formulations to be tested in other experimental models. Also, the data obtained could expand the knowledge about immune response after sensitization and also contribute to the development of safe, immunogenic and effective vaccines.

Characteristic profile of antibody responses to PPD, ESAT-6, and CFP-10 of Mycobacterium tuberculosis in pulmonary tuberculosis suspected cases in Surabaya, Indonesia.

Accurate and rapid diagnostic tools are important aspects of managing tuberculosis (TB) cases appropriately. However, the sensitivity and specificity of diagnostic kits based on immune response such as the tuberculin skin test (TST) and interferon gamma release assay (IGRA) are still debated. Thus, the exploration and assessment of specific biomarker-targeted antibodies are needed for the development of an accurate and rapid diagnostic tool. The present study was conducted in patients with a respiratory problem suspected to be TB at Dr. Soetomo Hospital, Surabaya, Indonesia. Among 102 patients tested by GeneXpert and AFB, 59 serum samples were from cases retrospectively determined to have active TB. A total of 102 serum of healthy controls (HC) was also collected. The PPD antigen and the recombinant CFP-10 and ESAT-6 proteins were prepared. Antibody responses against these proteins were evaluated by ELISA. All samples were also screened for the possibility of Mycobacterium avium-intracellulare complex (MAC) infection using Capilla MaC kit. The results showed that TB patients had a significantly higher concentration of IgG antibody in response to PPD than the HC. In addition, the receiver operating characteristic (ROC) curve analysis showed that PPD was acceptable for diagnostic purposes with an AUC value of 0.835 (95% CI 0.770-0.900, p < 0.0001). However, ESAT-6 and CFP-10 had low AUCs, and 32 samples from both groups showed a low concentration of IgA antibody against all antigens. The MAC detection results also showed that the concentration of IgA in the HC group was the highest. The current results indicate that PPD is a better antigen for antibody-based detection of TB than ESAT-6 and CFP-10. Based on the MAC detection assay, 53 people in the HC group were probably infected with rapidly growing nontuberculous mycobacteria (NTM), although antibody response to PPD was low.

Characteristic profile of antibody responses to PPD, ESAT-6, and CFP-10 of Mycobacterium tuberculosis in pulmonary tuberculosis suspected cases in Surabaya, Indonesia

Abstract Accurate and rapid diagnostic tools are important aspects of managing tuberculosis (TB) cases appropriately. However, the sensitivity and specificity of diagnostic kits based on immune response such as the tuberculin skin test (TST) and interferon gamma release assay (IGRA) are still debated. Thus, the exploration and assessment of specific biomarker-targeted antibodies are needed for the development of an accurate and rapid diagnostic tool. The present study was conducted in patients with a respiratory problem suspected to be TB at Dr. Soetomo Hospital, Surabaya, Indonesia. Among 102 patients tested by GeneXpert and AFB, 59 serum samples were from cases retrospectively determined to have active TB. A total of 102 serum of healthy controls (HC) was also collected. The PPD antigen and the recombinant CFP-10 and ESAT-6 proteins were prepared. Antibody responses against these proteins were evaluated by ELISA. All samples were also screened for the possibility of Mycobacterium avium-intracellulare complex (MAC) infection using Capilla MaC kit. The results showed that TB patients had a significantly higher concentration of IgG antibody in response to PPD than the HC. In addition, the receiver operating characteristic (ROC) curve analysis showed that PPD was acceptable for diagnostic purposes with an AUC value of 0.835 (95% CI 0.770-0.900, p < 0.0001). However, ESAT-6 and CFP-10 had low AUCs, and 32 samples from both groups showed a low concentration of IgA antibody against all antigens. The MAC detection results also showed that the concentration of IgA in the HC group was the highest. The current results indicate that PPD is a better antigen for antibody-based detection of TB than ESAT-6 and CFP-10. Based on the MAC detection assay, 53 people in the HC group were probably infected with rapidly growing nontuberculous mycobacteria (NTM), although antibody response to PPD was low.

The E3 ubiquitin ligase Itch restricts antigen-driven B cell responses.

The E3 ubiquitin ligase Itch regulates antibody levels and prevents autoimmune disease in humans and mice, yet how Itch regulates B cell fate or function is unknown. We now show that Itch directly limits B cell activity. While Itch-deficient mice displayed normal numbers of preimmune B cell populations, they showed elevated numbers of antigen-experienced B cells. Mixed bone marrow chimeras revealed that Itch acts within B cells to limit naive and, to a greater extent, germinal center (GC) B cell numbers. B cells lacking Itch exhibited increased proliferation, glycolytic capacity, and mTORC1 activation. Moreover, stimulation of these cells in vivo by WT T cells resulted in elevated numbers of GC B cells, PCs, and serum IgG. These results support a novel role for Itch in limiting B cell metabolism and proliferation to suppress antigen-driven B cell responses.

Immunoinformatics and structural vaccinology driven prediction of multi-epitope vaccine against Mayaro virus and validation through in-silico expression.

The Mayaro virus (MAYV) belongs to genus "Alphavirus" and family "Togaviridae". MAYV has distribution in the Amazonia, Central and Northeastern regions of Brazil. The abundance of mosquito vector Haemagogus janthinomys has major role in the outbreaks of arthralgia disease in Brazil. Vaccination or immunization is an alternative approach for the protection against this disease. To search the effective candidate for vaccine against Mayaro virus, various immunoinformatics tools were used to predict both the B and T cell epitopes from five structural polyproteins (capsid, E2, 6K, E3and E1). A multi subunit vaccine was designed and the final sequence was modeled for docking with TLR-3. Human b defensin based on previous studies was used as linker. The docked complexes of vaccine-TLR-3 were then subjected to dynamics stability and RMSD and RMSF results suggested that the complexes are stable. Further, to validate our final vaccine construct, in silico cloning was carried out using E. coli as host. The CAI value of 0.96 suggests that the vaccine construct properly expresses in the host. The current findings will be useful for the future experimental validations to ratify the immunogenicity and safety of the supposed structure of vaccine, and ultimately to treat the Mayaro virus, associated infections.

Cellular immune response induced by surface immunogenic protein with AbISCO-100 adjuvant vaccination decreases group B Streptococcus vaginal colonization.

Group B Streptococcus (GBS) represents one of the most common causes of bacterial infection in neonates; it is also associated with premature childbirth and stillbirth. A vaccine against GBS is needed, but no approved vaccines are yet available. The Surface Immunogenic Protein (SIP) of GBS is conserved in all serotypes and had been reported to be a good vaccine prototype in a mouse model of GBS infection. Also, we have previously shown that both subcutaneous and oral immunization with rSIP can induce an efficient immune response that decreases GBS vaginal colonization in mice. In this study, we show that a vaccine based on a mixture of rSIP and AbISCO-100 adjuvant reduces GBS vaginal colonization in mice and induces antibodies with opsonophagocytic activities. Moreover, the passive transfer of sera and total T-cells from mice immunized with rSIP mixed with AbISCO-100 to unvaccinated mice decreases vaginal GBS colonization in an infected mouse. This is the first report of cellular immunity associated with rSIP-based vaccine testing in a mouse model of GBS infection.

ZIKV-Specific NS1 Epitopes as Serological Markers of Acute Zika Virus Infection.

BACKGROUND: Zika virus (ZIKV) infections have reemerged as a global health issue due to serious clinical complications. Development of specific serological assays to detect and differentiate ZIKV from other cocirculating flaviviruses for accurate diagnosis remains a challenge. METHODS: We investigated antibody responses in 51 acute ZIKV-infected adult patients from Campinas, Brazil, including 7 pregnant women who later delivered during the study. Using enzyme-linked immunosorbent assays, levels of antibody response were measured and specific epitopes identified. RESULTS: Several antibody-binding hot spots were identified in ZIKV immunogenic antigens, including membrane, envelope (E) and nonstructural protein 1 (NS1). Interestingly, specific epitopes (2 from E and 2 from NS1) strongly recognized by ZIKV-infected patients' antibodies were identified and were not cross-recognized by dengue virus (DENV)-infected patients' antibodies. Corresponding DENV peptides were not strongly recognized by ZIKV-infected patients' antibodies. Notably, ZIKV-infected pregnant women had specific epitope recognition for ZIKV NS1 (amino acid residues 17-34), which could be a potential serological marker for early ZIKV detection. CONCLUSIONS: This study identified 6 linear ZIKV-specific epitopes for early detection of ZIKV infections. We observed differential epitope recognition between ZIKV-infected and DENV-infected patients. This information will be useful for developing diagnostic methods that differentiate between closely related flaviviruses.

IgG1 and IgG4 antibodies against Aedes aegypti salivary proteins and risk for dengue infections.

Dengue virus (DENV) is an arbovirus responsible for a significant number of deaths in Latin America. This virus is transmitted through the bite of Aedes aegypti, the main mosquito vector, and Ae. albopictus. During blood uptake, the mosquito injects its saliva into the host to facilitate the feeding process. Mosquito saliva contains potent immunogens capable of inducing antibody production directly related to mosquito bite exposure intensity and disease risk. In this study, we first determined the DENV infection status by two different DENV non-structural protein 1 (NS1) based rapid tests and qRT-PCR, then measured the levels of IgG1 and IgG4 antibodies against salivary proteins of Ae. aegypti female mosquitoes in volunteers living in a dengue endemic area. Our results show that people with a positive DENV diagnosis present higher levels of IgG4 antibodies than people with a negative diagnostic test, and that these antibody levels were higher in people with secondary DENV infections. With this study, we show that detection of IgG4 antibodies against mosquito saliva may be a reliable method to evaluate the risk of dengue infection.