Duration of antibody response to the receptor binding domain of SARS-CoV-2 in infected or vaccinated individuals - A one year retrospective cohort study.

The 2019 coronavirus (COVID-19) pandemic raised many scientific and medical questions. Of interest are the duration and effectiveness of the humoral immune response, especially since part of the pandemic occurred in the presence of anti-SARS-CoV-2 vaccines. We retrospectively studied 564 serum samples from 393 post-infected and vaccinated individuals to investigate the longevity and magnitude of the anti-spike IgG response. Our results showed that SARS-CoV-2 anti-spike IgG antibodies are retained for nine-twelve months, in both groups. In the vaccinated group we found higher IgG levels, but with a steeper decrease in titer over the study period. The recovered group's antibody levels correlated well with the national infection trendline for 2021. Both groups showed different, but distinct neutralizing capabilities towards RBD. The anti-Spike IgG response was sustained and efficient, independently of the triggering event, infection or vaccination, with the adaptive capacity against new viral variants being more valuable after infection.

SARS-CoV-2 spike-specific TFH cells exhibit unique responses in infected and vaccinated individuals.

Long-term humoral immunity to SARS-CoV-2 is essential for preventing reinfection. The production of neutralizing antibody (nAb) and B cell differentiation are tightly regulated by T follicular help (TFH) cells. However, the longevity and functional role of TFH cell subsets in COVID-19 convalescents and vaccine recipients remain poorly defined. Here, we show that SARS-CoV-2 infection and inactivated vaccine elicited both spike-specific CXCR3+ TFH cell and CXCR3- TFH cell responses, which showed distinct response patterns. Spike-specific CXCR3+ TFH cells exhibit a dominant and more durable response than CXCR3- TFH cells that positively correlated with antibody responses. A third booster dose preferentially expands the spike-specific CXCR3+ TFH cell subset induced by two doses of inactivated vaccine, contributing to antibody maturation and potency. Functionally, spike-specific CXCR3+ TFH cells have a greater ability to induce spike-specific antibody secreting cells (ASCs) differentiation compared to spike-specific CXCR3- TFH cells. In conclusion, the persistent and functional role of spike-specific CXCR3+ TFH cells following SARS-CoV-2 infection and vaccination may play an important role in antibody maintenance and recall response, thereby conferring long-term protection. The findings from this study will inform the development of SARS-CoV-2 vaccines aiming to induce long-term protective immune memory.

Combination of two rare mutations in the SARS-CoV-2 M gene in patients with severe and prolonged COVID-19.

BACKGROUND: The SARS-CoV-2 virus significantly changed our knowledge about coronaviruses. The interplay between SARS-CoV-2 and the human host, the infection ranges from asymptomatic to lethal, and differences in the degree of disease severity are important examples. METHODS: In this retrospective study, 24 nasopharyngeal swabs from 21 out of 457 patients with SARS-CoV-2 infection were analysed by whole-genome sequencing. The principal selection criteria were the duration of infection and disease severity. RESULTS: Two co-occurring rare mutations in the SARS-CoV-2 M gene were detected in six samples. Three of these samples were collected from an immunocompromised patient with fatal outcome, two from an immunocompetent patient, and one from a patient with severe disease and fatal outcome, all with a prolonged course of infection. CONCLUSIONS: Although this interesting finding was demonstrated in a small number of patients, the results increase the knowledge regarding the significance of mutations in the M gene of SARS-CoV-2 in the context of persistent infection and viral escape mechanisms.

Decreased ratio of FOXP3+/FOXP3-CD45RA+CD4+ T cells in peripheral blood is associated with unexplained infertility and ART failure.

Unexplained infertility has a huge social impact and is a significant challenge for both clinicians and researchers. Previous studies have shown the involvement of multiple factors in infertility. Among these, the subset of regulatory T cells is of particular interest for the maternal tolerance towards the semi-allogenic fetus. We investigated circulating CD45RA+ regulatory and non-regulatory CD4+ T cells in healthy women and patients with unexplained infertility in the context of thymic output and peripheral proliferation. The proportion of FOXP3+ and FOXP3-CD45RA+CD4+ T cells in peripheral blood was studied in control groups of healthy parous and nulliparous (never-pregnant) women and in patients with unexplained infertility. In the same groups thymic output and peripheral proliferation were defined by the sj/ßTREC ratio, and signal joint T-cell receptor excision circles (sjTREC) and Ki67 expression, respectively. In parous women a decrease in sjTREC/105 cells and CD45RA+ T lymphocytes, compared to nulliparous group was found. At the same time, the proportion of FOXP3-CD45RA+CD4+ cells, but not FOXP3+CD45RA+ Tregs was reduced. In contrast, in patients with unsuccessful pregnancy, proportions of both regulatory and non-regulatory T cell counterparts were lower. Taken together, our results provide evidence for group-specific properties in the CD45RA+ T cell compartment between healthy parous, nulliparous and women with unexplained infertility.

ABO-nonidentical liver transplantation from a deceased donor and clinical outcomes following antibody rebound: A case report.

BACKGROUND: Although ABO-nonidentical and ABO-incompatible liver transplantation (LT) are other options for end-stage liver disease treatment, the development of antibodies against blood group antigens (anti-A/B antibodies) is still a challenge in managing and follow-up of the recipients. CASE SUMMARY: A 56-year-old male with end-stage liver disease with rapid deterioration and poor prognosis was considered to receive a deceased ABO-nonidentical liver graft. All required tests were performed according to our pre-LT diagnostic protocol. The orthotopic LT procedure involving O+ donor and A1B+ recipient was performed. Our treatment strategy to overcome the antibody-mediated rejection included a systemic triple immunosuppressive regimen: methylprednisolone, mycophenolate mofetil, and tacrolimus. The immunological desensitization consisted of the chimeric anti-CD20 monoclonal antibody rituximab and intravenous immunoglobulins. The patient was also on antibiotic treatment with amoxicillin/clavulanate, cefotaxime, and metronidazole. On the 10th postoperative day, high titers of IgG anti-A and anti-B antibodies were found in the patient's plasma. We performed a liver biopsy, which revealed histological evidence of antibody-mediated rejection, but the rejection was excluded according to the Banff classification. The therapy was continued until the titer decreased significantly on the 18th postoperative day. Despite the antibiotic, antifungal, and antiviral treatment, the patient deteriorated and developed septic shock with anuria and pancytopenia. The conservative treatment was unsuccessful, which lead to the patient's fatal outcome on the 42nd postoperative day. CONCLUSION: We present a patient who underwent ABO-nonidentical LT from a deceased donor. Even though we implemented the latest technological advancements and therapeutic approaches in the management of the patient and the initial results were promising, due to severe infectious complications, the outcome was fatal.

The Dynamic Changes in Soluble CD30 and Regulatory T Cells Before and After Solid Organ Transplantations: A Pilot Study.

Among multiple parameters, applied in the immunologic monitoring of transplantation, the levels of serum soluble CD30 (sCD30) and peripheral regulatory T cells (Tregs) are very promising. These are relatively new biomarkers, considered to reflect immune activation and tolerance in solid organ transplantation. Results are shown here from a preliminary study on the relevance of sCD30 and Tregs in the monitoring of the early post-transplantation period. Sixteen patients with chronic liver or kidney disease were examined. Nine of them were further selected for transplantation. Follow-up of sCD30 and Tregs was carried out during the first month after transplantation. Until day 30 (D30) after transplantation, a progressive decrease in sCD30 levels was observed in all patients. Conversely, the dynamic of Tregs was dependent on the transplanted organ: in liver recipients, an increase of Tregs was detected at day 7 (D7) followed by a gradual decrease until D30, whereas in kidney recipients, a sustained downward trend starting on D7 was observed. In liver recipients, the increase in Tregs preceded albumin normalization, whereas in kidney recipients, sCD30 was found to have predictive significance for the creatinine levels. Our results demonstrated that peripheral blood sCD30 and Tregs are valuable parameters in the immunologic monitoring of transplanted patients.

Late Postpregnancy Modifications in the Subset of Peripheral Natural T Regulatory Cells in Healthy Women.

The establishment of a relevant regulatory T cell (Treg) pool in the periphery is of importance to ensure immune homoeostasis. Finely tuned signaling pathways in Tregs control the immune response during extreme endocrine changes in pregnancy and afterward. In this study, we investigate the population of Tregs and, in particular, the natural Tregs (nTregs) in healthy women divided into three groups according to the number of previous pregnancies, if any (Gr.1-one pregnancy, Gr.2-≥2 pregnancies, and Gr.0-no pregnancy). The overall analysis showed similar proportions in the entire Treg pool and nTregs (FoxP3+CD45RA+) in all the three groups (p > 0.05). However, the age-related trend of CD25+ nTregs was found to be different in parous and nonparous women. Analysis of phosphorylated ERK1/2, an important signaling molecule in T cell maintenance, showed a significantly higher percentage in CD25+ nTregs in the group of nonparous compared with parous women (p < 0.05). Thus, our results provide evidence that pregnancy may exert a long-lasting impact on the subset of nTregs due to the extreme changes in the hormonal status, which in turn, influences pre- and post-thymic maturation.

IFN-γ Attenuates Spontaneous Lymphocyte Proliferation by Fuelling Regulatory T Cells in HIV-1-Infected Patients.

HIV infection is characterized by a high degree of immune activation. It has an impact on CD4 cell count and populations' distribution and function. T regulatory cells (Tregs) were found to play a controversial role in the course of infection because of their beneficial effect on the degree of immune activation and unfavorable influence on the antigen-specific responses. The goal of the present work was to study the relationship among interferon-γ (IFN-γ), spontaneous lymphocyte proliferation, and regulatory T cells in HIV patients receiving therapy. Three lymphocyte populations, isolated after a stepwise magnetic separation from 17 individuals, were investigated-peripheral blood lymphocytes, CD4+CD45RA- (CD4+TM), and CD4+CD45RA-CD25- (TMCD25depl.) cells. The spontaneous, phytohemagglutinin (PHA) and HIV-1p24Ag-stimulated IFN-γ production and the spontaneous lymphocyte proliferation were evaluated. The potential of Tregs to establish a productive infection was determined by measurement of free HIV-1p24 antigen. Two types of constellations among subsets were found. In the first one (in 11 subjects), the spontaneous INF-γ inversely correlated with the spontaneous proliferation in all fractions (r = -0.9, p < 0.001). Conversely, in the second group (six subjects), no associations between the selected parameters were observed. The overall increase in p24-stimulated IFN-γ from TMCD25depl. cells was weak. Four samples: one in Tregs and three in TMCD25depl. cells were positive for the free p24 antigen. No association with the CD4+ T cell count, percentage of Tregs, and stage of infection was determined. In conclusion, our results demonstrate that IFN-γ could impact the proliferative capacity of non-Treg cells by fuelling Tregs. Furthermore, Tregs may control the spontaneous lymphocyte proliferation, but are less powerful in the suppression of Ag-specific IFN-γ production from non-Treg lymphocytes. The direct viral influence on Treg functions should be also considered.

Design of immunogenic peptides from Mycobacterium tuberculosis genes expressed during macrophage infection.

In vitro diagnosis of MTB-infection uses MTB-proteins coded for by genes of the region of differentiation 1 (RD1) of the MTB genome. This study wants to test if proteins preferentially expressed during MTB-intracellular growth might provide new targets for the diagnosis of MTB-infection. To this end seventy-five multiepitopic HLA-promiscuous MTB-peptides were designed by quantitative implemented peptide-binding motif analysis from 3 MTB-protein genes expressed in activated human macrophages (MA), 4 genes expressed during growth in non-activated human macrophages (MN-A), 12 housekeeping genes (HKG) and 6 genes of the RD1 region (RD1) as control. ELISpot for IFN-was performed to measure the responses of PBMCs deriving from 45 patients affected by active tuberculosis and 34 controls. In active-TB patients, the mean response to RD1-derived peptides was higher than that to either MA (p<0.01), MN-A (p<0.008) or HKG (p<0.01) derived peptides. In TST-positive subjects all selected peptides elicited significant IFN-T-cell responses (p<0.02 compared to TST-negatives), but without differences between the subgroups. Further, T-cell responses to RD1 peptides were lower in the 23 active-TB treated patients than in the untreated ones (p<0.01). The response to MA peptides in treated active-TB was higher than when untreated (p<0.01). These results demonstrate that the use of in vitro models of MTB-intracellular infection to select MTB gene products for further in silico and in vitro assessment of their immunogenicity have the potential to identify novel antigens amenable to the design of new tools for diagnosis and monitoring of tuberculosis.

Regulatory T cells and HIV-1 infection.

Recently, it has been emphasized that chronic generalized immune activation is a leading event in the pathogenesis of HIV-1 infection. Supporting evidence comes from observations that in cases of lack of activation, infected subjects maintain a high number of T cells and do not develop AIDS-related events. Despite intensive studies, the exact mechanisms of T-cell activation are still not well understood and options for their control are limited. Very promising in this direction is a recently described T-cell subpopulation--regulatory T cells. Their functional activity and vitality are strongly dependent on the presence of IL-2. Better understanding of the mechanisms of T-cell activation, as well as the contribution of regulatory T cells to its control will increase therapeutic options for HIV-1-infected subjects. The application of immune-based therapy together with highly active antiretroviral therapy will lend a helping hand to the natural regulatory mechanisms in the control of infection.

Low-dose prolonged intermittent interleukin-2 adjuvant therapy: results of a randomized trial among human immunodeficiency virus-positive patients with advanced immune impairment.

Twenty-two patients with CD4(+)cell counts