Effect of mesoporous silica under Neisseria meningitidis transformation process: environmental effects under meningococci transformation

Vaccination with outer membrane vesicles from Neisseria Meningitidis and SBa15, SBa16 mesoporous silica associated with SARS-CoV-2 induces protective humoral and cellular response against COVID-19 in mice

The global impact of the SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic in 2019-2020 has led to significant changes in worldwide vaccination and immune prophylactic approaches. In this study, our research delves into a new immunization strategy that does not involve the use of additional adjuvants or preservatives, focusing on the effects of virus fusion with a bacterial nanostructure. The experimental procedures outlined in this paper involved the cultivation of SARS-CoV-2, the production, extraction, and nanocharacterization of outer membrane vesicles (OMV) from Neisseria meningitidis, immunization of mice with two doses of OMV combined with SARS-CoV-2, and the use of mesoporous silica SBa15 and SBa16 adsorbed to the same virus. The immune response was assessed through an indirect elisa method, analysis of cytokine expression profiles, and seroneutralization of the SARS-CoV-2 strain. The characterizations of associated OMV - SARS-CoV-2 and adsorption SBa15 and SBa16 were performed using Nanosight Tracking Analysis (NTA), which showed a high density of particles in the formulation. mice were then immunized, resulting in an immune response that produced high levels of neutralizing antibodies in IgG and IgG1 mouse immunoglobulins. In addition, expressions of IL-2, IL-4, and IL-23 in spleen cells were reinforced after the vaccination process. The comparative study of these three vaccine formulations has shown that the development of new vaccines for SARS-CoV-2 should take into consideration the production of neutralizing antibodies and the maintenance of immunological memory.

Analysis of potential virulence genes and competence to transformation in Haemophilus influenzae biotype aegyptius associated with Brazilian Purpuric Fever

Brazilian Purpuric Fever (BPF) is a hemorrhagic pediatric illness caused by Haemophilus influenzae biogroup aegyptius (Hae), a bacterium that was formerly associated with self-limited purulent conjunctivitis. BPF is assumed to be eradicated. However, the virulence mechanisms inherent to Hae strains associated with BPF is still a mystery and deficient in studies. Here, we aim to analyze the role of the autotransporter genes related to adherence and colonization las, tabA1, and hadA genes through RT-qPCR expression profiling and knockout mutants. Relative quantification by real-time PCR after infection in human cells and infant rat model suggests that las was initially downregulated probably duo to immune evasion, tabA1, and hadA were overexpressed in general, suggesting an active role of TabA1 and HadA1 adhesins in Hae in vitro and in vivo. Transformation attempts were unsuccessful despite the use of multiple technical approaches and in silico analysis revealed that Hae lacks genes related to competence in Haemophilus, which could be part of the elucidation of the difficulty of genetically manipulating Hae strains.

Sub lethal levels of platinum nanoparticle cures plasmid and in combination with carbapenem, curtails carbapenem resistant Escherichia coli

Drug resistance traits are rapidly disseminated across bacteria by horizontal gene transfer, especially through plasmids. Plasmid curing agents that are active both in vitro and in vivo will resensitize Multi Drug Resistant (MDR) bacteria to antimicrobial agents. Pectin capped platinum nanoparticles (PtNPs) at sub MIC (20 µM) concentration was effective, in causing loss of Extended Spectrum Beta Lactamase (ESBL) harboring plasmid as evidenced by, absence of plasmid in agarose gel and by a concomitant (16-64 fold) drop in MIC for cell wall inhibitors ceftriaxone and meropenem, in carbapenem resistant Escherichia coli (CREC). Interestingly, the plasmid cured strain exhibited small colony morphology and displayed slower growth both in vitro and in vivo. Complementation of cured strain with plasmid from the wild type strain restored resistance towards meropenem and ceftriaxone. Relative to wild type, plasmid cured strain displayed 50% reduction in biofilm formation. Plasmid curing also occurred in vivo in infected zebrafish with curing efficiency of 17% for nanoparticle + meropenem treatment. PtNPs + meropenem reduced bioburden of CREC in infected zebrafish by 2.4 log CFU. Mechanistic studies revealed that nanoparticle interacted with cell surface and perturbed inner membrane integrity. PtNPs did not induce ROS, yet it caused plasmid DNA cleavage, as evidenced by gyrase inhibition assay. Our study for the first time reveals that PtNPs as plasmid curing agent can resensitize MDR bacteria to selective antimicrobial agents in vivo.

Analysis of the effects of mesoporous silica particles SBA-15 and SBA-16 in Streptococcus pneumoniae transformation process

Streptococcus pneumoniae are natural competent bacteria which requires the presence of a pheromone-like molecule to do the transformation process. This study verified the influence of mesoporous silica (SBA-15 and SBA-16) on the transformation process in S. pneumoniae using a donor DNA obtained from a mutant strain of this microorganism (Sp360∆luxS). The results showed that mesoporous silica SBA-15 and SBA-16 particles doubled the transformation ratio frequency compared with negative control (without nanoparticles) in using SBA-15 (ratio 1.81 ± 0.04) and SBA-16 (ratio 2.18 ± 0.22). We demonstrated the how mesoporous silica nanoparticles were able to increase the pneumococcus transformations, which could possibly lead to the acquisition of virulence factor genes and resistance of antibiotics.

Impact of nanoparticles on the Bacillus subtilis (3610) competence

Due to the physicochemical properties of nanoparticles, the use of nanomaterials increases every year in industrial and medical processes. At the same time, the increasing number of bacteria becoming resistant to many antibiotics, mostly by a horizontal gene transfer process, is a major public health concern. We herein report, for the first time, the role of nanoparticles in the physiological induction of horizontal gene transfer in bacteria. Besides the most well-known impacts of nanoparticles on bacteria, i.e. death or oxidative stress, two nanoparticles, n-ZnO and n-TiO₂, significantly and oppositely impact the transformation efficiency of Bacillus subtilis in biofilm growth conditions, by modification of the physiological processes involved in the induction of competence, the first step of transformation. This effect is the consequence of a physiological adaptation rather than a physical cell injury: two oligopeptide ABC transporters, OppABCDF and AppDFABC, are differentially expressed in response to nanoparticles. Interestingly, a third tested nanoparticle, n-Ag, has no significant effect on competence in our experimental conditions. Overall, these results show that nanoparticles, by altering bacterial physiology and especially competence, may have profound influences in unsuspected areas, such as the dissemination of antibiotic resistance in bacteria.

Antimicrobial Nanostructures for Neurodegenerative Infections

Nanostructures have been widely involved in changes in the drug delivery system. Nanoparticles have unique physicochemical properties, e.g., ultrasmall size, large surface area, and the ability to target specific actions. Various nanomaterials, like Ag, ZnO, Cu/CuO, and Al₂O₃, have antimicrobial activity. Basically, six mechanisms are involved in the production of antimicrobial activity, i.e., (1) destruction of the peptidoglycan layer, (2) release of toxic metal ions, (3) alteration of cellular pH via proton efflux pumps, (4) generation of reactive oxygen species, (5) damage of nuclear materials, and (6) loss of ATP production. Nanomedicine contributes to various pharmaceutical applications, like diagnosis and treatment of various ailments including microbial diseases. Furthermore, nanostructured antimicrobial agents are also involved in the treatment of the neuroinfections associated with neurodegenerative disorders. This chapter focuses on the nanostructure and nanomedicine of antimicrobial agents and their prospects for the possible management of infections associated with neurodegenerative disorders.

How the Knowledge of Interactions between Meningococcus and the Human Immune System Has Been Used to Prepare Effective Neisseria meningitidis Vaccines

In the last decades, tremendous advancement in dissecting the mechanisms of pathogenicity of Neisseria meningitidis at a molecular level has been achieved, exploiting converging approaches of different disciplines, ranging from pathology to microbiology, immunology, and omics sciences (such as genomics and proteomics). Here, we review the molecular biology of the infectious agent and, in particular, its interactions with the immune system, focusing on both the innate and the adaptive responses. Meningococci exploit different mechanisms and complex machineries in order to subvert the immune system and to avoid being killed. Capsular polysaccharide and lipooligosaccharide glycan composition, in particular, play a major role in circumventing immune response. The understanding of these mechanisms has opened new horizons in the field of vaccinology. Nowadays different licensed meningococcal vaccines are available and used: conjugate meningococcal C vaccines, tetravalent conjugate vaccines, an affordable conjugate vaccine against the N. menigitidis serogroup A, and universal vaccines based on multiple antigens each one with a different and peculiar function against meningococcal group B strains.

Haemophilus influenzae porine ompP2 gene transfer mediated by graphene oxide nanoparticles with effects on transformation process and virulence bacterial capacity

Background

H. influenzae is a natural competent bacterium that can uptake DNA from the environment and recombine into bacterial genome. The outbreaks of Brazilian purpuric fever, heavily polluted areas of a different H. influenzae biogroup - aegyptius - as well as gene transference between Neisseria meningitis make the transformation process an important evolutionary factor. This work studied the horizontal transference of the ompP2 gene from a multiresistant strain of H. influenzae 07 (NTHi), under the influence of graphene oxide nanoparticles in order to mimic an atmosphere rich in suspended particles and this way verify if the CFU transformants number was increased.

Material and methods

In this article the gene ompP2 was transformed into different strains of H. influenzae mediated or not by graphene oxide nanoparticles in suspension, followed by the adhesion tests in Hec-1B (human endometrium adenocarcinoma) and A549 (pulmonary epithelial carcinoma) cells lines. The transformation frequency and the adhesion capacity were determined in all the mutants to which the ompP2 gene was transferred and compared to their wild type strains.

Results

The nanoparticles increased the transformation ratio of one particular strain isolated from a pneumonia case. The adhesion patterns to A549 and Hec1b cell lines of these mutated bacteria has their capacity increased when compared to the wild type.

Conclusions

Graphene oxide nanoparticles aid the transformation process, helping to increase the number of CFUs, and the mutants generated with the ompP2 gene from a H. influenzae resistant strain not only present a chloramphenicol resistance but also have an increased adherence patterns in A549 and Hec1B cell lines.

Inflammatory response of Haemophilus influenzae biotype aegyptius causing Brazilian Purpuric Fever

The Brazilian Purpuric Fever (BPF) is a systemic disease with many clinical features of meningococcal sepsis and is usually preceded by purulent conjunctivitis. The illness is caused by Haemophilus influenza biogroup aegyptius, which was associated exclusively with conjunctivitis. In this work construction of the las gene, hypothetically responsible for this virulence, were fusioned with ermAM cassette in Neisseria meningitidis virulent strains and had its DNA transfer to non BPF H. influenzae strains. The effect of the las transfer was capable to increase the cytokines TNFα and IL10 expression in Hec-1B cells line infected with these transformed mutants (in eight log scale of folding change RNA expression). This is the first molecular study involving the las transfer to search an elucidation of the pathogenic factors by horizontal intergeneric transfer from meningococci to H. influenzae.

Effects of multi-walled carbon nanotubes (MWCNT) under Neisseria meningitidis transformation process

Background

This study aimed at verifying the action of multi-walled carbon nanotubes (MWCNT) under the naturally transformable Neisseria meningitidis against two different DNA obtained from isogenic mutants of this microorganism, an important pathogen implicated in the genetic horizontal transfer of DNA, causing the escape of the principal vaccination measured worldwide by the capsular switching process.

Materials and methods

The bacterium receptor strain C2135 was cultivated and had its mutant DNA donor M2 and M6, which received a receptor strain and MWCNT at three different concentrations. The inhibition effect of DNAse on the DNA in contact with nanoparticles was evaluated.

Results

The results indicated an in increase in the transformation capacity of N. meninigtidis in different concentrations of MWCNT when compared with negative control without nanotubes. A final analysis of the interaction between DNA and MWCNT was carried out using Raman Spectroscopy.

Conclusion

These increases in the transformation capacity mediated by MWCNT, in meningococci, indicate the interaction of these particles with the virulence acquisition of these bacteria, as well as with the increase in the vaccination escape process.