Virus-specific Antibodies Research Articles

Baloxavir marboxil use for critical human infection of avian influenza A H5N6 virus

Recent outbreaks of avian influenza and ongoing virus reassortment have drawn focus on spill-over infections. The increase in human infections with highly pathogenic avian influenza H5N6 virus and its high fatality rate posed a potential threat, necessitating the search for a more effective treatment. Longitudinal clinical data and specimens were collected from five H5N6 patients after admission. All patients received antiviral treatment of either sequential monotherapy of oseltamivir and baloxavir or the two drugs in combination. Severity of illness; viral load in sputum, urine, and blood; and cytokine levels in serum and sputum were serially analyzed. All patients developed acute respiratory distress syndrome (ARDS) and viral sepsis within 1week after disease onset. When delayed oseltamivir showed poor effects, baloxavir was administered and rapidly decreased viral load. In addition, levels of IL-18, M-CSF, IL-6, and HGF in sputum and Mig and IL-18 in serum that reflected ARDS and sepsis deterioration, respectively, were also reduced with baloxavir usage. However, three patients eventually died from exacerbation of underlying disease and secondary bacterial infection. Nonsurvivors had more severe extrapulmonary organ dysfunction and insufficient H5N6 virus-specific antibody response. For critical human cases of H5N6 infection, baloxavir demonstrated effects on viral load and pulmonary/extrapulmonary cytokines, even though treatment was delayed. Baloxavir could be regarded as a first-line treatment to limit continued viral propagation, with potential future application in avian influenza human infections and poultry workers exhibiting influenza-like illness. This work was funded by the National Natural Science Foundation of China (81761128014).

Covid-19 Induced Neonatal Immunity

December 2019 a few cases of severe pneumonia was detected in Wuhan, China The patients were exhibiting symptoms like fever, dry cough, sore throat, breathlessness, and fatigue. investigation employing next generation sequencing and phylogenetic analysis led to the identification of the causative agent of this respiratory disease, a novel coronavirus 2019 [1]. As more cases started to appear around the world, on February 11, 2020, the World Health Organization assigned a name, Corona Virus Disease 2019 or COVID-19, to the disease and declared it a pandemic on March 11, 2020. The virus was renamed from 2019-nCoV to SARS-CoV-2 by the International Committee on Taxonomy of Viruses on the basis of its genetic similarity to a previously known coronavirus, Severe Acute Respiratory Syndrome Coronavirus(SARS-CoV) [2].Coronavirus 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome SARS-CoV- 2, has resulted in more than six million deaths and has infected over 500 million people as of July 19, 2022 [3]. SARS-CoV-2 infected pregnant women are at increased risk of severe COVID- 19 than non-pregnant women and have a higher risk of adverse pregnancy outcomes like intrauterine/fetal distress and preterm birth.The most severe outcomes of COVID-19 have been documented in geriatric individuals and pregnant women with chronic diseases, including hypertension, diabetes, and cardiopulmonary problems [4]. Newborn protection from infection is primarily dependent on neonatal innate immune responses and maternally derived, transplacentally acquired antibodies. The extent to which maternal antibodies produced in response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection during pregnancy cross the placenta is important for understanding potential neonatal protection from coronavirus disease 2019 (COVID- 19.We investigated humoral responses to SARS-CoV-2 inmaternalandcordbloodpairedsamples in the case of natural infection during late second and third trimesters of pregnancy recruited at TSMU Department of Obstetrics and Gynecology TSMU First University Clinic. Georgia, Tbilisi. Maternal nasopharyngeal swabs were collected for SARS-CoV-2 detection by rate-PCR for confirmation of viral infection at the admission to the hospital. We measured IgG to spike (S) receptor-binding domain and nucleocapsid (N) Sixty-eight pregnant women SARS-CoV-2 positive by rRT- PCR were included in our study. Serology samples of maternal and cord blood has been collected immediately after delivery. For study design we have determined inclusion and exclusion criteria’s. General medical data of patients included in the study have been collected from medical records and Informed written consent was obtained from all the patients involved in the study. SARS-CoV-2, IgG has been detected by ELISA method.infected mothers had increased levels of virus-specific antibodies maternal IgG levels showed positive correlations with their counterparts in cord blood. PCR positive mothers showed stronger effect when infection was closer to delivery.Our results show that SARS- CoV-2 infection during the second and third trimester of pregnancy induces antibody response at delivery and causes lower level of the SARS-CoV-2-specific IgG trans placental transfer, when the infection is closer to delivery.

Content and specificity of the Anti-SARS-CoV-2 antibodies in solutions for immunoglobulin replacement therapy

BackgroundSpecific antibodies are important for post-vaccination and post-infection immune responses against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The role of antibodies in preventing and treating Coronavirus disease 2019 (COVID-19) in high-risk populations has been highlighted through the use of virus-specific monoclonal antibodies, which has raised the question of immunoglobulin replacement therapy (IRT) used in immunocompromised patients. MethodsVirus-specific anti-receptor-binding domain (RBD) and anti-nucleocapsid protein (NCAP) antibodies (assessed using a chemiluminescence assay and virus-neutralizing antibodies (virus neutralization test against Delta and Omicron variants)) were analyzed in 20 batches of 10 % (100 mg/mL) immunoglobulin solutions for intravenous IRT from two commercially available producers between January 2022 and March 2023 for clinical use. ResultsAnti-RBD and anti-NCAP antibodies were detected in all 20 batches of assessed IRT solutions (mean concentrations of 2817 IU/mL and 2380 IU/mL, respectively). Notably, the concentration of the virus-specific antibodies increased continuously during the follow-up period (from 822.5 IU/mL to 4066.4 IU/mL and 102 IU/mL to 3455.9 IU/mL). These antibodies demonstrated high virus-neutralizing activity against the Delta variant (mean titers of 436 and 325) but were limited to the Omicron variant (mean titers 78 and 70). The differences observed between the two brands were not statistically significant. ConclusionIRT solutions contain high concentrations of anti-SARS-CoV-2 specific antibodies, which may prevent COVID-19; however, the efficacy can be influenced by variable virus-neutralizing activities against different viral strains. Therefore, appropriate IRT should be combined with other approaches, such as vaccination or pre- and post-exposure prophylaxis. Passively transmitted specific antibodies may also lead to false-positive serological test results.

The effect of single mutations in Zika virus envelope on escape from broadly neutralizing antibodies.

The wide endemic range of mosquito-vectored flaviviruses-such as Zika virus and dengue virus serotypes 1-4-places hundreds of millions of people at risk of infection every year. Despite this, there are no widely available vaccines, and treatment of severe cases is limited to supportive care. An avenue toward development of more widely applicable vaccines and targeted therapies is the characterization of monoclonal antibodies that broadly neutralize all these viruses. Here, we measure how single amino acid mutations in viral envelope protein affect neutralizing antibodies with both broad and narrow specificities. We find that broadly neutralizing antibodies with potential as vaccine prototypes or biological therapeutics are quantifiably more difficult to escape than narrow, virus-specific neutralizing antibodies.

Abstract 18365: Elevated Biomarkers of Subclinical Myocardial Injury and Inflammation Among Community-Dwelling Adults With Covid-19

Background: Subclinical cardiovascular impact of SARS-CoV-2 infection in mild-moderate cases is unclear. Hypothesis We hypothesized that positive anti-nucleocapsid/spike SARS-CoV-2 antibodies will be associated with elevated subclinical cardiac and inflammatory biomarkers. Methods: This study was nested within a randomized controlled trial among community-dwelling adults. We used logistic regression to estimate adjusted odds of positive anti-nucleocapsid/ spike protein antibodies and elevated cardiac and inflammatory biomarkers (high-sensitivity cardiac troponin [hs-TnI], N-terminal pro-B-type natriuretic peptide [NT-proBNP], Galectin-3 [Gal-3], and C-reactive protein, [CRP]). Results: Among 231 adults, mean (±SD) age was 50 (±17.6) years, 63% were female, 57% were Black persons. Overall, 11% had detectable hs-cTnI (≥6 ng/L), 21% had elevated NT-proBNP (≥125pg/dL), 42% had elevated Gal-3 (≥18.5 ng/mL), 70% had elevated CRP (≥0.9 mg/dL). CRP levels were significantly higher among persons with positive spike protein antibodies [positive: median, 1.9 (Interquartile range IQR, 4.1) vs. negative: median, 0.7 (IQR, 2.1); p=0.014]. Those with positive spike protein antibodies were 3.49 (95% CI, 1.33-9.15) times more likely to have elevated CRP than those who were negative. Cardiac/inflammatory biomarkers were slightly higher in persons with positive SARS-CoV-2 IgG antibody detecting nucleocapsid protein (virus-specific antibody) versus negative ( Figure ). Conclusions: In this sample, we observed elevated cardiac and inflammatory biomarkers indicative of myocardial injury. Further research on the durability of elevated cardiac biomarkers and their contributions to post-acute sequela of COVID-19 is needed.

Heterologous prime-boost immunization induces protection against dengue virus infection in cynomolgus macaques.

Currently licensed dengue vaccines do not induce long-term protection in children without previous exposure to dengue viruses in nature. These vaccines are based on selected attenuated strains of the four dengue serotypes and employed in combination for two or three consecutive doses. In our search for a better dengue vaccine candidate, live attenuated strains were followed by non-infectious virus-like particles or the plasmids that generate these particles upon injection into the body. This heterologous prime-boost immunization induced elevated levels of virus-specific antibodies and helped to prevent dengue virus infection in a high proportion of vaccinated macaques. In macaques that remained susceptible to dengue virus, distinct mechanisms were found to account for the immunization failures, providing a better understanding of vaccine actions. Additional studies in humans in the future may help to establish whether this combination approach represents a more effective means of preventing dengue by vaccination.

Development of flavivirus subviral particles with low cross-reactivity by mutations of a distinct antigenic domain

The most conserved fusion loop (FL) domain present in the flavivirus envelope protein has been reported as a dominant epitope for cross-reactive antibodies to mosquito-borne flaviviruses (MBFVs). As a result, establishing accurate serodiagnosis for MBFV infections has been difficult as anti-FL antibodies are induced by both natural infection and following vaccination. In this study, we modified the most conserved FL domain to overcome this cross-reactivity. We showed that the FL domain of lineage I insect-specific flavivirus (ISFV) has differences in antigenicity from those of MBFVs and lineage II ISFV and determined the key amino acid residues (G106, L107, or F108), which contribute to the antigenic difference. These mutations were subsequently introduced into subviral particles (SVPs) of dengue virus type 2 (DENV2), Zika virus (ZIKV), Japanese encephalitis virus (JEV), and West Nile virus (WNV). In indirect enzyme-linked immunosorbent assays (ELISAs), these SVP mutants when used as antigens reduced the binding of cross-reactive IgG and total Ig induced by infection of ZIKV, JEV, and WNV in mice and enabled the sensitive detection of virus-specific antibodies. Furthermore, immunization of ZIKV or JEV SVP mutants provoked the production of antibodies with lower cross-reactivity to heterologous MBFV antigens compared to immunization with the wild-type SVPs in mice. This study highlights the effectiveness of introducing mutations in the FL domain in MBFV SVPs with lineage I ISFV-derived amino acids to produce SVP antigens with low cross-reactivity and demonstrates an improvement in the accuracy of indirect ELISA-based serodiagnosis for MBFV infections.Key points• The FL domain of Lineage I ISFV has a different antigenicity from that of MBFVs.• Mutated SVPs reduce the binding of cross-reactive antibodies in indirect ELISAs.• Inoculation of mutated SVPs induces antibodies with low cross-reactivity.

African Swine Fever Vaccine Candidate ASFV-G-ΔI177L Produced in the Swine Macrophage-Derived Cell Line IPKM Remains Genetically Stable and Protective against Homologous Virulent Challenge.

ASFV vaccine candidate ASFV-G-ΔI177L has been shown to be highly efficacious in inducing protection against challenges with the parental virus, the Georgia 2010 isolate, as well as against field strains isolated from Vietnam. ASFV-G-ΔI177L has been shown to produce protection even when used at low doses (102 HAD50) and shows no residual virulence even when administered at high doses (106 HAD50) or evaluated for a relatively long period of time (6 months). ASFV-G-ΔI177L stocks can only be massively produced in primary cell macrophages. Alternatively, its modified version (ASFV-G-ΔI177L/ΔLVR) grows in a swine-derived cell line (PIPEC), acquiring significant genomic modifications. We present here the development of ASFV-G-ΔI177L stocks in a swine macrophage cell line, IPKM, and its protective efficacy when evaluated in domestic pigs. Successive passing of ASFV-G-ΔI177L in IPKM cells produces minimal genomic changes. Interestingly, a stock of ASFV-G-ΔI177L obtained after 10 passages (ASFV-G-ΔI177Lp10) in IPKM cells showed very small genomic changes when compared with the original virus stock. ASFV-G-ΔI177Lp10 conserves similar growth kinetics in primary swine macrophage cultures than the original parental virus ASFV-G-ΔI177L. Pigs infected with 103 HAD50 of ASFV-G-ΔI177Lp10 developed a strong virus-specific antibody response and were completely protected against the challenge with the parental virulent field isolate Georgia 2010. Therefore, IPKM cells could be an effective alternative for the production of ASFV vaccine stocks for those vaccine candidates exclusively growing in swine macrophages.

Protective mechanisms of nonneutralizing antiviral antibodies.

Antibodies that can bind to viruses but are unable to block infection in cell culture are known as "nonneutralizing antibodies." Such antibodies are nearly universally elicited following viral infection and have been characterized in viral infections such as influenza, rotavirus, cytomegalovirus, HIV, and SARS-CoV-2. It has been widely assumed that these nonneutralizing antibodies do not function in a protective way in vivo and therefore are not desirable targets of antiviral interventions; however, increasing evidence now shows this not to be true. Several virus-specific nonneutralizing antibody responses have been correlated with protection in human studies and also shown to significantly reduce virus replication in animal models. The mechanisms by which many of these antibodies function is only now coming to light. While nonneutralizing antibodies cannot prevent viruses entering their host cell, nonneutralizing antibodies work in the extracellular space to recruit effector proteins or cells that can destroy the antibody-virus complex. Other nonneutralizing antibodies exert their effects inside cells, either by blocking the virus life cycle directly or by recruiting the intracellular Fc receptor TRIM21. In this review, we will discuss the multitude of ways in which nonneutralizing antibodies function against a range of viral infections.

Machine learning to optimize cerebrospinal fluid dilution for analysis of MRZH reaction.

To create a supervised machine learning algorithm aimed at predicting an optimal cerebrospinal fluid (CSF) dilution when determining virus specific antibody indices to reduce the need for repeated tests. The CatBoost model was trained, optimized, and tested on a dataset with five input variables: albumin quotient, immunoglobulin G (IgG) in CSF, IgG quotient (QIgG), intrathecal synthesis (ITS) and limes quotient (LIM IgG). Albumin and IgG concentrations in CSF and serum were performed by immunonephelometry on Atellica NEPH 630 (Siemens Healthineers, Erlangen, Germany) and ITS and LIM IgG were calculated according to Reiber. Concentrations of IgG antibodies to measles, rubella, varicella zoster and herpes simplex 1/2 viruses were analysed in CSF and serum by ELISA (Euroimmun, Lübeck, Germany). Optimal CSF dilution was defined for each virus and used as a classification variable while the standard operating procedure was set to start at 2×-dilution of CSF. The dataset included 571 samples with the imbalanced distribution of the optimal CSF dilutions: 2× dilution n=440, 3× dilution n=109, 4× dilution n=22. The optimized CatBoost model achieved an area under the curve (AUC) score of 0.971, and a test accuracy of 0.900. The model falsely classified 14 (9.9 %) samples of the testing set but reduced the need for repeated testing compared to the standard protocol by 42 %. The output of the CatBoost model is mostly dependant on the QIgG, ITS and CSF IgG variables. An accurate algorithm was achieved for predicting the optimal CSF dilution, which reduces the number of test repeats.

Epidemiology and risk factors of Japanese encephalitis in Taiwan, 2010-2022.

Taiwan introduced a two-dose inactivated Japanese encephalitis (JE) mouse brain-derived (JE-MB) vaccine into routine childhood immunization in 1968, with booster vaccination implemented in 1974 and 1983. In 2017, JE-MB vaccine was replaced by a two-dose live-attenuated chimeric vaccine (JE-CV). After implementation of JE vaccination programs, JE cases have shifted from children to adults. In this study, we described the JE epidemiology and identify high-risk groups to further inform vaccine policy. We extracted data from Taiwan's notifiable disease surveillance database, vital statistics, and employment statistics from 2010 to 2022. Diagnosis of JE was confirmed by JE seroconversion, a four-fold increase in virus-specific antibodies, a positive JE viral nucleic-acid test, or JE virus isolation. From 2010 to 2022, a total of 313 cases of JE were diagnosed, resulting in an overall incidence rate of 0.10 cases per 100,000 person-years and a mortality rate of 0.006 per 100,000 population per year. Among these patients, 64% were male, and the median age was 51 years (range 0-82). Compared with people born in or after 1976 (vaccinated with four doses of JE-MB vaccine or two doses of JE-CV), those born in or before 1962 (unvaccinated) and those born during 1963-1975 (vaccinated with two or three doses of JE-MB vaccine) had a 4.2-fold (95% confidence interval [CI] 3.0-5.7) and 5.9-fold (95% CI 4.3-8.1) higher risk of JE, respectively. The relative risk of working in agriculture, forestry, fishing, or animal husbandry, compared to other occupations, was 5.0 (95% CI 3.5-7.0). In Taiwan, individuals born before 1976 and those employed in agriculture, forestry, fishing, or animal husbandry had a higher risk of JE. We recommend JE vaccination for people in these high-risk groups who have not been fully vaccinated or have an unknown vaccination history.

Interferon regulatory factor 7 modulates virus clearance and immune responses to alphavirus encephalomyelitis.

Viral encephalomyelitis outcome is dependent on host responses to neuronal infection. Interferon (IFN) is an important component of the innate response, and IFN regulatory factor (IRF) 7 is an inducible transcription factor for the synthesis of IFN-α. IRF7-deficient mice develop fatal paralysis after CNS infection with Sindbis virus, while wild-type mice recover. Irf7 -/- mice produce low levels of IFN-α but high levels of IFN-β with induction of IFN-stimulated genes, so the reason for this difference is not understood. The current study shows that Irf7 -/- mice developed inflammation earlier but failed to clear virus from motor neuron-rich regions of the brainstem and spinal cord. Levels of IFN-γ and virus-specific antibody were comparable, indicating that IRF7 deficiency does not impair expression of these known viral clearance factors. Therefore, IRF7 is either necessary for the neuronal response to currently identified mediators of clearance or enables the production of additional antiviral factor(s) needed for clearance.

Rift Valley Fever Virus-Infection, Pathogenesis and Host Immune Responses.

Rift Valley Fever Virus is a mosquito-borne phlebovirus causing febrile or haemorrhagic illness in ruminants and humans. The virus can prevent the induction of the antiviral interferon response through its NSs proteins. Mutations in the NSs gene may allow the induction of innate proinflammatory immune responses and lead to attenuation of the virus. Upon infection, virus-specific antibodies and T cells are induced that may afford protection against subsequent infections. Thus, all arms of the adaptive immune system contribute to prevention of disease progression. These findings will aid the design of vaccines using the currently available platforms. Vaccine candidates have shown promise in safety and efficacy trials in susceptible animal species and these may contribute to the control of RVFV infections and prevention of disease progression in humans and ruminants.

Highly pathogenic avian influenza A virus (HPAIV) H5N1 infection in two European grey seals (Halichoerus grypus) with encephalitis

ABSTRACT Recent reports documenting sporadic infections in carnivorous mammals worldwide with highly pathogenic avian influenza virus (HPAIV) H5N1 clade 2.3.4.4b have raised concerns about the potential risk of adaptation to sustained transmission in mammals, including humans. We report H5N1 clade 2.3.4.4b infection of two grey seals (Halichoerus grypus) from coastal waters of The Netherlands and Germany in December 2022 and February 2023, respectively. Histological and immunohistochemical investigations showed in both animals a non-suppurative and necrotising encephalitis with viral antigen restricted to the neuroparenchyma. Whole genome sequencing showed the presence of HPAIV H5N1 clade 2.3.4.4b strains in brain tissue, which were closely related to sympatric avian influenza viruses. Viral RNA was also detected in the lung of the seal from Germany by real-time quantitative PCR. No other organs tested positive. The mammalian adaptation PB2-E627K mutation was identified in approximately 40% of the virus population present in the brain tissue of the German seal. Retrospective screening for nucleoprotein-specific antibodies, of sera collected from 251 seals sampled in this region from 2020 to 2023, did not show evidence of influenza A virus-specific antibodies. Similarly, screening by reverse transcription PCR of tissues of 101 seals that had died along the Dutch coast in the period 2020–2021, did not show evidence of influenza virus infection. Collectively, these results indicate that individual seals are sporadically infected with HPAIV-H5N1 clade 2.3.4.4b, resulting in an encephalitis in the absence of a systemic infection, and with no evidence thus far of onward spread between seals.

Nasal mucosal IgA levels against SARS-CoV-2 and seasonal coronaviruses are low in children but boosted by reinfection

Repeated coronavirus infections in childhood drive progressive maturation of systemic immune responses into adulthood. Analyses of immune responses in children have focused primarily upon systemic assessment but the importance of mucosal immunity is increasingly recognised. We studied virus-specific antibody responses in contemporaneous nasal swabs and blood samples from 99 children (4-15 years) and 28 adults (22-56 years), all of whom had prior SARS-CoV-2 infection. Whilst mucosal IgA titres against Influenza and Respiratory Syncytial virus were comparable between children and adults, those against all coronaviruses, including SARS-CoV-2, were lower in children. Mucosal IgA antibodies demonstrated comparable relative neutralisation capacity in both groups and retained activity against recent omicron variants such as XBB.1 which are highly evasive of IgG neutralisation. SARS-CoV-2 reinfection preferentially enhanced mucosal IgA responses whilst the impact of vaccination was more modest. Nasal IgA levels against coronaviruses thus display a pattern of incremental response to reinfection which likely determines the natural history of reinfection. This highlights the particular significance of developing mucosal vaccines against coronaviruses in children.

Effect of Different Levels of Maternally Derived Genotype VII Newcastle Disease Virus-Specific Hemagglutination Inhibition Antibodies on Protection against Virulent Challenge in Chicks.

Newcastle disease (ND), caused by the virulent Newcastle disease virus (NDV), is an acute, highly contagious, and economically significant avian disease worldwide. Vaccination is the most effective measure for controlling ND. In recent years, vaccines matched with the prevalent strains of genotype VII have been developed and are now commercially available. These vaccines can provide full protection for chickens against clinical disease and mortality after challenges with genotype VII viruses and significantly decrease virus shedding compared to conventional vaccines belonging to genotypes I and II. Vaccinated hens can transfer antibodies to their offspring through the egg yolk. Maternally derived antibodies can provide passive protection against diseases but can also interfere with vaccination efficacy early in life. This study was conducted on chicks hatched from hens vaccinated with a commercial genotype VII NDV-matched vaccine to investigate the correlation between hemagglutination inhibition (HI) antibody levels in chicks and hens and the decaying pattern of maternally derived HI antibodies, and to evaluate the protective efficacy of different levels of maternally derived HI antibodies against challenge with a virulent NDV strain of genotype VII based on survivability and virus shedding. The HI antibody titers in chicks at hatching were about 1.3 log2 lower than those in hens, indicating an antibody transfer rate of approximately 41.52%. The estimated half-life of these antibodies was about 3.2 days. The protective efficacy of maternally derived HI antibodies was positively correlated with the titer. These antibodies could effectively protect chicks against mortality when the titer was 7 log2 or higher, but they were unable to prevent virus shedding or infection even at a high titer of 11 log2. The obtained results will greatly assist producers in determining the immune status of chicks and formulating appropriate vaccination schedules against ND.

SARS-COV-2 SEROSURVEY AMONG BULGARIAN HEALTHCARE WORKERS BEFORE AND AFTER VACCINATION

Background: In the response to the current COVID-19 pandemic caused by the novel SARS-CoV-2, one of the groups at higher risk were healthcare workers (HCWs), especially those who worked on the frontline. The presence of SARS-CoV-2 specific IgG antibodies (seropositivity) in certain populations provides better understanding of virus circulation and transmission. Our aim was to study the seroprevalence rates of anti-SARS-CoV-2 antibodies among a group of healthcare workers before and after vaccination/COVID-19 infection. Material and Methods: We determined the presence of SARS-CoV-2 specific IgG and IgA antibodies against S-antigen of by ELISA method. In this study, we enrolled 74 healthcare workers and three months later, 48 of the participants were followed up. At the baseline, none of the participants was vaccinated or had suffered COVID-19. Results: SARS-Cov-2 specific IgG antibodies were found in 32.4% of the participants. Higher prevalence of class IgA antibodies – 44.6% was detected. All samples that were IgG seropositive were also positive or borderline for IgA antibodies. Overall, virus-specific antibodies were not detected in 40.6% of HCWs in the group. During the follow-up (after vaccination and/or COVID-19 infection) high rates of both IgG and IgA seroprevalence were established. SARS-C0V-2 specific IgG antibodies were detected in 95.8% of the participants. Statistically significant difference was found in the levels of IgG and IgA antibodies both before and after vaccination, p<0.0001. Conclusions: Based on detection of anti-SARS-CoV-2 IgG antibodies, seroprevalence of 32.4% was established in an unvaccinated group of HCWs. Our survey demonstrated that asymptomatic COVID-19 infection may induce weaker humoral immune response, with production of IgA but not of IgG antibodies.

Higher MRI lesion load in multiple sclerosis is related to the N-glycosylation changes of cerebrospinal fluid immunoglobulin G

BackgroundIntrathecal clonal expansion of antibody-producing plasma cells in multiple sclerosis (MS) perpetuates central nervous system injury and is associated with active demyelination. Immunoglobulin G (IgG) effector functions are modulated by linked N-glycan structures. The aim of the study was to detect potential differences in N-glycosylation of IgG in serum and cerebrospinal fluid (CSF) and total sera proteins between people with MS and those in whom the diagnosis of MS was excluded. Furthermore, we investigated the association with standard laboratory biomarkers of intrathecal inflammation as well as clinical and neuroradiological disease activity. MethodsThis cross-sectional study included patients with suspected demyelinating disease. MS diagnosis was based on the 2017 McDonald criteria and controls were patients with excluded MS diagnosis. N-glycans were compared with Expanded Disability Status Scale (EDSS), magnetic resonance imaging (MRI) markers of disease activity and biomarkers of intrathecal inflammation (cell count, CSF-IgG concentration, percentage of intrathecal IgG, oligoclonal bands (OCB), virus-specific antibody index (MRZH reaction)). ResultsDifferences between groups were observed only in the CSF-IgG N-glycome. In MS, the presence of bisecting N-acetylglucosamine (Padj=2.63E-05) and monogalactosylation (Padj=1.49E-06) were more abundant and associated with positive OCBs. N-glycans monogalactosylated at the α6 arm FA2[6]G1 (r = 0.56) and FA2[6]BG1 (r = 0.45) correlated with percentage of intrathecal IgG, but not total CSF-IgG. This trait was also more abundant in MRZH positive people with MS who had higher MRI lesion load (P = 0.018) but unrelated to active lesions or EDSS. ConclusionsMore abundant monogalactosylation of intrathecally synthesized IgG is the most prominent trait in MS and is associated with higher MRI lesion load.

Prevalence of SARS-CoV-2 RNA and antibody-detection, and vaccination status in patients with ocular vascular occlusion.

To analyze the annual prevalence of ocular vascular occlusion in relation to COVID-19 infection and vaccination status in a prospective study. All patients were examined for an active SARS-CoV-2 infection by RNA detection, for a previous infection by virus-specific antibody detection (ECLIA), their vaccination status was documented. Data from pandemic year 2020 and previous years, before COVID-19 (2019, 2018, 2017), were retrospectively analyzed. In 2021, a total of 103 patients with the first diagnosis of ocular vascular occlusion were treated. Most frequent sub-diagnoses were central retinal vein occlusion (20.4%), non-arteriitic anterior ischemic optic neuropathy (18.4%), central retinal artery occlusion (13.6%) and branch retinal artery occlusion (12.6%). Thereof, only 3 patients (2.9%) presented with virus-specific SARS-CoV-2-antibodies, none was PCR-positive. Patients with preceded SARS-CoV-2 vaccination (59.2%) presented with comparable characteristics as unvaccinated patients with vascular occlusion regarding age, gender distribution, systemic risk factors, duration of symptoms, visual acuity and the present sub-diagnoses (p>0.05). The total number of cases in 2021 (103 cases) was comparable to the pandemic year 2020, at which no vaccination was available (114 cases), and to earlier years 2017, 2018, and 2019 without COVID pandemic (100, 120 and 119 cases). Furthermore, we did not reveal any differences between pandemic and reference years regarding patients' characteristics (p>0.05). Our study did not reveal an increased annual prevalence of ocular vascular occlusions during COVID-19 pandemic years 2020 and 2021. Patients with previous COVID vaccination did not present differences regarding the risk profile nor symptoms, compared to unvaccinated individuals.

Antibody-Dependent Enhancement with a Focus on SARS-CoV-2 and Anti-Glycan Antibodies.

Antibody-dependent enhancement (ADE) is a phenomenon where virus-specific antibodies paradoxically cause enhanced viral replication and/or excessive immune responses, leading to infection exacerbation, tissue damage, and multiple organ failure. ADE has been observed in many viral infections and is supposed to complicate the course of COVID-19. However, the evidence is insufficient. Since no specific laboratory markers have been described, the prediction and confirmation of ADE are very challenging. The only possible predictor is the presence of already existing (after previous infection) antibodies that can bind to viral epitopes and promote the disease enhancement. At the same time, the virus-specific antibodies are also a part of immune response against a pathogen. These opposite effects of antibodies make ADE research controversial. The assignment of immunoglobulins to ADE-associated or virus neutralizing is based on their affinity, avidity, and content in blood. However, these criteria are not clearly defined. Another debatable issue (rather terminological, but no less important) is that in most publications about ADE, all immunoglobulins produced by the immune system against pathogens are qualified as pre-existing antibodies, thus ignoring the conventional use of this term for natural antibodies produced without any stimulation by pathogens. Anti-glycan antibodies (AGA) make up a significant part of the natural immunoglobulins pool, and there is some evidence of their antiviral effect, particularly in COVID-19. AGA have been shown to be involved in ADE in bacterial infections, but their role in the development of ADE in viral infections has not been studied. This review focuses on pros and cons for AGA as an ADE trigger. We also present the results of our pilot studies, suggesting that AGAs, which bind to complex epitopes (glycan plus something else in tight proximity), may be involved in the development of the ADE phenomenon.