The SARS-CoV-2 pandemic persists with global repercussions. Initial COVID-19 symptoms encompass pneumonia, fever, myalgia, and fatigue. The human immune system produces IgM and IgG antibodies in response to SARS-CoV-2. Despite previous research, a comprehensive understanding of the interplay between clinical manifestations and humoral immune responses remains elusive. This study aims to scrutinize this association. 134 COVID-19 patients were enrolled, and stratified into mild, moderate, and severe symptom groups. Serum IgM and IgG levels were assessed thrice at one-month intervals using ELISA. The findings reveal significant elevation in serum IgG levels in moderate compared to mild cases (P < 0.001). Additionally, IgG production was significantly heightened in severe cases compared to both mild (P < 0.0001) and moderate (P < 0.05) groups. IgM and IgG levels peaked initially and diminished over time. While anti-SARS-CoV-2 antibodies are expected to confer protection, the direct correlation between IgG levels and symptom severity may arise from delayed immune activation, resulting in an intense antibody response in severe cases. Given evidence linking delayed immune function with a dysregulated innate immune response, comprehensive data collection should encompass not only serum IgG and IgM, but also early measurement of type I interferons at symptom onset. This could provide a more thorough understanding of COVID-19 progression.

To evaluate the dynamic changes of antibody levels in different groups after inoculation with the coronavirus disease 2019 (COVID-19) vaccine. The 1493 subjects who were tested for IgM and IgG against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at Qionglai Medical Center Hospital from June to October in 2021 were accepted for analyses of geometric mean titre (GMT) of IgG and IgM. The overall GMT of IgM and IgG in the population of Qionglai reached at a peak value at 1.497 (+3.810, −3.810) S/CO and 4.048 (+2.059, −2.059) S/CO in the second week, and then gradually decreased to 0.114 (+2.707, −2.707) and 1.885 (+1.506, −1.506) S/CO in the 11th–25th weeks, respectively. IgG was positive within 1 day, after that GMT increased continuously and peaked on the 13th day. There was a significant difference between male and female groups for titre of IgM during the prior 2 weeks and among three age groups for titre of IgG during the 2nd–3rd week after vaccination. The GMT level of IgG in the population vaccinated with the COVID-19 vaccine remained at a high level within 25 weeks and peaked on the 13th day, indicating that IgG could exist for a longer period and exhibiting positive SARS-CoV-2- defending effect.

Immune complexes (ICs) are found in canine visceral leishmaniasis (CVL) and interfere with the serum detection of antibodies. Dissociation of these monovalent complexes by dissociative enzyme-linked immunosorbent assay (ELISA) removes false-negative results and allows some characterization of antibodies and antigens. We studied the serology of dogs with suspected CVL in an endemic area, testing two Leishmania (Leishmania) [L. (L.)] <full form>infantum antigens. We analysed the presence of immunoglobulin G (IgG), immunoglobulin A (IgA) and immunoglobulin M (IgM) antibodies specific to promastigote soluble extract (PSE) and low-molecular weight glycans (glycan–bovine serum albumin (BSA) complex – GBC) by conventional and dissociative ELISA. Our results showed a significant fraction of IgA ICs (46.5% for PSE and 47.6% for GBC), followed by IgG ICs (10% for PSE and 23.5% for GBC). IgM ICs were more frequent for PSE (22.7%). Hypergammaglobulinaemia in CVL would be related to the presence of IgA and IgG ICs, resulting in deficient elimination of these antibodies. Our data confirmed the presence of ICs that can generate false-negative results in conventional serology. The production of IgA antibodies and the high frequency of blockade by glycan antigens suggest the active participation of this immunoglobulin and its ICs in the immunopathology of CVL, indicating a new path for further research.

In Hungary, between February 2017 and July 2019, 70 confirmed measles cases were reported, raising questions about the adequacy of population-level immunity. Although the assumed vaccination coverage is ≥99%, in a recent study, we detected potential gaps in the anti-measles humoral immunity. In Hungary, according to a decree by the Ministry of Public Welfare, beginning from 2021, the healthcare provider should conduct a serosurvey of anti-measles protection levels of healthcare professionals. To facilitate the compliance with this requirement, we developed a quick ‘three-in-one’ or ‘triple’ MMR (measles, mumps and rubella) indirect ELISA (IgG); an assay format that is currently not available commercially. High throughput applicability of the ‘three-in-one’ ELISA was verified using 1736 sera from routine laboratory residual samples, using an automated platform (Siemens BEP 2000 Advance). Assay verification was performed by comparing the full antigen repertoire-based ‘target’ assay with in-house ‘control’ assays using recombinant viral antigen coatings, and by validated commercially available kits. Indirect immunofluorescence was used as an independent reference method. Data were analysed using OriginLab, IBM SPSS, RStudio and MedCalc. In case of measles, we combined our current results with previously published data (Ntotal measles = 3523). Evaluation of anti-mumps and anti-rubella humoral antibody levels was based on the measurement of 1736 samples. The lowest anti-measles seropositivity (79.3%) was detected in sera of individuals vaccinated between 1978 and 1987. Considering the antigen-specific seropositivity ratios of all samples measured, anti-measles, -mumps and -rubella IgG antibody titres were adequate in 89.84%, 91.82% and 92.28%, respectively. Based on the virus-specific herd immunity threshold (HIT) values (HITMeasles = 92–95%, HITMumps = 75–86%, HITRubella = 83–86), it can be stated that regarding anti-measles immunity, certain age clusters of the population may have inadequate levels of humoral immunity. Despite the potential gaps in herd immunity, the use of MMR vaccine remains an effective and low-cost approach for the prevention of measles, mumps and rubella infections.

Hepatitis E virus (HEV) infection is endemic in Cambodia. However, little relevant data were available and there is no clue if HEV is an emerging or decreasing pathogen in that setting. The aim of our study was to describe temporal trends of anti-HEV IgG and IgM prevalences during the last two decades (1996–2017) in the context of population growth and urbanisation in Cambodia. A total of 2004 human plasma samples collected between 1996 and 2017 were tested for anti-HEV IgG and IgM using the commercial Wantai anti-HEV assays. Overall, the prevalences of anti-HEV IgG and IgM were 41.1% and 2.7%, respectively. Analysis by calendar period showed a decreasing trend of anti-HEV IgG prevalence over the last 21 years. After age- and gender-standardisation, the anti-HEV IgG prevalence rates decreased from 61.3% during the 1996–2000 period to 32.3% during the 2016–2017 period, but no trends were observed for anti-HEV IgM rates, which fluctuated around the overall one. In conclusion, our results suggest that HEV is not an emerging pathogen, but rather seems to circulate less in Cambodia, in particular, in Phnom Penh, since the prevalence of anti-HEV IgG has been significantly decreased during the past two decades.

Providing the neonatal calf with a sufficient quantity and quality of colostrum may optimise future health, performance and reduce the risk of morbidity. A 6-month double blind trial with 80 prepartum dairy cows was conducted to determine if supplementation with mannan oligosaccharide (MOS) influences colostrum quality, quantity and subsequent calf performance. The Holstein cross Friesian 80 cows (no heifers) were allocated into a control and treatment group at the point of drying off by previous lactation number and yield. The control and treatment group were fed the same commercial standard dry cow diet throughout the trial supplemented with a mineral concentrate without or with 1.33% MOS, respectively. Cows were milked out of colostrum within 40 min of calving prior to calf suckling, weight was recorded. Mannan oligosaccharide fed cows produced significantly more colostrum on first milking (7.5 kg, SEM±0.69) compared with cows fed without MOS (5.6 kg, SEM±0.43). The immunoglobulin G (IgG) concentrations (control 53.7 IgG g/l, SEM±5.8 and MOS of 42.7 IgG g/l, SEM±4.9) and total mass of IgG did not differ between treatments. No significant observable MOS-derived effect on calf health or weight gain occurred during the study.

Oesophageal tube feeding colostrum is used to ensure sufficient colostrum intake in newborn calves but the impact of tube feeding on animal behaviour is unclear. Therefore the objective of this study was to compare lying behaviour of tube-fed or bottle-fed dairy calves. Calves (n = 37) in 3 groups were offered 3·5 l colostrum 2 h after birth. Calves of the bottle group were fed with a nipple bottle. Calves of the placebo tubing group were tubed for 4 min but no colostrum was given and they were then fed with a nipple bottle. Calves of the tubing group received 3·5 l colostrum via tube feeding. Consumed amount of bottle and placebo tubing calves was recorded. If they refused some of the offered 3·5 l the rest was offered in a second feeding 2 h later. Lying behaviour was measured by data loggers fitted to right hind leg for 3 d. Blood samples were taken 24 h after birth for determination of IgG concentration. The voluntary colostrum intake differed significantly between bottle-fed and placebo tubed calves at first feeding. Considering both colostrum feedings, bottle-fed calves consumed 3·44 ± 0·14 l and placebo tubed calves consumed 3·20 ± 0·38 l colostrum. ImmunoglobulinG intake (255·6 ± 77·5 g IgG), serum IgG concentration 24 h after birth (22·8 ± 6·7 g/l) and total serum protein concentration (6·1 ± 0·6 g/dl) did not differ between groups. None of the calves had a failure of passive transfer. There was no effect of tubing on lying behaviour.

A high variation in immunoglobulin G1 (IgG1) concentration in first milked quarter colostrum has been reported, but BSA quarter colostrum variation is not known. The occurrence of serum albumin in milk has been attributed to increased blood-milk barrier penetration. Reports of serum albumin binding to the Fc Receptor of the neonate, the receptor thought to be responsible for IgG1 transcytosis, suggested that a correlation with the appearance of IgG1 in colostrum of dairy cows was likely. The objective of the study was to establish the quarter colostrum concentration and mass of immunoglobulins and serum albumin. First colostrum was quarter collected within 4 h of parturition from healthy udders of 31 multiparous dairy cows. Individual quarter colostrum weight was determined and a sample of each was frozen for subsequent analysis. Concentrations of immunoglobulin G1, G2, and BSA were measured by ELISA and total mass of components was calculated. In addition, colostrum was also analysed for L-lactate dehydrogenase activity. Analysis of concentration and mass of BSA, immunoglobulin G1, G2 established that the quarter variations were different by cow, quarter and quarter within cow. Partial correlations corrected for colostrum weight indicated that BSA and IgG2 concentration and mass are closely correlated while that of BSA and IgG1 concentration and mass exhibited no correlation suggesting that BSA and IgG1 may have different transport mechanisms. Interestingly, immunoglobulin G1 and G2 concentration and mass exhibited strong correlations suggesting that also some unknown mechanism of immunoglobulin G2 appearance in colostrum is occurring. Finally, no measured protein exhibited any correlation with the activity of lactate dehydrogenase in colostrum.

On-farm instruments for assessing colostrum quality are needed in order to ensure that the calf is supplied with enough IgG to avoid failure of passive transfer. The aim of this study was to evaluate methods for estimating the IgG concentration in cows' colostrum. This research included 126 colostrum samples from 21 Danish farms with different breeds, ensuring a broad variation pattern in IgG, total protein and fat concentration. Approximately one third of the samples did not fulfil the recommendation of >50 g IgG/l colostrum, and the IgG concentration decreased with time from calving to milking. The ratio of IgG to total protein varied from 6 to 61%, however IgG and total protein were correlated with r2 = 0·70. The variation in fat was independent of variations in protein and IgG. The IgG concentration was measured by ELISA and compared to fast measurements by specific gravity by colostrometer, Brix by refractometer and prediction from infrared spectroscopy. The three fast methods were all correlated to the total protein concentration of colostrum; however specific gravity was also influenced by the fat concentration. Furthermore, specific gravity generally overestimated the IgG concentration, and the cut-off level should be raised to 1050 in order to ensure adequate IgG in colostrum. None of the methods estimated IgG concentration better than the correlation of total protein and IgG, meaning that they all depended on the indirect correlation between total protein and IgG. The results suggest that using a refractometer for quality control of colostrum is an easy and feasible method, and a cut-off level of Brix 22 seems sufficient to assure adequate IgG concentration in colostrum fed to the calf.

Pancreatic insufficiency cystic fibrosis (CF) patients receive vitamin E supplementation according to CF-specific recommendations in order to prevent deficiencies. It has been suggested that higher serum α-tocopherol levels could have protective effects on pulmonary function (PF) in patients with CF. Whether current recommendations are indeed optimal for preventing deficiency and whether vitamin E has therapeutic benefits are subjects of debate. Therefore, we studied vitamin E intake as well as the long-term effects of vitamin E intake, the coefficient of fat absorption (CFA) and IgG on α-tocopherol levels. We also examined the long-term effects of serum α-tocopherol and serum IgG on forced expiratory volume in 1 s expressed as percentage of predicted (FEV1% pred.) in paediatric CF patients during a 7-year follow-up period. We found that CF patients failed to meet the CF-specific vitamin E recommendations, but serum α-tocopherol below the 2·5th percentile was found in only twenty-three of the 1022 measurements (2 %). Furthermore, no clear effect of vitamin E intake or the CFA on serum α-tocopherol was found (both P≥ 0·103). FEV1% pred. was longitudinally inversely associated with age (P< 0·001) and serum IgG (P= 0·003), but it was not related to serum α-tocopherol levels. We concluded that in the present large sample of children and adolescents with CF, vitamin E intake was lower than recommended, but serum α-tocopherol deficiency was rare. We found no evidence that higher serum α-tocopherol levels had protective effects on PF. Adjustment of the recommendations to the real-life intake of these patients may be considered.

Acquisition of acute toxoplasmosis during the first trimester of pregnancy can have catastrophic consequences for the foetus. Diagnosis is routinely based on the detection of maternal Toxoplasma gondii – antibodies using whole parasite extracts as detection antigen. While such assays are sensitive, they show no specificity for the stage of infection. We hypothesized diagnosis might be improved using recombinant antigens for detection, particularly if antibodies to certain antigen(s) were associated with early or late stages of infection. To address this, protein microarrays comprising 1513 T. gondii exon products were probed with well-characterized sera from seronegative (‘N’) controls, and acute (‘A’), chronic/IgM-persisting (‘C/M’) and chronic (‘C’) toxoplasmosis cases from Turkey. Three reactive exon products recognized preferentially in A infections, and three recognized preferentially in C/M infections, were expressed in Escherichia coli and tested for discrimination in IgG ELISAs. The best discriminators were exon 1 of TGME49_086450 (GRA5) which detected C/M infections with 70·6% sensitivity and 81·8% specificity, and exon 6 of TGME49_095700 (ubiquitin transferase domain-containing protein) which detected A infections with 84·8% sensitivity and 82·4% specificity. Overall, the data support a recombinant protein approach for the development of improved serodiagnostic tests for toxoplasmosis.

In both conventional and automatic milking systems (AMS), sensitive and reliable mastitis detection is important for profitable milk production. Mastitis detection parameters must be able to detect mastitis when the somatic cell count (SCC) is only slightly elevated. Owing to the pre-milking teat cleaning process in AMS, sampling cannot take place before the occurrence of alveolar milk ejection and importantly, this can affect the ability of parameters to detect mastitis. The aim of the present study was to examine the effect of alveolar milk ejection on l-lactate, lactate dehydrogenase (LDH), serum albumin (SA) and immunoglobulin G (IgG) compared with SCC, a commonly used indicator of mastitis. In this experiment, milk samples were collected every 20 s from one quarter during a 120-s manual teat stimulation in ten cows. Samples were analysed for SCC, l-lactate, LDH, SA and IgG. Quarters were grouped by low (<5·0 log10 cells/ml), mid (5·0–5·7 log10 cells/ml), and high (>5·7 log10 cells/ml) SCC using the sample at t=0 s. Neither l-lactate nor LDH could statistically differentiate between low and mid-SCC quarters, but there were a significant difference in levels between the high-SCC quarters and low and mid-SCC quarters. SA could not differentiate between the low and mid-SCC quarters, but the SA levels for the high SCC quarters remained statistically different compared with low and mid-SCC quarters throughout the experiment. IgG could statistically differentiate between low and mid-SCC, although the high-SCC quarters were not statistically different from the mid-SCC quarters after 60 s. In the high-SCC quarters, a decrease was shown in all parameters during milk ejection, after t=60 s. In conclusion, alveolar milk ejection reduces the effectiveness of detection parameters when compared with SCC. With the exception of IgG, the ability of other tested parameters was not satisfactory to differentiate between quarters with low to mid-SCC levels

The length of the dry period in commercial dairy production is under close scrutiny. While the main concern is the composition and volume of milk produced, the evaluation of colostrum quality under these new paradigms has suggested a decline in IgG concentrations, while some reports indicate no change. Colostrum quality has been defined as an adequate concentration (>50 mg/ml) of immunoglobulin in the secretions to provide the newborn with maximal disease resistance. We investigated the appearance of IgG in mammary pre- and post partum secretions in cows without a dry period (continuously milked, Dry0) and compared the secretions with cows that experienced a dry period of 60 d (Dry60). Blood was collected during the experimental period and plasma analysed for progesterone (P4) and prolactin (Prl). Approximately −6 d relative to parturition, the Dry0 animals exhibited increased concentration of IgG in their secretions to an average of ∼35 mg/ml that remained rather constant through subsequent pregnancy and following parturition. Dry0 cows were producing an average IgG concentration in parturition colostrum of 44·2±17·6 mg/ml that was not different than that of controls (66·86±16·8 mg/ml). However, Dry0 cows exhibited high variation, different peak times (day) of IgG concentration including times that occurred both pre and post parturition. IgG mass of the Dry0 cows remained rather constant pre- and post partum and did not show the same declining mass following parturition that was shown for the Dry60 cows. The change in plasma P4 and Prl were shown to have no timing effect on colostrum IgG concentration.

This study aimed to describe Toxoplasma gondii prevalence in Polish pregnant women and the incidence rates of congenital infections in their neonates observed between 2004 and 2012. Serological tests for T. gondii-specific IgG and IgM antibodies were performed on serum samples of 8281 pregnant women treated at the Polish Mother's Memorial Hospital Research Institute in Lodz. The yearly seroconversion rate for T. gondii IgG antibodies was estimated using a mathematical model to determine the dependency between age and prevalence. Mean prevalence of IgG antibodies between 2004 and 2012 in pregnant women was 40·6% [95% confidence interval (CI) 39·6–41·7] and increased with age with a yearly seroconversion rate of 0·8% (95% CI 0·6–1·0, P < 0·001). Assuming a T. gondii materno-fetal transmission rate of 30% gave an estimate of 1·80/1000 neonates as congenitally infected. The increased mean age (28·7 vs 26·7 years, P < 0·001) of pregnant women was probably the most important factor in abolishing the effect of falling prevalence rates.

Improving immune status in neonates is crucial to health and production. Gut active carbohydrates (GAC) have been associated with increasing immunoglobin levels and immonucompetence development in mammals. The objective of the following studies was to evaluate whether GAC (mannan-oligosaccharides) applied orally to progeny immediately following parturition, improved blood plasma immunoglobulin (Ig) type G concentrations in piglets and calves. Three trials were conducted comparing control groups with those receiving GAC orally. The first two trials used piglets that were monitored for blood IgG at 2 days of age and for changes in body weight (BW), and the third trial monitored calf IgG from birth to 21 days of age. Piglets in the experimental group received 0.75 g GAC in 10 ml saline at birth and 24 h of age. The calf trial compared the control group against calves that received 22.5 g GAC mixed into 4.5 l of colostrum (to give 5 g/l) in the first 24 h after parturition. Blood serum samples were taken at 2 days post partum in piglets, and at several time points from 6 h to 21 days of age in calves, and were analysed for IgG levels by radial immunodiffusion. In the first piglet trial, significantly higher levels (32%) of IgG were observed for piglets fed GAC (P < 0.001), and in the second, IgG concentration was elevated by 23% (P < 0.01) and BW increased by 9% (P = 0.023) with GAC supplementation. Significant improvements for calves were recorded at all time points in those fed GAC (P < 0.05), with an increase in serum IgG observed after the first day, which was maintained throughout the sampling period, resulting in a difference of 39% at the end of the trial (21 d). These findings form a basis for further studies, which are required to investigate possible modes of action involved in enhancing blood immunoglobulin concentrations in young animals, and the longer-term effects this may have on the development of the immune response.

The aim of this study was to examine whether there was an increase of suppressor T cells, relative to helper T cells, in the intestinal lamina propria of Hymenolepis diminuta-infected rats, a condition which might allow the parasite to survive for the life-span of the host. Lamina propria cells were isolated by enzymatic procedure. All lymphocytes were passed over nylon wool columns in order to remove B cells; then the T cells were purified by a panning technique using monoclonal anti-T cell antibodies. Changes in the mitogen-stimulated synthesis of 1gM, IgG and IgA by normal peripheral blood indicator lymphocytes, as measured by sandwich ELISA, was used as an index of help and/or suppression. No significant suppressor T cell activity was observed in the cultures, either from control or infected intestine.

In common with other taeniid cestodes, host or host-like proteins, especially immunoglobulins, occur on the surface and in the cyst fluid of Taenia crassiceps metacestodes. Here, several approaches have been used to determine the origin of the immunoglobulins present on the tegument. Indirect IFAT showed that IgG was almost totally lost from the surface of bladders after 6 days culture in vitro. There was a rapid reacquisition of immunoglobulins following incubation of the cultured metacestodes with either normal mouse serum or mouse anti-T. crassiceps antiserum. Immunoprecipitation of in vitro translation products and biosynthetically labelled T. crassiceps proteins with a panel of anti-IgG antisera failed to positively identify any molecule with homology to mammalian immunoglobulins. These results suggest strongly that the immunoglobulins located on the surface of T. crassiceps are of host rather than parasite origin. The occurrence of a relatively low abundance receptor in the surface of the bladders, which binds non-specific host immunoglobulin, together with surface-bound specific anti-T. crassiceps antibodies can account for the presence of these host proteins. Freshly obtained bladders and metacestodes cultured in vitro for 6 days were transplanted into naive mice and the survival and development of the resulting parasites compared. In some individual mice there was a decrease in the number and volume of metacestodes and an increase in encapsulated parasites arising from cultured bladders. This was probably not related to the loss of host immunoglobulins from the parasite surface during culture as the reacquisition of these proteins after transplantation is likely to be far more rapid than any immune response could evoke in a naive host.