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Heart transplant patients are at an increased risk of COVID-19 infection adverse outcomes because of underlying immunosuppression and concomitant comorbidities. To date, all large-scale randomized controlled trials for various COVID-19 vaccines have excluded solid organ transplant recipients. Therefore, the efficacy and safety of coronavirus infection prevention using COVID-19 vaccines in transplant heart patients has not been sufficiently studied. In this research, the evaluation of virus-specific immunological reactions after vaccination (double Vero Cell vaccination and Sputnik Light booster vaccination) in heart transplant patients has been carried out. In vaccinated heart transplant individuals who did not have a history of COVID-19, starting from 4–6 months after the 2nd dose of the vaccine, an increase in antibodies to S protein level of was observed, while maintaining statistically significant differences for 9–12 months after vaccination (regardless of whether with or without booster vaccination). However, the concentration of antibodies remained low, and 37% of patients detected no antibodies. In vaccinated heart transplant individuals following the previous COVID-19 infection, as compared to seronegative patients, post-vaccination immunity is accompanied by maintaining a high level of virus-specific IgG antibodies to the S protein of the SARS-CoV-2 virus in the dynamics of the post-vaccination period with a statistically significant increase of these antibodies by 9–12 months after booster vaccination. The specific cellular response (according to the assessment of CD3⁺154⁺ and CD3⁺IFNγ⁺ TNFα⁺ cells) to the S protein of the SARS-CoV-2 virus remained low throughout the entire follow-up period, was recorded in 5–40% of heart transplant patients and statistically significant changes in the number of spikereactive lymphocytes were observed in patients with a history of COVID-19 by 4–6 months after administration of the 2nd dose of the vaccine. This, together with the results of the assessment of the humoral response, indicates a more pronounced post-vaccination immunity in patients with a hybrid immunity. While developing a methodology for assessing the risk and benefit of a vaccination strategy for individual heart transplant patients, clinical efficacy, ongoing monitoring of rare serious adverse events, and data on vaccine immunogenicity should be taken into account.

Postmortem diagnosis of enzootic bovine leukosis is made on the basis of the results of tests of biological materials from emergently slaughtered or fallen animals using pathomorphological, histological and molecular genetic methods that have some disadvantages. Results of post-slaughter diagnostic tests for bovine leukosis with enzyme-linked immunosorbent assay are described in the paper. For this purpose, 83 swabs were collected from different carcass parts including 71 swabs from carcasses of the animals that were not pre-slaughter tested and 12 samples from the carcasses of the animals that were pre-slaughter tested with immunodiffusion assay and found bovine leukemia virus-seronegative (control samples). Sterile scalpels, cotton wool, 5 mL tubes with caps were used for swab collection. The samples were taken from incisions in carcasses and internal organs of slaughtered animals with sterile cotton-wool swabs and placed in single-use tubes. Distilled water (or isotonic solution – 0.85% NaCl) was added to the tubes with samples, 0.1 to 0.2 mL per tube depending on the sample size, and the tubes were left at room temperature (22–26 °С) for 1.5–2.0 hours and regularly shaken. Resulting homogeneous substrate was used for enzyme-linked immunosorbent assay carried out in accordance with the instructions for the test-kit for detection of antibodies against bovine leukemia virus. Specific antibodies to bovine leukemia virus gp51 antigen were detected in 6 (8.5%) out of 71 swabs subjected to the laboratory tests. Therewith, the antibodies were detected only in 3 swabs (4.2%) when the swabs were tested with immunodiffusion assay. All 12 control samples from animals that were pre-slaughter tested and found seronegative were negative when tested with enzyme-linked immunosorbent assay. Therefore, the above-said serological method can be used for post-slaughter diagnosis of bovine leukosis together with conventional methods.

The role of Mycoplasma canis in canine fertility disorders is still poorly understood. As infection is often asymptomatic, there is an increasing need for appropriate diagnostic methods and treatment plans that would allow the reliable detection of M. canis infection and rapid alleviation of infection symptoms in affected dogs. In this study, we included 14 dogs with fertility problems and 16 dogs without fertility disorder signs. We compared clinical examination data and selected laboratory parameters (hematology and biochemistry) between the groups. We performed PCR-based detection of M. canis and 16S rRNA gene-based microbiota profiling of DNA isolated from vaginal and preputial swabs. Dog sera were tested for the presence of M. canis-specific antibodies. Hematological and selected biochemical parameters showed no differences between groups. PCR-based detection of M. canis in the samples was consistent with the results of 16S microbiota profiling. Several other bacterial taxa were also identified that could potentially be involved in different fertility disorders. Serological methods were not accurate enough since high cross-reactivity rates were observed. In the future, more accurate and efficient methods will be needed to determine the role of M. canis and its true role in the pathogenesis of specific fertility disorders in dogs. [ABSTRACT FROM AUTHOR]

Many pathogens are related to carcinogenesis. Chronic inflammation, as a result of persistent infection, leads to DNA damage, higher expression of oncogenes, decreased apoptosis and immunosuppression, which are some of the reasons for cancer induction. Among parasites, Schistosoma, Opistorchis and Clonorchis are recognised as infectious agents which contribute to cancer. A relationship between Anisakis and cancer was hypothesised because cellular responses to Anisakis products could result in inflammation and DNA damage. Previous research has shown a decrease in CD8+ γδ T-cells and an increase in αβ and γδ T-cell apoptosis in colon cancer (CC) samples. Ninety-two CC patients and 60 healthy subjects were recruited. γδ and αβ T-cells were analysed, and their apoptosis was evaluated. Anti-Anisakis antibodies were tested in sera from CC patients and controls. Anti-Anisakis IgG, IgM, IgA and IgE antibodies were significantly higher in CC patients. A significant increase in anti-Anisakis IgA levels was observed in patients with angiolymphatic invasion. The number of all γδ T-cells, as well as CD3+ CD4+ αβ T-cells, was significantly lower in CC patients. The apoptosis of all T-cells was significantly increased in patients with CC. We observed a significantly higher percentage of anti-Anisakis IgE positive patients having a deficit of CD3+ γδ T-cells. Our results suggest a relationship between Anisakis and CC. [ABSTRACT FROM AUTHOR]

Background and Aim: Salmonella abortion in mares is caused by Salmonella enterica subspecies enterica serovar abortus equi infection and is characterized by premature (abortion) or non-viable fetus birth. Although all horses are susceptible to infection, the condition is more often clinically manifested in pregnant mares, with most abortions recorded in young females. In addition, nonspecific clinical disease signs and poorly sensitive and effective bacteriological diagnostic methods hinder rapid and reliable infection diagnoses. Immunochemical methods such as enzyme-linked immunosorbent assay (ELISA) and immunochromatography assays can facilitate effective and rapid diagnoses. However, they require highly specific and active antigens and antibodies. This study aimed to generate a recombinant S. enterica outer membrane protein X (OmpX) and evaluate its suitability for serological diagnosis of Salmonella abortion in mares. Materials and Methods: Outer membrane protein X from the S. enterica antigen was synthesized de novo and expressed in Escherichia coli using the pET28 vector. Transformed E. coli cells were cultured under different conditions to detect recombinant OmpX (rOmpX) expression, and rOmpX purification and refolding were both conducted using metal affinity chromatography. Refolded and purified rOmpX was characterized by western blotting, liquid chromatography with tandem mass spectrometry, and ELISA. Results: After optimized rOmpX expression, a 23 kDa molecular weight protein was identified. Amino acid sequence analysis using Mascot program suggested that these peptides were the OmpX protein from S. enterica. High specificity and diagnostic efficiency were recorded when rOmpX was used in ELISA against 89 serum samples from aborted and contact mares. Conclusion: Recombinant outer membrane protein, in comparison to the O antigen, demonstrated better diagnostic characteristics against sera from mares who aborted and contact horses. [ABSTRACT FROM AUTHOR]

The implementation of animal health improvement and disease prevention activities with respect to bovine leukosis involves a need for timely detection of cattle infected with bovine leukaemia virus (BLV) on livestock farms. That is why early diagnosis using more sensitive and highly accurate methods is of particular importance. The paper presents the results of cattle serum tests for bovine leukosis with enzyme-linked immunosorbent assay (ELISA) and immunodiffusion (ID), as well as the comparative assessment of their effectiveness. A total of 440 cattle blood samples were subjected to serological testing with immunodiffusion; 37 (8.4%) of them tested positive for bovine leukaemia virus. The cattle blood samples were submitted from the Kumtorkalinsky (127), Karabudakhkentsky (122), Buynaksky (89) Raions, from Makhachkala (56) and Kaspiysk (46). Seropositivity was 17 (13.4%), 8 (6.6%), 5 (5.6%), 4 (7.1%) and 3 (6.5%), respectively. For the comparative assessment of the diagnostic tests, 100 (5 ID-positive and 95 ID-negative) serum samples were taken and tested with ELISA. As a result, specific antibodies against BLV gp51 antigen were detected in 4 ID-negative serum samples. All ID-positive serum samples also tested positive with ELISA. All in all 9 virus carriers were detected with ELISA, that is 44.4% more than with immunodiffusion. Thus, enzyme-linked immunosorbent assay is characterized by a higher sensitivity, as compared with immunodiffusion, and allows for improved detection of infected animals. However, alongside the advantages, this technique has certain disadvantages, one of which is the high price of the diagnostic test kit for anti-BLV antibody detection and the equipment required.

Background. There are many aspects of the development of immunity to the SARSCoV-2 virus, that remain poorly understood, like the influence of age-related characteristics on the intensity of immunity and the course of the disease. Studies of the state of immunity are widely used, mainly in the adults. But questions of the patho- and immunogenesis in children remain unsolved. Determining the nature of seroconversion of antibodies to SARS-CoV-2 in this age group is important information for serological monitoring for targeted immunoprophylaxis of the population and forecasting the epidemic situation in the region.The aim. Evaluation of the dynamics of seroprevalence of specific antibodies to SARS-CoV-2 in children of the Irkutsk region during the pandemic of a new coronavirus infection.Materials and methods. Study was conducted among the child population of the Irkutsk region in the period June 2020 – December 2021 as part of the Rospotrebnadzor project to assess population immunity to SARS-CoV-2 in the population of the Russian Federation. The content of antibodies to SARS-CoV-2 was determined by ELISA using native commercial test systems.Results. Population immunity among the child population of the Irkutsk region was characterized by an upward trend from 7.8 % at stage 1 to 98.4 % at stage 6 of the study. IgG to SARS-CoV-2 remained in 72.8 % and formed in 25.6 % of previously seronegative children. Antibodies were detected in 66.1 % of cases and persisted for up to 10–15 months after COVID-19 infection. The proportion of asymptomatic forms of infection among seropositive volunteers was 69.5 %, which determines the high intensity of the latent epidemic process.Conclusion. The level of seroprevalence was 98.4%. The current results of serological monitoring serve as a scientific basis for adjusting the list and scope of management decisions on the organization of preventive anti-epidemic measures, including vaccination.

Introduction. Yellow fever (YF) remains one of the most common natural focal infectious diseases in the world. In connection with the increasing tourist flow to countries endemic for YF, the discovery of stable populations of Aedes aegypti and Ae. albopictus which are the main vectors of the yellow fever virus (YFV), in the southern regions of Russia, and the fact that in medical institutions in our country it is possible to obtain a live attenuated vaccine against YF, but there is no way to evaluate the effectiveness of vaccination, the question arises of the development and implementation of diagnostic kits for detecting antibodies (AB) to the pathogen by enzyme immunoassay (ELISA). The aim of this study was to develop a method for detecting specific IgG antibodies to the E protein of YFV by ELISA and assessing its diagnostic characteristics. Materials and methods. A specific cDNA was synthesized by reverse transcription on an RNA template of YFV isolated on a cell culture of Aedes albopictus clone C6/36, and a fragment of the genome coding the YFV E protein was amplified and subsequently cloned into the plasmid pET160 (Thermo Fisher Scientific, USA). The resulting gene fragment was used as a DNA template to obtain a recombinant analog of the third domain of the YFV E protein in Escherichia coli cells (BL-21(DE3)). Next, the immunogenicity of the obtained antigen was evaluated and the analysis conditions were optimized. Results. The optimal conditions for the production of the obtained recombinant E protein of YFV were determined, its specificity was confirmed by immunological methods (Western blot and ELISA), sorption buffers and blocking solutions were selected, and sensitivity and specificity of detection of antibodies to YFV using the recombinant antigen were assessed. Conclusion. A method for the detection of specific IgG antibodies to the YFV E protein by ELISA was developed. This diagnostic kit can be used both to study the protective properties of the YF vaccine and to detect imported cases of infection in non-endemic areas.

ABSTRACT In the situation of mass vaccination against COVID-19, few studies have reported on the early kinetics of specific antibodies (IgG/IgM/IgA) of vaccine breakthrough cases. There is still a lack of epidemiological evidence about the value of serological indicators in the auxiliary diagnosis of COVID-19 infection, especially when the nucleic acid results were undetectable. Omicron breakthrough cases post-inactivated vaccination (n = 456) and COVID-19-naive individuals with two doses of inactivated vaccination (n = 693) were enrolled. Blood samples were collected and tested for SARS-CoV-2 antibody levels based on the magnetic chemiluminescence enzyme immunoassay. Among Omicron breakthrough cases, the serum IgG antibody level was 36.34 Sample/CutOff (S/CO) (95% confidence interval [CI], 31.89 to 40.79) in the acute phase and 88.45 S/CO (95% CI, 82.79 to 94.12) in the recovery phase. Serum IgA can be detected in the first week post-symptom onset (PSO) and showed an almost linear increase within 5 weeks PSO. Compared with those of breakthrough cases, IgG and IgA titers of the postimmune group were much lower (4.70 S/CO and 0.46 S/CO, respectively). Multivariate regression showed that serum IgG and IgA levels in Omicron breakthrough cases were mainly affected by the weeks PSO (P

In this article, we report the development of an electrochemical biosensor for the determination of the SARS-CoV-2 spike protein (rS). A gold disc electrode was electrochemically modified to form the nanocrystalline gold structure on the surface. Then, it was further altered by a self-assembling monolayer based on a mixture of two alkane thiols: 11-mercaptoundecanoic acid (11-MUA) and 6-mercapto-1-hexanol (6-MCOH) (SAMmix). After activating carboxyl groups using a N-(3-dimethylaminopropyl)-N'-ethyl-carbodiimide hydrochloride and N-hydroxysuccinimide mixture, the rS protein was covalently immobilized on the top of the SAMmix. This electrode was used to design an electrochemical sensor suitable for determining antibodies against the SARS-CoV-2 rS protein (anti-rS). We assessed the association between the immobilized rS protein and the anti-rS antibody present in the blood serum of a SARS-CoV-2 infected person using three electrochemical methods: cyclic voltammetry, differential pulse voltammetry, and potential pulsed amperometry. The results demonstrated that differential pulse voltammetry and potential pulsed amperometry measurements displayed similar sensitivity. In contrast, the measurements performed by cyclic voltammetry suggest that this method is the most sensitive out of the three methods applied in this research. [ABSTRACT FROM AUTHOR]

This study aimed at investigating the influence of genetic and non‐genetic factors on immune traits to inform on possibilities of genetic improvement of disease resistance traits in local chicken of Kenya. Immune traits such as natural and specific antibodies are considered suitable indicators of an individual's health status and consequently, used as indicator traits of disease resistance. In this study, natural antibodies binding to Keyhole Limpet Hemocyanin (KLH‐NAbs) was used to measure general disease resistance. Specific antibodies binding to Newcastle disease virus (NDV‐IgG) post vaccination was used to measure specific disease resistance. Titers of KLH‐NAbs isotypes (KLH‐IgM, KLH‐IgG and KLH‐IgA) and NDV‐IgG were measured in 1,540 chickens of different ages ranging from 12 to 56 weeks. A general linear model was fitted to determine the effect of sex, generation, population type, phylogenetic cluster, line, genotype and age on the antibody traits. A multivariate animal mixed model was fitted to estimate heritability and genetic correlations among the antibody traits. The model constituted of non‐genetic factors found to have a significant influence on the antibody traits as fixed effects, and animal and residual effects as random variables. Overall mean (±SE) concentration levels for KLH‐IgM, KLH‐IgG, KLH‐IgA and NDV‐IgG were 10.33 ± 0.04, 9.08 ± 0.02, 6.00 ± 0.02 and 10.12 ± 0.03, respectively. Sex, generation and age (linear covariate) significantly (p < 0.05) influenced variation across all the antibody traits. Genotype effects (p < 0.05) were present in all antibody traits, apart from KLH‐IgA. Interaction between generation and line was significant (p < 0.05) in KLH‐IgM and NDV‐IgG while nesting phylogenetic cluster within population significantly (p < 0.05) influenced all antibody traits, apart from KLH‐IgA. Heritability estimates for KLH‐IgM, KLH‐IgG, KLH‐IgA and NDV‐IgG were 0.28 ± 0.08, 0.14 ± 0.06, 0.07 ± 0.04 and 0.31 ± 0.06, respectively. There were positive genetic correlations (0.40–0.61) among the KLH‐NAbs while negative genetic correlations (−0.26 to −0.98) were observed between the KLH‐NAbs and NDV‐IgG. Results from this study indicate that non‐genetic effects due to biological and environmental factors influence natural and specific antibodies and should be accounted for to reduce bias and improve accuracy when evaluating the traits. Subsequently, the moderate heritability estimates in KLH‐IgM and NDV‐IgG suggest selection possibilities for genetic improvement of general and specific immunity, respectively, and consequently disease resistance. However, the negative correlations between KLH‐NAbs and NDV‐IgG indicate the need to consider a suitable approach that can optimally combine both traits in a multiple trait selection strategies. [ABSTRACT FROM AUTHOR]

The serologic diagnosis of coronavirus disease 2019 (COVID-19) and the evaluation of vaccination effectiveness are identified by the presence of antibodies specific to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this paper, we present the electrochemical-based biosensing technique for the detection of antibodies specific to the SARS-CoV-2 proteins. Recombinant SARS-CoV-2 spike proteins (rSpike) were immobilised on the surface of a gold electrode modified by a self-assembled monolayer (SAM). This modified electrode was used as a sensitive element for the detection of polyclonal mouse antibodies against the rSpike (anti-rSpike). Electrochemical impedance spectroscopy (EIS) was used to observe the formation of immunocomplexes while cyclic voltammetry (CV) was used for additional analysis of the surface modifications. It was revealed that the impedimetric method and the elaborate experimental conditions are appropriate for the further development of electrochemical biosensors for the serological diagnosis of COVID-19 and/or the confirmation of successful vaccination against SARS-CoV-2. [ABSTRACT FROM AUTHOR]

We performed a seroepidemiological survey of the level and structure of population immunity to SARS-CoV-2 among employees of medical institution in the Irkutsk region during the COVID-19 pandemic. Seroprevalence assessment was organized from May 2020 to April 2021. The level of antibodies to SARS-CoV-2 was measured by ELISA. It was found that 139 (46%) of 299 examined workers were seropositive, including 50 (36%) vaccinated against COVID-19, 75 (54%) patients diagnosed with COVID-19, and 14 (10%) asymptomatic cases of SARS-CoV-2. The results obtained should be taken into account when predicting the dynamics of the epidemic process and organizing preventive (antiepidemic) measures, including vaccination. [ABSTRACT FROM AUTHOR]

Understanding how older people respond to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is critical if we are to confront the coronavirus disease 2019 (COVID-19) pandemic and establish effective vaccination strategies. Immunosenescence reduces the ability to respond to neoantigens and may compromise the life of infected individuals. Here, we analyzed the immunological memory to SARS-CoV-2 in 102 recovered patients aged over 60 years several months after the infection had been resolved. Specific memory T lymphocytes against the virus were measured by interferon-γ (IFN-γ) and granzyme B release by ELISpot; memory B-lymphocyte responses were quantified by detection of anti-S IgG1 producer cells by ELISpot and anti-S and anti-N antibodies were determined by enzyme-linked immunosorbent assay (ELISA). Memory T lymphocytes were found in peripheral blood of most of the studied donors, more than 7 months after the infection in some of them. Fewer patients maintained memory B lymphocytes, but antibodies, mainly anti-S, were highly durable and positively correlated with T responses. More robust humoral responses were found in patients who had more severe symptoms and had been admitted to hospital. We concluded that specific immunity against SARS-CoV-2 is effectively preserved regardless of age, despite the great heterogeneity of their immune responses, and that memory T lymphocytes and anti-S IgG might be more durable than memory B cells and anti-N IgG. [ABSTRACT FROM AUTHOR]

Fasciola hepatica is the causative agent of fasciolosis, a significant parasitic disease occurring worldwide. Despite ongoing efforts, there is still no vaccine to control liver fluke infections in livestock. Recently, it has been suggested that natural antibodies (NAbs) can amplify specific antibodies (SpAb) and have a direct killing effect, but it is unknown if this phenomenon occurs during parasitic helminth infection or targeted vaccination. NAbs are antibodies produced by the innate immune system, capable of binding antigens without prior exposure. This study explores the role of bovine NAbs, using the exogenous glycoprotein keyhole limpet hemocyanin (KLH), in response to F. hepatica infection and SpAb production after infection and vaccination. The cattle’s NAbs were differently influenced by parasite infection and vaccination, with an increase in KLH-binding IgG and IgM levels after infection and reduced KLH-binding IgM levels following vaccination. Underlying NAbs reacting to KLH showed no correlations to the final fluke burdens after experimental infection or vaccination. However, NAbs reacting to whole-worm extract (WWE) prior to infection were positively correlated to increased fluke burdens within the infected bovine host. Furthermore, after infection, the specific IgG reacting to WWE was positively reflected by the underlying NAb IgG response. Following subcutaneous vaccination with F. hepatica native glutathione S-transferase (GST), there was a non-significant 33% reduction in fluke burden. Vaccinated animals with higher underlying NAbs had a higher induction of vaccine-induced SpAbs, with trends observed between KLH-binding IgM and anti-GST IgG and IgM. Our findings provide a platform to allow further investigation to determine if NAb levels could mirror fluke-SpAb production for exploitation in a combined selective breeding and vaccination program. Additionally, this work suggests that liver fluke could possibly evade the host’s immune system by utilising surface-bound IgM NAbs.

In the situation of mass vaccination against COVID-19, few studies have reported on the early kinetics of specific antibodies (IgG/IgM/IgA) of vaccine breakthrough cases. There is still a lack of epidemiological evidence about the value of serological indicators in the auxiliary diagnosis of COVID-19 infection, especially when the nucleic acid results were undetectable. Omicron breakthrough cases post-inactivated vaccination ( n  = 456) and COVID-19-naive individuals with two doses of inactivated vaccination ( n  = 693) were enrolled. Blood samples were collected and tested for SARS-CoV-2 antibody levels based on the magnetic chemiluminescence enzyme immunoassay. Among Omicron breakthrough cases, the serum IgG antibody level was 36.34 Sample/CutOff (S/CO) (95% confidence interval [CI], 31.89 to 40.79) in the acute phase and 88.45 S/CO (95% CI, 82.79 to 94.12) in the recovery phase. Serum IgA can be detected in the first week post-symptom onset (PSO) and showed an almost linear increase within 5 weeks PSO. Compared with those of breakthrough cases, IgG and IgA titers of the postimmune group were much lower (4.70 S/CO and 0.46 S/CO, respectively). Multivariate regression showed that serum IgG and IgA levels in Omicron breakthrough cases were mainly affected by the weeks PSO ( P  < 0.001). Receiver operating characteristic ROC0 curve analysis showed that the area under the curve (AUC) was 0.744 and 0.806 when the cutoff values of IgA and IgG were 1 S/CO and 15 S/CO, respectively. Omicron breakthrough infection can lead to a further increase in IgG and IgA levels relative to those of the immunized population. When nucleic acid real-time PCR was negative, we would use the kinetics of IgG and IgA levels to distinguish the breakthrough cases from the immunized population. IMPORTANCE This study fills a gap in the epidemiological evidence by investigating the value of serological indicators, particularly IgG and IgA levels, in the auxiliary diagnosis of COVID-19 infections when nucleic acid results are undetectable. The findings reveal that among Omicron breakthrough cases, both IgG and IgA antibody levels exhibit significant changes. Serum IgG levels increase during the acute phase and rise further in the recovery phase. Serum IgA can be detected as early as the first week post-symptom onset (PSO), showing a consistent linear increase within 5 weeks PSO. Furthermore, receiver operating characteristic (ROC) curve analysis demonstrates the potential of IgG and IgA cutoff values as diagnostic markers. The study's conclusion underscores the importance of monitoring IgG and IgA kinetics in distinguishing Omicron breakthrough cases from vaccinated individuals. These findings contribute to the development of more accurate diagnostic approaches and help inform public health strategies during the ongoing COVID-19 pandemic., Competing Interests: The authors declare no conflict of interest.

• There is an association between anti-Anisakis antibodies and IL-7 levels. • IL-7 levels significantly increased in anti-Anisakis IgA-positive subjects. • IL-7 showed an inverse correlation with CD3+ and CD3 + CD8 + γδ+ T cells. • IgA was associated with a decrease of CD3 + CD4+, CD3 + CD8 + and CD3 + CD56 + αβ + T cells. • IgA was associated with a decrease of CD3 + CD4-CD8- and CD3 + CD56 + γδ + T cells. IL-7 is a crucial factor for the development of lymphocytes, and it is absolutely necessary for γδ T cells. Mice deficient in L-7 have a deficit of B and αβ T lymphocytes, and an absence of mature γδ TCR cells. IL-7 is essential for the survival, development and maturation of Schistosoma sp., although its production is associated with protection against intestinal helminths. The presence of anti- Anisakis simplex antibodies, especially IgA, is related to a lower frequency in CD3 + CD56 + αβ + lymphocytes and all subpopulations of γδ T cells. In this work, the relationship of IL-7 with humoral and cellular responses against A. simplex in 100 healthy subjects was studied. We have found significantly higher IL-7 levels in anti- A. simplex IgA-positive subjects (p < 0.001). The positivity of anti- A. simplex IgA was associated with a significant reduction in the frequency of CD3 + αβ+ (p < 0.01), CD3 + CD4 + αβ+, CD3 + CD8 + αβ+, CD3 + CD56 + αβ+, CD3 + γδ+, CD3 + CD4-CD8-γδ+ and CD3 + CD56 + γδ+ (p < 0.05) cells. In the case of NKT cells, this same phenomenon was also associated with IgE positivity. There was a weak inverse correlation (Spearman) of IL-7 levels with the frequencies of CD3 + CD4 + αβ+ (−0.125, p = 0.047), CD3 + CD8 + αβ+ (−0.204, p = 0.032), CD3 + CD56 + αβ+ (−0.247, p = 0.007), CD3 + γδ+ (−0.267, p = 0.007), CD3 + CD4-CD8-γδ+ (−0.266, p = 0.003), and CD3 + CD8 + γδ + (−0.302, p = 0.002) cells. The role of NKT cells in the anti- A. simplex response was confirmed and an association between IL and 7 levels and specific antibodies, especially IgA, was demonstrated. The higher production of IL-7 would represent a compensatory mechanism in response to the reduction in lymphocyte populations associated with the response against this parasite. [ABSTRACT FROM AUTHOR]

The effect of physical (heat treatment at 82 °C and 100 °C), the combination of physical and chemical (buffer pH: 3,5,11 and 12, saccharides: D -glucose and maltose) treatments on the immunoreactive properties of fish proteins and its subset of protein; fish parvalbumins were investigated by two sandwich enzyme-linked immunosorbent assays (sELISA). Calculated immunoreactive protein concentration was inversely proportional to the heat treatment time at 82 °C and 100 °C as assayed by sELISA targeted soluble antigenic proteins. During the first fifteen minutes, the decreased immunoreactive protein concentration was significant (p < 0.0001) for both temperatures. By contrast, immunoreactive parvalbumin concentration in the heated crude extract was significantly increased (p < 0.0001) after 25 min at 82 °C and 15 min at 100 °C to the maximum level as assayed by sELISA targeted parvalbumins (sELISA PV). Combined treatments such as heating the crude extracts altered with pH limited the recognition of immunoreactive parvalbumins by the additional decrease results from the thermally-induced processing step. Solubility drastically decreased near the isoelectric point, correlated with the rapid changes in the immunoreactive parvalbumin concentration. Although low-temperature treatment was favored for glycation of parvalbumins through maillard reaction, faster reactions were observed at high temperatures for both saccharides. • Immunoreactive protein concentration was inversely proportional to the heating time. • Immunoreactive parvalbumin concentration of heated crude extract increased with heating time. • Combined treatments limited the capacity of parvalbumin to bind their antibodies. • The protein profile of native parvalbumin and 36 kDa proteins were analyzed by SDS-PAGE. [ABSTRACT FROM AUTHOR]

In this article, we report the development of an electrochemical biosensor for the determination of the SARS-CoV-2 spike protein (rS). A gold disc electrode was electrochemically modified to form the nanocrystalline gold structure on the surface. Then, it was further altered by a self-assembling monolayer based on a mixture of two alkane thiols: 11-mercaptoundecanoic acid (11-MUA) and 6-mercapto-1-hexanol (6-MCOH) (SAM mix ). After activating carboxyl groups using a N-(3-dimethylaminopropyl)-N'-ethyl-carbodiimide hydrochloride and N-hydroxysuccinimide mixture, the rS protein was covalently immobilized on the top of the SAM mix . This electrode was used to design an electrochemical sensor suitable for determining antibodies against the SARS-CoV-2 rS protein (anti-rS). We assessed the association between the immobilized rS protein and the anti-rS antibody present in the blood serum of a SARS-CoV-2 infected person using three electrochemical methods: cyclic voltammetry, differential pulse voltammetry, and potential pulsed amperometry. The results demonstrated that differential pulse voltammetry and potential pulsed amperometry measurements displayed similar sensitivity. In contrast, the measurements performed by cyclic voltammetry suggest that this method is the most sensitive out of the three methods applied in this research.

Fasciola hepatica is the causative agent of fasciolosis, a significant parasitic disease occurring worldwide. Despite ongoing efforts, there is still no vaccine to control liver fluke infections in livestock. Recently, it has been suggested that natural antibodies (NAbs) can amplify specific antibodies (SpAb) and have a direct killing effect, but it is unknown if this phenomenon occurs during parasitic helminth infection or targeted vaccination. NAbs are antibodies produced by the innate immune system, capable of binding antigens without prior exposure. This study explores the role of bovine NAbs, using the exogenous glycoprotein keyhole limpet hemocyanin (KLH), in response to F. hepatica infection and SpAb production after infection and vaccination. The cattle's NAbs were differently influenced by parasite infection and vaccination, with an increase in KLH-binding IgG and IgM levels after infection and reduced KLH-binding IgM levels following vaccination. Underlying NAbs reacting to KLH showed no correlations to the final fluke burdens after experimental infection or vaccination. However, NAbs reacting to whole-worm extract (WWE) prior to infection were positively correlated to increased fluke burdens within the infected bovine host. Furthermore, after infection, the specific IgG reacting to WWE was positively reflected by the underlying NAb IgG response. Following subcutaneous vaccination with F. hepatica native glutathione S-transferase (GST), there was a non-significant 33% reduction in fluke burden. Vaccinated animals with higher underlying NAbs had a higher induction of vaccine-induced SpAbs, with trends observed between KLH-binding IgM and anti-GST IgG and IgM. Our findings provide a platform to allow further investigation to determine if NAb levels could mirror fluke-SpAb production for exploitation in a combined selective breeding and vaccination program. Additionally, this work suggests that liver fluke could possibly evade the host's immune system by utilising surface-bound IgM NAbs. [ABSTRACT FROM AUTHOR]