BACKGROUND: The longitudinal study was conducted over the initial 2 years of the COVID-19 pandemic, spanning from June 2020 to December 2022, in healthcare workers (HCWs) of the Thomayer University Hospital. A total of 3892 blood samples were collected and analyzed for total nucleocapsid (N) antibodies. The aim of the study was to evaluate the dynamics of N antibodies, their relationship to the PCR test, spike (S) antibodies, interferon-gamma, and prediction of reinfection with SARS-CoV-2. METHODS: Blood collections were performed in three rounds, along with questionnaires addressing clinical symptoms of past infection, PCR testing, and vaccination. Antibody measurements included total N antibodies (Roche Diagnostics) and postvaccination S antibodies (Euroimmun). Cellular immunity was tested by interferon-gamma release assay (Euroimmun). RESULTS: At the end of the study, 35.9% of HCWs were positive for N antibodies, and 39.5% of HCWs had either known PCR positivity or N antibodies or both. Ten percent of participants had no knowledge of a COVID-19 infection and 35% of positive individuals exhibited no symptoms. The values of positive antibodies decrease over a period of 6 months to 1 year, depending on the initial value, and their dynamics are highly variable. The study also demonstrated that the highest levels of spike antibodies and interferon-gamma occur during so-called hybrid immunity. CONCLUSION: Nucleocapsid antibodies proved valuable in monitoring SARS-CoV-2 infection dynamics, and they may detect cases of SARS-CoV-2 infection missed by PCR tests. The study identified distinct patterns in antibody dynamics and protection of hybrid immunity during reinfection.

• Klíčová slova
• COVID‐19, IGRA, SARS‐CoV‐2, hybrid immunity, nucleocapsid antibodies, serological marker, spike antibodies,
• MeSH
• biologické markery krev   MeSH
• COVID-19 * imunologie   krev   diagnóza   epidemiologie   MeSH
• dospělí MeSH
• fosfoproteiny MeSH
• glykoprotein S, koronavirus imunologie   MeSH
• interferon gama krev   MeSH
• koronavirové nukleokapsidové proteiny imunologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• longitudinální studie MeSH
• nemocnice univerzitní MeSH
• nukleokapsida imunologie   MeSH
• protilátky virové * krev   MeSH
• SARS-CoV-2 * imunologie   MeSH
• sérologické testování na COVID-19 metody   MeSH
• zdravotnický personál * statistika a číselné údaje   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• biologické markery MeSH
• fosfoproteiny MeSH
• glykoprotein S, koronavirus MeSH
• interferon gama MeSH
• koronavirové nukleokapsidové proteiny MeSH
• nucleocapsid phosphoprotein, SARS-CoV-2 MeSH Prohlížeč
• protilátky virové * MeSH

Despite the lower virulence of current SARS-CoV-2 variants and high rates of vaccinated and previously infected subjects, COVID-19 remains a persistent threat in kidney transplant recipients (KTRs). This study evaluated the parameters of anti-SARS-CoV-2 antibody production in 120 KTRs. The production of neutralizing antibodies in KTRs, following booster vaccination with the mRNA vaccine BNT162b2, was significantly decreased and their decline was faster than in healthy subjects. Factors predisposing to the downregulation of anti-SARS-CoV-2 neutralizing antibodies included age, lower estimated glomerular filtration rate, and a full dose of mycophenolate mofetil. Neutralizing antibodies correlated with those targeting the SARS-CoV-2 receptor binding domain (RBD), SARS-CoV-2 Spike trimmer, total SARS-CoV-2 S1 protein, as well as with antibodies to the deadly SARS-CoV-1 virus. No cross-reactivity was found with antibodies against seasonal coronaviruses. KTRs exhibited lower postvaccination production of neutralizing antibodies against SARS-CoV-2; however, the specificity of their humoral response did not differ compared to healthy subjects.

• Klíčová slova
• Antibodies, COVID-19, Kidney transplantation, SARS-CoV-2, Vaccination,
• MeSH
• COVID-19 * imunologie   prevence a kontrola   MeSH
• dospělí MeSH
• glykoprotein S, koronavirus imunologie   MeSH
• humorální imunita MeSH
• lidé středního věku MeSH
• lidé MeSH
• neutralizující protilátky * krev   imunologie   MeSH
• příjemce transplantátu * MeSH
• protilátky virové * krev   imunologie   MeSH
• SARS-CoV-2 * imunologie   MeSH
• sekundární imunizace MeSH
• senioři MeSH
• transplantace ledvin * škodlivé účinky   MeSH
• vakcína BNT162 imunologie   aplikace a dávkování   MeSH
• vakcíny proti COVID-19 imunologie   aplikace a dávkování   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• glykoprotein S, koronavirus MeSH
• neutralizující protilátky * MeSH
• protilátky virové * MeSH
• spike protein, SARS-CoV-2 MeSH Prohlížeč
• vakcína BNT162 MeSH
• vakcíny proti COVID-19 MeSH

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been associated with significant cardiovascular complications, including myocardial infection and pulmonary embolism. This study aims to elucidate the relationship between the presence of SARS-CoV-2 RNA in the myocardium of the left ventricle and the levels of IgG and IgM antibodies against the SARS-CoV-2 virus in deceased COVID-19 patients. We conducted a post-mortem examination on 91 individuals who succumbed to COVID-19-related complications. The presence of SARS-CoV-2 RNA in the myocardium of the left ventricle was analyzed reverse transcription real time PCR (RT-qPCR) (EliGene® COVID19 UKV/SAV RT kit, Elisabeth Pharmacon), and antibody levels in serum were analyzed by serological assays (VIDAS SARS-COV-2 IgM and VIDAS SARS-COV-2 IgG II tests, BioMérieux). Of the heart tissue samples, 44 % tested positive for SARS-CoV-2 RNA. Our findings indicate that any detectable level of IgG antibodies against SARS-CoV-2 reduces the risk of viral penetration into the myocardium by more than fourfold. Specifically, individuals with detectable levels of IgG and IgM antibodies exhibited a significantly reduced presence of SARS-CoV-2 RNA in cardiac tissues (p<0.0001 for IgG and p<0.001 for IgM). Notably, all patients who died from pulmonary embolism had elevated levels of IgG antibodies. The study underscores the protective role of IgG and IgM antibodies in preventing SARS-CoV-2 penetration into cardiac tissues. However, high antibody titers were associated with fatal outcomes such as pulmonary embolism, pointing to the intricate balance of immune response in COVID-19 pathology. Key words SARS-CoV-2, Antibody, IgG, IgM, Cardiac damage, qPCR, Pneumonia, Pulmonary embolism, Heart failure.

• MeSH
• COVID-19 * imunologie   virologie   MeSH
• dospělí MeSH
• imunoglobulin G * krev   MeSH
• imunoglobulin M * krev   MeSH
• lidé středního věku MeSH
• lidé MeSH
• myokard * imunologie   metabolismus   MeSH
• protilátky virové * krev   MeSH
• RNA virová krev   MeSH
• SARS-CoV-2 * imunologie   MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• imunoglobulin G * MeSH
• imunoglobulin M * MeSH
• protilátky virové * MeSH
• RNA virová MeSH

AIMS: To evaluate antibody response to mRNA vaccine, identify subgroups with poor response and to determine long-term antibody durability in hematological patients. MATERIALS AND METHODS: We have vaccinated 292 patients with all hematological malignancies with a third dose of mRNA COMIRNATY vaccine with a 12-month follow-up period in our center in Ostrava, Czech Republic. RESULTS: Antibody response for the whole cohort exceeded 74% through the whole 12-month follow-up. Lowest seroconversion was observed in CLL cohort (20/41, 48.8%), patients who received anti-CD20 therapy < 6 months before vaccination (8/30, 26.7%) and BTK inhibitors (3/6, 50.0%). On the contrary, patients with chronic myeloproliferative neoplasms and acute leukemia performed comparably with healthy population (33/33; 100% and 12/13; 92.3%, respectively). We have seen better results if the time interval between anti-CD20 therapy and additional vaccine dose was longer than 6 months (5/8 patients achieved seroconversion on 4th booster dose after previous failure). Also, 36 patients received a 4th dose of vaccine as a booster with measurable increase in protective antibodies in 50% (18/36). CONCLUSIONS: Additional doses show promise for a well-timed revaccination even in poor responders. To our knowledge, no study comparable to our work in terms of follow-up length, vaccine consistency or variety of hematological malignancies and/or treatment has been reported yet. Our findings shed more light on long-term antibody response to mRNA vaccines against SARS-CoV-2 in patients with hematological cancer and bring important data for the evaluation of possible vaccine failure and scheduling of subsequent doses.

• Klíčová slova
• COVID‐19, Cancer, Leukemia, Lymphoma, Myeloma, Vaccination,
• MeSH
• časové faktory MeSH
• COVID-19 * prevence a kontrola   imunologie   MeSH
• dospělí MeSH
• hematologické nádory * imunologie   terapie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• mRNA vakcíny MeSH
• následné studie MeSH
• protilátky virové * krev   imunologie   MeSH
• SARS-CoV-2 * imunologie   MeSH
• sekundární imunizace * MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• vakcíny proti COVID-19 * imunologie   aplikace a dávkování   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• mRNA vakcíny MeSH
• protilátky virové * MeSH
• vakcíny proti COVID-19 * MeSH

AIM: We aimed to determine the prevalence of SARS-CoV-2 infection, including both symptomatic and asymptomatic courses, and to identify predictors of asymptomatic or symptomatic SARS-CoV-2 infection in patients within seven months after allo-HSCT (allogenic hematopoietic stem cell transplantation) in the Omicron period. METHODS: Prevalence of the past SARS-CoV-2 infection was determined in patients within seven months after allo-HSCT in the Omicron period using the cellular and humoral immune response against the SARS-CoV-2 nucleoprotein (NCP). RESULTS: Positive markers of past infection were identified in 45.2% of patients (n = 42). The infection was asymptomatic in 68.4% of anti-NCP positive patients. The search for risk factors for symptomatic SARS-CoV-2 infection in allo-HSCT recipients revealed that a low level of B cell reconstitution was the only significantly associated risk factor. CONCLUSION: A high proportion of allo-HSCT recipients who were asymptomatically infected within up to seven months after transplantation from 2022 to 2023 despite being immunosuppressed and unvaccinated indicates an attenuation of the circulating virus and may signal less risk for transplanted patients from SARS-CoV-2 infection in the Omicron period. Vaccination of these patients against SARS-CoV-2 was shown to be associated with a low but significant risk of exacerbation of cured chronic GVHD (graft versus host disease) and the risk of de novo GVHD. The low level of B-cell reconstitution was the only significant risk factor for symptomatic SARS-CoV-2 infection in HSCT recipients.

• Klíčová slova
• Omicron variant, T cell response, allogenic hematopoietic stem cell transplantation, asymptomatic SARS-CoV-2 infection, nucleoprotein,
• MeSH
• asymptomatické infekce * epidemiologie   MeSH
• COVID-19 * imunologie   epidemiologie   MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• prevalence MeSH
• protilátky virové krev   MeSH
• rizikové faktory MeSH
• SARS-CoV-2 * imunologie   MeSH
• senioři MeSH
• transplantace hematopoetických kmenových buněk * škodlivé účinky   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• protilátky virové MeSH

Natural killer (NK) cells play a pivotal role in the immune response against viral infections, including SARS-CoV-2. However, our understanding of memory NK cell responses in the context of SARS-CoV-2 remains limited. To address this, we investigated the memory-like response of NK cells to SARS-CoV-2 peptides, presented by autologous cells. Blood samples from 45 donors underwent analysis for SARS-CoV-2 IgG antibodies, categorizing them into four groups based on the antibody kind and level. NK cells from SARS-CoV-2-experienced donors demonstrated enhanced degranulation and activation levels, IFNγ production and proliferative potential in response to SARS-CoV-2 peptides. Investigation of highly proliferating NK cells demonstrated the formation of distinct clusters depending on the SARS-CoV-2 peptide supplementation and the donor group. RNA sequencing revealed differential gene expression patterns, highlighting metabolism, protein transport, and immune response genes. Notably, KIR2DS4 expression correlated with enhanced IFNγ production, degranulation and proliferation levels, suggesting a role in SARS-CoV-2 recognition. Collectively, these findings provide detailed insights into antigen-specific NK cell responses to SARS-CoV-2 peptides, indicating potential mechanisms underlying NK cell activation in antiviral immunity.

• Klíčová slova
• KIR2DS4, NK cells, SARS‐CoV‐2, antigen‐specific NK cells,
• MeSH
• aktivace lymfocytů MeSH
• buňky NK * imunologie   MeSH
• COVID-19 * imunologie   MeSH
• degranulace buněk MeSH
• dospělí MeSH
• imunoglobulin G MeSH
• imunologická paměť MeSH
• interferon gama * imunologie   metabolismus   MeSH
• lidé středního věku MeSH
• lidé MeSH
• protilátky virové krev   imunologie   MeSH
• receptory KIR genetika   metabolismus   MeSH
• SARS-CoV-2 * imunologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• imunoglobulin G MeSH
• interferon gama * MeSH
• protilátky virové MeSH
• receptory KIR MeSH

Extensive research has been conducted on the SARS-CoV-2 virus in association with various infectious diseases to understand the pathophysiology of the infection and potential co-infections. In tropical countries, exposure to local viruses may alter the course of SARS-CoV-2 infection and coinfection. Notably, only a portion of the antibodies produced against SARS-CoV-2 proteins demonstrate neutralizing properties, and the immune response following natural infection tends to be temporary. In contrast, long-lasting IgG antibodies are common after dengue virus infections. In cases where preexisting antibodies from an initial dengue virus infection bind to a different dengue serotype during a subsequent infection, there is a potential for antibody-dependent enhancement (ADE) and the formation of immune complexes associated with disease severity. Both SARS-CoV-2 and dengue infections can result in immunodeficiency. Viral proteins of both viruses interfere with the host's IFN-I signaling. Additionally, a cytokine storm can occur after viral infection, impairing a proper response, and autoantibodies against a wide array of proteins can appear during convalescence. Most of the reported autoantibodies are typically short-lived. Vaccines against both viruses alter the immune response, affecting the course of viral infection and enhancing clearance. A comprehensive analysis of both viral infections and pathogenicity is revisited to prevent infection, severity, and mortality.

• Klíčová slova
• COVID-19, SARS-CoV-2 infection, antibodies, antibody-dependent enhancement (ADE), cytokine storm, dengue infection, platelets,
• MeSH
• COVID-19 * imunologie   virologie   MeSH
• dengue * imunologie   virologie   MeSH
• koinfekce imunologie   virologie   MeSH
• lidé MeSH
• protilátky virové * imunologie   MeSH
• SARS-CoV-2 * imunologie   MeSH
• virus dengue * imunologie   MeSH
• zvýšená infektivita v přítomnosti protilátek imunologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• protilátky virové * MeSH

Secretory (S) IgA antibodies against severe acute respiratory syndrome (SARS)-CoV-2 are induced in saliva and upper respiratory tract (URT) secretions by natural infection and may be critical in determining the outcome of initial infection. Secretory IgA1 (SIgA1) is the predominant isotype of antibodies in these secretions. Neutralization of SARS-CoV-2 is most effectively accomplished by polymeric antibodies such as SIgA. We hypothesize that cleavage of SIgA1 antibodies against SARS-CoV-2 by unique bacterial IgA1 proteases to univalent Fabα antibody fragments with diminished virus neutralizing activity would facilitate the descent of the virus into the lungs to cause serious disease and also enhance its airborne transmission to others. Recent studies of the nasopharyngeal microbiota of patients with SARS-CoV-2 infection have revealed significant increases in the proportions of IgA1 protease-producing bacteria in comparison with healthy subjects. Similar considerations might apply also to other respiratory viral infections including influenza, possibly explaining the original attribution of influenza to Haemophilus influenzae, which produces IgA1 protease.

• Klíčová slova
• COVID-19, SARS-CoV-2, bacterial IgA1 protease, immunoglobulin A, mucosal immunity,
• MeSH
• Bacteria enzymologie   MeSH
• COVID-19 * přenos   imunologie   virologie   mikrobiologie   MeSH
• Haemophilus influenzae enzymologie   imunologie   MeSH
• imunoglobulin A sekreční * metabolismus   MeSH
• imunoglobulin A imunologie   MeSH
• lidé MeSH
• nazofarynx mikrobiologie   virologie   MeSH
• neutralizující protilátky imunologie   MeSH
• protilátky virové imunologie   MeSH
• SARS-CoV-2 * imunologie   MeSH
• serinové endopeptidasy metabolismus   imunologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• IgA-specific serine endopeptidase MeSH Prohlížeč
• imunoglobulin A sekreční * MeSH
• imunoglobulin A MeSH
• neutralizující protilátky MeSH
• protilátky virové MeSH
• serinové endopeptidasy MeSH

BACKGROUND: SARS-CoV-2, which causes COVID-19, has killed more than 7 million people worldwide. Understanding the development of postinfectious and postvaccination immune responses is necessary for effective treatment and the introduction of appropriate antipandemic measures. OBJECTIVES: We analysed humoral and cell-mediated anti-SARS-CoV-2 immune responses to spike (S), nucleocapsid (N), membrane (M), and open reading frame (O) proteins in individuals collected up to 1.5 years after COVID-19 onset and evaluated immune memory. METHODS: Peripheral blood mononuclear cells and serum were collected from patients after COVID-19. Sampling was performed in two rounds: 3-6 months after infection and after another year. Most of the patients were vaccinated between samplings. SARS-CoV-2-seronegative donors served as controls. ELISpot assays were used to detect SARS-CoV-2-specific T and B cells using peptide pools (S, NMO) or recombinant proteins (rS, rN), respectively. A CEF peptide pool consisting of selected viral epitopes was applied to assess the antiviral T-cell response. SARS-CoV-2-specific antibodies were detected via ELISA and a surrogate virus neutralisation assay. RESULTS: We confirmed that SARS-CoV-2 infection induces the establishment of long-term memory IgG+ B cells and memory T cells. We also found that vaccination enhanced the levels of anti-S memory B and T cells. Multivariate comparison also revealed the benefit of repeated vaccination. Interestingly, the T-cell response to CEF was lower in patients than in controls. CONCLUSION: This study supports the importance of repeated vaccination for enhancing immunity and suggests a possible long-term perturbation of the overall antiviral immune response caused by SARS-CoV-2 infection.

• Klíčová slova
• COVID-19, ELISpot, SARS-CoV-2, adaptive immunity, antibody, immune memory, virus neutralisation assay,
• MeSH
• B-lymfocyty imunologie   MeSH
• buněčná imunita imunologie   MeSH
• COVID-19 * imunologie   MeSH
• dospělí MeSH
• ELISPOT MeSH
• glykoprotein S, koronavirus imunologie   MeSH
• humorální imunita MeSH
• imunologická paměť MeSH
• leukocyty mononukleární imunologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• protilátky virové * krev   imunologie   MeSH
• SARS-CoV-2 * imunologie   MeSH
• senioři MeSH
• T-lymfocyty imunologie   MeSH
• vakcíny proti COVID-19 imunologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• glykoprotein S, koronavirus MeSH
• protilátky virové * MeSH
• spike protein, SARS-CoV-2 MeSH Prohlížeč
• vakcíny proti COVID-19 MeSH

PURPOSE: Convalescent plasma (CP) collected from people who recovered from COVID-19 became a rapidly available treatment modality in numerous countries, including the Czech Republic. The aims of our study were to evaluate the effectiveness and safety of CP in the treatment of COVID-19. METHODS: This retrospective observational study involved six Czech hospitals. This study enrolled patients with and without CP treatment who were hospitalized between April 2020 and April 2021. Propensity score matching and logistic regression analysis were performed to evaluate the influence of CP administration and its timing on the in-hospital survival of COVID-19 patients. RESULTS: A total of 1,498 patients were enrolled in the study; 406 (27%) were administered CP, and 1,092 (73%) were not treated with CP. The propensity score-matched control group consisted of 1,218 subjects. The survival of patients treated with CP was 79%, while that of patients in the matched control group was 62% (P<0.001). Moreover, the chance of survival was significantly greater when CP was administered within three days after the onset of COVID-19 symptoms than when CP was administered after four or more days (87% vs. 76%, P <0.001). In addition, adverse effects related to CP administration were recorded in only 2% of patients and were considered mild in all patients. CONCLUSIONS: Our study demonstrated that the administration of CP was safe and possibly associated with positive effects that were more pronounced if CP was administered within the first three days after the onset of COVID-19 symptoms.

• Klíčová slova
• COVID-19, Convalescent plasma, Outcome, SARS-CoV-2,
• MeSH
• COVID-19 * terapie   mortalita   MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• pasivní imunizace * metody   MeSH
• protilátky virové krev   MeSH
• retrospektivní studie MeSH
• SARS-CoV-2 * imunologie   MeSH
• senioři MeSH
• sérologická léčba covidu-19 * MeSH
• výsledek terapie MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• pozorovací studie MeSH
• Geografické názvy
• Česká republika MeSH
• Názvy látek
• protilátky virové MeSH