Search Results (2,504)

Background: Toxoplasma gondii infection during pregnancy may lead to congenital toxoplasmosis and serious pregnancy complications. In Kenya, however, toxoplasmosis is not screened during routine antenatal care, and there is limited local data on maternal seroprevalence and associated risk factors. This study determined the seroprevalence of T. gondii infections. It examined its association with socio-demographic, obstetric characteristics, awareness levels, and exposure behaviours among pregnant women visiting the antenatal clinic at Pumwani Maternity Hospital in Nairobi, Kenya. Methods: A cross-sectional study was conducted among 298 pregnant women consecutively recruited at Pumwani Maternity Hospital in Nairobi County between July and October 2025. Data on socio-demographics, obstetric characteristics, knowledge, and exposure practices were collected using a structured questionnaire. Blood specimens were obtained from consenting prenatal patients, and anti-T. gondii IgG antibodies were detected by indirect enzyme-linked immunosorbent assay (ELISA). Associations between seropositivity and risk factors were assessed using univariable logistic regression, followed by two separate multivariable models. Variables with p < 0.25 were considered for multivariable analysis, followed by backward likelihood-ratio elimination. Model calibration was assessed using the Hosmer–Lemeshow test. Results: The overall seroprevalence of anti-T. gondii IgG was 24.5% (73 of 298). In the sociodemographic model, women who were self-employed (adjusted odds ratio [AOR] = 0.26, 95% CI: 0.13–0.53) and formally employed (AOR = 0.25, 95% CI: 0.11–0.59) had lower odds of seropositivity than unemployed women. Women aged 25–33 years had higher odds than those aged 18–24 years (AOR = 2.45, 95% CI: 1.06–5.62). Having two children was associated with lower odds than a first birth (AOR = 0.40, 95% CI: 0.18–0.90), while parity of four or more showed a borderline increase in odds (AOR = 3.11, 95% CI: 0.99–9.76). In the knowledge/exposure model, good awareness of population risk groups was linked to higher odds of seropositivity (AOR = 3.34, 95% CI: 1.21–9.24), but exposure-practice variables were not independently associated. Stratified analyses showed significant demographic differences in exposure practices, such as eating undercooked meat in the third trimester of pregnancy (p = 0.021) and unwashed vegetable consumption by pregnant women from Kamkunji Sub-County (p = 0.005). Parity of three increased infection risk (p = 0.007). Conclusions: About 25% of participants showed evidence of prior T. gondii exposure. Seropositivity correlated with specific sociodemographic and obstetric factors as well as awareness of groups at risk. These results endorse targeted antenatal education that emphasises practical food safety and environmental hygiene, aligned with a One Health approach. Further longitudinal and multicenter research, including IgM and IgG avidity testing, is needed to differentiate recent from past infections and to better understand risks associated with congenital toxoplasmosis. Full article

Dengue virus (DENV) serotypes 1–4 cause dengue, a major re-emerging disease in tropical and subtropical regions. This study evaluated the antigenicity of a recombinant DENV-2 premembrane protein (rprM-DENV-2) and its ability to detect anti-DENV human IgA antibodies. The rprM-DENV-2 protein was expressed in Escherichia coli, purified, and assessed for immunogenicity and antigenicity. The recombinant protein induced IgG antibodies in rats, which detected DENV infection in Vero cells. Importantly, in paired saliva and serum samples from patients diagnosed with dengue, IgA antibodies were detected by ELISA using the rprM-DENV-2 antigen, but not in samples from the negative control group (subjects residing in a non-endemic area), with a significant difference (p < 0.0001). These findings demonstrate that rprM-DENV-2 retains antigenic properties similar to the native viral protein; this may be useful for in vitro studies of DENV infection and IgA detection in non-invasive clinical samples. Full article

Hantaan virus (HTNV) is the predominant causative agent of hemorrhagic fever with renal syndrome (HFRS) in China, yet no specific antiviral therapy is currently available. Neutralizing antibodies (NAbs) represent a promising strategy, but most existing anti-HTNV NAbs are heterologous and carry immunogenicity risks. Here, two fully human antibodies from a previously established human anti-HTNV phage display library were generated and characterized. KJJ3, a VL-VL tandem antibody derived from clone 3–12, showed weak binding to inactivated HTNV and minimal neutralizing activity (IC₅₀ = 27.12 μg/mL). However, KJJ4, an engineered IgG4 antibody derived from clone 4–19 and carrying the S108P hinge mutation to prevent Fab-arm exchange, bound inactivated HTNV antigen and recombinant glycoprotein Gn (residues 19–371) in a dose-dependent manner, with only weak binding to Gc. Surface plasmon resonance yielded an association rate constant of 4.70 × 10³ M⁻¹s⁻¹, a dissociation rate constant of 3.06 × 10⁻³ s⁻¹, and an equilibrium dissociation constant of 650 nM for monomeric Gn_19–371. In a Vero E6 focus-reduction microneutralization assay, KJJ4 neutralized HTNV in vitro with an IC₅₀ of 2.879 μg/mL. These data establish KJJ4 as a fully human anti-HTNV antibody with experimentally defined in vitro binding and neutralizing activity, warranting further evaluation in animal models of HTNV infection. Full article

Lyme borreliosis (LB) is a tick-borne disease caused by a diverse and expanding group of spirochetes characterized by complex biology and advanced immune evasion mechanisms. It presents a wide range of clinical symptoms affecting multiple organ systems and can lead to persistent complications. The pathogenesis of LB remains incompletely understood, and diagnosis typically relies on serologic assays to detect antibodies against LB. However, the standard two-tiered testing (STTT) algorithm is limited by cross-reactivity, low sensitivity, and delayed results, hindering timely and accurate diagnosis. Although molecular tests are considered the gold standard, their reliance on centralized laboratories can delay critical treatment decisions. This underscores the urgent need for rapid, reliable diagnostic tools, particularly for use at the point of hospital admission. Point-of-care serological and direct antigen testing can provide actionable information, supporting decentralized healthcare systems in diagnosing complex diseases, such as LB. In this study, we developed two fluorescent polarization immunoassays (FPIAs) using IgM and IgG LB-specific synthetic epitopes/peptides to evaluate their diagnostic potential. These FPIAs showed high sensitivity and specificity in detecting IgM or IgG anti-LB antibodies in patient sera within minutes. The fluorescently labeled synthetic peptides produced significant polarization differences between infected and healthy samples, allowing clear discrimination. The FPIA-LB functions as a one-step assay, eliminating the need for secondary antibodies or complex protocols. This work highlights the FPIA technique as a robust, rapid, and efficient tool for LB diagnosis, offering a promising advance in improving early detection and patient outcomes, which could save lives and reduce long-term health complications. Full article

Background/Objectives: Cadherin-16 (CDH16, Ksp-cadherin) possesses unique seven extracellular cadherin repeats, and its expression is restricted to normal kidney epithelium. CDH16 is downregulated in renal cell carcinoma (RCC) and is associated with poor prognosis. Therefore, developing mAbs that specifically recognize cell-surface CDH16 is essential for tumor diagnosis and for isolating CDH16-positive renal epithelial cells. Methods: Anti-human CDH16 mAbs (designated as Ca₁₆Mabs) were developed by immunizing mice with CDH16-overexpressed tumor cells, followed by a high-throughput flow cytometry-based screening. Results: Among the 58 established Ca₁₆Mabs, a clone, Ca₁₆Mab-56 (IgG₁, κ), specifically recognized CDH16-overexpressed Chinese hamster ovary-K1 (CHO/CDH16) cells with no detectable cross-reactivity to 21 other CDHs in flow cytometry. Ca₁₆Mab-56 also detected endogenous CDH16 in human RCC cell lines (OS-RC-2 and KMRC-20) and normal kidney epithelial cell lines. The dissociation constant (K_D) values of Ca₁₆Mab-56 for CHO/CDH16 and OS-RC-2 were determined as 6.5 × 10⁻⁹ M and 1.2 × 10⁻⁹ M, respectively. Furthermore, Ca₁₆Mab-56 detected endogenous CDH16 by Western blotting and showed potent staining in normal kidney tubular epithelium and clear membranous staining in renal cell carcinoma in immunohistochemistry. Conclusions: Ca₁₆Mab-56 is a versatile tool for detecting CDH16 and has potential for tumor diagnosis. Full article

(1) Background: Brazil features one of the largest recycling workforces worldwide, with around 800,000 informal waste pickers, mostly living in urban areas of major cities and dealing with low income and precarious working conditions. This context of vulnerability may lead to a high risk of food insecurity, which may be associated with infectious diseases, particularly toxocariasis, a cosmopolitan neglected parasitic zoonosis with high seroprevalence in tropical countries. (2) Methods: Accordingly, this study assessed Toxocara spp. seropositivity and associated risk factors (including food insecurity) in recycling workers of Curitiba, a major Brazilian (fully urban) city currently ranked 8th in population with 1.83 million habitants, 7th in Gross Domestic Product (GDP), and 10th in Human Development Index (HDI) with 0.823 (very high), out of 5569 Brazilian cities. Recycling and non-recycling (used as population control) workers living in the same neighborhood were invited, voluntarily signed consent forms, and had blood serum samples collected and tested by ELISA for detecting anti-Toxocara spp. (IgG) antibodies; in addition, an epidemiological questionnaire (socioeconomic characteristics, owning dog/cat, food and hygiene habits) was applied. (3) Results: Overall, 95/177 (53.7%) recycling and 38/100 (38.0%) non-recycling workers tested positive by ELISA, with recycling workers more likely seropositive than non-recycling population (53.7% vs. 38.0%; OR: 1.89; 95% CI: 1.15–3.12%). Food insecurity (OR = 2.01, 95% CI: 1.04–3.91) and low (<1 minimum wage) monthly household income (OR = 3.03, 95% CI: 1.01–9.71) were associated with Toxocara spp. seropositivity by multivariate analysis. As expected, cohabitation with both dogs and cats was also significantly associated with seropositivity (OR = 3.75, 95% CI: 1.48–9.75). However, other assessed variables (gender, age, ethnicity, hygienic habits, contact with soil, raw meat ingestion) were not associated with seropositivity. (4) Conclusions: The study herein has filled a gap regarding toxocariasis in vulnerable populations and suggests food insecurity as a socioeconomic indicator for Toxocara spp. seropositivity in recycling workers. Furthermore, recycling workers are at higher risk of infection and, as such, need to be prioritized in healthcare programs. Full article

Rabbit monoclonal antibodies (RabMAbs) are valuable for biomedical research and diagnostic applications because of their high affinity, specificity, and broad epitope recognition; here, we established an integrated phenotype-linked workflow for rapid RabMAb discovery using serum-derived polyclonal mouse IgG as a proof-of-concept model antigen. Three Big-Eared White rabbits were immunized in parallel, and the rabbit exhibiting the highest serum endpoint titer was selected for the complete downstream single-B-cell discovery workflow. Approximately 5 × 10⁵ activated B cells were subjected to polydisperse oblate dispersion system (POD)-based screening, yielding 13,266 antigen-positive POD events. Following recovery and 10× Genomics single-cell V(D)J sequencing, 4294 B-cell barcodes yielded valid/interpretable V(D)J data, of which 2099 contained at least one complete, productive, and translatable heavy-chain/light-chain pair, generating 2199 functional VH/VL pairing records. AbFinder™-assisted prioritization generated a computationally recommended pool of 158 candidates, and the five highest-ranked VH/VL pairs within this pool were selected for recombinant expression and validation. All five yielded antigen-reactive RabMAbs with an endpoint ELISA titer of 1:256,000 and BLI-derived apparent K_D values ranging from 4.19 × 10⁻¹⁰ to 9.79 × 10⁻⁹ M. The antibodies showed differential concentration-dependent reactivity toward mouse IgG1, IgG2a, IgG2b, and IgG3 preparations, weak reactivity toward human IgG, and clone-dependent reactivity toward rat IgG. The workflow from spleen collection to functional validation was completed within approximately three weeks. Because only five prioritized candidates from one selected responder rabbit were evaluated, the 5/5 validation outcome should not be interpreted as an overall platform hit rate or definitive validation of the prioritization algorithm. These findings support the feasibility of this workflow for research-grade and diagnostic antibody discovery, while broader evaluation will require larger candidate cohorts, independent biological validation, and additional antigen classes. Full article

Many people are affected by difficult-to-understand clinical phenomena associated with acute SARS-CoV-2 infection and by post-acute sequelae of COVID-19 (PASC, or long COVID, LC). The mechanisms responsible for the clinical phenomena have not been well established. The host cell receptor for SARS-CoV-2 is human angiotensin-converting enzyme 2 (ACE2), which binds the SARS-CoV-2 spike protein receptor-binding domain (RBD) to initiate infection. We hypothesized that some people may produce anti-RBD antibodies that sufficiently resemble ACE2 structure to have ACE2-like catalytic activity after infection, and such antibodies are hypothesized to contribute to disease pathogenesis. Our previous studies showed that ACE2-like catalytic activity was associated with immunoglobulin in some acute and convalescent COVID-19 patients. ACE2-like catalytic activity correlated with blood pressure changes following a moderate exercise challenge in people convalescing from COVID-19. To further establish that ACE2-like catalytic activity could be attributed to antibodies, we screened human monoclonal antibodies (mAbs) against SARS-CoV-2 spike protein from three different research centers and others purchased from a commercial source for ACE2-like catalytic activity. We identified four human monoclonal antibodies with ACE2-like catalytic activity. The ACE2-like catalytic activity of these mAbs was not inhibited by MLN-4760, a compound that inhibits native human ACE2 catalytic activity, nor by EDTA, unlike native ACE2, a zinc metalloprotease, but was inhibited by an overlapping pool of spike peptides. Enzyme kinetic studies showed that the mAbs had substantially lower Vmax and K_m values than native ACE2, consistent with the characteristics of other catalytic antibodies. The data therefore suggested that the antibodies cleave ACE2 substrate via a mechanism different from native ACE2. The identification of specific mAbs with ACE2-like catalytic activity supports the hypothesis that antibodies induced by SARS-CoV-2 infection could help mediate the pathogenesis of COVID-19 and LC, and, more generally, the hypothesis that catalytic antibodies induced by infectious agents can contribute to disease pathogenesis. Full article

Background/Objectives: Antiphospholipid antibodies (aPL) comprise anticardiolipin antibodies (aCL), antibodies against β2 glycoprotein I (anti-β2GPI) and lupus anticoagulant (LA). LA is an established risk factor for thrombosis and pregnancy morbidity in the general population. In people with type 1 diabetes (T1D), aPL have been proposed as potential predictors of microvascular and macrovascular diabetes-related complications. The aim of the present prospective, observational study was to investigate the prevalence of aPL in a well-defined cohort of adults presenting with uncomplicated T1D compared with healthy controls. In addition, we prospectively examined whether aPL titers or positivity were potentially associated with the subsequent development of diabetes-related complications. Methods: Two hundred (200) adults with T1D and without microvascular or macrovascular complications participated (mean age, 37.9 ± 10.6 years; mean diabetes duration, 21.00 ± 9.20 years). We also included 200 age- and sex-matched healthy controls (mean age, 37.7 ± 10.1 years) without diabetes mellitus or other autoimmune diseases. The aPL panel, including aCL ΙgG/IgM, anti- β2GPI IgG/IgM, and LA, was assessed using standardized laboratory methods. Participants with T1D were re-evaluated after a mean follow-up of 7.6 years. Results: Titers of aCL IgG/IgM and anti-β2GPI IgG, as well as positivity of aCL-IgG and aCL-IgM, were higher in participants with T1D compared with healthy controls, whereas LA positivity was very low in both groups. In the T1D group, aCL-IgG titers significantly correlated with age and diabetes duration. Neither aCL-IgG titers nor positivity was associated with the development of microvascular or macrovascular complications or with all-cause mortality during follow-up. Conclusions: In adults with long-standing, uncomplicated T1D, most aPL titers and positivity rates were higher than those observed in healthy controls. However, aCL-IgG titers and positivity were not associated with the subsequent development of diabetes-related complications. Larger prospective studies are required to determine whether aPL have predictive value for diabetes-related complications and to identify subgroups of people with T1D who may benefit from aPL testing. Full article

The G protein-coupled receptor, CXC chemokine receptor 5 (CXCR5), is predominantly expressed on B cells located in the secondary lymphoid tissues, follicular helper T cells, and lymphoma cells. Binding to its ligand, CXCL13, mediates cell migration and regulates lymphocyte trafficking. Aberrant CXCL13/CXCR5 expression and signaling have been implicated in tumor progression, autoimmune diseases, and chronic inflammatory disorders. Therefore, specific mAbs against CXCR5 are expected to be useful for diagnosis and therapeutic applications. In this study, novel anti-human CXCR5 mAbs (Cx₅Mabs) were developed through flow cytometry-based high-throughput screening. One clone, Cx₅Mab-6 (IgG_2b, κ), recognized CXCR5-overexpressed Chinese hamster ovary (CHO)-K1 cells but did not react with the other five CXCR receptors-overexpressed CHO-K1 cells in flow cytometry. Additionally, Cx₅Mab-6 recognized endogenous CXCR5 in the human Burkitt lymphoma Raji cell line. The dissociation constant (K_D) values of Cx₅Mab-6 for CHO/CXCR5 and Raji were 3.4 × 10⁻⁹ M and 1.2 × 10⁻¹⁰ M, respectively. Furthermore, Cx₅Mab-6 is useful for Western blotting and can detect CXCR5 in human lymphoma tissue by immunohistochemistry. These findings suggest that Cx₅Mab-6 is versatile for basic research and has potential applications in clinical diagnosis. Full article

Background/Objectives: Maternal antibodies can inhibit vaccine-specific humoral responses in early life, leaving infants at increased risk for severe disease for vaccine-preventable infections. In the case of SARS-CoV-2, infants under the age of 3 months represented most child hospitalizations, yet there is no approved vaccine for children under the age of 6 months. There is a clear need for effective immunization in early life to prevent infant morbidity and mortality. Here, we established a mouse model to define how maternally derived antibodies shape early-life responses to mRNA vaccination. Methods: Adult female mice were immunized with PBS or 5 mcg of the SARS-CoV-2 mRNA-1273 vaccine via intramuscular injection and paired with a male. Pups from subsequent litters were immunized with PBS or 5 mcg of mRNA-1273 vaccine via intramuscular injection. Peripheral blood and spleens were collected at time points post-immunization. We measured vaccine-elicited anti-Spike IgG in mouse pups exposed or unexposed to vaccine-specific maternal IgG. Results: Spike-specific maternal IgG is detectable at high levels immediately after pup immunization or mock immunization; however, in mock immunized pups, it wanes by three weeks post-pup immunization. Pups born to immunized dams developed Spike specific IgG comparable to pups born to naïve dams. IgG subclass analyses distinguished passively acquired antibodies from vaccine-induced responses. Despite robust binding antibody responses, neutralizing activity against D614G pseudovirus was heterogeneous and did not scale proportionally with IgG titers, showing qualitative differences in early-life humoral immunity. Splenic Spike-specific B cell frequencies and T follicular helper (Tfh) cell responses were detectable in vaccinated pups irrespective of maternal immunization status, with Tfh cell frequencies peaking at day 7 post-immunization in both groups. Conclusions: Using SARS-CoV-2 as a model pathogen, we found that early-life mRNA vaccination can elicit humoral immune responses in the presence of maternal antibodies. Furthermore, the presence of maternal antibody did not inhibit the development of antigen-specific B cells or Tfh cells in the spleen. Our findings support the potential of extending vaccination strategies into early infancy and provide a framework for optimizing mRNA-based vaccine timing and design in the context of maternal immunity. Full article

Background and Objectives: Convalescent plasma (CP) was widely used during the early phase of the COVID-19 pandemic; however, evidence regarding its clinical benefit has remained inconsistent. This study evaluated the associations of CP administration timing and the ELISA antibody level of the transfused unit with clinical outcomes among patients with COVID-19. Materials and Methods: This retrospective real-world cohort study included 272 adults with RT-PCR-confirmed COVID-19 who received a single CP unit at the University of Health Sciences Trabzon Kanuni Training and Research Hospital, Türkiye, between 1 April 2020 and 1 April 2021. At CP administration, 180 patients were hospitalized, and 92 were treated as outpatients; initial cohort assignment was retained throughout follow-up. Anti-SARS-CoV-2 IgG was assessed using the semi-quantitative Euroimmun ELISA, and exploratory low (0.00–0.99), medium (1.00–4.99), and high (≥5.00) categories were used. The primary outcome was 30-day all-cause mortality. Results: During follow-up, 18 of 92 outpatients (19.6%) required hospitalization. Thirty-day mortality was higher among hospitalized patients than among outpatients (39.4% vs. 1.1%; p < 0.001), reflecting major baseline clinical differences between the groups. Median ELISA indices did not differ significantly between hospitalized patients and outpatients [4.23 (IQR, 2.65–6.43) vs. 3.64 (IQR, 2.16–6.13); p = 0.308]. Among hospitalized patients, ELISA-index distributions were similar between survivors and non-survivors (p = 0.427), and the index was not associated with mortality when analyzed continuously after log2 transformation (OR per doubling, 0.89; 95% CI, 0.67–1.19; p = 0.425). The high-versus-medium category comparison was also non-significant (OR, 0.88; 95% CI, 0.48–1.62; p = 0.757), as was the timing-by-ELISA interaction (p = 0.074). Conclusions: In this CP-treated cohort, the ELISA index of the transfused unit was not independently associated with 30-day mortality. The exploratory subgroup findings do not establish CP effectiveness or superiority of a particular timing or antibody-level category. Full article

Soluble variants of recombinant T cell receptors (TCRs) have become attractive tools for the retargeting of cytotoxic T cells toward intracellular tumor or viral antigens by combining them with CD3-binding antibodies in bispecific T cell engagers; however, TCR-based NK cell engagers have not been studied so far. Here, we developed TCR-based bispecific agents for the redirection of NK cells utilizing a bivalent IgG1-like format. Trifunctional NK engagers included an Fc part with enhanced binding to FcγRIII/CD16A and single-chain (scFv) antibodies recognizing either NKp46 or CD16A, activating NK cell receptors. HCMV pp65/HLA-A2 reactive TCR-scFv-Fc fusion proteins incorporating an affinity-matured TCR and anti-NKp46 scFv activated peripheral blood NK cells and induced cytotoxicity in an antigen-specific manner. For T cell redirection, TCR-scFv-Fc fusion proteins included an scFv antibody recognizing CD3ε. Compared with NK cell engagers, T cell engagers showed similar sensitivity but lower peptide selectivity. For two TCRs recognizing melanoma-associated peptides, affinity-matured TCR-scFv-Fc fusion proteins enabled NK and T cell redirection and activation, and killing of tumor target cells loaded with exogenous peptides. Our results expand the versatility of the soluble TCR technology to NK cell engagers; however, they still require improvement in sensitivity to target tumor cells with low peptide/MHC-I complex densities. Full article

Background/Objectives: Therapeutic antibodies have become an important modality for cancer treatment; however, effective targeted antibody therapies for T-cell acute lymphoblastic leukemia (T-ALL) remain limited. CD99 is a promising therapeutic target due to its high expression in leukemic T cells and its capacity to transmit apoptotic signals. However, the efficacy of antibody-mediated apoptosis may depend on the CD99 region recognized by the antibody. This study compared the in vitro apoptotic activity of two chimeric anti-CD99 antibodies, ChAbMT99/1 and ChAbMT99/3, which recognize distinct regions of CD99 in T-ALL models. Methods: ChAbMT99/1 and ChAbMT99/3 were generated as human IgG1 antibodies. Antibody reactivity and binding site specificity were characterized using peptide-based ELISA. Binding to native CD99, apoptosis induction in two-dimensional (2D) Jurkat E6.1 and MOLT-4 suspension cultures and three-dimensional (3D) Jurkat E6.1-derived spheroid models, and cytotoxic effects on peripheral blood mononuclear cells (PBMCs) were assessed by flow cytometry. In vitro hematologic effects were assessed using hemagglutination and platelet aggregation assays. Results: ChAbMT99/1 and ChAbMT99/3 specifically recognized peptides corresponding to distinct CD99 regions, with peptide-binding EC₅₀ values of 0.813 and 0.819 μg/mL, respectively. Both antibodies exhibited binding reactivity to native CD99 on the tested cells. Functionally, both antibodies induced Annexin V/7-AAD-defined cell death in both 2D and 3D T-ALL models compared with controls in a crosslinking-dependent manner. In contrast, both antibodies induced low levels of cell death (<10%) in bulk PBMCs, with no visible hemagglutination or platelet aggregation observed in samples from five selected donors under the stated assay conditions. Conclusions: Both chimeric anti-CD99 antibodies demonstrated in vitro apoptotic activity against T-ALL models despite recognizing distinct regions of CD99. These findings provide a rationale for further investigation of their other mechanisms of action to support the future development of CD99-targeted antibody therapy for T-ALL. Full article

Strongyloidiasis is a neglected, potentially lifelong disease caused by Strongyloides stercoralis that can lead to a high mortality rate in immunocompromised hosts; therefore, it is necessary to increase the accuracy of infection diagnosis. In the current study, we used Wistar rats experimentally infected with different burdens of Strongyloides venezuelensis to characterize circulating leukocytes and IgM, IgG, IgG1, IgG2a, and IgA reactivity before and after anthelmintic treatment or immunosuppression. Infection, especially with 500 L3, induced an increase in circulating leukocytes, particularly during the acute phase. Animals treated with ivermectin showed complete elimination of the parasite and an early reduction in circulating eosinophils. The production of IgM, IgG, and IgG1 anti-L3 (infective larvae) and anti-Sv (adult worm) antigens was significantly elevated in all infected groups but did not allow differentiation between cured and infected animals. Treatment with dexamethasone delayed worm elimination and temporarily reduced cellular response and parasite-specific IgG production but did not alter IgM reactivity. IgG2a anti-L3 and anti-Sv reactivity showed a progressive reduction, returning to baseline levels in ivermectin-treated rats. IgA anti-ES/L3 (excretory and secretory larval antigens) reactivity significantly decreased in intestinal wash after parasitological cure. These data would help the development of more efficient immunodiagnostic alternatives for human strongyloidiasis based on antibody isotype reactivity. Full article