Frontiers in Cellular and Infection Microbiology

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EISSN : 2235-2988
Published by: Frontiers Media SA (10.3389)
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Aaron D. Gingerich,
Frontiers in Cellular and Infection Microbiology, Volume 12; https://doi.org/10.3389/fcimb.2022.824788

Abstract:
The gram-positive bacterium Streptococcus pneumoniae is a leading cause of pneumonia, otitis media, septicemia, and meningitis in children and adults. Current prevention and treatment efforts are primarily pneumococcal conjugate vaccines that target the bacterial capsule polysaccharide, as well as antibiotics for pathogen clearance. While these methods have been enormously effective at disease prevention and treatment, there has been an emergence of non-vaccine serotypes, termed serotype replacement, and increasing antibiotic resistance among these serotypes. To combat S. pneumoniae, the immune system must deploy an arsenal of antimicrobial functions. However, S. pneumoniae has evolved a repertoire of evasion techniques and is able to modulate the host immune system. Antibodies are a key component of pneumococcal immunity, targeting both the capsule polysaccharide and protein antigens on the surface of the bacterium. These antibodies have been shown to play a variety of roles including increasing opsonophagocytic activity, enzymatic and toxin neutralization, reducing bacterial adherence, and altering bacterial gene expression. In this review, we describe targets of anti-pneumococcal antibodies and describe antibody functions and effectiveness against S. pneumoniae.
Liu Cao, Tiefeng Xu, Xue Liu, Yanxi Ji, Siyao Huang, Hong Peng, Chunmei Li,
Frontiers in Cellular and Infection Microbiology, Volume 12; https://doi.org/10.3389/fcimb.2022.823306

Abstract:
SARS-CoV-2 is evolving with mutations throughout the genome all the time and a number of major variants emerged, including several variants of concern (VOC), such as Delta and Omicron variants. In this study, we demonstrated that mutations in the regions corresponding to the sequences of the probes and 3’-end of primers have a significant impact on qPCR detection efficiency. We also found that the G28916T mutation of the N gene accounts for 78.78% sequenced genomes of Delta variant. It was found that detection sensitivity of G28916T mutant was 2.35 and 1.74 times less than that of the wt sequence and detection limit was reduced from 1 copy/μl to 10 copies/μl for the commercially available CP3 and CP4 primer/probe sets. These results indicate that the detection probes and primers should be optimized to keep maximal detection efficiency in response to the emergence of new variants.
He Xu, Bijun Tian, Weihua Shi, Jing Tian, Xuexi Zhang, Jin Zeng,
Frontiers in Cellular and Infection Microbiology, Volume 11; https://doi.org/10.3389/fcimb.2021.724142

Abstract:
Tonsillar hypertrophy is a common disease in 3-to-6-year-old children, which may cause serve symptoms like airway obstruction. Microbiological factors play an important role in the etiology of tonsillar hypertrophy. As the starting point of digestive and respiratory tracts, the microbial composition of the oral cavity is not only unique but also closely related to the resident microbiota in other body sites. Here we reported a correlation study of the microbiota between oral cavity and tonsils in children with tonsillar hypertrophy. Saliva, supragingival plaque, and wiped samples from the tonsil surface were collected from both tonsillar hypertrophy patients and participants with healthy tonsils and were then analyzed using Illumina Miseq Sequencing of the 16S rRNA gene. In the tonsillar hypertrophic state, more genera were detected on the tonsil surface than in the tonsil parenchyma, with more intra-microbiota correlations. When tonsillar hypertrophy occurred, both the oral cavity and tonsil surface endured microbiome shift with increased genera category and more active bacterial interactions. Over half of the newly detected genera from the tonsillar hypertrophic state were associated with infection and inflammation process or exhibited antibiotic-resistant characters. Of each individual, the microbial composition and structure of saliva seemed more similar to that of the tonsil surface, compared with the supragingival plaque. In salivary microbiota, genus Johnsonella might be relative with the healthy state of tonsils, while Pseudoxanthomonas might be relative with tonsillar hypertrophy. Our study supported the link between oral microbiota with the healthy and hypertrophic states of tonsils and may provide new directions for future researches in the specific role of oral microbiota in the etiology of tonsil diseases.
Marcos Rogério André, Pradeep Neupane, Michael Lappin, Brian Herrin, Vicki Smith, Taufika Islam Williams, Leonard Collins, Hongxia Bai, Gabriel Lemes Jorge, Tiago Santana Balbuena, et al.
Frontiers in Cellular and Infection Microbiology, Volume 12; https://doi.org/10.3389/fcimb.2022.828082

Abstract:
Among the Ctenocephalides felis felis-borne pathogens, Bartonella henselae, the main aetiological agent of cat scratch disease (CSD), is of increasing comparative biomedical importance. Despite the importance of B. henselae as an emergent pathogen, prevention of the diseases caused by this agent in cats, dogs and humans mostly relies on the use of ectoparasiticides. A vaccine targeting both flea fitness and pathogen competence is an attractive choice requiring the identification of flea proteins/metabolites with a dual effect. Even though recent developments in vector and pathogen -omics have advanced the understanding of the genetic factors and molecular pathways involved at the tick-pathogen interface, leading to discovery of candidate protective antigens, only a few studies have focused on the interaction between fleas and flea-borne pathogens. Taking into account the period of time needed for B. henselae replication in flea digestive tract, the present study investigated flea-differentially abundant proteins (FDAP) in unfed fleas, fleas fed on uninfected cats, and fleas fed on B. henselae-infected cats at 24 hours and 9 days after the beginning of blood feeding. Proteomics approaches were designed and implemented to interrogate differentially expressed proteins, so as to gain a better understanding of proteomic changes associated with the initial B. henselae transmission period (24 hour timepoint) and a subsequent time point 9 days after blood ingestion and flea infection. As a result, serine proteases, ribosomal proteins, proteasome subunit α-type, juvenile hormone epoxide hydrolase 1, vitellogenin C, allantoinase, phosphoenolpyruvate carboxykinase, succinic semialdehyde dehydrogenase, glycinamide ribotide transformylase, secreted salivary acid phosphatase had high abundance in response of C. felis blood feeding and/or infection by B. henselae. In contrast, high abundance of serpin-1, arginine kinase, ribosomal proteins, peritrophin-like protein, and FS-H/FSI antigen family member 3 was strongly associated with unfed cat fleas. Findings from this study provide insights into proteomic response of cat fleas to B. henselae infected and uninfected blood meal, as well as C. felis response to invading B. henselae over an infection time course, thus helping understand the complex interactions between cat fleas and B. henselae at protein levels.
Zhaoke Wu, Shenshen Zhu, Juanfeng Qian, Yanmin Hu, WangQuan Ji, Dong Li, Peiyu Zhu, Ruonan Liang,
Frontiers in Cellular and Infection Microbiology, Volume 12; https://doi.org/10.3389/fcimb.2022.765445

Abstract:
Coxsackievirus A2 (CVA2) has recently been constantly detected, and is associated with viral myocarditis in children. Our previous study demonstrated that CVA2 led to heart damage in a neonatal murine model. However, the molecular mechanism of heart injury caused by CVA2 remains largely unknown. Emerging evidence suggests the significant functions of miRNAs in Coxsackievirus infection. To investigate potential miRNAs involved in heart injury caused by CVA2, our study, for the first time, conducted a RNA-seq in vivo employing infected mice hearts. In total, 87, 101 and 76 differentially expressed miRNAs were identified at 3 days post infection (dpi), 7 dpi and 7 dpi vs 3 dpi. Importantly, above 3 comparison strategies shared 34 differentially expressed miRNAs. These results were confirmed by quantitative PCR (qPCR). Next, we did GO, KEGG, and miRNA-mRNA integrated analysis of differential miRNAs. The dual-luciferase reporter assay confirmed the miRNA-mRNA pairs. To further confirm the above enriched pathways and processes, we did Western blotting and immunofluorescence staining. Our results suggest that inflammatory responses, T cell activation, apoptosis, autophagy, antiviral immunity, NK cell infiltration, and the disruption of tight junctions are involved in the pathogenesis of heart injury caused by CVA2. The dysregulated miRNAs and pathways recognized in the current study can improve the understanding of the intricate interactions between CVA2 and the heart injury, opening a novel avenue for the future study of CVA2 pathogenesis.
Frontiers in Cellular and Infection Microbiology, Volume 11; https://doi.org/10.3389/fcimb.2021.812920

Abstract:
Non-invasive biomarker analysis has made repetitive and painless sampling over time possible. Exosomes are being released from a parent cell and their cargo mirrors the cell micromilieu of the parent cell. Therefore, exosomes are promising surrogates for their parent cells. That is also why exosomes provide an improved signal-to-noise ratio. Current studies have identified valid non-invasive biomarkers that may be able to monitor disease severity. Exosomes are suggested to play an important role in interepithelial communication and are suggested to play a role in the initiation and maintenance of inflammation in CRS. They are, however, also involved simultaneously in several immunological processes including immune protection and immunosuppression. As the isolation of exosomes is time-consuming their value in everyday routine diagnostics has yet to be determined.
Clara Jabal-Uriel, Verónica N. Albarracín, Joaquín Calatayud, Mariano Higes,
Frontiers in Cellular and Infection Microbiology, Volume 11; https://doi.org/10.3389/fcimb.2021.823050

Abstract:
The microsporidia Nosema ceranae is an intracellular parasite of honeybees’ midgut, highly prevalent in Apis mellifera colonies for which important epidemiological information is still unknown. Our research aimed at understanding how age and season influence the onset of infection in honeybees and its development in the colony environment. Adult worker honeybees of less than 24h were marked and introduced into 6 different colonies in assays carried out in spring and autumn. Bees of known age were individually analyzed by PCR for Nosema spp. infection and those resulting positive were studied to determine the load by Real Time-qPCR. The age of onset and development of infection in each season was studied on a total of 2401 bees and the probability and the load of infection for both periods was established with two statistical models. First N. ceranae infected honeybees were detected at day 5 post emergence (p.e.; spring) and at day 4 p.e. (autumn) and in-hive prevalence increased from that point onwards, reaching the highest mean infection on day 18 p.e. (spring). The probability of infection increased significantly with age in both periods although the age variable better correlated in spring. The N. ceranae load tended to increase with age in both periods, although the age-load relationship was clearer in spring than in autumn. Therefore, age and season play an important role on the probability and the development of N. ceranae infection in honeybees, bringing important information to understand how it spreads within a colony.
Xiaoling Li, Lingyi Shen, Zhao Xu, Wei Liu, Aihua Li,
Frontiers in Cellular and Infection Microbiology, Volume 12; https://doi.org/10.3389/fcimb.2022.821596

Abstract:
Protein palmitoylation—a lipid modification in which one or more cysteine thiols on a substrate protein are modified to form a thioester with a palmitoyl group—is a significant post-translational biological process. This process regulates the trafficking, subcellular localization, and stability of different proteins in cells. Since palmitoylation participates in various biological processes, it is related to the occurrence and development of multiple diseases. It has been well evidenced that the proteins whose functions are palmitoylation-dependent or directly involved in key proteins’ palmitoylation/depalmitoylation cycle may be a potential source of novel therapeutic drugs for the related diseases. Many researchers have reported palmitoylation of proteins, which are crucial for host-virus interactions during viral infection. Quite a few explorations have focused on figuring out whether targeting the acylation of viral or host proteins might be a strategy to combat viral diseases. All these remarkable achievements in protein palmitoylation have been made to technological advances. This paper gives an overview of protein palmitoylation modification during viral infection and the methods for palmitoylated protein detection. Future challenges and potential developments are proposed.
, Nancy Malla
Frontiers in Cellular and Infection Microbiology, Volume 12; https://doi.org/10.3389/fcimb.2022.838799

Abstract:
Editorial on the Research TopicImmune Responses in Sexually Transmitted Infections Caused by Parasites and DNA Viruses: New Insights Sexually transmitted infections (STIs) caused by sexually transmissible pathogens affect more than 300 million people annually. More than 30 sexually transmitted pathogens which include bacteria, parasites, and viruses are known. Human trichomoniasis is the most common non-viral STI caused by Trichomonas vaginalis (TV), a protozoan parasite. STIs caused by viruses include herpes simplex virus (HSV), hepatitis A & B virus, human papillomavirus (HPV), and cytomegalovirus. If these infections remain untreated, it may lead to severe complications, significant morbidity, and mortality. Although much literature is available on STIs, different aspects need further exploration especially in terms of immune factors for early diagnosis and effective treatment. Innate and adaptive immune responses affect the establishment of and contribute to pathology. The role of innate and adaptive immunity in vaccine development and the role of cell-mediated responses in the genital tract are under investigation. Nod-like receptors (NLRs), Toll-like receptors (TLRs), and T-regulatory (Tregs) cells have been investigated. The role of TLRs in immune responses to Trichomonas infections is well documented (Yadav et al., 2021). In this Research Topic, we discuss the role of different TLRs in various STIs caused by viral, bacterial, and protozoan pathogens, focusing on specific ligands and signaling by TLRs. We also discuss the role of single nucleotide polymorphisms (SNPs) of TLRs in STIs. The aim of the Research Topic entitled “Immune Responses in Sexually Transmitted Infections Caused by Parasites and DNA Viruses: New Insights” is to provide details of the different aspects of STIs caused by parasites and DNA viruses with special focus on immune responses for healthcare professionals interested in these infections. Under this Research Topic, five publications contribute updated knowledge on this subject. The research article entitled ‘Protozoan-Viral-Bacterial Co-Infections Alter Galectin Levels and Associated Immunity Mediators in the Female Genital Tract’ (Fichorova et al.) details a new role of galectins, a glycan-sensing family of proteins, in mixed infections. The authors assessed participants in the HIV Epidemiology Research Study at each of their incident visits matched to controls who remained Trichomonas vaginalis (TV) negative throughout the study. Incident TV was associated with higher levels of galectin-1, galectin-9, IL-1β, and chemokines. Galectin-9, IL-1β, and chemokines were up and galectin-3 down in TV cases with bacterial vaginosis (BV) or intermediate Nugent versus normal Nugent scores (p <0.001). Galectin-9, IL-1β, and chemokines were increased in TV-HIV and reduced in TV-HPV co-infections. In-vitro, TV synergized with its endosymbiont Trichomonas virus (TVV) and Prevotella bivia (BV) bacteria to upregulate galectin-1, galectin-9, and inflammatory cytokines. The BV-bacterium alone, and together with TV, downregulated galectin-3 and synergistically upregulated galectin-1, galectin-9, and IL-1β, suggesting galectin-mediated immunity may be dysregulated and exploited by viral-protozoan-bacterial synergisms exacerbating inflammatory complications from dysbiosis and STIs. Further studies are required in diverse populations to address the role of socio-demographic factors and health disparities in galectin-mediated immunity underlying susceptibility to mixed protozoan-viral-bacterial infections. The review article titled ‘The Immune Microenvironment in Human Papilloma Virus-Induced Cervical Lesions - Evidence for Estrogen as an Immunomodulator’ (Jayshree R. S.) describes the local immune responses in human papillomavirus (HPV) infection of the uterine cervix. Persistent infection by high risk HPV genotypes is assisted by other risk factors in the progression through precancer (various grades of cervical intraepithelial neoplasia-CIN) to cervical cancer (CxCa). During the gradual evolution of CIN 1 to CxCa, the microenvironment of the lesions undergo the three ‘Es’ of cancer immunoediting, viz., elimination, equilibrium, and escape. Both cell-intrinsic and extrinsic mechanisms operate in eliminating virally infected/precancerous cells. Amongst the cell-extrinsic players, which converge into the lesions, are varied types of anti-tumor/antiviral effectors like the Th1 subset of CD4+ T cells, CD8+ cytotoxic T cells, natural killer cells, etc., and pro-tumorigenic/immunosuppressive cells like regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSCs), type 2 macrophages, etc. The final outcome of the infection/precancer nevertheless is dependent on which of these cell populations gain an upper hand in the lesion. Estradiol has been well recognized to be a co-factor in cervical carcinogenesis. The review highlights the role played by elevated tissue levels of the hormone as a growth factor for cervical epithelial cells and more importantly also as a potentiator of the function of various stromal and infiltrating immunosuppressive cells, viz., Tregs, MDSCs, and carcinoma-associated fibroblasts operating via estrogen receptor-α. The immunomodulatory role of estradiol in HPV-mediated cervical lesions is reviewed. Another compelling study entitled ‘Genotype Distribution Change After Human Papillomavirus Vaccination in Two Autonomous Communities in Spain’ (Freire-Salinas et al.) has addressed the need to change the screening strategy of uterine cervical cancer. Screening based on molecular tests is desired, and distribution of the HPV genotypes after the introduction of the vaccination program with Cervarix® and Gardasil 4® in two...
Frontiers in Cellular and Infection Microbiology, Volume 12; https://doi.org/10.3389/fcimb.2022.784430

Abstract:
Tick-borne diseases are a significant threat to human and animal health throughout the world. How tick-borne pathogens successfully infect and disseminate in both their vertebrate and invertebrate hosts is only partially understood. Pathogens have evolved several mechanisms to combat host defense systems, and to avoid and modulate host immunity during infection, therefore benefitting their survival and replication. In the host, pathogens trigger responses from innate and adaptive immune systems that recognize and eliminate invaders. Two important innate defenses against pathogens are the programmed cell death pathways of apoptosis and autophagy. This Mini Review surveys the current knowledge of apoptosis and autophagy pathways in tick-pathogen interactions, as well as the strategies evolved by pathogens for their benefit. We then assess the limitations to studying both pathways and discuss their participation in the network of the tick immune system, before highlighting future perspectives in this field. The knowledge gained would significantly enhance our understanding of the defense responses in vector ticks that regulate pathogen infection and burden, and form the foundation for future research to identify novel approaches to the control of tick-borne diseases.
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