Neutralizing antibodies in milk and blood of lactating women vaccinated for SARS-CoV-2: a systematic review / Anticorpos neutralizantes no leite e no sangue de lactantes vacinadas para SARS-CoV-2: uma revisão sistemática

ABSTRACT Objective: To compare the presence of neutralizing antibodies against SARS-CoV-2 found in the breast milk and blood of vaccinated lactating women with those not vaccinated. Data source: The study was registered in the International Prospective Register of Systematic Reviews (PROSPERO) under CRD42021287554 and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Cohort, case-control, and cross-sectional studies that evaluated antibodies against SARS-CoV-2 in the milk and blood of vaccinated mothers and had as control group unvaccinated mothers were eligible. Health Sciences Descriptors (DeCs), Medical Subject Headings (MeSH) and Emtree descriptors were used for the Virtual Health Library (VHL), Medical Literature Analysis and Retrieval System Online (Medline/Pubmed), and Embase databases, respectively. In the Web of Science and Scopus, the strategy was adapted. No restrictions on the publication period and language were set. Data synthesis: The search identified 233 records, of which 128 duplicates and 101 papers that did not meet the inclusion criteria were excluded. Hence, four cohort studies were eligible. Nursing mothers vaccinated with the Pfizer-BioNTech and Moderna vaccines showed antibodies against SARS-CoV-2 in their blood and breast milk. Conclusions: Vaccinated lactating women had higher levels of immunoglobulin G (IgG) and A (IgA) in serum and breast milk than unvaccinated women.

RESUMO Objetivo: Comparar a presença de anticorpos neutralizantes contra o SARS-CoV-2 no leite materno e no sangue das lactantes vacinadas em relação àquelas não vacinadas. Fontes de dados: Foi efetuado registro no International Prospective Register of Systematic Reviews — PROSPERO (CRD42021287554) e foram seguidas as diretrizes do Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Foram elegíveis estudos de coorte, caso-controle e transversais que avaliaram anticorpos contra o SARS-CoV-2 no leite e no sangue de lactantes vacinadas e tiveram como grupo controle lactantes não vacinadas. Utilizaram-se os Descritores em Ciências da Saúde (DeCs), Medical Subject Heading (MeSH) e Emtree para as bases Biblioteca Virtual em Saúde (BVS), Medical Literature Analysis and Retrieval System Online (Medline/PubMed) e Embase, respectivamente. Na Web of Science e Scopus foi feita adaptação da estratégia. Não foram estabelecid as restrições quanto ao período de publicação e idioma. Síntese dos dados: As buscas identificaram 233 registros. Foram excluídos 128 duplicados e 101 fora dos critérios de inclusão, e quatro estudos de coorte foram elegíveis. As lactantes vacinadas com Pfizer-BioNTech e Moderna apresentaram anticorpos contra SARS-CoV-2 no sangue e no leite materno. Conclusões: As mulheres lactantes vacinadas apresentaram níveis mais elevados de imunoglobulina G (IgG) e A (IgA) no soro e no leite materno em comparação com as mulheres não vacinadas.

Eculizumab as first-line treatment for patients with severe presentation of complement factor H antibody-mediated hemolytic uremic syndrome.

BACKGROUND: Complement factor H (FH) antibody-mediated hemolytic uremic syndrome (HUS) has varying prevalence globally. Plasmapheresis and immunosuppressive drugs are the standard treatment. Recently, eculizumab has been reported as an effective alternative. This study aims to report four children with FH antibody-mediated HUS managed with eculizumab plus immunosuppression as first-line therapy. METHODS: A retrospective chart review was conducted for children aged ≤ 18 years old with complement-mediated HUS in two referral centers. Patients with FH antibody-mediated HUS treated with eculizumab as first-line therapy were included. RESULTS: Four children (aged 6-11 years old) were included. Dialysis was necessary in three patients. Eculizumab was administered 5-23 days after onset. None of them received plasmapheresis. Prednisone and mycophenolate mofetil were added after receiving positive FH antibody results. Hematological signs and kidney function improved after the second eculizumab dose. Eculizumab was discontinued in three patients after 6 months. One patient required rituximab due to persistent high FH antibody titers; discontinuation of eculizumab occurred after 15 months without recurrence. No treatment-related complications were observed. During a mean 12-month follow-up (range 6-24 months), no relapses were recorded and all patients ended with normal GFR. CONCLUSION: Our data suggest that a short course of 6 months of C5 inhibitor might be sufficient to reverse thrombotic microangiopathy symptoms and improve kidney function in patients with severe FH antibody-mediated HUS. Simultaneously, adding immunosuppressive agents might reduce the risk of relapse and allow cessation of C5 inhibition in a shorter period of time.

Therapeutic antibodies in oncology: an immunopharmacological overview.

The biotechnological development of monoclonal antibodies and their immunotherapeutic use in oncology have grown exponentially in the last decade, becoming the first-line therapy for some types of cancer. Their mechanism of action is based on the ability to regulate the immune system or by interacting with targets that are either overexpressed in tumor cells, released into the extracellular milieu or involved in processes that favor tumor growth. In addition, the intrinsic characteristics of each subclass of antibodies provide specific effector functions against the tumor by activating antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, and antibody-dependent cellular phagocytosis, among other mechanisms. The rational design and engineering of monoclonal antibodies have improved their pharmacokinetic and pharmacodynamic features, thus optimizing the therapeutic regimens administered to cancer patients and improving their clinical outcomes. The selection of the immunoglobulin G subclass, modifications to its crystallizable region (Fc), and conjugation of radioactive substances or antineoplastic drugs may all improve the antitumor effects of therapeutic antibodies. This review aims to provide insights into the immunological and pharmacological aspects of therapeutic antibodies used in oncology, with a rational approach at molecular modifications that can be introduced into these biological tools, improving their efficacy in the treatment of cancer.

Jamaican fruit bats mount a stable and highly neutralizing antibody response after bat influenza virus infection.

Antibodies are an essential component of the antiviral response in many species, but to date, there is no compelling evidence that bats are capable of eliciting a robust humoral immunity, including neutralizing antibodies. Here, we report that infection of Jamaican fruit bats with the bat influenza A virus H18N11 elicits a rapid and stable humoral immune response with a strong neutralizing capacity, associated with no detectable viral shedding after repeat challenge infection. Thus, the neutralizing antibody response of bats might play an important role in the bat immunity.

Human leukocyte antigen compatibility and incidence of donor-specific antibodies in pediatric liver transplant recipients.

BACKGROUND: Antibody-mediated rejection following liver transplantation (LT) has been increasingly recognized, particularly with respect to the emergence of de novo donor-specific antibodies (DSAs) and their impact on graft longevity. While substantial evidence for adult populations exists, research focusing on pediatric LT outcomes remains limited. AIM: To investigate the prevalence of human leukocyte antigen (HLA) mismatches and DSA and evaluate their association with rejection episodes after pediatric LT. METHODS: A cohort of pediatric LT recipients underwent HLA testing at Santa Casa de Porto Alegre, Brazil, between December 2013 and December 2023. Only patients who survived for > 30 days after LT with at least one DSA analysis were included. DSA classes I and II and cross-matches were analyzed. The presence of de novo DSA (dnDSA) was evaluated at least 3 months after LT using the Luminex® single antigen bead method, with a positive reaction threshold set at 1000 MFI. Rejection episodes were confirmed by liver biopsy. RESULTS: Overall, 67 transplanted children were analyzed; 61 received grafts from living donors, 85% of whom were related to recipients. Pre-transplant DSA (class I or II) was detected in 28.3% of patients, and dnDSA was detected in 48.4%. The median time to DSA detection after LT was 19.7 [interquartile range (IQR): 4.3-35.6] months. Biopsy-proven rejection occurred in 13 patients at follow-up, with C4d positivity observed in 5/13 Liver biopsies. The median time to rejection was 7.8 (IQR: 5.7-12.8) months. The presence of dnDSA was significantly associated with rejection (36% vs 3%, P < 0.001). The rejection-free survival rates at 12 and 24 months were 76% vs 100% and 58% vs 95% for patients with dnDSA anti-DQ vs those without, respectively. CONCLUSION: Our findings highlight the importance of incorporating DSA assessment into pre- and post-transplantation protocols for pediatric LT recipients. Future implications may include immunosuppression minimization strategies based on this analysis in pediatric LT recipients.

In Silico Design of miniACE2 Decoys with In Vitro Enhanced Neutralization Activity against SARS-CoV-2, Encompassing Omicron Subvariants.

The COVID-19 pandemic has overwhelmed healthcare systems and triggered global economic downturns. While vaccines have reduced the lethality rate of SARS-CoV-2 to 0.9% as of October 2024, the continuous evolution of variants remains a significant public health challenge. Next-generation medical therapies offer hope in addressing this threat, especially for immunocompromised individuals who experience prolonged infections and severe illnesses, contributing to viral evolution. These cases increase the risk of new variants emerging. This study explores miniACE2 decoys as a novel strategy to counteract SARS-CoV-2 variants. Using in silico design and molecular dynamics, blocking proteins (BPs) were developed with stronger binding affinity for the receptor-binding domain of multiple variants than naturally soluble human ACE2. The BPs were expressed in E. coli and tested in vitro, showing promising neutralizing effects. Notably, miniACE2 BP9 exhibited an average IC50 of 4.9 µg/mL across several variants, including the Wuhan strain, Mu, Omicron BA.1, and BA.2 This low IC50 demonstrates the potent neutralizing ability of BP9, indicating its efficacy at low concentrations.Based on these findings, BP9 has emerged as a promising therapeutic candidate for combating SARS-CoV-2 and its evolving variants, thereby positioning it as a potential emergency biopharmaceutical.

Waning immune response to CoronaVac in health care workers from different age groups.

Introduction: The waning of serum antibodies against severe acute respiratory syndrome coronavirus 2 observed in several studies raises questions about long-term immunity. Lower antibody levels are associated with new cases of COVID-19 even postvaccination, leading to the administration of booster doses. Objectives: To evaluate the postvaccination immune humoral response and the relationship between postvaccination seropositivity rates and demographic data among health care workers 6 months after CoronaVac vaccination. Methods: This was a cross-sectional study including health care workers vaccinated with two doses of CoronaVac after 6 months or more. The present study was conducted with the analysis of postvaccination serology test to assess the level of humoral response (anti-receptor binding domain IgG) after vaccination. Results: A total of 325 participants were enrolled, of whom 76% were female, with a median age of 42 years (20-85; interquartile range 31-53). Overall, 18.8% (61) of the participants results were seropositive for anti-receptor binding domain IgG; 81.2% did not have sufficient quantitative titers. The IgG titers obtained from female health care workers did not differ from those obtained from seropositive male health care workers, regardless of age. Conclusions: A group of positive quantitative titers was identified in the serology test for IgG antibodies against severe acute respiratory syndrome coronavirus 2. Further studies are needed to determine the durability of postvaccination antibodies and how serology testing can be used to determine the ideal timing for booster doses of the vaccine.

Introdução: O declínio dos anticorpos séricos contra a síndrome respiratória aguda grave do coronavirus 2 observado em vários estudos levanta questões sobre a imunidade a longo prazo. Níveis mais baixos de anticorpos estão associados a novos casos de covid-19 mesmo após a vacinação, levando à administração de doses de reforço. Objetivos: Avaliar a resposta imunitária humoral após a vacinação e a relação entre as taxas de soropositividade após a vacinação e dados demográficos em trabalhadores da saúde por mais de 6 meses após a imunização com CoronaVac. Métodos: Estudo transversal incluindo profissionais de saúde vacinados com duas doses de CoronaVac após 6 meses ou mais. O estudo foi realizado com a análise do teste sorológico após a vacinação para avaliar os níveis de resposta humoral (anti-domínio de ligação ao receptor IgG) após a vacinação. Resultados: Neste estudo foram incluídos 325 participantes, 76% do sexo feminino e a idade mediana foi de 42 anos (20-85; intervalo interquartil 31-53). No geral, 18,8% (61) dos resultados dos participantes foram soropositivos para IgG anti-domínio de ligação ao receptor; 81,2% não apresentaram títulos quantitativos suficientes. Os títulos de IgG obtidos para os profissionais de saúde do sexo feminino não foram diferentes daqueles obtidos para os participantes do sexo masculino com soropositividade, independentemente da idade. Conclusões: Foi possível identificar um grupo com títulos quantitativos positivos no teste sorológico para anticorpo IgG contra a síndrome respiratória aguda grave do coronavírus 2. Mais investigações são necessárias para determinar a durabilidade dos anticorpos após a vacinação e como os testes sorológicos podem determinar o momento ideal das doses de reforço da vacina.

Detection of Neutralizing Antibodies in Serum Samples Using a SARS-CoV-2 Pseudotyped Virus Assay.

Conventional live virus research on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of coronavirus disease-19 (COVID-19), requires Biosafety Level 3 (BSL-3) facilities. SARS-CoV-2 pseudotyped viruses have emerged as valuable tools in virology, mimicking the entry process of the SARS-CoV-2 virus into human cells by expressing its spike glycoprotein in a surrogate system using recombinant plasmids. One significant application of this tool is in functional assays for the evaluation of neutralizing antibodies. Pseudotyped viruses have the advantage of being competent for only a single cycle of infection, providing better safety and versatility and allowing them to be studied in BSL-2 laboratories. Here, we describe three protocols for the detection of SARS-CoV-2 neutralizing antibodies through a pseudotyped virus assay. First, SARS-CoV-2 S pseudotyped viruses (PV SARS-CoV-2 S) are produced using a Moloney murine leukemia virus (MuLV) three-plasmid system. The plasmids are designed to express the GagPol packing proteins, enhanced green fluorescent protein (eGFP) as a readout system, and the SARS-CoV-2 S protein modified to remove the endoplasmic reticulum retention domain and to improve infection. Next, the internalization of PV SARS-CoV-2 S protein in human embryonic kidney 293T (HEK-293T) cells overexpressing angiotensin-converting enzyme 2 (HEK-293T-ACE2) is confirmed by fluorescence microscopy and quantified using flow cytometry. Finally, PV SARS-CoV-2 S is used to screen neutralizing antibodies in serum samples from convalescent COVID-19 patients; it can also be used for studying the cell entry mechanisms of different SARS-CoV-2 variants, evaluating antiviral agents, and designing vaccines. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Generation of PV SARS-CoV-2 S pseudotyped virus Basic Protocol 2: Assay of PV SARS-CoV-2 S internalization in target cells. Basic Protocol 3: Detection of neutralizing antibodies in serum samples.

Single center experience with more than 600 drug desensitization in Colombia.

Background: Drug hypersensitivity reactions (DHRs) have a significant impact on both, patient and their treating physicians; it is considered a public health concern. The history of allergy to drugs, limits therapeutic options and will lead to the use of more expensive and potentially less effective options. Drug desensitization (DD) is considered as a procedure with a positive impact on the prognosis of the patient's disease. The objective of this study is to describe the experience with a substantial number of drugs desensitization in a fourth level center in Cali, Colombia. Methods: An observational, cross-sectional and descriptive study was conducted. Patients with DHRs who underwent a standardized institutional DD protocol, between March of 2012 and May of 2023, were included. Results: Two hundred forty-one patients were included. The median age was 47.8 years (4-88). One hundred fifty-six (64.7%) were women, including three who were pregnant. A total of 641 DDs were performed. The most frequent groups of drugs for which the desensitization was performed were monoclonal antibodies in 83 patients (34.4%), chemotherapeutic agents in 53 (21.6%), NSAIDs in 44 (18.2%), and antibiotics in 42 (17.4%). Eighty-seven patients (36.1%) experienced hypersensitivity to the culprit drug on first exposure, while 154 (63.9%) exhibited reactions during subsequent cycles. The main clinical presentation that gave rise to desensitization was anaphylaxis in 125 patients (51.8%), followed by cutaneous symptoms in 106 patients (44%). The predominant observed endophenotype was type 1 in 188 patients (78.3%), followed by mixed type in 46 patients (19.2%). Breakthrough reactions were observed in 50 patients (20.7%). Tolerance to DD was achieved in 636 of the procedures (99.2%), allowing the continuity of treatment of choice for the underlying disease. Conclusions: Most desensitized patients were women with type I reactions. Monoclonal antibodies were the most frequent culprit drugs. DD in patients with DHRs is a useful, safe and effective procedure. The administration of the implicated drug had a positive impact on the course of the disease in these patients.

Detection of Shiga toxin-producing Escherichia coli in dairy cows: genetic characterization and inhibition of adherence by cattle anti-STEC antibodies to HEp-2 cell.

Shiga toxin-producing Escherichia coli (STEC) is a zoonotic pathogen associated with severe disease. Cattle are recognized as the primary animal reservoir of STEC. This study reports the occurrence and characterization of STEC from dairy cows and evaluates the inhibition of adherence by cattle anti-STEC antibodies to the HEp-2 cell. From 151 samples, 30% (n = 45) were positive for stx by PCR screening (25.21% of dairy cows and 46.8% of growing calves). From these positive samples, 17 STEC isolates were characterized. In dairy cows, 3 out of 17 samples carried stx2, 3 out of 17 possessed stx1, and 2 out of 17 carried stx1/stx2. In growing cows, 8 out of 17 samples carried stx1 and 1 out of 17 carried stx1/stx2. Other virulence factors such as ehxA, saa, iha, cah, and eae were detected. The strains were typed into 3 E. coli O groups (O26, O91, and O130). The analysis of the HEp-2 adherence assays indicated that all serum from both cattle categories presented high levels of inhibition of adherence. Considering the severity of the symptoms caused by STEC in humans, searching for factors influencing the colonization of STEC in cattle would help identify strategies to avoid transmission and STEC infection.

Platelet antibody detection assays: a single-laboratory comparison of MAIPA, PIFT, and microsphere-based multiplex assays Pak-Lx.

BACKGROUND AND OBJECTIVES: The identification of platelet antibodies is essential for diagnosing and managing conditions such as fetal and neonatal alloimmune thrombocytopenic purpura, post-transfusion purpura, and immune platelet refractoriness. Monoclonal antibody immobilization of platelet antigens (MAIPA) is the standard method for detecting anti-human platelet antigen (HPA) antibodies, while the detection of anti-HLA antibodies once relied on the complement-dependent cytotoxicity method, however advanced technologies such as enzyme-linked immunosorbent assay and Luminex have significantly improved sensitivity and accuracy in identifying these antibodies. Flow cytometry-based techniques (platelet immunofluorescence test - PIFT) and Luminex platform-driven microsphere-based multiplex assays (Pak-Lx) are widely employed in platelet immunology laboratories owing to their remarkable flexibility and versatility. The present study compared the sensitivity, specificity, and concordance of these different serological techniques used in platelet antibody identification. MATERIAL AND METHODS: One hundred serum samples from patients suspected of immune-mediated platelet disorders were examined. Initially, the samples underwent testing using the MAIPA method. Subsequently, the results were compared with three alternative methods: PIFT and microsphere-based multiplex assays for both HLA and HPA antibodies. RESULTS: Pak-Lx demonstrated a 94 % agreement with MAIPA, while PIFT had 88 % agreement for HPA antibodies. For HLA antibody detection, Pak-Lx versus DLX had 75 % concordance, MAIPA versus DLX showed 77 %, and PIFT versus DLX displayed an 81 % concordance rate. Remarkably, there were no significant differences in concordance levels between Pak-Lx and PIFT compared to MAIPA and DLX for anti-HPA and HLA antibodies, respectively. CONCLUSION: This study found no significant differences in concordance among the tested assays for detecting anti-HPA and anti-HLA antibodies. These data suggest that no single method can detect all clinically important antibodies. Therefore, it is advisable that each laboratory develops customized protocols based on their expertise and employs complementary methods for comprehensive patient assessments.

Influence of previous COVID-19 exposure and vaccine type (CoronaVac, ChAdOx1 nCov-19 or BNT162b2) on antibody and cytokine (Th1 or Th2) responses.

To achieve global herd immunity, widespread vaccination is the most effective strategy. Vaccines stimulate the immune system, generating cytokines and chemokines, isotype antibodies, and neutralizing antibodies; all these molecules collectively provide a more comprehensive characterization of the immune response post-vaccination. We conducted a longitudinal study in northwestern Mexico, involving 120 individuals before vaccination and after the first dose of the SARS-CoV-2 vaccine, and 46 individuals after their second dose. Our findings reveal that antibody levels stabilize over time; cytokine levels generally increase following the first dose but decrease after the second dose and higher than normal levels in IgG1 and IgG3 concentrations are present. Most of the innate cytokines determined in this study were higher after the first dose of the vaccine. Regardless of previous infection history, this finding suggests that the first dose of the vaccine is crucial and may stimulate immunity by enhancing the innate immune response. Conversely, increased levels of IL-4, indicative of a Th2 response, were found in individuals without prior exposure to the virus and in those vaccinated with CoronaVac. These results suggest that the immune response to COVID-19 vaccines is multi-faceted, with preexisting immunity potentiating a more robust innate response. Vaccine type plays a critical role, with genetic vaccines favoring a Th1 response and inactivated vaccines like CoronaVac skewing toward a Th2 profile.

Hyperthyroidism keeps immunoglobulin levels but reduces milk fat and CD11b/c+ cells on early lactation.

Thyroid hormones influence mammary gland differentiation and lactation by binding to thyroid hormone receptors. Hyperthyroidism disrupts pregnancy and lactation, affecting offspring growth and milk production. Despite maternal milk is a vital source of bioactive compounds and nutrients for newborns, it is unclear whether hyperthyroidism alters its composition, mainly immune factors. Therefore, our work aimed to evaluate the influence of hyperthyroidism on milk quality and immunological parameters during early lactation. Twelve-week-old female Wistar rats received daily injections of 0,25 mg/kg T4 (HyperT, n = 20) or vehicle (control, n = 19) starting 8 days before mating and continuing throughout pregnancy. Rats were euthanized on day 2 of lactation for analyzing the impact of hyperthyroidism on mammary gland, serum and milk samples. HyperT pups exhibited reduced weight, length and head circumference with altered serum hormones, glucose and albumin levels. HyperT mammary gland analysis revealed structural changes, including decreased alveolar area, adipose tissue, increased connective tissue and reduced epithelial elongation, accompanied by decreased TRß1 RNA expression. HyperT milk displayed lower caloric value and fat concentration. HyperT animals exhibited altered milk immune cell counts, displaying increased numbers of CD45+ and CD3+ cells and decreased CD11b/c+ cells without changes on milk and serum IgA, IgG and IgG2a levels. In summary, we have demonstrated that hyperthyroidism affects mammary gland morphology, disrupts pup development and alters biochemical and immunological parameters. Our findings highlight the impact of maternal hyperthyroidism on offspring early development and milk immune composition, underscoring the importance of thyroid function in maternal and neonatal immune health.

The 1H, 15N, and 13C resonance assignments of a single-domain antibody against immunoglobulin G.

Research on camelid-derived single-domain antibodies (sdAbs) has demonstrated their significant utility in diverse biotechnological applications, including therapy and diagnostic. This is largely due to their relative simplicity as monomeric proteins, ranging from 12 to 15 kDa, in contrast to immunoglobulin G (IgG) antibodies, which are glycosylated heterotetramers of 150-160 kDa. Single-domain antibodies exhibit high conformational stability and adopt the typical immunoglobulin domain fold, consisting of a two-layer sandwich of 7-9 antiparallel beta-strands. They contain three loops, known as complementary-determining regions (CDRs), which are assembled on the sdAb surface and are responsible for antigen recognition. The single-domain antibody examined in this study, sdAb-mrh-IgG, was engineered to recognize IgG from rats, mice, but it also weakly recognizes IgG from humans (Pleiner et al. 2018). A search of the Protein Data Bank revealed only one NMR structure of a single-domain antibody, which is unrelated to sdAb-mrh-IgG. The NMR chemical shift assignments of sdAb-mrh-IgG will be utilized to study its molecular dynamics and interactions with antigens in solution, which is fundamental for the rational design of novel single-domain antibodies.

Sputnik V-Induced Antibodies against SARS-CoV-2 Variants during the Dissemination of the Gamma Variant in Venezuela.

The COVID-19 pandemic was characterized by the emergence and succession of SARS-CoV-2 variants able to evade the antibody response induced by natural infection and vaccination. To evaluate the IgG reactivity and neutralizing capacity of the serum of individuals vaccinated with Sputnik V (105 volunteers vaccinated) against different viral variants. IgG reactivity to the Spike protein (S) was evaluated by ELISA. A plaque reduction neutralization test was performed using different viral variant isolates. At 42 days post-vaccination, the frequency of recognition and reactivity to the S protein of the Omicron variant was lower compared to that of the other variants. In general, a higher average neutralization titer was seen against the ancestral variant compared to the variants, especially Omicron. However, some sera exhibited a higher neutralization titer to the Gamma variant compared to the ancestral variant, suggesting unapparent exposure during the clinical trial. Antibodies induced by Sputnik V can recognize, persist, and neutralize SARS-CoV-2 variants, with Omicron being the one that best evades this response. These results represent a unique report on the humoral response induced by a globally lesser-studied vaccine in terms of efficacy and immune escape, offering insights into developing vaccines targeting unknown coronaviruses.

CoronaVac-vaccinated kidney transplant recipients with hybrid immunity have strong neutralizing responses against Omicron and Mu variants of SARS-CoV-2.

Neutralizing antibody (nAb) responses against SARS-CoV-2 variants after inactivated virus vaccine (CoronaVac) in kidney transplant recipients (KTRs) with or without SARS-CoV-2 infection history remains unclear. We aimed to evaluate the neutralizing antibody responses against emerging SARS-CoV-2 variants after two doses of CoronaVac in these patients. 22.2% of participants had hybrid immunity. Anti-spike IgG antibodies were evidenced in 44% of the patients. nAbs against B.1.111, Mu, and Omicron were detected in 28.5%, 17.9%, and 21.4% of naïve KTRs, respectively. Furthermore, nearly 100% of KTRs with hybrid immunity had nAbs against the variants evaluated. Thus, a significant proportion of infection-naïve KTRs had no detectable nAb titers against Mu and Omicron variants after two doses of the CoronaVac vaccine. However, the nAb titers were significantly higher in patients with hybrid immunity, and it was no association between the immunosuppressive regimen and the seropositivity rate of anti-SARS-CoV-2 neutralizing antibodies. Therefore, hybrid KTRs are protected against COVID-19 by emerging variants able to escape from vaccine-elicited nAbs such as Mu and Omicron.

The 2023 ACR/EULAR antiphospholipid syndrome classification criteria identify patients at high risk of complications.

OBJECTIVES: This study aims to evaluate the utility of the 2023 ACR/EULAR antiphospholipid syndrome (APS) classification criteria in identifying primary APS patients at high risk of complications. METHODS: In this single-center study, primary APS patients were classified according to both the revised Sapporo criteria and the 2023 ACR/EULAR criteria. The risk of complications was assessed using the adjusted Global Antiphospholipid Syndrome Score (aGAPSS). RESULTS: Forty-five patients (73% females, median age 49 years) were included. Thirty-six patients met the 2023 ACR/EULAR criteria, all of whom also fulfilled the revised Sapporo criteria. Additionally, four out of nine patients not meeting the 2023 ACR/EULAR criteria satisfied the revised Sapporo criteria. Agreement rate between the two classification criteria was 91%, with a Cohen's kappa index of 0.66. Patients meeting the 2023 ACR/EULAR criteria had significantly higher aGAPSS scores compared to those who did not (13, 8-13 vs. 3, 0-5; p = 0.005). Furthermore, 55% of patients meeting the 2023 ACR/EULAR criteria were categorized as high risk based on aGAPSS scores, while those not meeting the criteria were predominantly categorized as low risk (77%). Interestingly, patients not meeting the 2023 ACR/EULAR criteria but fulfilling the revised Sapporo criteria had significantly higher aGAPSS scores compared to those not meeting either set of criteria (7, 5-13 vs. 0, 0-1.5; p = 0.015). CONCLUSION: The 2023 ACR/EULAR criteria effectively identify primary APS patients at increased risk of complications, as indicated by the aGAPSS score. Key Points • Identifying primary APS patients at high risk of complications remains a significant challenge. • The 2023 ACR/EULAR criteria show a correlation with the aGAPSS score, exhibiting the highest correlation with laboratory domains and minimal correlation with clinical domains. • The 2023 ACR/EULAR classification criteria are effective in identifying primary APS patients at high risk of complications.

Influence of Maternal and Neonatal Factors on Transplacental Passive Immunity after Vaccination against COVID-19.

In the present study, we evaluated the influence of maternal and neonatal factors on the efficiency of the placental transfer of neutralizing antibodies against SARS-CoV-2. Vaccination during pregnancy provides fetal and neonatal protection through the passive transplacental transfer of maternal neutralizing antibodies. To date, little information is available regarding the factors that affect the transfer of antibodies against SARS-CoV-2. A retrospective, cross-sectional, observational, and analytical study was carried out. It was found that several biological factors could be altering transplacental passive immunity after vaccination against COVID-19. In our study population, type 2 diabetes mellitus and chronic hypertension tended to decrease efficiency, while data from women with pre-eclampsia showed better indices compared to those from women with healthy pregnancies. Neonates born prematurely showed lower transfer rates when compared to healthy neonates. The premature rupture of membranes significantly decreased antibody transfer. Taken together, the data suggest that vaccination against COVID-19 during pregnancy is effective even under certain unfavorable clinical conditions for the mother, fetus, and neonate. It is important to create and disseminate immunization strategies in vulnerable populations to reduce maternal and perinatal morbidity and mortality associated with infections preventable by vaccination.

Booster Vaccination with BNT162b2 Improves Cellular and Humoral Immune Response in the Pediatric Population Immunized with CoronaVac.

The SARS-CoV-2 Omicron variant and its sublineages continue to cause COVID-19-associated pediatric hospitalizations, severe disease, and death globally. BNT162b2 and CoronaVac are the main vaccines used in Chile. Much less is known about the Wuhan-Hu-1 strain-based vaccines in the pediatric population compared to adults. Given the worldwide need for booster vaccinations to stimulate the immune response against new Omicron variants of SARS-CoV-2, we characterized the humoral and cellular immune response against Omicron variant BA.1 in a pediatric cohort aged 10 to 16 years who received heterologous vaccination based on two doses of CoronaVac, two doses of CoronaVac (2x) plus one booster dose of BNT162b2 [CoronaVac(2x) + BNT162b2 (1x)], two doses of CoronaVac plus two booster doses of BNT162b2 [CoronaVac(2x) + BNT162b2 (2x)], and three doses of BNT162b2. We observed that the [CoronaVac(2x) + BNT162b2 (2x)] vaccination showed higher anti-S1 and neutralizing antibody titers and CD4 and CD8 T cell immunity specific to the Omicron variant compared to immunization with two doses of CoronaVac alone. Furthermore, from all groups tested, immunity against Omicron was highest in individuals who received three doses of BNT162b2. We conclude that booster vaccination with BNT162b2, compared to two doses of CoronaVac alone, induces a greater protective immunity.

Co-administration of recombinant BCG and SARS-CoV-2 proteins leads to robust antiviral immunity.

SARS-CoV-2 is the causative virus of COVID-19, which has been responsible for millions of deaths worldwide since its discovery. After its emergence, several variants have been identified that challenge the efficacy of the available vaccines. Previously, we generated and evaluated a vaccine based on a recombinant Bacillus Calmette-Guérin (rBCG) expressing the nucleoprotein (N) of SARS-CoV-2 (rBCG-N-SARS-CoV-2). This protein is a highly immunogenic antigen and well conserved among variants. Here, we tested the administration of this vaccine with recombinant N and viral Spike proteins (S), or Receptor Binding Domain (RBD-Omicron variant), plus a booster with the recombinant proteins only, as a novel and effective strategy to protect against SARS-CoV-2 variants. METHODS: BALB/c mice were immunized with rBCG-N-SARS-CoV-2 and recombinant SARS-CoV-2 proteins in Alum adjuvant, followed by a booster with recombinant proteins to assess the safety and virus-specific cellular and humoral immune responses against SARS-CoV-2 antigens. RESULTS: Immunization with rBCG-N-SARS-CoV-2 + recombinant proteins as a vaccine was safe and promoted the activation of CD4+ and CD8+ T cells that recognize SARS-CoV-2 N, S, and RBD antigens. These cells were able to secrete cytokines with an antiviral profile. This immunization strategy also induced robust titers of specific antibodies against N, S, and RBD and neutralizing antibodies of SARS-CoV-2. CONCLUSIONS: Co-administration of the rBCG-N-SARS-CoV-2 vaccine with recombinant SARS-CoV-2 proteins could be an effective alternative to control particular SARS-CoV-2 variants. Due to its safety and capacity to induce virus-specific immune responses, we believe the rBCG-N-SARS-CoV-2 + Proteins vaccine could be an attractive candidate to protect against this virus, especially in newborns.