Infection Process Research Articles

Reactive Arthritis in Children: Case Report, Narrative Review and Proposed Therapy.

Reactive arthritis is an acute inflammatory aseptic arthritis that is preceded by an infectious process in genetically predisposed individuals. It has been associated with gastrointestinal or genitourinary infection. Reactive arthritis is rare in children. In this review, we present two index cases that need biologic treatment followed by a thorough review of reactive arthritis in children and adolescents with proposed treatment algorithm.

Involvement of E3 Ubiquitin Ligases in Viral Infections of the Human Host.

Viral infections are one of the principal causes of global primary health crises, with increased rate of infection and mortality demonstrated by the newer progeny of viruses. Viral invasion of the host involves utilization of various cellular machinery. Ubiquitination is one of a few central regulatory systems used by viruses for establishment of the infections in the host. Members of the ubiquitination system are involved in carrying out proteasomal degradation or functional modification of proteins in numerous cellular processes. E3 ubiquitin ligases play a major role in this system through recognition and recruitment of protein substrates and catalyzing the transfer of ubiquitin to these substrates. The versatility of ubiquitin ligases frequently makes them useful tools for the viruses, for either utilizing or degrading other cellular machineries, for carrying out their multiplication or inactivating the defensive strategies of the host. Therefore, these ligases are important targets for aiming at major pathways causing viral protein degradation or functional modification of the infection process. In this review, we have discussed the role and mechanism of different types of ubiquitin ligases in the context of infections of mainly human viruses, highlighting the viral proteins directly interacting with the ligases. Knowledge about these direct interactions is central in understanding the ubiquitin-dependent processes. This comprehensive account may also be beneficial for pharmaceutical exploration of E3 ligase-based broad-spectrum antiviral treatment.

Virulence perspective genomic research unlocks the secrets of Rhizoctonia solani associated with banded sheath blight in Barnyard Millet (Echinochloa frumentacea)

IntroductionBanded sheath blight (Bsb) disease, caused by Rhizoctonia solani, is an emerging problem in barnyard millet cultivation. One of the significant goals of pathogenomic research is to identify genes responsible for pathogenicity in the fungus.MethodsA virulence profiling-based approach was employed and six R. solani isolates were collected from various ecological zones of India. The morphological parameters and virulence of all of the six R. solani isolates were investigated. The most virulent strain was designated as RAP2 and its genome has been sequenced, assembled, and annotated.ResultsThe RAP2 genome is 43.63 megabases in size and comprises 10.95% repetitive DNA, within which 46% are retroelements, 8% are DNA transposons, and 46% are unidentified DNA. The Gene Ontology (GO) annotation of RAP2 proteins revealed that “phosphorylation”, “membrane”, and “ATP binding” have the highest gene enrichment in the “biological process”, “cellular component” and “molecular function” domains, respectively. The genome comprises a majority of secretory proteins in the pectin lyase fold/virulence factor superfamily, which break down plant cell wall polymers to extract saccharides. The RAP2 genome is comparable to R. solani, which infects maize and rice, but it diverges further from soybean in terms of nucleotide-level genetic similarity. Orthologous clustering of RAP2 protein sequences with R. solani infecting maize, rice, and soybean yields 5606 proteins shared across all genomes. GO analysis of 25 proteins specific to the RAP2 genome found enrichment in the ethylene response, which can cause spore germination and infection in host plants.DiscussionInterestingly, a 28-bp deletion in the RAP2 strain’s cutinase domain was discovered in the cutinase protein, which might be important in the infection process, perhaps rendering the enzyme inactive or allowing the pathogen to infect barnyard millet while avoiding host defense. This study sheds light on the genetic makeup of R. solani, allowing researchers to discover critical genes related with pathogenicity as well as potential targets for fungicide development.

The impact of pine wilt disease on the endophytic microbial communities structure of Pinus koraiensis

Pine Wilt Disease (PWD) is a devastating pine tree disease characterized by rapid onset, high mortality rate, quick spread, and difficulty in control. Plant microbiome plays a significant role in the development of PWD. However, the endophytic microbial communities of Pinus koraiensis infected by pine wood nematode (PWN) Bursaphelenchus xylophilus remain largely unexplored. In this study, we analyzed the structural changes of endophytic communities of P. koraiensis after infection by the PWN using high-throughput sequencing technology. The results showed that the community structure underwent significant changes as the degree of PWN infection intensified. The diversity and abundance of endophytic fungi in P. koraiensis increased, while those of endophytic bacteria in P. koraiensis decreased during the infection process. Meanwhile, the abundance of some dominant microorganisms has also changed, including species such as Graphilbum and Pseudoalteromonas. Functional prediction analysis showed that the functional composition of endophytic fungi in P. koraiensis was significantly different across the development of PWD, while the composition of endophytic bacteria remained essentially similar. The results indicated that PWN infection had a significant impact on the structure, diversity, abundance, and functional gene composition of endophytic microbial communities in P. koraiensis, and most of the main endophytic microbial groups tended to coordinate with each other. This work provides a better understanding of the changes in endophytic community structure and function caused by PWD infection of P. koraiensis, which may benefit the exploration of potential endophytes for PWN biocontrol.

The results of vaccination against novel coronavirus infection in adolescents with allergic diseases

Novel coronavirus infection requires analyzing its course in patients with allergic diseases. Patients with atopic allergic diseases remain insufficiently studied with regard to the peculiarities of the course of both the underlying allergic disease and infectious processes caused by viruses and bacteria. Epithelial cells in bronchial asthma do not respond sufficiently to interferons, suggesting that SARS-CoV-2 infection may suppress spontaneous upregulation of angiotensin-converting enzyme expression, which ultimately reduces disease severity, but at the same time makes patients with allergic atopic diseases susceptible to other viral infections. The results obtained indicate statistically significant differences in the formation of anti-RBD IgG antibodies to SARS-CoV-2 between the group of adolescents with bronchial asthma vaccinated against a new coronavirus infection and those not vaccinated against it. During the follow-up period after 6 months, a statistically significant increase in anti-RBD IgG titer to SARS-CoV-2 due to novel coronavirus infection was observed among the unimmunized children. Clinical parameters indicated a favorable course of atopic process and control of bronchial asthma exacerbations in adolescents who received vaccination against both new coronavirus infection and influenza, while those who did not receive vaccination against these viral infections had bronchial asthma exacerbations due to respiratory infection. Also among patients with bronchial asthma who received influenza vaccination, there were no cases of influenza A and bronchial asthma exacerbations due to respiratory infections. In this regard, influenza vaccination is an important intervention to maintain control of asthma exacerbations. It is noteworthy that no new coronavirus infection was reported among vaccinated adolescents within a year after immunization. At the same time, 6 months after vaccination against a new coronavirus infection, we observed a statistically significant increase in antibody levels in unvaccinated adolescents, indicating the presence of high viral neutralizing activity. Vaccination against novel coronavirus infection in patients with bronchial asthma may be considered a possibility.

The paradigm of possibilities leading to the formation of autoimmune and infectious phenotypes of common variable immune deficiency

The term variable in the definition of CVID is associated with the heterogeneity of the genetic nature and clinical manifestation of this variant of PI. Deciphering of the mechanisms or identifying biomarkers of clinical heterogeneity may be important in the timely diagnosis and prognosis of the course of CVID. The purpose of the study was to identify distinctive features in the parameters of the innate and adaptive immune response of the patients with infectious and autoimmune manifestations of CVID in remission and clinical manifestation. Fifteen patients, 11 women and 4 men with an average age 39.7±11.7 years were examined, and they were divided into two subgroups depending on clinical verification: infectious phenotype (10 people) and autoimmune phenotype (5 people). In the absence of clinical signs of activation of autoimmune pathology or exacerbation of chronic infectious processes, peripheral blood monocytes became the application point of distinctive values. An increase in the number of TLR9-expressing monocytes has been shown in patients with autoimmune clinical verification of CVID. The differences in the parameters of the immune status of patients conducted during the period of clinical manifestation consisted of a decrease in the relative content and absolute number of T regulatory lymphocytes, and an increase in the number of monocytes containing TLR9, TLR2 and HLA-DR in patients with an autoimmune phenotype relative to the subgroup with infectious manifestation. The data obtained reflect the involvement of the immunoregulatory potential of the immune system in the clinical manifestation of primary immunodeficiency, even under the conditions of pathogenetic substitution therapy. The evidence of the stated position is a decrease in immunosuppression in autoimmune manifestation due to a decrease in the number of peripheral T-regulatory cells and a smaller proportion of monocyte cells belonging to the M2 suppressive category. Attention is also drawn to the increased potential of primary response to patterns of various nature in autoimmune manifestation due to an increase in the number of monocytes expressing Toll-like receptors of various specificity. The presented results can be proposed as a diagnostic and prognostic indicator of the difference in clinical phenotypes of CVID.

The state of psychological and immunological indicators in graduate students of a medical university

Training future doctors for professional practice usually entails building awareness and embracing the significant responsibility inherent in the field. This, in turn, leads to significant psycho-emotional stress by the time of graduation from academic institution. With the aim of identifying the correlation between homeostatic system indicators, a comparative analysis was conducted to characterize the immunological and psychological parameters of final-year medical university students, contingent upon their respective training programs. The study involved sixth-year students of the Therapeutic and Preventive Faculty [TPF] (29 individuals) and the Military Training Center [MTC] (34 individuals) of Rostov State Medical University, a Federal State Budgetary Educational Institution of Higher Education. The exclusion criteria for all participants included the presence of chronic diseases and any infectious process of any origin within three months prior to the study. The groups were similar in terms of age (23.8±1.82 and 23.9±2.2 years, respectively), gender (all male), and corresponded to health group I. Psychological evaluation was conducted employing the Spielberger–Hanin Scale to gauge levels of personal and situational anxiety. The assessment of immunological status was carried out at the Scientific Research Institute of Clinical Immunology using standard methodological approaches. Registration cards for immunopathology analysis were used to characterize health status over the year. Analysis of the obtained data from psychological questionnaires revealed that students of the Therapeutic and Preventive Faculty, compared to their counterparts from the Military Training Center, demonstrated a higher degree of situational and, particularly, personal anxiety. Differences in the immune response system between the compared groups were identified with regards to indicators that characterize both adaptive and innate immunity. These differences were expressed in a more significant number of circulating regulatory T lymphocytes, a less pronounced lytic potential of effector cells, a greater number of TLR9+ monocytes with a decrease in the proportion of cells of the monocyte series carrying HLA-DR in medical students compared to their counterparts studying in the medical service officers’ program. Thus, the period of psychological preparation in a medical university for the commencement of professional activity varies based on the characteristics of the educational process and proves to be more effective for sixth-year students of MTC. Students from the TPF exhibit more pronounced psycho-emotional stress compared to their counterparts in military medical training, leading to evident signs of immune system dysregulation. It is imperative to develop strategies for timely detection of changes in both psychological and immunological adaptive capacities.

Symptomatic Multi-Nodular Fourth Ventricular Choroid Plexus Papillary Fibrosis in the Context of Chiari II Malformation: Case Report and Literature Review

Introduction: Chiari II malformation (CM-II) is a congenital malformation characterized by the caudal displacement of the cerebellar tonsils, inferior cerebellar vermis, and fourth ventricle through the foramen magnum. Although rare, the association between CM-II and the development of a variety of mass lesions within the fourth ventricle and craniocervical junction has been described in the literature. Case Presentation: We present the case of a 9-year-old boy with a history of mid-lumbar myelomeningocele, CM-II, and ventriculoperitoneal shunt-dependent hydrocephalus who was discovered to have a syringomyelia and numerous spherical/ovoid masses within the caudal fourth ventricle and dorsal cervicomedullary subarachnoid space on a surveillance brain MRI. On questioning, the patient endorsed a longstanding history of poor bilateral hand dexterity and grip strength. After further imaging workup, the patient underwent suboccipital craniectomy and C1 laminectomy for resection of the mass lesions arising from the fourth ventricular choroid plexus (CP) and performance of an expansile pericranial duraplasty. The patient tolerated surgery well and had progressive improvement in hand dexterity/strength as well as radiographic improvement in the cervical cord syrinx after surgery. Pathologic analysis of the resected mass lesions demonstrated the lesions to be predominantly characterized by dense nodular fibrosis of the CP stromal cores which we are describing as choroid plexus papillary fibrosis. A minority of the lesional stromal cores were noted to be edematous, imparting a more “reticular” appearance. There were no features to suggest a neoplastic or infectious process. Conclusion: This combination of dysplastic/reactive CP histologic findings has not been previously reported in an extramedullary location. The unique pathology of this patient’s CP lesions will be discussed, and previously reported fourth ventricular mass lesions seen in association with CM-II will be reviewed.

Gene co-expression analysis reveals conserved and distinct gene networks between resistant and susceptible Lens ervoides challenged by hemibiotrophic and necrotrophic pathogens

As field crops are likely to be challenged by multiple pathogens during their development, the investigation of broad-spectrum resistance in the host is of great interest for crop genetic enhancement. In this study, we attempted to address this question by adopting a weighed gene co-expression approach to study the temporal transcriptome dynamics of resistant and susceptible recombinant inbred lines (RILs) derived from an intraspecific Len ervoides cross during the infection process with either the necrotrophic pathogens Ascochyta lentis or Stemphylium botryosum, or the hemibiotrophic pathogen Colletotrichum lentis. By comparing networks of resistant and susceptible RILs, seven network module pairs were found to possess high correlation coefficients (R > 0.70) and large number of overlapping genes (n > 100). The conserved co-regulation of genes in these network module pairs were involved in plant cell wall synthesis, cell division, cytoskeleton organization, and protein ubiquitin related processes and appeared to be common disease responses against these pathogens. On the other hand, we also identified eight modules with low correlation between resistance and susceptibility networks. Among those, a stronger gene co-expression in R-genes and small RNA processes in the resistant hosts may be enhancing L. ervoides resistance against A. lentis, C. lentis, and S. botryosum, whereas the higher level of synergistic regulation in the synthesis of arginine and glutamine and phospholipid and glycerophospholipids in the susceptible hosts may contribute to increased susceptibility in L. ervoides.

The association of increased incidence of congenital heart disease in newborns with maternal COVID-19 infection during pregnancy

This paper aims to examine the potential link between maternal COVID-19 infection during pregnancy and the increased risk of congenital heart disease (CHD) in newborns. A comparative analysis was conducted involving two groups: mothers infected with COVID-19 during pregnancy and a control group. Data on maternal characteristics, pregnancy-related complications, and newborn outcomes were collected and analyzed. Additionally, the annual incidence rates of CHD from 2020 to 2023 were evaluated to assess trends over time. No significant differences were found between the COVID-19 cases and the control group in terms of maternal age, BMI, gravidity, parity, use of assisted reproductive technology, adverse obstetric history, or complications during pregnancy, including diabetes mellitus, preeclampsia, and thyroid abnormalities. For newborn outcomes, there were no significant differences in sex distribution, rate of cesarean delivery, Apgar scores, or birth weight. However, a significantly higher prevalence of cardiac ultrasound abnormalities was observed in the COVID-19 group (10.08%) compared to the control group (4.13%, p = 0.012). Further analysis revealed that the majority of cardiac abnormalities in the COVID-19 group occurred in mothers infected before 8 weeks of pregnancy. The annual incidence rates of CHD showed a significant increase during the COVID-19 pandemic, with the highest rate in 2023 (5.46%) compared to previous years. Maternal COVID-19 infection during pregnancy may adversely affect the development of the newborn’s heart. This could be due to the inflammatory response caused by the viral infection or other pathological processes. The findings underscore the importance of vigilant prenatal care and early detection of cardiac abnormalities during the pandemic and suggest the need for further research to explore potential mechanisms and intervention strategies.

Systemic effect of the oncological process on the dog’s body

The article presents the results of an analysis of a non-randomized study of the prevalence of paraneoplastic syndromes in primary spontaneous malignant neoplasms in dogs. The study was conducted in 2022–2024 on the basis of the Department of Diseases of Small Domestic, Laboratory and Exotic Animals and the Research Laboratory of Oncology, Ophthalmology and Animal Biochemistry of the Russian Biotechnological University “ROSBIOTECH”. The object of the study were 948 dogs with primary spontaneous malignant neoplasms confirmed by morphological methods.The aim of the work was to study the frequency of paraneoplastic syndromes in dogs with neoplasia.The diagnosis of paraneoplastic syndrome was made by excluding other possible etiological factors for the development of clinical and laboratory abnormalities identified during a comprehensive examination of dogs. As a result of the study, the incidence of paraneoplasia was 54.54% of cases. Hematological (44.41%) and gastrointestinal (37.13%) paraneoplastic syndromes were most often recorded, less often endocrine (3.27%) and ophthalmological (3.38%), extremely rarely renal (1.27%), osteoarticular (0.42%) and dermatological (0.42%). The main hematological manifestations of the systemic effect of the oncological process were: anemia (12.87%), neutrophilic leukocytosis (12.76%) and thrombocytopenia (8.86%). Gastrointestinal paraneoplastic syndrome in most cases was manifested by a decrease in body weight (33.65%) and hyporexia (18.04%), inflammatory and erosive ulcerative lesions of the gastrointestinal tract (7.59%). During the study, a case of a nonspecific systemic reaction to a malignant tumor in the form of fever in the absence of infectious and inflammatory processes (0.11%) was registered.

The Fossilised Birth-Death Model is Identifiable.

Time-dependent birth-death sampling models have been used in numerous studies for inferring past evolutionary dynamics in different biological contexts, e.g. speciation and extinction rates in macroevolutionary studies, or effective reproductive number in epidemiological studies. These models are branching processes where lineages can bifurcate, die, or be sampled with time-dependent birth, death, and sampling rates, generating phylogenetic trees. It has been shown that in some subclasses of such models, different sets of rates can result in the same distributions of reconstructed phylogenetic trees, and therefore the rates become unidentifiable from the trees regardless of their size. Here we show that widely used time-dependent fossilised birth-death (FBD) models are identifiable. This subclass of models makes more realistic assumptions about the fossilisation process and certain infectious disease transmission processes than the unidentifiable birth-death sampling models. Namely, FBD models assume that sampled lineages stay in the process rather than being immediately removed upon sampling. Identifiability of the time-dependent FBD model justifies using statistical methods that implement this model to infer the underlying temporal diversification or epidemiological dynamics from phylogenetic trees or directly from molecular or other comparative data. We further show that the time-dependent fossilised-birth-death model with an extra parameter, the removal after sampling probability, is unidentifiable. This implies that in scenarios where we do not know how sampling affects lineages we are unable to infer this extra parameter together with birth, death, and sampling rates solely from trees.

The effect of spermidine supplementation on polyamine metabolism and Fusarium infection in Linum usitatissimum

Flax (Linum usitatissimum) is a valuable industrial crop in temperate climate zones. However, the prevalence of fungal diseases, particularly those caused by Fusarium oxysporum sp. linii, poses a substantial threat, leading to significant crop losses and diminished interest in flax cultivation. In this study, flax plants were treated with spermidine and subsequently infected with Fusarium oxysporum to investigate multiple aspects: (1) the uptake of exogenous spermidine by the plants, (2) the impact of this uptake on the levels of other polyamines and the expression of polyamine biosynthesis genes, and (3) the effects of fungal infection on these parameters. The results demonstrated that flax plants effectively absorb spermidine, leading to substantial changes in the levels of polyamines and the expression of related genes in both roots and shoots. Notably, spermidine treatment resulted in significant alterations in the levels of putrescine and spermine, as well as in the transcript levels of key genes involved in polyamine biosynthesis. Moreover, Fusarium oxysporum infection itself induced changes in polyamine content and gene expression, which varied between root and shoot tissues. When spermidine-treated plants were infected with Fusarium oxysporum, a more complex response was observed, characterized by modifications in polyamine levels and gene expression that suggest an enhanced defense mechanism against the pathogen. These findings indicate that polyamine treatment not only affects the infection process but also modulates the plant's internal polyamine metabolism and gene expression, contributing to an improved resistance to fungal attack. This study highlights the potential of spermidine as a protective agent in flax and provides a foundation for further exploration of polyamine-related defense mechanisms.

Identification of receptor-binding protein and host receptor of non-lytic dsRNA phage phiNY.

To date, complete genome sequences of 14 double-stranded RNA (dsRNA) phages are available, and studies have shown that the host range of dsRNA phages is limited. The hosts of most dsRNA phages belong to the genus Pseudomonas. However, the dsRNA phage phiNY, which has a non-lytic life cycle, was isolated from Microvirgula aerodenitrificans. Currently, the interaction between dsRNA phage phiNY and its host bacteria is unclear, which is not beneficial to a comprehensive understanding of dsRNA phage biology and the exploitation of dsRNA phage with non-lytic life cycle for biomedical applications and others. Phage adsorption is a crucial step through the interactions between receptor-binding protein (RBP) of the phage and its receptors to initiate the infection process, which dictates host range specificity. Thus, we identified the RBP and host receptor of phiNY. Through homology alignment, amino acid sequence similarity analysis, and the phylogenetic tree analysis, orf11, located in the M-segment of dsRNA phage phiNY, encodes a putative RBP. We further performed the whole-cell enzyme-linked immunosorbent assay (ELISA), western blotting assay, and indirect immunofluorescence assay and demonstrated that this orf11 is an RBP. Finally, using affinity chromatography, ELISA, and dynamic light scattering, we identified lipopolysaccharides (LPSs) on the surface of the host M. aerodenitrificans strain LH9 as host receptors involved in the adsorption of the dsRNA bacteriophage phiNY and observed the state of phiNY RBP after combining with LPS by atomic force microscopy. These results will guide future studies on phage-host interaction in a dsRNA phage with a non-lytic life cycle.IMPORTANCEThe interactions between the lytic dsRNA phages and their host receptors have been clarified in previous studies. However, the interaction between the dsRNA phage phiNY (which has a non-lytic life cycle) and its host receptors during the dsRNA phage adsorption process was unknown. Here, we found that phiNY uses the orf11 protein as a receptor-binding protein (RBP). In addition, we found that this orf11 recognizes lipopolysaccharide from the host bacterium Microvirgula aerodenitrificans strain LH9 as a specific receptor. These results suggest that phiNY, like lytic dsRNA phages, uses an RBP to bind to a similar host receptor (i.e., lipopolysaccharide). Determining the interaction between the dsRNA phage phiNY and its host receptors will help to elucidate the mechanisms underlying the phiNY non-lytic life cycle and enhance our understanding of its infection mechanism.

Treatment of patients with periprosthetic infection and management of Paprosky type 2C cavitary defects at the stage of articulating spacer installation

Introduction Due to the constant increase in the number of primary and revision hip arthroplasties, the incidence of complications has been also increasing. Periprosthetic joint infection (PJI) is the most common and dangerous complication in joint arthroplasty, including PJI with cavitary defects of the acetabulum (Paprosky type 2C).The purpose of the work was to demonstrate successful results of managing acetabular defects in patients with periprosthetic infection at the stage of installing an articulating spacer.Materials and methods The patients underwent surgical management of cavitary defects of the acetabulum with allobone plastic material at the stage of installation of an articulating spacer impregnated with antibacterial drugs. A clinical and functional assessment of the effectiveness of treatment of patients with PJI of the hip joint, who underwent bone grafting of acetabular defects at the first stage of two-stage revision arthroplasty, was carried out. Remission of the infectious process was assessed according to the ICM 2013 (International Consensus Meeting), and the function of the affected limb was assessed according to the HHS (Harris Hip Score).Results At a 6-month follow-up after implantation, there were no clinical and laboratory manifestations of PJI and radiological signs of instability of the implant components. Bone grafting was evaluated to be satisfactory; the function of the affected joint restored to 80–90 to HHS points. Remission of the infectious process according to ICM was achieved.Discussion Clinical cases studied demonstrate a positive result of treatin PJI with plastic surgery of cavitary defects of the acetabular bottom at the stage of articulating spacer installation. Filling acetabular defects at the sanitizing stage (implantation of a spacer) subsequently provides improvement of primary fixation and osseointegration of the acetabular component when converting the spacer to a permanent implant. This is due to an increase in the contact area of the acetabular component with bone tissue (native bone and remodeled allobone material).Conclusion The treatment of the first clinical case improved joint function from 24 to 85 HHS points, and in the second from 27 to 76 HHS points. The use of defect filling techniques enabled to stop the infection and improve functional results.

Computational identification and characterization of chitinase 1 and chitinase 2 from neotropical isolates of Beauveria bassiana

BackgroundThe fungus Beauveria bassiana is widely used for agronomical applications, mainly in biological control. B. bassiana uses chitinase enzymes to degrade chitin, a major chemical component found in insect exoskeletons and fungal cell walls. However, until recently, genomic information on neotropical isolates, as well as their metabolic and biotechnological potential, has been limited.MethodsEight complete B. bassiana genomes of Neotropical origin and three references were studied to identify chitinase genes and its corresponding proteins, which were curated and characterized using manual curation and computational tools. We conducted a computational study to highlight functional differences and similarities for chitinase proteins in these Neotropical isolates.ResultsEleven chitinase 1 genes were identified, categorized as chitinase 1.1 and chitinase 1.2. Five chitinase 2 genes were identified but presented a higher sequence conservation across all sequences. Interestingly, physicochemical parameters were more similar between chitinase 1.1 and chitinase 2 than between chitinase 1.1 and 1.2.ConclusionChitinases 1 and 2 demonstrated variations, especially within chitinase 1, which presented a potential paralog. These differences were observed in their physical parameters. Additionally, CHIT2 completely lacks a signal peptide. This implies that CHIT1 might be associated with infection processes, while CHIT2 could be involved in morphogenesis and cellular growth. Therefore, our work highlights the importance of computational studies on local isolates, providing valuable resources for further experimental validation. Intrinsic changes within local species can significantly impact our understanding of complex pathogen-host interactions and offer practical applications, such as biological control.

Dynamics of Hydrogen Peroxide Accumulation During Tip Growth of Infection Thread in Nodules and Cell Differentiation in Pea (Pisum sativum L.) Symbiotic Nodules.

Hydrogen peroxide (H2O2) in plants is produced in relatively large amounts and plays a universal role in plant defense and physiological responses, including the regulation of growth and development. In the Rhizobium-legume symbiosis, hydrogen peroxide plays an important signaling role throughout the development of this interaction. In the functioning nodule, H2O2 has been shown to be involved in bacterial differentiation into the symbiotic form and in nodule senescence. In this study, the pattern of H2O2 accumulation in pea (Pisum sativum L.) wild-type and mutant nodules blocked at different stages of the infection process was analyzed using a cytochemical reaction with cerium chloride. The observed dynamics of H2O2 deposition in the infection thread walls indicated that the distribution of H2O2 was apparently related to the stiffness of the infection thread wall. The dynamics of H2O2 accumulation was traced, and its patterns in different nodule zones were determined in order to investigate the relationship of H2O2 localization and distribution with the stages of symbiotic nodule development in P. sativum. The patterns of H2O2 localization in different zones of the indeterminate nodule have been partially confirmed by comparative analysis on mutant genotypes.

Chemical Profile, Antibacterial and Toxicological Study of Asparagus setaceus (KUNTH)

Objective: The objective of this work was to obtain the chemical profile and verify the biological activities of ethanolic extract from the leaves of Asparagus setaceus. Method: The extract was obtained with cold ethanol and the classes of secondary metabolites were identified with specific reagents. The antibacterial assays were performed using the microdilution method against the standard bacteria, Gram +: Sthaphylococcus aureus, Streptococcus mutans and Enterococcus faecalis and Gram -: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoneae and two multidrug-resistant strains: Escherichia coli 27 and Staphylococcus aureus 358 and the resistance modulation assay was performed using aminoglycoside and beta- lactam antibiotics. Toxicity was tested against the microcrustacean Artemia salina (Leach) ranging in concentrations from 10 to 500 μg/mL Results and Discussion: The ethanolic extract of Asparagus setaceus (EEAS) indicated the presence of phenols, condensed tannins, anthocyanins, anthocyanidins, flavones, flavonols, xanthones, chalcones, aurones, flavononols, catechins, leukoanthocyanidins, flavones and saponins. The EEAS presented CL50 of 90.22 μg/ mL. The microbial assay showed inhibition for standard strains of Gram + and Gram bacteria - but in the multidrug-resistant strains it showed clinically non-signific results. For the modulation of antibiotic action against bacterial strains, EEAS presented both synergistic and antagonistic action, with the synergistic action being more expressive on benzylpenicillin, amikacin and gentamicin in front of Escherichia coli 27. The aminoglycoside antibiotics showed synergistic activity on all bacteria tested. Research Implications: Given the results, it was found that the ethanolic extract of the leaves of Asparagus setaceus (Kunth) disp of chemical and biological properties that can contribute to the elaboration of therapeutic resources against inflammatory and bacterial infectious processes. Keywords: Antibacterial Assay, Secondary Metabolites, Modulation, Asparagus setaceus.

Study of non-silent and deletion mutations of SARS-CoV-2 in relation to viral behavior in the infectious process

SARS-CoV-2 is a 30,000-nucleotide single-stranded RNA virus encoding structural, non-structural and accessory proteins. Its origin is uncertain, with hypotheses suggesting evolution from bats or pangolins. Genetic recombination events between strains may have resulted in the emergence of SARS-CoV-2, making it capable of infecting humans and increasing its transmissibility. Its mutability rate is similar to that of other coronaviruses, however, due to the occurrence of the pandemic and the propagation clusters, there was an intensification in the number of mutations generated, which evolutionarily gave rise to lineages, sublineages, variants and strains, consecutively. Such mutations, especially non-synonymous ones, phenotypically reflect a variation in virulence, associated with factors of transmissibility, pathogenicity, multiplication, immunological evasion that differ from their ancestors, which are accumulating and becoming fixed in the lineages of this sarbecovirus. In this way, this study aims to understand such non-silent mutations by correlating changes to the viral infectious process.

Single-cell spatiotemporal analysis reveals alveolar dendritic cell–T cell immunity hubs defending against pulmonary infection

How immune cells are spatiotemporally coordinated in the lung to effectively monitor, respond to, and resolve infection and inflammation in primed form needs to be fully illustrated. Here we apply immunocartography, a high-resolution technique that integrates spatial and single-cell RNA sequencing (scRNA-seq) through deconvolution and co-localization analyses, to the SARS-CoV-2-infected Syrian hamster model. We generate a comprehensive transcriptome map of the whole process of pulmonary infection from physiological condition, infection initiation, severe pneumonia to natural recovery at organ scale and single-cell resolution, with 142,965 cells and 45 lung lobes from 25 hamsters at 5 time points. Integrative analysis identifies that alveolar dendritic cell–T cell immunity hubs, where Ccr7+Ido1+ dendritic cells, Cd160+Cd8+ T cells, and Tnfrsf4+Cd4+ T cells physiologically co-localize, rapidly expand during SARS-CoV-2 infection, eliminate SARS-CoV-2 with the aid of Slamf9+ macrophages, and then restore to physiological levels after viral clearance. We verify the presence of these cell subpopulations in the immunity hubs in normal and SARS-CoV-2-infected hACE2 mouse models, as well as in publicly available human scRNA-seq datasets, demonstrating the potential broad relevance of our findings in lung immunity.