Combinatorial analysis of deletion repair in SARS-CoV-2 variants of concern

Resumen del póster presentado a las III Jornadas Científicas PTI+ Salud Global, celebradas en el Centro de Ciencias Humanas y Sociales (CCHS), CSIC (Madrid) del 20 al 22 de noviembre de 2023.[Background] The spike protein of SARS-CoV-2 is a key determinant of viral fitness and immune evasion, and its N-terminal domain (NTD) is prone to mutations that may confer fitness advantages to the virus. Most variants of concern (VOCs), including Alpha, Delta, and Omicron, have harbored distinct NTD lineage-defining mutations. However, the relationship between genotype and the impact on viral transmission and viral phenotype is not yet fully understood.[Methods] We analyzed over 10 million SARS-CoV-2 genomes from GISAID to investigate the prevalence and estimate the transmission of different combinations of NTD mutations across the Alpha and the Omicron variants. Additionally, we characterized the viral phenotype of deletion repair events in a surrogate in vitro system, assessing their infectivity, fusogenicity, thermal stability, protein surface expression, and neutralization sensitivity.[Results] Some NTD mutations, such the repair of deleted amino acids at sites S:69/70 and S:144 in Alpha viruses, were associated with an increased transmission rate and higher frequency among older age groups. These deletion repairs were also detected in Omicron, but with different patterns and effects. For instance, the repair of deletion at site S:143/145 in Omicron enhanced viral fusogenicity and neutralization by sera from vaccinated individuals. However, the repair of the deletion at site S:69/70 reduced viral infectivity and did not affect these traits. The co-occurrence of both repairs resulted in reduced fusogenicity.[Conclusions] Our study reveals the complex interplay between NTD mutations, including those that lead to deletion repair, and viral success in SARS-CoV-2. This may have implications for viral transmission, immunity, and vaccine efficacy. Our findings improve our understanding of SARS- CoV-2 evolution, and provide insights for future research and public health interventions.Peer reviewe

Neutralizing antibodies against Omicron BA.4/5 after COVID-19 vaccination in SARS-CoV-2 experienced versus naïve individuals in the general population

This work was supported in part by the European Commission NextGenerationEU fund, awarded to RG through CSIC's Global Health Platform (PTI Salud Global).Peer reviewe

Deficient neutralizing antibody response and specific lack of RBD-responsive B cells in elderly long-term convalescent patients from severe COVID-19

Resumen del póster presentado a las III Jornadas Científicas PTI+ Salud Global, celebradas en el Centro de Ciencias Humanas y Sociales (CCHS), CSIC (Madrid) del 20 al 22 de noviembre de 2023.[Background] Severe COVID-19 is defined by admission to intensive care units with respiratory support. This condition increases with age. To investigate in the possible mechanisms by which severe COVID-19 occurs, we compared the response of specific antibodies against the viral antigens RBD, Spike (S), nuclear (N), and membrane (Mpro) and the neutralizing titers in plasma of elderly patients convalescent from severe COVID-19 with convalescent patients from mild disease.[Methods] Plasma was collected from cohort 1: 20 healthy donors (vaccinated and unvaccinated), cohort 2: 40 elderly long-term convalescent patients from severe COVID-19 (mean: 73 years old, 60/40 ratio men/women, and 10 months after infection), and cohort 3: 60 convalescent from mild COVID-19 patients, who were vaccinated (mean: 42 years old, 30/70 ration men/women, 8 months after mild infection, and 5.7 months after last vaccination shoot). To compare reactivity against native S protein, we used a sensitive method to measure specific IgG1 and IgA in plasma by flow cytometry. We assessed the neutralization titers in plasma by infection assays in HEK-293T cells or Vero cells expression ACE-2, using S- and GFP-expressing pseudotyped viruses, and quantified IgG, IgA, and IgM antibodies against RBD, S, N, and mPro antigens using the Multiplex Serological SARS-CoV-2 assay (Immunostep). To evaluate the presence of specific T and B cells specific for S and RBD antigens, we used kits from Miltenyi Biotech and analyzed the expression of activation antigens after cell stimulation with these antigens by flow cytometry.[Results] Significant levels of IgG and IgA against S protein were found in the plasma of convalescent patients from cohorts 2 and 3, with no differences in total anti-S antibody response between the two cohorts. Interestingly, anti-RBD IgG levels were found to be extremely low in plasma samples from cohort 2, but not in plasma samples from cohort 3. In accordance with these results, the neutralizing titers (IC50) found were very low in the plasma samples from cohort 2, compared to those from cohort 3. Analysis of the presence of RBD- and S-specific B cells present in peripheral blood mononuclear cells (PBMCs) of these cohorts revealed significantly lower levels of RBD-specific B cells, but of not S-specific B lymphocytes, in the PBMCs from cohort 2 cells but not in those from cohort 3. Furthermore, lower B cell activation, as demonstrated by CD25 expression, was observed in PBMCs from cohort 2 compared to those from cohort 3 after their stimulation with RBD, but not with S, N or Mpro proteins. These results together indicate the specific lack of RBD-specific B cells in cohort 2 patients.[Conclusions] The low neutralizing capacity observed in the plasma of elderly long-term convalescent patients, who recovered from severe COVID-19 (cohort 2) correlates with low specific levels of anti-RBD antibodies and reduced levels of RBD-responsive B cells. These results could help explain the severity of COVID-19 in patients from cohort 2 compared to those from cohort 3, who had a mild disease. Future experiments will evaluate the presence of neutralizing antibodies in cohort 2 patients after vaccination.Peer reviewe

SARS-CoV-2 adaptive immunity in nursing home residents following a third dose of the Comirnaty® COVID-19 vaccine

A third Comirnaty® vaccine dose increased SARS-CoV-2-receptor binding domain antibody levels (median of 93-fold) and neutralizing antibody titers against Wuhan-Hu-1 (median, 57-fold), Beta (median, 22-fold), Delta, (median, 43-fold) and Omicron (median, 8-fold) variants, particularly in SARS-CoV-2-naïve individuals, but had a negligible impact on S-reactive T-cell immunity in nursing home residents.Peer reviewe

Cumulative incidence of SARS-CoV-2 infection in the general population of the Valencian Community (Spain) after the surge of the Omicron BA.1 variant

Background Studies investigating the cumulative incidence of and immune status against SARS-CoV-2 infection provide valuable information for shaping public health decision-making. Methods The current cross-sectional, population-based study, conducted in April 2022 in the Valencian Community (VC), recruited 935 participants of all ages. Anti-SARS-CoV-2-Receptor Binding Domain-RBD-total antibodies and anti-Nucleocapsid (N)- IgGs were measured by electrochemiluminescence assays. To account for past SARS-CoV-2 infection the VC microbiology registry (RedMiVa) was interrogated. |Quantitation of neutralizing antibodies (NtAb) against the ancestral and Omicron BA.1 and BA.2 (sub)variants by an S-pseudotyped neutralization assay and for enumeration of SARS-CoV-2-S specific-IFNγ-producing CD4+ and CD8+ T cells by Intracellular Cytokine Staining assay was performed in a subset of participants (n=100 and 137, respectively). Findings The weighted cumulative incidence was 51□9% (95% CI, 48□7–55□1), and was inversely related to age. Anti-RBD total antibodies were detected in 906/931 (97□3%) participants, those vaccinated and SARS-CoV-2-experienced (VAC-ex;=442) displaying higher levels (P<0.001) than vaccinated/naïve (VAC-n;(n=472) and non-vaccinated/experienced (UNVAC-ex; n(n=63). Antibody levels correlated inversely with the time elapsed since receipt of last vaccine dose in VAC-n (Rho, -0□52; 95% CI, -0□59 to -0□45; P<0.001) but not in VAC-ex. NtAbs against Omicron BA.1 were detected in 94%, 75% and 50% of VAC-ex, VAC-n and UNVAC-ex groups, respectively, while in 97%, 84% and 40%, against Omicron BA.2. SARS-CoV-2-S-reactive IFN-γ T cells were detected in 73%, 75%, and 64% for VAC-ex, VAC-n, UNVAC-ex, respectively. Interpretation By April 2022 around half of the VC population had been infected with SARS-CoV-2 and due to extensive vaccination display hybrid immunity. The large percentage of participants with detectable functional antibody and T-cell responses against SARS-CoV-2, which may be cross-reactive to some extent, points towards lower expected severity than in previous waves.We also thank Ana Berenguer, General Director of Analysis and Public Policies of the Presidency of the Generalitat. Eliseo Albert (Juan Rodés Contract; JR20/00011) Estela Giménez (Juan Rodés Contract, JR18/00053) and Ignacio Torres (Río Hortega Contract; CM20/00090) hold contracts funded by the Carlos III Health Institute (co-financed by the European Regional Development Fund, ERDF/FEDER). Ron Geller holds a Ramon y Cajal fellowship from the Spanish Ministry of Economics and Competitiveness (RYC-2015-17517).N

Breastfeeding during the COVID-19 pandemic: analysis of the breastmilk antibodies, neutralization capacity and microbiota profile from infected and vaccinated wome

Resumen del póster presentado a las III Jornadas Científicas PTI+ Salud Global, celebradas en el Centro de Ciencias Humanas y Sociales (CCHS), CSIC (Madrid) del 20 al 22 de noviembre de 2023.[Background] Breastmilk is considered the gold standard in infant nutrition and provides bioactive compounds to the neonate, among them antibodies and microbiota. In the context of the COVID- 19 pandemics, there were great concerns about a possible mother-to-infant transfer of SARS-CoV-2, since limited knowledge about the safety of breastfeeding after natural infection or vaccination, as well as the transfer of protective antibodies and their neutralization capacity, was available. Additionally, there are concerns about potential short- and long-term adverse effects of SARS-CoV-2 infection and vaccine-induced changes to the breastmilk microbiome composition, which contributes in shaping the early-life microbiome.[Methods] This study included 60 mothers which had a confirmed SARS-CoV-2 infection and also, 86 mothers vaccinated with mRNA-based (Comirnaty, mRNA-1273) and adenoviral-vectored vaccines (ChAdOx1 nCoV-19) were recruited and breastmilk samples were collected longitudinally from baseline up to 30 days after the second dose at seven or eight time points (depending on vaccine type). In COVID-19 lactating mothers, the presence of SARS-CoV-2 was assessed by RT-qPCR targeting the N1 region of the nucleocapsid gene and the envelope (E) gene. In both studies, the levels of SARS-CoV-2 RBD-specific IgA, IgM and IgG were determined by ELISA. The neutralization capacity was tested using pseudotyped vesicular stomatitis virus carrying either the Wuhan-Hu-1, Delta, or BA.1 Omicron spike proteins. To assess the microbiome composition, DNA from breastmilk samples was extracted and the V3-V4 region of the 16S rRNA gene was sequenced using the MiSeq system of Illumina.[Results] After SARS-CoV-2 infection, no virus-specific RNA was detected in breastmilk samples. Determination of antibody levels in mothers with confirmed SARS-CoV-2 infection showed that 82.9% (58 of 70) of milk samples were positive for at least one of the three tested antibody isotypes. Vaccination elicited also a strong induction of SARS-CoV-2-specific antibodies, which was higher in IgG when compared to COVID-19 convalescent women and was strongly increased after the 2nd dose. mRNA-based vaccines induced higher IgG and IgA levels when compared to the adenovirus- vectored vaccine, and women with previous virus exposure increased their IgG antibodies levels after the first dose to a similar level observed in vaccinated women after the second dose. When assessing the neutralization capacity, natural infection resulted in higher neutralizing titers that correlated positively with levels of SARS-CoV-2-specific immunoglobulin A in breastmilk. Breastmilk samples from COVID-19 convalescent mothers infected during the first wave (Wuhan-Hu-1 strain) neutralized less effectively Omicron BA.1 than the Wuhan-Hu-1 variant. In addition, significant differences in the capacity to produce neutralizing antibodies were observed between both mRNA- based vaccines and the adenovirus-vectored ChAdOx1 COVID-19 vaccine. First results of the analysis of the breastmilk microbiome found no significant differences in the mean diversity of species (alpha-diversity) after natural SARS-CoV-2 infection, whereas some specific bacterial groups were increased (e.g. Enterobacteriaceae).[Conclusions] Overall, our results indicate that breastmilk from naturally infected women or those vaccinated with mRNA-based vaccines contain SARS-CoV-2 neutralizing antibodies that could potentially provide protection to breastfed infants from infection.Peer reviewe

SARS-CoV-2-spike antibody and T-cell responses elicited by a homologous third mRNA COVID-19 dose in hemodialysis and kidney transplant recipients

This article belongs to the Section Medical Microbiology.The effect of a third vaccine dose (3D) of homologous mRNA vaccine on blood levels of SARS-CoV-2-receptor binding domain (RBD)-total antibodies was assessed in 40 hemodialysis patients (HD) and 21 kidney transplant recipients (KTR) at a median of 46 days after 3D. Anti-RBD antibodies were detected in 39/40 HD and 19/21 KTR. Overall, 3D boosted anti-RBD antibody levels (median: 58-fold increase). Neutralizing antibodies (NtAb) against the Wuhan-Hu-1, Delta, and Omicron variants were detected in 14, 13, and 11 out of 14 HD patients, and in 5, 5, and 4 out of 8 KTR patients, respectively. The median fold increase in NtAb titers in HD patients was 77, 28, and 5 and 56, 37, and 9 in KTR patients for each respective variant. SARS-CoV-2-S S-IFN-γ-producing CD8+ and CD4+ T-cell responses were detected in the majority of HD (35 and 36/37, respectively) and all KTR (16/16) patients at 3D. Overall, the administration of 3D boosted T-cell levels in both population groups. In conclusion, a homologous mRNA COVID-19 vaccine 3D exerts a booster effect on anti-RBD antibodies, NtAb binding to Wuhan-Hu-1, Delta, and Omicron variants, and SARS-CoV-2-S-IFN-γ-producing T cells in both HD and KTR patients. The magnitude of the effect was more marked in HD than KTR patients.This research work was supported by funding from the Instituto de Salud Carlos III, Madrid, Spain (FIS, PI21/00563) to DN and by funding from the European Commission NextGenerationEU fund (EU 2020/2094), through CSIC’s Global Health Platform (PTI Salud Global), to RG, and funding from the Valencian Society of Neprology. The project received the Isabel Burches grant from the Valencian Society of Nephrology (2/2/21).Peer reviewe

SARS-CoV-2 Omicron BA.1 variant breakthrough infections in nursing home residents after an homologous third dose of the Comirnaty® COVID-19 vaccine: Looking for correlates of protection

8 páginas, 2 figuras. Texto completo en PubMedCentral: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9348298/pdf/JMV-94-4216.pdfWe investigated whether peripheral blood levels of SARS-CoV-2 Spike (S) receptor binding domain antibodies (anti-RBD), neutralizing antibodies (NtAb) targeting Omicron S, and S-reactive-interferon (IFN)-γ-producing CD4+ and CD8+ T cells measured after a homologous booster dose (3D) with the Comirnaty® vaccine was associated with the likelihood of subsequent breakthrough infections due to the Omicron variant. An observational study including 146 nursing home residents (median age, 80 years; range, 66-99; 109 female) evaluated for an immunological response after 3D (at a median of 16 days). Anti-RBD total antibodies were measured by chemiluminescent immunoassay. NtAb were quantified by an Omicron S pseudotyped virus neutralization assay. SARS-CoV-2-S specific-IFNγ-producing CD4+ and CD8+ T cells were enumerated by whole-blood flow cytometry for intracellular cytokine staining. In total, 33/146 participants contracted breakthrough Omicron infection (symptomatic in 30/33) within 4 months after 3D. Anti-RBD antibody levels were comparable in infected and uninfected participants (21 123 vs. 24 723 BAU/ml; p = 0.34). Likewise, NtAb titers (reciprocal IC50 titer, 157 vs. 95; p = 0.32) and frequency of virus-reactive CD4+ (p = 0.82) and CD8+ (p = 0.91) T cells were similar across participants in both groups. anti-RBD antibody levels and NtAb titers estimated at around the time of infection were also comparable (3445 vs. 4345 BAU/ml; p = 0.59 and 188.5 vs. 88.9; p = 0.70, respectively). Having detectable NtAb against Omicron or SARS-CoV-2-S-reactive-IFNγ-producing CD4+ or CD8+ T cells after 3D was not correlated with increased protection from breakthrough infection (OR, 1.50; p = 0.54; OR, 0.0; p = 0.99 and OR 3.70; p = 0.23, respectively). None of the immune parameters evaluated herein, including NtAb titers against the Omicron variant, may reliably predict at the individual level the risk of contracting COVID-19 due to the Omicron variant in nursing home residents.Ignacio Torres (Río Hortega Contract; CM20/00090), Estela Giménez (Juan Rodés Contract, JR18/00053), and Eliseo Albert (Juan Rodés Contract; JR20/00011) hold contracts funded by the Carlos III Health Institute (cofinanced by the European Regional Development Fund, ERDF/FEDER). Ron Geller holds a Ramon y Cajal fellowship from the Spanish Ministerio de Economía y Competitividad (RYC‐2015‐17517). This study work was supported by Instituto de Salud Carlos III, Madrid, Spain (FIS, PI21/00563) to David Navarro, and by the European Commission NextGenerationEU fund (EU 2020/2094), through CSIC's Global Health Platform (PTI Salud Global) to Ron Geller.Peer reviewe

Plasma glial fibrillary acidic protein is raised in progranulin-associated frontotemporal dementia

Background There are few validated fluid biomarkers in frontotemporal dementia (FTD). Glial fibrillary acidic protein (GFAP) is a measure of astrogliosis, a known pathological process of FTD, but has yet to be explored as potential biomarker. Methods Plasma GFAP and neurofilament light chain (NfL) concentration were measured in 469 individuals enrolled in the Genetic FTD Initiative: 114 C9orf72 expansion carriers (74 presymptomatic, 40 symptomatic), 119 GRN mutation carriers (88 presymptomatic, 31 symptomatic), 53 MAPT mutation carriers (34 presymptomatic, 19 symptomatic) and 183 non-carrier controls. Biomarker measures were compared between groups using linear regression models adjusted for age and sex with family membership included as random effect. Participants underwent standardised clinical assessments including the Mini-Mental State Examination (MMSE), Frontotemporal Lobar Degeneration-C linical Dementia Rating scale and MRI. Spearman's correlation coefficient was used to investigate the relationship of plasma GFAP to clinical and imaging measures. Results Plasma GFAP concentration was significantly increased in symptomatic GRN mutation carriers (adjusted mean difference from controls 192.3 pg/mL, 95% CI 126.5 to 445.6), but not in those with C9orf72 expansions (9.0, -61.3 to 54.6), MAPT mutations (12.7, -33.3 to 90.4) or the presymptomatic groups. GFAP concentration was significantly positively correlated with age in both controls and the majority of the disease groups, as well as with NfL concentration. In the presymptomatic period, higher GFAP concentrations were correlated with a lower cognitive score (MMSE) and lower brain volume, while in the symptomatic period, higher concentrations were associated with faster rates of atrophy in the temporal lobe. Conclusions Raised GFAP concentrations appear to be unique to GRN-related FTD, with levels potentially increasing just prior to symptom onset, suggesting that GFAP may be an important marker of proximity to onset, and helpful for forthcoming therapeutic prevention trials

Age at symptom onset and death and disease duration in genetic frontotemporal dementia : an international retrospective cohort study

Background: Frontotemporal dementia is a heterogenous neurodegenerative disorder, with about a third of cases being genetic. Most of this genetic component is accounted for by mutations in GRN, MAPT, and C9orf72. In this study, we aimed to complement previous phenotypic studies by doing an international study of age at symptom onset, age at death, and disease duration in individuals with mutations in GRN, MAPT, and C9orf72. Methods: In this international, retrospective cohort study, we collected data on age at symptom onset, age at death, and disease duration for patients with pathogenic mutations in the GRN and MAPT genes and pathological expansions in the C9orf72 gene through the Frontotemporal Dementia Prevention Initiative and from published papers. We used mixed effects models to explore differences in age at onset, age at death, and disease duration between genetic groups and individual mutations. We also assessed correlations between the age at onset and at death of each individual and the age at onset and at death of their parents and the mean age at onset and at death of their family members. Lastly, we used mixed effects models to investigate the extent to which variability in age at onset and at death could be accounted for by family membership and the specific mutation carried. Findings: Data were available from 3403 individuals from 1492 families: 1433 with C9orf72 expansions (755 families), 1179 with GRN mutations (483 families, 130 different mutations), and 791 with MAPT mutations (254 families, 67 different mutations). Mean age at symptom onset and at death was 49\ub75 years (SD 10\ub70; onset) and 58\ub75 years (11\ub73; death) in the MAPT group, 58\ub72 years (9\ub78; onset) and 65\ub73 years (10\ub79; death) in the C9orf72 group, and 61\ub73 years (8\ub78; onset) and 68\ub78 years (9\ub77; death) in the GRN group. Mean disease duration was 6\ub74 years (SD 4\ub79) in the C9orf72 group, 7\ub71 years (3\ub79) in the GRN group, and 9\ub73 years (6\ub74) in the MAPT group. Individual age at onset and at death was significantly correlated with both parental age at onset and at death and with mean family age at onset and at death in all three groups, with a stronger correlation observed in the MAPT group (r=0\ub745 between individual and parental age at onset, r=0\ub763 between individual and mean family age at onset, r=0\ub758 between individual and parental age at death, and r=0\ub769 between individual and mean family age at death) than in either the C9orf72 group (r=0\ub732 individual and parental age at onset, r=0\ub736 individual and mean family age at onset, r=0\ub738 individual and parental age at death, and r=0\ub740 individual and mean family age at death) or the GRN group (r=0\ub722 individual and parental age at onset, r=0\ub718 individual and mean family age at onset, r=0\ub722 individual and parental age at death, and r=0\ub732 individual and mean family age at death). Modelling showed that the variability in age at onset and at death in the MAPT group was explained partly by the specific mutation (48%, 95% CI 35\u201362, for age at onset; 61%, 47\u201373, for age at death), and even more by family membership (66%, 56\u201375, for age at onset; 74%, 65\u201382, for age at death). In the GRN group, only 2% (0\u201310) of the variability of age at onset and 9% (3\u201321) of that of age of death was explained by the specific mutation, whereas 14% (9\u201322) of the variability of age at onset and 20% (12\u201330) of that of age at death was explained by family membership. In the C9orf72 group, family membership explained 17% (11\u201326) of the variability of age at onset and 19% (12\u201329) of that of age at death. Interpretation: Our study showed that age at symptom onset and at death of people with genetic frontotemporal dementia is influenced by genetic group and, particularly for MAPT mutations, by the specific mutation carried and by family membership. Although estimation of age at onset will be an important factor in future pre-symptomatic therapeutic trials for all three genetic groups, our study suggests that data from other members of the family will be particularly helpful only for individuals with MAPT mutations. Further work in identifying both genetic and environmental factors that modify phenotype in all groups will be important to improve such estimates. Funding: UK Medical Research Council, National Institute for Health Research, and Alzheimer's Society