56 research outputs found
Centenarians, semi and supercentenarians, COVID-19 and Spanish flu: a serological assessment to gain insight into the resilience of older centenarians to COVID-19
No full textBackground: Although it is well known that the older people have been the most susceptible to COVID-19, there are conflicting data on the susceptibility of centenarians. Two epidemiological study have shown that older centenarians (> 101 years old at the time of the 2020 pandemic peak) are more resilient than the remaining centenarians, suggesting that this resilience might be linked to the 1918 Spanish Flu pandemic. To gain insight into this matter, specifically whether the resilience of older centenarians to SARS-CoV-2 infection is linked to the Spanish Flu they had been affected by, we conducted a retrospective serological study. This study examined serum samples from 33 centenarians, encompassing semi- (aged > 104 109 years, N = 4), born between 1905 and 1922, against both SARS-CoV-2 and 1918 H1N1 pseudotype virus.
Results: Anamnestic and laboratory data suggest that SARS-CoV-2 infection occurred in 8 centenarians. The infection appeared to have been asymptomatic or mild, and hospitalization was not required, despite 3 out of 8 being between 109 and 110 years old. The levels of anti-spike antibodies in centenarians infected and/or vaccinated were higher, although not significantly, than those produced by a random sample of seventy-year-old individuals used as controls. All centenarians had antibody levels against the 1918 H1N1 virus significantly higher (almost 50 times) than those observed in the quoted group of seventy-year-old subjects, confirming the key role in maintaining immunological memory from a priming that occurred over 100 years ago. Centenarians whose blood was collected prior to the pandemic outbreak demonstrated neutralising antibodies against the 1918 H1N1 virus, but all these subjects tested negative for SARS-CoV-2.
Conclusion: This retrospective study shows that older centenarians are quite resilient to COVID-19, as they are capable of producing good levels of neutralising antibodies and experiencing mild or asymptomatic disease. This could be attributed to the 1918 Spanish flu pandemic through mechanisms other than the presence of cross-reactive antibodies between the 1918 H1N1 virus and SARS-CoV-2. Another possibility is that the association is purely temporal, solely correlated with the advanced age of resilient centenarians compared to those born after 1918, since older centenarians are known to have better control of immune-inflammatory responses
Development and optimisation of influenza C and influenza D pseudotyped viruses
No full textTo facilitate the study of influenza C (ICV) and influenza D (IDV) viruses, we generated lentiviral pseudotyped viruses (PVs) expressing the hemagglutinin-esterase fusion (HEF) glycoprotein from ICV (C/Minnesota/33/2015) and IDV (D/Swine/Italy/199724-3/2015, D/Bovine/France/5920/2014, and D/Bovine/Ibaraki/7768/2016). The production of these PVs was optimised using different amount of human airway trypsin-like (HAT) protease to enhance HEF maturation, and the transduction efficiency was evaluated in multiple cell lines. Using these PVs, we established a pseudovirus-based microneutralisation (pMN) assay to measure neutralising antibody responses and adapted an esterase activity assay to evaluate PV. Specific antisera neutralised PVs but failed to inhibit esterase activity. These findings confirm that ICV and IDV PVs provide a scalable, sensitive, and safe tool for antiviral screening, and sero-epidemiological research
Generation, Epitope swapping and stability studies of Filovirus pseudotypes and their utilisation in specific antibody assays
No full textDifferent decay of antibody response and VOC sensitivity in naïve and previously infected subjects at 15 weeks following vaccination with BNT162b2
No full textBackground: COVID-19 vaccines have demonstrated effectiveness in reducing SARS-CoV-2 mild and severe outcomes. In vaccinated subjects with SARS-CoV-2 history, RBD-specific IgG and pseudovirus neutralization titers were rapidly recalled by a single BTN162b2 vaccine dose to higher levels than those in naïve recipients after the second dose, irrespective of waning immunity. In this study, we inspected the long-term kinetic and neutralizing responses of S-specific IgG induced by two administrations of BTN162b2 vaccine in infection-naïve subjects and in subjects previously infected with SARS-CoV-2. Methods: Twenty-six naïve and 9 previously SARS-CoV-2 infected subjects during the second wave of the pandemic in Italy were enrolled for this study. The two groups had comparable demographic and clinical characteristics. By means of ELISA and pseudotyped-neutralization assays, we investigated the kinetics of developed IgG-RBD and their neutralizing activity against both the ancestral D614G and the SARS-CoV-2 variants of concern emerged later, respectively. The Wilcoxon matched pair signed rank test and the Kruskal–Wallis test with Dunn’s correction for multiple comparison were applied when needed. Results: Although after 15 weeks from vaccination IgG-RBD dropped in all participants, naïve subjects experienced a more dramatic decline than those with previous SARS-CoV-2 infection. Neutralizing antibodies remained higher in subjects with SARS-CoV-2 history and conferred broad-spectrum protection. Conclusions: These data suggest that hybrid immunity to SARS-CoV-2 has a relevant impact on the development of IgG-RBD upon vaccination. However, the rapid decay of vaccination-elicited antibodies highlights that the administration of a third dose is expected to boost the response and acquire high levels of cross-neutralizing antibodies
Human Surfactant Protein D Facilitates SARS-CoV-2 Pseudotype Binding and Entry in DC-SIGN Expressing Cells, and Downregulates Spike protein Induced Inflammation
No full textData availability statement: The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: https://biorxiv.org/cgi/content/short/2022.05.16.491949v1.Lung surfactant protein D (SP-D) and Dendritic cell-specific intercellular adhesion molecules-3 grabbing non-integrin (DC-SIGN) are pathogen recognising C-type lectin receptors. SP-D has a crucial immune function in detecting and clearing pulmonary pathogens; DC-SIGN is involved in facilitating dendritic cell interaction with naïve T cells to mount an anti-viral immune response. SP-D and DC-SIGN have been shown to interact with various viruses, including SARS-CoV-2, an enveloped RNA virus that causes COVID-19. A recombinant fragment of human SP-D (rfhSP-D) comprising of α-helical neck region, carbohydrate recognition domain, and eight N-terminal Gly-X-Y repeats has been shown to bind SARS-CoV-2 Spike protein and inhibit SARS-CoV-2 replication by preventing viral entry in Vero cells and HEK293T cells expressing ACE2. DC-SIGN has also been shown to act as a cell surface receptor for SARS-CoV-2 independent of ACE2. Since rfhSP-D is known to interact with SARS-CoV-2 Spike protein and DC-SIGN, this study was aimed at investigating the potential of rfhSP-D in modulating SARS-CoV-2 infection. Coincubation of rfhSP-D with Spike protein improved the Spike Protein: DC-SIGN interaction. Molecular dynamic studies revealed that rfhSP-D stabilised the interaction between DC-SIGN and Spike protein. Cell binding analysis with DC-SIGN expressing HEK 293T and THP- 1 cells and rfhSP-D treated SARS-CoV-2 Spike pseudotypes confirmed the increased binding. Furthermore, infection assays using the pseudotypes revealed their increased uptake by DC-SIGN expressing cells. The immunomodulatory effect of rfhSP-D on the DC-SIGN: Spike protein interaction on DC-SIGN expressing epithelial and macrophage-like cell lines was also assessed by measuring the mRNA expression of cytokines and chemokines. RT-qPCR analysis showed that rfhSP-D treatment downregulated the mRNA expression levels of pro-inflammatory cytokines and chemokines such as TNF-α, IFN-α, IL-1β, IL- 6, IL-8, and RANTES (as well as NF-κB) in DC-SIGN expressing cells challenged by Spike protein. Furthermore, rfhSP-D treatment was found to downregulate the mRNA levels of MHC class II in DC expressing THP-1 when compared to the untreated controls. We conclude that rfhSP-D helps stabilise the interaction between SARS- CoV-2 Spike protein and DC-SIGN and increases viral uptake by macrophages via DC-SIGN, suggesting an additional role for rfhSP-D in SARS-CoV-2 infection.Department of Biotechnology, India [No. BT/PR40165/BTIS/137/12/2021]; Wellcome Trust (GB-CHC-210183)
Immune signature in vaccinated versus non-vaccinated aged people with COVID-19 pneumonia
No full textBackground
A definition of the immunological features of COVID-19 pneumonia is needed to support clinical management of aged patients. In this study, we characterized the humoral and cellular immune responses in presence or absence of SARS-CoV-2 vaccination, in aged patients admitted to the IRCCS San Raffaele Hospital (Italy) for COVID-19 pneumonia between November 2021 and March 2022.
Methods
The study was approved by local authorities. Disease severity was evaluated according to WHO guidelines. We tested: (A) anti-SARS-CoV-2 humoral response (anti-RBD-S IgG, anti-S IgM, anti-N IgG, neutralizing activity against Delta, BA1, BA4/5 variants); (B) Lymphocyte B, CD4 and CD8 T-cell phenotype; (C) plasma cytokines. The impact of vaccine administration and different variants on the immunological responses was evaluated using standard linear regression models and Tobit models for censored outcomes adjusted for age, vaccine doses and gender.
Result
We studied 47 aged patients (median age 78.41), 22 (47%) female, 33 (70%) older than 70 years (elderly). At hospital admission, 36% were unvaccinated (VACno), whilst 63% had received 2 (VAC2) or 3 doses (VAC3) of vaccine. During hospitalization, WHO score > 5 was higher in unvaccinated (14% in VAC3 vs. 43% in VAC2 and 44% VACno). Independently from vaccination doses and gender, elderly had overall reduced anti-SARS-CoV-2 humoral response (IgG-RBD-S, p = 0.0075). By linear regression, the anti-RBD-S (p = 0.0060), B (p = 0.0079), CD8 (p = 0.0043) and Th2 cell counts (p = 0.0131) were higher in VAC2 + 3 compared to VACno. Delta variant was the most representative in VAC2 (n = 13/18, 72%), detected in 41% of VACno, whereas undetected in VAC3, and anti-RBD-S production was higher in VAC2 vs. VACno (p = 0.0001), alongside neutralization against Delta (p = 0141), BA1 (p = 0.0255), BA4/5 (p = 0.0162). Infections with Delta also drove an increase of pro-inflammatory cytokines (IFN-α, p = 0.0463; IL-6, p = 0.0010).
Conclusions
Administration of 3 vaccination doses reduces the severe symptomatology in aged and elderly. Vaccination showed a strong association with anti-SARS-CoV-2 humoral response and an expansion of Th2 T-cells populations, independently of age. Delta variants and number of vaccine doses affected the magnitude of the humoral response against the original SARS-CoV-2 and emerging variants. A systematic surveillance of the emerging variants is paramount to define future vaccination strategies
Pseudotyped Viruses As a Molecular Tool to Monitor Humoral Immune Responses Against SARS-CoV-2 Via Neutralization Assay
No full textPseudotyped viruses (PVs) are molecular tools that can be used to study host-virus interactions and to test the neutralizing ability of serum samples, in addition to their better-known use in gene therapy for the delivery of a gene of interest. PVs are replication defective because the viral genome is divided into different plasmids that are not incorporated into the PVs. This safe and versatile system allows the use of PVs in biosafety level 2 laboratories. Here, we present a general methodology to produce lentiviral PVs based on three plasmids as mentioned here: (1) the backbone plasmid carrying the reporter gene needed to monitor the infection; (2) the packaging plasmid carrying the genes for all the structural proteins needed to generate the PVs; (3) the envelope surface glycoprotein expression plasmid that determines virus tropism and mediates viral entry into the host cell. In this work, SARS-CoV-2 Spike is the envelope glycoprotein used for the production of non-replicative SARS-CoV-2 pseudotyped lentiviruses.
Briefly, packaging cells (HEK293T) were co-transfected with the three different plasmids using standard methods. After 48 h, the supernatant containing the PVs was harvested, filtered, and stored at -80 °C. The infectivity of SARS-CoV-2 PVs was tested by studying the expression of the reporter gene (luciferase) in a target cell line 48 h after infection. The higher the value for relative luminescence units (RLUs), the higher the infection/transduction rate. Furthermore, the infectious PVs were added to the serially diluted serum samples to study the neutralization process of pseudoviruses' entry into target cells, measured as the reduction in RLU intensity: lower values corresponding to high neutralizing activity
Analysis of Antibody Neutralisation Activity against SARS-CoV-2 Variants and Seasonal Human Coronaviruses NL63, HKU1, and 229E Induced by Three Different COVID-19 Vaccine Platforms
No full textCoronaviruses infections, culminating in the recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic beginning in 2019, have highlighted the importance of effective vaccines to induce an antibody response with cross-neutralizing activity. COVID-19 vaccines have been rapidly developed to reduce the burden of SARS-CoV-2 infections and disease severity. Cross-protection from seasonal human coronaviruses (hCoVs) infections has been hypothesized but is still controversial. Here, we investigated the neutralizing activity against ancestral SARS-CoV-2 and the variants of concern (VOCs) in individuals vaccinated with two doses of either BNT162b2, mRNA-1273, or AZD1222, with or without a history of SARS-CoV-2 infection. Antibody neutralizing activity to SARS-CoV-2 and the VOCs was higher in BNT162b2-vaccinated subjects who were previously infected with SARS-CoV-2 and conferred broad-spectrum protection. The Omicron BA.1 variant was the most resistant among the VOCs. COVID-19 vaccination did not confer protection against hCoV-HKU1. Conversely, antibodies induced by mRNA-1273 vaccination displayed a boosting in their neutralizing activity against hCoV-NL63, whereas AZD1222 vaccination increased antibody neutralization against hCoV-229E, suggesting potential differences in antigenicity and immunogenicity of the different spike constructs used between various vaccination platforms. These data would suggest that there may be shared epitopes between the HCoVs and SARS-CoV-2 spike proteins
Quantitative characterisation of extracellular vesicles designed to decoy or compete with SARS-CoV-2 reveals differential mode of action across variants of concern and highlights the diversity of Omicron
No full textBackground
The converging biology between enveloped viruses and extracellular vesicles (EVs) has raised interest in the application of engineered EVs as antiviral therapeutics. Following the recent COVID-19 pandemic, EVs engineered with either the ACE2-receptor or Spike-protein have been proposed as strategy to either decoy SARS-CoV-2, or to compete with its cell entry. For generic use as a platform for future pandemic preparedness, a systematic and quantitative comparison of both strategies is required to assess their limitations and benefits across different variants of concern.
Methods
Here we generated EVs decorated with either the ACE2-receptor or the Spike-protein of (Wuhan)-SARS-CoV-2 and used single vesicle imaging for in-depth quantitative characterisation. These vesicles were then systematically tested for anti-viral activity across SARS-CoV-2 variants of concern using both, pseudotype and live virus cellular infection models including primary human bronchial and nasal explants.
Results
Spike-protein EVs or ACE2-EVs recovered from transiently transfected HEK293T cells comprised only a small fraction of the EV secretome (5% or 20%, respectively) and were primarily derived from the plasma membrane rather than multivesicular bodies. Redirecting intracellular trafficking of the Spike protein by mutating its transmembrane or subcellular localisation domains did not increase the yields of Spike-EVs. Both types of vesicles inhibited SARS-CoV-2 (D614G) in a dose dependent manner with kinetics and immunohistochemistry consistent with an inhibition at the initial cell entry stage. ACE2-EVs were more potent than Spike-EVs and at least 500–1000 times more potent than soluble antibodies in a pseudotype model. Surprisingly, ACE2-EVs switched from an inhibitory to an enhancer activity for the Omicron BA.1 variant whereas Spike-EVs retained their activity across all variants of concern.
Conclusions
While our data show that both types of engineered EVs potently inhibit SARS-CoV, the decoy versus competition strategy may result in diverging outcomes when considering viral evolution into new variants of concern. While Spike-EVs retain their competition for receptor binding even against higher affinity viral Spike mutations, the formation of complexes between ACE2-EVs and the virus may not only result in inhibition by decoy. As EVs are actively internalised by cells themselves, they may shuttle the virus into cells, resulting in a productive alternative cell entry route for variants such as Omicron, that diverge from strict plasma membrane protease cleavage to the use of endosomal proteases for release of their genome
The Role of Pseudotype Neutralisation Assays in Understanding SARS CoV-2
No full textNeutralisation assays are crucial tools to quantify the presence of functional neutralising antibodies in serum samples. Since the SARS-CoV-2 virus (the causative agent of COVID-19) is designated as a category 3 biosafety level pathogen, pseudotyped viruses bearing the SARS-CoV-2 spike protein permit extensive and widespread serum/plasma screening in a BSL 2 laboratory. These assays can be used to assess viral tropism, vaccine immunogenicity, efficacy of antiviral compounds (incl. therapeutic mAbs) and serosurveillance studies. In this article, we highlight approaches to SARS-CoV-2 viral pseudotyping, its practicality, and utility in increasing our understanding of neutralising antibodies against SARS-CoV-2
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