| 1. |
- Andersson, Maria, et al.
(författare)
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Local and Systemic Immunity During Five Vaccinations Against SARS-CoV-2 in Zanubrutinib-Treated Patients With Chronic Lymphocytic Leukemia
- 2023
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Ingår i: Journal of Hematology. - : Elmer Press, Inc.. - 1927-1212 .- 1927-1220. ; 12:4, s. 170-175
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patients with chronic lymphocytic leukemia (CLL) are vulnerable to coronavirus disease 2019 (COVID-19) and are at risk of inferior response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination, especially if treated with the first-generation Bruton’s tyrosine kinase inhibitor (BTKi) ibrutinib. We aimed to evaluate the impact of the third-generation BTKi, zanubrutinib, on systemic and mucosal response to SARS-CoV-2 vaccination.Methods: Nine patients with CLL with ongoing zanubrutinib therapy were included and donated blood and saliva during SARS-CoV-2 vaccination, before vaccine doses 3 and 5 and 2 - 3 weeks after doses 3, 4, and 5. Ibrutinib-treated control patients (n = 7) and healthy aged-matched controls (n = 7) gave blood 2 - 3 weeks after vaccine dose 5. We quantified reactivity and neutralization capacity of SARS-CoV-2-specific IgG and IgA antibodies (Abs) in both serum and saliva, and reactivity of T cells activated with viral peptides.Results: Both zanubrutinib- and ibrutinib-treated patients had significantly, up to 1,000-fold, lower total spike-specific Ab levels after dose 5 compared to healthy controls (P < 0.01). Spike-IgG levels in serum from zanubrutinib-treated patients correlated well to neutralization capacity (r = 0.68; P < 0.0001) and were thus functional. Mucosal immunity (specific IgA in serum and saliva) was practically absent in zanubrutinib-treated patients even after five vaccine doses, whereas healthy controls had significantly higher levels (tested in serum after vaccine dose 5) (P < 0.05). In contrast, T-cell reactivity against SARS-CoV-2 peptides was equally high in zanubrutinib- and ibrutinib-treated patients as in healthy control donors.Conclusions: In our small cohort of zanubrutinib-treated CLL patients, we conclude that up to five doses of SARS-CoV-2 vaccination induced no detectable IgA mucosal immunity, which likely will impair the primary barrier defence against the infection. Systemic IgG responses were also impaired, whereas T-cell responses were normal. Further and larger studies are needed to evaluate the impact of these findings on disease protection.
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| 2. |
- Bailey, Leslie, et al.
(författare)
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Small molecule inhibitors of type III secretion in Yersinia block the Chlamydia pneumoniae infection cycle
- 2007
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Ingår i: FEBS Letters. - : Elsevier. - 0014-5793 .- 1873-3468. ; 581:4, s. 587-595
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Tidskriftsartikel (refereegranskat)abstract
- Intracellular parasitism by Chlamydiales is a complex process involving transmission of metabolically inactive particles that differentiate, replicate, and re-differentiate within the host cell. A type three secretion system (T3SS) has been implicated in this process. We have here identified small molecules of a chemical class of acylated hydrazones of salicylaldehydes that specifically blocks the T3SS of Chlamydia. These compounds also affect the developmental cycle showing that the T3SS has a pivotal role in the pathogenesis of Chlamydia. Our results suggest a previously unexplored avenue for development of novel anti-chlamydial drugs.
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| 3. |
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| 4. |
- Bergman, Peter, et al.
(författare)
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Safety and efficacy of the mRNA BNT162b2 vaccine against SARS-CoV-2 in five groups of immunocompromised patients and healthy controls in a prospective open-label clinical trial
- 2021
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Ingår i: EBioMedicine. - : Elsevier BV. - 2352-3964. ; 74
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Tidskriftsartikel (refereegranskat)abstract
- Background: Patients with immunocompromised disorders have mainly been excluded from clinical trials of vaccination against COVID-19. Thus, the aim of this prospective clinical trial was to investigate safety and efficacy of BNT162b2 mRNA vaccination in five selected groups of immunocompromised patients and healthy controls.Methods: 539 study subjects (449 patients and 90 controls) were included. The patients had either primary (n=90), or secondary immunodeficiency disorders due to human immunodeficiency virus infection (n=90), allogeneic hematopoietic stem cell transplantation/CAR T cell therapy (n=90), solid organ transplantation (SOT) (n=89), or chronic lymphocytic leukemia (CLL) (n=90). The primary endpoint was seroconversion rate two weeks after the second dose. The secondary endpoints were safety and documented SARS-CoV-2 infection.Findings: Adverse events were generally mild, but one case of fatal suspected unexpected serious adverse reaction occurred. 72.2% of the immunocompromised patients seroconverted compared to 100% of the controls (p=0.004). Lowest seroconversion rates were found in the SOT (43.4%) and CLL (63.3%) patient groups with observed negative impact of treatment with mycophenolate mofetil and ibrutinib, respectively.Interpretation: The results showed that the mRNA BNT162b2 vaccine was safe in immunocompromised patients. Rate of seroconversion was substantially lower than in healthy controls, with a wide range of rates and antibody titres among predefined patient groups and subgroups. This clinical trial highlights the need for additional vaccine doses in certain immunocompromised patient groups to improve immunity.
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| 5. |
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| 6. |
- Castro Dopico, Xaquin, et al.
(författare)
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Probabilistic classification of anti-SARS-CoV-2 antibody responses improves seroprevalence estimates
- 2022
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Ingår i: Clinical & Translational Immunology (CTI). - : John Wiley & Sons. - 2050-0068. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Population-level measures of seropositivity are critical for understanding the epidemiology of an emerging pathogen, yet most antibody tests apply a strict cutoff for seropositivity that is not learnt in a data-driven manner, leading to uncertainty when classifying low-titer responses. To improve upon this, we evaluated cutoff-independent methods for their ability to assign likelihood of SARS-CoV-2 seropositivity to individual samples. Methods: Using robust ELISAs based on SARS-CoV-2 spike (S) and the receptor-binding domain (RBD), we profiled antibody responses in a group of SARS-CoV-2 PCR+ individuals (n = 138). Using these data, we trained probabilistic learners to assign likelihood of seropositivity to test samples of unknown serostatus (n = 5100), identifying a support vector machines-linear discriminant analysis learner (SVM-LDA) suited for this purpose. Results: In the training data from confirmed ancestral SARS-CoV-2 infections, 99% of participants had detectable anti-S and -RBD IgG in the circulation, with titers differing > 1000-fold between persons. In data of otherwise healthy individuals, 7.2% (n = 367) of samples were of uncertain serostatus, with values in the range of 3-6SD from the mean of pre-pandemic negative controls (n = 595). In contrast, SVM-LDA classified 6.4% (n = 328) of test samples as having a high likelihood (> 99% chance) of past infection, 4.5% (n = 230) to have a 50–99% likelihood, and 4.0% (n = 203) to have a 10–49% likelihood. As different probabilistic approaches were more consistent with each other than conventional SD-based methods, such tools allow for more statistically-sound seropositivity estimates in large cohorts. Conclusion: Probabilistic antibody testing frameworks can improve seropositivity estimates in populations with large titer variability.
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| 7. |
- Chen, Puran, et al.
(författare)
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Real-world assessment of immunogenicity in immunocompromised individuals following SARS-CoV-2 mRNA vaccination : a one-year follow-up of the prospective clinical trial COVAXID
- 2023
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Ingår i: EBioMedicine. - : Elsevier. - 2352-3964. ; 94
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Tidskriftsartikel (refereegranskat)abstract
- Background: Immunocompromised patients have varying responses to SARS-CoV-2 mRNA vaccination. However, there is limited information available from prospective clinical trial cohorts with respect to long-term immunogenicity-related responses in these patient groups following three or four vaccine doses, and in applicable cases infection.Methods: In a real-world setting, we assessed the long-term immunogenicity-related responses in patients with primary and secondary immunodeficiencies from the prospective open-label clinical trial COVAXID. The original clinical trial protocol included two vaccine doses given on days 0 and 21, with antibody titres measured at six different timepoints over six months. The study cohort has subsequently been followed for one year with antibody responses evaluated in relation to the third and fourth vaccine dose, and in applicable cases SARS-CoV-2 infection. In total 356/539 patients were included in the extended cohort. Blood samples were analysed for binding antibody titres and neutralisation against the Spike protein for all SARS-CoV-2 variants prevailing during the study period, including Omicron subvariants. SARS-CoV-2 infections that did not require hospital care were recorded through quarterly in-person, or phone-, interviews and assessment of IgG antibody titres against SARSCoV-2 Nucleocapsid. The original clinical trial was registered in EudraCT (2021-000175-37) and clinicaltrials.gov (NCT04780659).Findings: The third vaccine dose significantly increased Spike IgG titres against all the SARS-CoV-2 variants analysed in all immunocompromised patient groups. Similarly, neutralisation also increased against all variants studied, except for Omicron. Omicron-specific neutralisation, however, increased after a fourth dose as well as after three doses and infection in many of the patient subgroups. Noteworthy, however, while many patient groups mounted strong serological responses after three and four vaccine doses, comparably weak responders were found among patient subgroups with specific primary immunodeficiencies and subgroups with immunosuppressive medication.Interpretation: The study identifies particularly affected patient groups in terms of development of long-term immunity among a larger group of immunocompromised patients. In particular, the results highlight poor vaccine-elicited neutralising responses towards Omicron subvariants in specific subgroups. The results provide additional knowledge of relevance for future vaccination strategies.
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| 8. |
- Codemo, Mario, et al.
(författare)
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Immunomodulatory Effects of Pneumococcal Extracellular Vesicles on Cellular and Humoral Host Defenses
- 2018
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Ingår i: mBio. - : American Society for Microbiology. - 2161-2129 .- 2150-7511. ; 9:2
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Tidskriftsartikel (refereegranskat)abstract
- Gram-positive bacteria, including the major respiratory pathogen Streptococcus pneumoniae, were recently shown to produce extracellular vesicles (EVs) that likely originate from the plasma membrane and are released into the extracellular environment. EVs may function as cargo for many bacterial proteins, however, their involvement in cellular processes and their interactions with the innate immune system are poorly understood. Here, EVs from pneumococci were characterized and their immunomodulatory effects investigated. Pneumococcal EVs were protruding from the bacterial surface and released into the medium as 25 to 250 nm lipid stained vesicles containing a large number of cytosolic, membrane, and surface-associated proteins. The cytosolic pore-forming toxin pneumolysin was significantly enriched in EVs compared to a total bacterial lysate but was not required for EV formation. Pneumococcal EVs were internalized into A549 lung epithelial cells and human monocyte-derived dendritic cells and induced proinflammatory cytokine responses irrespective of pneumolysin content. EVs from encapsulated pneumococci were recognized by serum proteins, resulting in C3b deposition and formation of C5b-9 membrane attack complexes as well as factor H recruitment, depending on the presence of the choline binding protein PspC. Addition of EVs to human serum decreased opsonophagocytic killing of encapsulated pneumococci. Our data suggest that EVs may act in an immunomodulatory manner by allowing delivery of vesicle-associated proteins and other macromolecules into host cells. In addition, EVs expose targets for complement factors in serum, promoting pneumococcal evasion of humoral host defense.Importance: Streptococcus pneumoniae is a major contributor to morbidity and mortality worldwide, being the major cause of milder respiratory tract infections such as otitis and sinusitis and of severe infections such as community-acquired pneumonia, with or without septicemia, and meningitis. More knowledge is needed on how pneumococci interact with the host, deliver virulence factors, and activate immune defenses. Here we show that pneumococci form extracellular vesicles that emanate from the plasma membrane and contain virulence properties, including enrichment of pneumolysin. We found that pneumococcal vesicles can be internalized into epithelial and dendritic cells and bind complement proteins, thereby promoting pneumococcal evasion of complement-mediated opsonophagocytosis. They also induce pneumolysin-independent proinflammatory responses. We suggest that these vesicles can function as a mechanism for delivery of pneumococcal proteins and other immunomodulatory components into host cells and help pneumococci to avoid complement deposition and phagocytosis-mediated killing, thereby possibly contributing to the symptoms found in pneumococcal infections.
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| 9. |
- Cuapio, Angelica, et al.
(författare)
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NK cell frequencies, function and correlates to vaccine outcome in BNT162b2 mRNA anti-SARS-CoV-2 vaccinated healthy and immunocompromised individuals
- 2022
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Ingår i: Molecular Medicine. - : BioMed Central (BMC). - 1076-1551 .- 1528-3658. ; 28:1
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Tidskriftsartikel (refereegranskat)abstract
- Adaptive immune responses have been studied extensively in the course of mRNA vaccination against COVID-19. Considerably fewer studies have assessed the effects on innate immune cells. Here, we characterized NK cells in healthy individuals and immunocompromised patients in the course of an anti-SARS-CoV-2 BNT162b2 mRNA prospective, open-label clinical vaccine trial. See trial registration description in notes. Results revealed preserved NK cell numbers, frequencies, subsets, phenotypes, and function as assessed through consecutive peripheral blood samplings at 0, 10, 21, and 35 days following vaccination. A positive correlation was observed between the frequency of NKG2C+ NK cells at baseline (Day 0) and anti-SARS-CoV-2 Ab titers following BNT162b2 mRNA vaccination at Day 35. The present results provide basic insights in regards to NK cells in the context of mRNA vaccination, and have relevance for future mRNA-based vaccinations against COVID-19, other viral infections, and cancer.Trial registration: The current study is based on clinical material from the COVAXID open-label, non-randomized prospective clinical trial registered at EudraCT and clinicaltrials.gov (no. 2021–000175-37). Description: https://clinicaltrials.gov/ct2/show/NCT04780659?term=2021-000175-37&draw=2&rank=1.
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| 10. |
- Gao, Yu, et al.
(författare)
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Immunodeficiency syndromes differentially impact the functional profile of SARS-CoV-2-specific T cells elicited by mRNA vaccination
- 2022
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Ingår i: Immunity. - : Elsevier. - 1074-7613 .- 1097-4180. ; 55:9, s. 1732-1746.e5
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Tidskriftsartikel (refereegranskat)abstract
- Many immunocompromised patients mount suboptimal humoral immunity after SARS-CoV-2 mRNA vaccination. Here, we assessed the single-cell profile of SARS-CoV-2-specific T cells post-mRNA vaccination in healthy individuals and patients with various forms of immunodeficiencies. Impaired vaccine-induced cell-mediated immunity was observed in many immunocompromised patients, particularly in solid-organ transplant and chronic lymphocytic leukemia patients. Notably, individuals with an inherited lack of mature B cells, i.e., X-linked agammaglobulinemia (XLA) displayed highly functional spike-specific T cell responses. Single-cell RNA-sequencing further revealed that mRNA vaccination induced a broad functional spectrum of spike-specific CD4+ and CD8+ T cells in healthy individuals and patients with XLA. These responses were founded on polyclonal repertoires of CD4+ T cells and robust expansions of oligoclonal effector-memory CD45RA+ CD8+ T cells with stem-like characteristics. Collectively, our data provide the functional continuum of SARS-CoV-2-specific T cell responses post-mRNA vaccination, highlighting that cell-mediated immunity is of variable functional quality across immunodeficiency syndromes.
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| 11. |
- Ghorbani, Mahin, et al.
(författare)
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Persistence of salivary antibody responses after COVID-19 vaccination is associated with oral microbiome variation in both healthy and people living with HIV
- 2023
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Ingår i: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Coevolution of microbiome and immunity at mucosal sites is essential for our health. Whether the oral microbiome, the second largest community after the gut, contributes to the immunogenicity of COVID-19 vaccines is not known. We investigated the baseline oral microbiome in individuals in the COVAXID clinical trial receiving the BNT162b2 mRNA vaccine. Participants (n=115) included healthy controls (HC; n=57) and people living with HIV (PLHIV; n=58) who met the study selection criteria. Vaccine-induced Spike antibodies in saliva and serum from 0 to 6 months were assessed and comparative analyses were performed against the individual salivary 16S ASV microbiome diversity. High- versus low vaccine responders were assessed on general, immunological, and oral microbiome features. Our analyses identified oral microbiome features enriched in high- vs. low-responders among healthy and PLHIV participants. In low-responders, an enrichment of Gram-negative, anaerobic species with proteolytic activity were found including Campylobacter, Butyrivibrio, Selenomonas, Lachnoanaerobaculum, Leptotrichia, Megasphaera, Prevotella and Stomatobaculum. In high-responders, enriched species were mainly Gram-positive and saccharolytic facultative anaerobes: Abiotrophia, Corynebacterium, Gemella, Granulicatella, Rothia, and Haemophilus. Combining identified microbial features in a classifier using the area under the receiver operating characteristic curve (ROC AUC) yielded scores of 0.879 (healthy controls) to 0.82 (PLHIV), supporting the oral microbiome contribution in the long-term vaccination outcome. The present study is the first to suggest that the oral microbiome has an impact on the durability of mucosal immunity after Covid-19 vaccination. Microbiome-targeted interventions to enhance long-term duration of mucosal vaccine immunity may be exploited.
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| 12. |
- Healy, Katie, et al.
(författare)
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Salivary IgG to SARS-CoV-2 indicates seroconversion and correlates to serum neutralization in mRNA-vaccinated immunocompromised individuals
- 2022
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Ingår i: Med. - : Cell Press. - 2666-6359 .- 2666-6340. ; 3:2, s. 137-153.e3
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Tidskriftsartikel (refereegranskat)abstract
- Background: Immunocompromised individuals are highly susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Whether vaccine-induced immunity in these individuals involves oral cavity, a primary site of infection, is presently unknown.Methods: Immunocompromised patients (n = 404) and healthy controls (n = 82) participated in a prospective clinical trial (NCT04780659) encompassing two doses of the mRNA BNT162b2 vaccine. Primary immunodeficiency (PID), secondary immunodeficiencies caused by human immunodeficiency virus (HIV) infection, allogeneic hematopoietic stem cell transplantation (HSCT)/chimeric antigen receptor T cell therapy (CAR-T), solid organ transplantation (SOT), and chronic lymphocytic leukemia (CLL) patients were included. Salivary and serum immunoglobulin G (IgG) reactivities to SARS-CoV-2 spike were measured by multiplex bead-based assays and Elecsys anti-SARS-CoV-2 S assay.Findings: IgG responses to SARS-CoV-2 spike antigens in saliva in HIV and HSCT/CAR-T groups were comparable to those of healthy controls after vaccination. The PID, SOT, and CLL patients had weaker responses, influenced mainly by disease parameters or immunosuppressants. Salivary responses correlated remarkably well with specific IgG titers and the neutralizing capacity in serum. Receiver operating characteristic curve analysis for the predictive power of salivary IgG yielded area under the curve (AUC) = 0.95 and positive predictive value (PPV) = 90.7% for the entire cohort after vaccination.Conclusions: Saliva conveys vaccine responses induced by mRNA BNT162b2. The predictive power of salivary spike IgG makes it highly suitable for screening vulnerable groups for revaccination.
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| 13. |
- Iovino, Federico, et al.
(författare)
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pIgR and PEC AM-1 bind to pneumococcal adhesins RrgA and PspC mediating bacterial brain invasion
- 2017
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Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 0022-1007 .- 1540-9538. ; 214:6, s. 1619-1630
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae is the main cause of bacterial meningitis, a life-threating disease with a high case fatality rate despite treatment with antibiotics. Pneumococci cause meningitis by invading the blood and penetrating the blood-brain barrier (BBB). Using stimulated emission depletion (STED) super-resolution microscopy of brain biopsies from patients who died of pneumococcal meningitis, we observe that pneumococci colocalize with the two BBB endothelial receptors: polymeric immunoglobulin receptor (pIgR) and platelet endothelial cell adhesion molecule (PECAM-1). We show that the major adhesin of the pneumococcal pilus-1, RrgA, binds both receptors, whereas the choline binding protein PspC binds, but to a lower extent, only pIgR. Using a bacteremia-derived meningitis model and mutant mice, as well as antibodies against the two receptors, we prevent pneumococcal entry into the brain and meningitis development. By adding antibodies to antibiotic (ceftriaxone)-treated mice, we further reduce the bacterial burden in the brain. Our data suggest that inhibition of pIgR and PECAM-1 has the potential to prevent pneumococcal meningitis.
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| 14. |
- Lagerqvist, Nina, et al.
(författare)
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Evaluation of 11 SARS-CoV-2 antibody tests by using samples from patients with defined IgG antibody titers
- 2021
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated the performance of 11 SARS-CoV-2 antibody tests using a reference set of heat-inactivated samples from 278 unexposed persons and 258 COVID-19 patients, some of whom contributed serial samples. The reference set included samples with a variation in SARS-CoV-2 IgG antibody titers, as determined by an in-house immunofluorescence assay (IFA). The five evaluated rapid diagnostic tests had a specificity of 99.0% and a sensitivity that ranged from 56.3 to 81.6% and decreased with low IFA IgG titers. The specificity was > 99% for five out of six platform-based tests, and when assessed using samples collected ≥ 22 days after symptom onset, two assays had a sensitivity of > 96%. These two assays also detected samples with low IFA titers more frequently than the other assays. In conclusion, the evaluated antibody tests showed a heterogeneity in their performances and only a few tests performed well with samples having low IFA IgG titers, an important aspect for diagnostics and epidemiological investigations.
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| 15. |
- Muschiol, Sandra, et al.
(författare)
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A small-molecule inhibitor of type III secretion inhibits different stages of the infectious cycle of Chlamydia trachomatis
- 2006
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Ingår i: National Academy of Sciences, USA. - Washington : Proceedings of the National Academy of Sciences. ; , s. 14566-71
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The intracellular pathogen Chlamydia trachomatis possesses a type III secretion (TTS) system believed to deliver a series of effector proteins into the inclusion membrane (Inc-proteins) as well as into the host cytosol with perceived consequences for the pathogenicity of this common venereal pathogen. Recently, small molecules were shown to block the TTS system of Yersinia pseudotuberculosis. Here, we show that one of these compounds, INP0400, inhibits intracellular replication and infectivity of C. trachomatis at micromolar concentrations resulting in small inclusion bodies frequently containing only one or a few reticulate bodies (RBs). INP0400, at high concentration, given at the time of infection, partially blocked entry of elementary bodies into host cells. Early treatment inhibited the localization of the mammalian protein 14-3-3beta to the inclusions, indicative of absence of the early induced TTS effector IncG from the inclusion membrane. Treatment with INP0400 during chlamydial mid-cycle prevented secretion of the TTS effector IncA and homotypic vesicular fusions mediated by this protein. INP0400 given during the late phase resulted in the detachment of RBs from the inclusion membrane concomitant with an inhibition of RB to elementary body conversion causing a marked decrease in infectivity.
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| 16. |
- Muschiol, Sandra
(författare)
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Small molecule inhibitors of type III secretion and their effect on chlamydia development
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Chlamydiae are obligate intracellular pathogens that cause a variety of diseases with clinical and public health importance. Like many Gram-negative bacteria, Chlamydiae employ a type III secretion (T3S) system for invasion and establishment of a protected intracellular niche for successful replication and survival within host cells. Understanding the role of T3S and bacterial effector proteins in Chlamydia infection will provide new insights into chlamydial pathogenesis and is important to identify novel therapeutic targets for drug intervention. In this thesis we employed different small molecule inhibitors of T3S activity in Yersinia, named INPs, and analyzed their effect on Chlamydia development. In addition, we identified and characterized a new family of T3S effector proteins. In paper I, we assessed the effect of INP0400 on C. trachomatis development and invasion. INP0400 caused a dose and growth phase-dependent inhibition of RB multiplication at micromolar concentrations. When INP0400 was given at different stages during the infectious cycle, we observed a partial inhibition of Chlamydia entry, inhibition of translocation of IncG and IncA and a bacterial detachment from the inclusion membrane during the late stage of infection concomitant with an inhibition of RB to EB conversion causing a marked decrease in infectivity. Our data suggest that INPs impair progression through the infectious cycle suggesting that the T3S system is essential for Chlamydia pathogenesis. In paper II, we found that INP0010 displays a strong growth inhibitory effect on C. pneumoniae development, affects translocation of the C. pneumoniae effector proteins IncB and IncC and leads to down-regulation of T3S associated genes collectively suggesting that INP0010 impairs T3S activity in C. pneumoniae. In paper III, we further investigated the effect of INPs on Chlamydia invasion. We show that INPs impair Chlamydia development after entry into host cells because the efficiency of C. trachomatis L2 and C. caviae entry into epithelial cells was not altered in the presence of INPs. Moreover, entry appeared normally with recruitment of actin and the small GTPases Rac, Cdc42 and Arf6 to the bacterial entry site. Finally, in paper IV we set out to identify novel T3S effectors in Chlamydia. We found a family of chlamydial proteins, represented by a C-terminal domain of unknown function referred to as DUF582 that contains an amino-terminal T3S signal. C. trachomatis members of this family were expressed late during the infectious cycle and found to be secreted into the lumen of the inclusion and the cytoplasm of infected cells.
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| 17. |
- Pathak, Anuj, et al.
(författare)
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Factor H binding proteins protect division septa on encapsulated Streptococcus pneumoniae against complement C3b deposition and amplification
- 2018
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Ingår i: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus pneumoniae evades C3-mediated opsonization and effector functions by expressing an immuno-protective polysaccharide capsule and Factor H (FH)-binding proteins. Here we use super-resolution microscopy, mutants and functional analysis to show how these two defense mechanisms are functionally and spatially coordinated on the bacterial cell surface. We show that the pneumococcal capsule is less abundant at the cell wall septum, providing C3/C3b entry to underlying nucleophilic targets. Evasion of C3b deposition at division septa and lateral amplification underneath the capsule requires localization of the FH-binding protein PspC at division sites. Most pneumococcal strains have one PspC protein, but successful lineages in colonization and disease may have two, PspC1 and PspC2, that we show affect virulence differently. We find that spatial localization of these FH-recruiting proteins relative to division septa and capsular layer is instrumental for pneumococci to resist complement-mediated opsonophagocytosis, formation of membrane-attack complexes, and for the function as adhesins.
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| 18. |
- Reithuber, Elisabeth, et al.
(författare)
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THCz : Small molecules with antimicrobial activity that block cell wall lipid intermediates
- 2021
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 118:47
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Tidskriftsartikel (refereegranskat)abstract
- Emerging antibiotic resistance demands identification of novel antibacterial compound classes. A bacterial whole-cell screen based on pneumococcal autolysin-mediated lysis induction was developed to identify potential bacterial cell wall synthesis inhibitors. A hit class comprising a 1-amino substituted tetrahydrocarbazole (THCz) scaffold, containing two essential amine groups, displayed bactericidal activity against a broad range of gram-positive and selected gram-negative pathogens in the low micromolar range. Mode of action studies revealed that THCz inhibit cell envelope synthesis by targeting undecaprenyl pyrophosphate-containing lipid intermediates and thus simultaneously inhibit peptidoglycan, teichoic acid, and polysaccharide capsule biosynthesis. Resistance did not readily develop in vitro, and the ease of synthesizing and modifying these small molecules, as compared to natural lipid II-binding antibiotics, makes THCz promising scaffolds for development of cell wall-targeting antimicrobials.
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