Major Agent Research Articles

Glutathione peroxidase LtGPX3 contributes to oxidative stress tolerance, virulence, and plant defense suppression in the peach gummosis fungus Lasiodiplodia theobromae

The notorious woody plant-degrading pathogen Lasiodiplodia theobromae is a major causal agent of peach gummosis, one of the prevalent and devastating trunk diseases to peach production; however, its pathogenesis is largely unknown. Our previous study showed that L. theobromae LtGPX3, which encodes a glutathione peroxidase resembling yeast GPX3/HYR1-like, was constantly and dramatically upregulated at the infectious stages. Here, we functionally characterized LtGPX3 using the CRISPR-Cas9-aided split marker approach. The ΔLtgpx3 deletion mutants displayed increased sensitivity to the osmotic stress agent KCl and less sensitivity to the cell wall-damaging agent calcofluor white. Exogenous oxidants highly induced the expression of LtGPX3, and the ΔLtgpx3 mutants displayed increased sensitivity to ROS-generating oxidants. Pathogenicity assays revealed that ΔLtgpx3 mutants showed compromised virulence in peach shoots, which was partially restored when peach shoots were pretreated with an NADPH oxidase inhibitor before inoculation. Moreover, ROS levels were strongly boosted, and transcripts of plant defense-related genes were highly induced in the ΔLtgpx3 mutants-infected peach shoots compared with the wild-type-inoculated. Overall, our results showed the essential roles of LtGPX3 in the oxidative stress response and tolerance and pathological functions in L. theobromae. These findings deepen our understanding of the survival strategies of the woody plant-degrading pathogen L. theobromae and provide new insights into developing new strategies for peach gummosis disease control.

The vaccination changed the profile of rotavirus infection with the increase of non-rotavirus A species diagnosis in one-week-old diarrheic piglets.

Porcine rotavirus (RV) is a major viral agent associated with severe diarrhea in newborn piglets. RVA, RVB, RVC, and RVH are RV species that have already been identified in pigs. RVA is considered the most prevalent and relevant virus in pig production worldwide. This study aimed to evaluate the frequency of RV infection associated with diarrhea in suckling piglets from regular RVA-vaccinated Brazilian pig herds between 2015 and 2021. Therefore, 511 diarrheic fecal samples were collected from suckling piglets aged up to 3weeks from 112 pig farms located in three main Brazilian pork production regions. All piglets were born to RVA-vaccinated sows. The nucleic acids of RVA, RVC, and RVH were investigated by RT-PCR assays and RVB by semi-nested RT-PCR assay. Of the diarrheic fecal samples analyzed, 221/511 (43.3%) were positive for at least one of the RV species. Regarding the distribution of RV species among the positive fecal samples that presented with only one RV species, 99 (44.8%), 63 (28.5%), and 45 (20.4%) were identified as RVB, RVC, and RVA, respectively. RVH was not identified in diarrheic piglets with a single infection. More than one RV species was identified in 14/221 (6.3%) of the diarrheic fecal samples evaluated. Co-detection of RVB + RVH (11/221; 5.0%), RVA + RVB (1/221; 0.4%), RVA + RVC (1/221; 0.4%), and RVB + RVC (1/221; 0.4%) was identified in fecal samples. The results demonstrated a significant increase in the RVC and, mainly, RVB detection rates in single infections. This study allowed us to characterize the importance of other RV species, in addition to RVA, in the etiology of neonatal diarrhea in piglets from pig herds with a regular vaccination program for RVA diarrhea control and prophylaxis.

A single-domain antibody detects and neutralises toxic Aβ42 oligomers in the Alzheimer’s disease CSF

BackgroundAmyloid-β42 (Aβ42) aggregation consists of a complex chain of nucleation events producing soluble oligomeric intermediates, which are considered the major neurotoxic agents in Alzheimer’s disease (AD). Cerebral lesions in the brain of AD patients start to develop 20 years before symptom onset; however, no preventive strategies, effective treatments, or specific and sensitive diagnostic tests to identify people with early-stage AD are currently available. In addition, the isolation and characterisation of neurotoxic Aβ42 oligomers are particularly difficult because of their transient and heterogeneous nature. To overcome this challenge, a rationally designed method generated a single-domain antibody (sdAb), named DesAb-O, targeting Aβ42 oligomers.MethodsWe investigated the ability of DesAb-O to selectively detect preformed Aβ42 oligomers both in vitro and in cultured neuronal cells, by using dot-blot, ELISA immunoassay and super-resolution STED microscopy, and to counteract the toxicity induced by the oligomers, monitoring their interaction with neuronal membrane and the resulting mitochondrial impairment. We then applied this approach to CSF samples (CSFs) from AD patients as compared to age-matched control subjects.ResultsDesAb-O was found to selectively detect synthetic Aβ42 oligomers both in vitro and in cultured cells, and to neutralise their associated neuronal dysfunction. DesAb-O can also identify Aβ42 oligomers present in the CSFs of AD patients with respect to healthy individuals, and completely prevent cell dysfunction induced by the administration of CSFs to neuronal cells.ConclusionsTaken together, our data indicate a promising method for the improvement of an early diagnosis of AD and for the generation of novel therapeutic approaches based on sdAbs for the treatment of AD and other devastating neurodegenerative conditions.

Exploring DNA repair deficient CHO cell response to low dose rate radiation

IntroductionDNA double-strand breaks (DSBs) induced by ionizing radiation pose a significant threat to genome integrity, necessitating robust repair mechanisms. This study explores the responses of repair-deficient cells to low dose rate (LDR) radiation. Non-homologous end joining (NHEJ) and homologous recombination (HR) repair pathways play pivotal roles in maintaining genomic stability. The hypothesis posits distinct cellular outcomes under LDR exposure compared to acute radiation, impacting DNA repair mechanisms and cell survival. Materials and methodsChinese hamster ovary (CHO) cells, featuring deficiencies in NHEJ, HR, Fanconi Anemia, and PARP pathways, were systematically studied. Clonogenic assays for acute and LDR gamma-ray exposures, cell growth inhibition analyses, and γ-H2AX foci assays were conducted, encompassing varied dose rates to comprehensively assess cellular responses. ResultsNHEJ mutants exhibited an unexpected inverse dose rate effect, challenging conventional expectations. HR mutants displayed unique radiosensitivity patterns, aligning with responses to major DNA-damaging agents. LDR exposure induced cell cycle alterations, growth delays, and giant cell formation, revealing context-dependent sensitivities. γ-H2AX foci assays indicated DSB accumulation during LDR exposure. DiscussionThese findings challenge established paradigms, emphasizing the intricate interplay between repair pathways and dose rates. The study offers comprehensive insights into repair-deficient cell responses, urging a reevaluation of conventional dose-response models and providing potential avenues for targeted therapeutic strategies in diverse radiation scenarios.

A Comparative Review of Two Major Topical Hemostasis Agents in Spine Surgery

Achieving adequate hemostasis in spine surgery is critical for both the patient and surgeon. Currently, there are two major topical hemostatic matrix agents used in spine surgery—Floseal (Baxter Healthcare, Deerfield, Illinois, USA) and Surgiflo (Ethicon Inc., Raritan, New Jersey, USA). While both products have been shown to be effective at achieving hemostasis, there is no consensus supporting the use of one agent over another in spine surgery. There are studies comparing outcomes and cost between Floseal and Surgiflo, but a significant portion of the studies have industry affiliations. Generally, existing literature reports low to moderate cost savings in favor of one agent or the other, with no clinically significant differences in other patient-based outcomes such as postoperative hematomas. Animal model studies also suggest unique complications, including epidural fibrosis and associated nerve root compression with use of a flowable topical hemostatic agent. Further non-industry-affiliated studies are warranted to compare efficacy, patient outcomes, cost analyses, and possible unique complications associated with the two hemostatic agents.

Polyketides/nonribosomal peptides from Streptococcus mutans and their ecological roles in dental biofilm.

Streptococcus mutans is the major etiological agent of dental caries in humans. S. mutans overgrowth within dental biofilms can trigger biofilm dysbiosis, ultimately leading to the initiation or progression of dental caries. Polyketides and nonribosomal peptides (PKs/NRPs) are secondary metabolites with complex structures encoded by a cluster of biosynthetic genes. Although not essential for microbial growth, PKs/NRPs play important roles in physiological regulation. Three main classes of hybrid PKs/NRPs in S. mutans have been identified, including mutanobactin, mutanocyclin, and mutanofactin, encoded by the mub, muc, and muf gene clusters, respectively. These three hybrid PKs/NRPs play important roles in environmental adaptation, biofilm formation, and interspecies competition of S. mutans. In this review, we provide an overview of the major hybrid PKs/NRPs of S. mutans, including mutanobactin, mutanocyclin, and mutanofactin and address their ecological roles in dental biofilms. We place specific emphasis on important questions that are yet to be answered to provide novel insights into the cariogenic mechanism of S. mutans and facilitate improved management of dental caries. We highlight that S. mutans PKs/NRPs may be potential novel targets for the prevention and treatment of S. mutans-induced dental caries. The development of genomics, metabolomics, and mass spectrometry, together with the integration of various databases and bioinformatics tools, will allow the identification and synthesis of other secondary metabolites. Elucidating their physicochemical properties and their ecological roles in oral biofilms is crucial in the identification of novel targets for the ecological management of dental caries.

Cell-to-cell heterogeneity drives host-virus coexistence in a bloom-forming alga.

Algal blooms drive global biogeochemical cycles of key nutrients and serve as hotspots for biological interactions in the ocean. The massive blooms of the cosmopolitan coccolithophore Emiliania huxleyi are often infected by the lytic E. huxleyi virus, which is a major mortality agent triggering bloom demise. This multi-annual "boom and bust" pattern of E. huxleyi blooms suggests that coexistence is essential for these host-virus dynamics. To investigate host-virus coexistence, we developed a new model system from an E. huxleyi culture that recovered from viral infection. The recovered population coexists with the virus, as host cells continue to divide in parallel to viral production. By applying single-molecule fluorescence in situ hybridization (smFISH) to quantify the fraction of infected cells, and assessing infection-specific lipid biomarkers, we identified a small subpopulation of cells that were infected and produced new virions, whereas most of the host population could resist infection. To further assess population heterogeneity, we generated clonal strain collections using single-cell sorting and subsequently phenotyped their susceptibility to E. huxleyi virus infection. This unraveled substantial cell-to-cell heterogeneity across a continuum of susceptibility to resistance, highlighting that infection outcome may vary depending on the individual cell. These results add a new dimension to our understanding of the complexity of host-virus interactions that are commonly assessed in bulk and described by binary definitions of resistance or susceptibility. We propose that phenotypic heterogeneity drives the host-virus coexistence and demonstrate how the coexistence with a lytic virus provides an ecological advantage for the host by killing competing strains.

Novel therapies for multiple myeloma

B-cell maturation antigen (BCMA)-targeting therapy is the most common approach to immunotherapy and cellular therapy for multiple myeloma (MM). Three major agents, CAR-T cells, bispecific antibodies, and ADC have been developed as novel therapeutic agents. CAR-T therapy showed favorable efficacy in the treatment of relapsed and refractory MM (RR MM) and was tried in early lines of therapy. Similarly, bispecific antibodies targeting BCMA or other targets have also shown promising effects in treatment of RR MM, and have been now tested in combination with other agents. Although issues such as poor fitness or exhaustion of T cells and increased susceptibility to viral infection remain to be fully resolved, novel immunotherapies and cellular therapies should further improve the prognosis of patients with RR MM.

Oncoproteins E6 and E7 upregulate topoisomerase I to activate the cGAS-PD-L1 pathway in cervical cancer development.

Background: Cervical cancer (CC) stands as a significant health threat to women globally, with high-risk human papillomaviruses as major etiologic agents. The DNA damage repair (DDR) protein topoisomerase I (TOP1) has been linked to various cancers, yet its distinct roles and mechanisms in CC are not fully elucidated. Methods: We investigated TOP1 expression in cervical intraepithelial neoplasia (CIN) and CC tissues utilizing qRT-PCR and IHC, correlating findings with patient prognosis. Subsequent knockdown studies were performed in vitro and in vivo to evaluate the influence of TOP1 on tumor growth, DNA repair, and inflammatory responses. Results: TOP1 was highly expressed in CIN and CC, negatively correlating with patient prognosis. Inhibition of TOP1 impeded CC cell growth and disrupted DNA repair. TOP1 was shown to regulate tumor-promoting inflammation and programmed death-ligand 1 (PD-L1) production in a cGAS-dependent manner. HPV oncoproteins E6 and E7 upregulated TOP1 and activated the cGAS-PD-L1 pathway. Conclusions: TOP1 acts as a DNA repair mediator, promoting CC development and immune evasion. Targeting the TOP1-cGAS-PD-L1 axis could be a potential therapeutic strategy for CC.

In vivo studies could not confirm in vitro prophylactic synergism between Moringa essential oil and Lactobacillus reuteri (MT180537).

Aerobic vaginitis (AV) is a recently defined vaginal recurring infection, which is treated with antibiotics. However, excessive and prolonged use of antibiotics disrupts healthy vaginal microflora and leads to the emergence of antibiotic resistance among pathogens. This situation has directed researchers to explore alternative antimicrobials. The current study describes in vitro and in vivo antimicrobial efficacy and pharmaceutical interactions between plant essential oils (EOs) and five lactic acid bacteria (LABs), isolated from the healthy vagina, against E. faecalis, one of the major etiological agents of AV. In vitro experiments confirm good antimicrobial activity of both plant EOs and cell free supernatant (CFS) from LABs. Based on high antimicrobial efficacy, Moringa essential oil (MO) was selected to determine its nature of interaction with CFS of five LAB strains. Synergism was recorded between MO and CFS of L. reuteri (MT180537). To validate in vitro findings, prophylactic responses of individual and synergistic application of MO and L. reuteri (MT180537) were evaluated in an E. faecalis (MW051601) induced AV murine model. The prophylactic efficacy was evidenced by a reduction in intensity of clinical symptoms, E. faecalis (MW051601) count per vaginal tissue along with a reduction in AV associated changes in histological markers of infection in animals receiving Moringa essential oil and L. reuteri (MT180537) alone or in combination. However, significant synergism between Moringa essential oil and L. reuteri (MT180537) could not be observed. Our data confirms the importance of in vivo experiments in deducing pharmacological interactions.

Transcriptional responses of cytokines, immunoglobulin A, and nitric oxide genes in 1-day-old chicks post Salmonella typhimurium infection: An experimental study.

Salmonella has become one of the hazards prevalent foodborne pathogens causing different diseases in chickens. However, Salmonella typhimurium (ST), a nonhost-specific serovar, is a major avian agent that causes severe disturbance in young chicken wellness. The occurrence of Salmonella in chickens and their antimicrobial resistance were explored in this study. In addition, the immune response of 1-day-old broiler chicks, against multidrug resistant (MDR) ST infection, was also assessed at 4 and 24 hours post infection (pi) in the cecum and spleen, representing their mucosal and systemic immune responses, respectively. A total of 375 samples from 130 diseased and apparently healthy broiler and layer chickens were randomly collected for Salmonella isolation, identification, and resistance profile evaluation, from farms and different clinical laboratories. The immune response of 1-day-old broiler chicks, Ross 308, against in-vivo ST infection was ascertained through the evaluation of heterophile phagocytosis and s expression of cytokines, immunoglobulin A and other immune-regulating genes in the cecum and spleen. Twenty-four, 1-day-old nonvaccinated broiler chicks were used and divided into two groups. The chicks in the infected group were orally inoculated with 0.5 ml of 2 × 108 colony forming units (CFU)/ml of MDR ST suspension, while those in the control group were taken nutrient broth. Seven out of 130 (5.38%) examined chickens were positive for Salmonella. All isolates (100%) were resistant to amoxicillin-clavulanic acid (AMC), cefazolin (CZ), cefoxitin (FOX), ciprofloxacin (CIP), nalidixic acid (NA), tetracycline (TE), fosfomycin (FOS), and colistin (CT) with multiple antimicrobial resistances (MARs) index range of 0.72-0.83, where none of them was resistant to meropenem (MEM). The results of immune response revealed that chicks infected with ST showed significantly different phagocytosis percentages and index values compared to controls. According to the real-time quantitative polymerase chain reaction (RT-qPCR) results, the transcription of IL-8, iNOS, IL-18, IgA, and IFN-γ for chicks infected by ST showed a significantly increased trend (p < 0.01) with increasing chicken age and was higher in the cecum than spleen compared to controls (p < 0.05) during 24 hours after infection. The findings indicated a strong mucosal immune response in the chicks after the ST challenge, which reflects humoral and cellular responses. Our insight recommended the occurrence of a natural immune response stimulator at 1 day age to face the infection, and this can prevent the resistance transfer, with efficient control measures.

First evaluation of the impact of a targeted subunit vaccine against bovine viral diarrhea virus in feedlot cattle.

Bovine respiratory disease (BRD) is a serious health and economic problem in the beef industry, which is often associated with transportation and caused by different pathogens. In this study, we evaluated the effect of a novel subunit targeted vaccine against bovine viral diarrhea virus (BVDV) in feedlot cattle, a major viral agent of BRD. The core of this novel vaccine is the fusion of the BVDV structural glycoprotein, E2, to a single-chain antibody, APCH, together termed, APCH-E2. The APCH antibody targets the E2 antigen to the major histocompatibility type II molecule (MHC-II) present in antigen-presenting cells. To evaluate the vaccine, 2,992 animals were randomly allocated into two groups, control group (N = 1,491) and treatment group (N = 1,501). Animals of both groups received the routine sanitary plan: two doses of clostridial, respiratory, and rabies vaccines. Animals within the treatment group also received two doses of a targeted subunit vaccine against BVDV. Serum samples were taken on the day of the first inoculation (T0) and 90 d later (T90). Viral circulation was monitored using an anti-P80 ELISA (virus-specific) and immune response was evaluated by anti-E2 ELISA (detects virus and vaccine immune responses). Only animals treated for respiratory disease were considered positive cases of BRD. Results demonstrate that the control group had significantly more animals treated for BRD cases compared to the treatment group (5.9% vs. 3.7%, P = 0.02). The control group had a greater number of animals positive for anti-P80 antibodies and significantly fewer animals positive for anti-E2 antibodies compared to the treatment group (69% vs. 61% and 71% vs. 99%, respectively, P = 0.003), consistent with natural viral circulation within this group. The treatment group, conversely, had fewer animals positive for anti-P80 antibodies and a greater number of animals positive for anti-E2 antibodies, consistent with a robust vaccine-induced antibody response and a reduction of the BVDV circulation within this group. The data indicate the new subunit targeted vaccine induced greater anti-E2 antibodies and reduced the amount of BVD virus circulation within the treatment group leading to a fewer number of animals needing to be treated for BRD.

Bioremediation of Engine Oil-Contaminated Soil using Selected Indigenous Moulds

The polycyclic aromatic hydrocarbons (PAHs) utilizing the potential of moulds from engine oil-polluted soils were assessed. These PAHs are known to be toxic, mutagenic and carcinogenic in the environment. Consequently, the study aims to evaluate the potential of indigenous moulds from engine oil in the remediation of contaminated soil. Samples were collected from engine oil-polluted soils from Samonda, Ibadan, Oyo State Nigeria. The ability of four potential indigenous moulds to degrade the PAH fraction of the engine oil-polluted soil sample was assessed using the gas chromatography technique. Four moulds were identified based on their cultural and microscopic characteristics and were confirmed as Aspergillus flavus, Aspergillus parasiticus, Aspergillus oryzae and Aspergillus nidulans. The highest biodegradation potential was observed in treated soil sample containing Aspergillus flavus (55.15%) followed by Aspergillus parasiticus (55.00%), Aspergillus oryzae (44.51%) and the least biodegradation potential was observed in the sample containing Aspergillus nidulans (24.16%) after 60 days of treatment. This study revealed that indigenous mould has the ability to utilize toxic fractions of petroleum products as their sole carbon sources therefore are the major bio-remediating agents in the sampling area.

Prevalence of Major Parasitic Agents Involved in Camel Skin Diseases in Babile District, Eastern Ethiopia

Aim A cross-sectional study was conducted from October 2017 up to April 2018 in Babile district, Eastern Hararghe zone, Oromiya regional state of Ethiopia. Objective To determine the prevalence of major parasitic agents involved in camel skin diseases and their risk factors. Method A cross-sectional study design was implemented to determine the prevalence of major parasitic pathogens, particularly mange mites and ticks affecting camel skin, and associated risk factors. The target animals for the study were dromedary camels reared under pastoral and agro-pastoral production systems in Babile district of Oromia Regional State of Ethiopia. The sample size for the study was estimated by taking an expected prevalence of 50%, an accepted error of 5%, and a confidence level of 95%. A chi-square test was used to evaluate the differences in the occurrence of parasites among categorical variables (age, sex, herd size, and season). A p-value≤0.05 was considered statistically significant. Results Out of 768 camels examined, 122 (15.9%) and 113 (14.7%) were found to be infested with ticks of various species and Sarcoptes species, respectively. Nine hundred twenty-nine (929) adult tick species, including 329 (35.4%) males and 600 (64.59%) females, were collected from selected camels. The tick species identified in the present study were Rhipicephalus pulchellus (29.7%), Amblyomma gemma (4.84%), Hyalomma dromedarii (13.56%), Boophilus decoloratus (2.58%), Amblyomma variegatum (23.04%), Amblyomma coherence (8.61%), Rhipicephalus evertsievertsi (9.15%), Rhipicephalus pravus (2.37%), Rhipicephalus sanguines (4.2%), Rhipicephalus appendiculatus (1.08%) and Hyalomma marginatum (0.86%). The mean tick burden observed was 1.2 ticks per camel. Sarcoptes species was the only mite observed during this study. The tick infestation rate varied significantly (p&lt;0.05) between seasons (dry and wet), between sex groups, and between herd sizes of camels. However, there was no statistically significant difference (p&gt;0.05) in the prevalence of tick infestation between the age groups. Mange mite infestation varied significantly between age groups (young and adults). Conclusion Finally, the tick and mange mite infestations were highly prevalent in the indigenous dromedary camels in the Babile district. Therefore, special attention should be given to the programmed tick and mite control campaign in the area.

Integrated application of grafted ZnO and fungicide to control the fungicide-resistant Colletotrichum spp

BackgroundThe Food and Agriculture Organization has reported approximately 40 % of food loss due to damage from plant pests and diseases, including fungal infections. Continuous application of agrichemicals for controlling fungal infection cause the occurrence of fungicide resistance. Colletotrichum spp., major causal agents for strawberry anthracnose, have gained concern for fungicide resistance issues. MethodsWe developed novel antifungal strategies in the present study by integrating multibranched flower-like ZnO (fZnO) and agrochemicals (trifloxystrobin). fZnO compounds were synthesised using an eco-friendly and efficient hydrothermal method. Charged polymers with steric structures, such as hydrophilic polyacrylic acid (PAA) and polyethyleneimine (PEI), were grafted onto fZnO surfaces to improve the suspension ability of the compounds. We used the grafted fZnO compounds in combination with the fungicide trifloxystrobin to evaluate the in vitro and in vivo activities. Significant findingsGrafted fZnO (80 ppm) and trifloxystrobin (100 ppm) effectively inhibited the growth of fungicide-resistant Colletotrichum spp. and limited strawberry anthracnose on leaves. PEI-grafted fZnO shows promise as an eco-friendly additive in sustainable agriculture due to its photocatalytic activity and ability to withstand environmental factors.

Factors Affecting on Students’ Preference on Choosing Academic Track for Higher Education in Pokhara

The students joining higher education undergo various confusions while selecting academic track for their further studies. Students who pass the tenth grade are supposed to join the subject of their interest in grade eleven or intermediate level which will be the fundamental course for their higher education ahead. Grade eleven is the main entry point for students to establish their future in the higher education. Higher education in Nepal starts from bachelor level but students are supposed to identify their major subject starting from grade eleven. It seems that SEE graduates tend to select the major subject while joining higher education depending on various aspects like intelligence of a person, the interest towards that subject, family, peer pressure, social inputs, guidance from teachers , etc. Family (57.47%) is the major agent to assist students to take decisions for choosing the academic track while joining grade eleven. 92.52% students were not forced but 7.4% students were forced by the parents to choose the major subjects for higher education. It is surprising that 59.19% students wish to go abroad for university level education. The children joining senior high school need to be provided career guidance and counseling before choosing and handling major academic track for their higher education.

Antigenic similarities and clinical cross-protection between variant and classic non-viscous strains of Moritella viscosa in Atlantic salmon in Norway

Moritella viscosa (M. viscosa) is one of the major etiological agents of winter-ulcers in Atlantic salmon (Salmo salar) in Norway. Outbreaks of ulcerative disease in farmed fish occur across the North Atlantic region, causing reduced animal welfare and economical challenges, and are of hindrance for sustainable growth within the industry. Commercially available multivalent core vaccines containing inactivated bacterin of M. viscosa reduce mortality and clinical signs related to winter ulcer disease. It has previously been described two major genetic clades within M. viscosa, typical (hereafter referred to as classic) and variant, based on gyrB sequencing. In addition, there are phenotypical traits such as viscosity that may differ between different types of isolates. Western blot using salmon plasma showed that classic non-viscous strains are antigenically different from the classic viscous type included in core vaccines. Further, Western blot also showed that there are similarities in binding patterns between Norwegian variant and classic non-viscous isolates, indicating they may be antigenically related. Vaccination-challenge trials using Norwegian gyrB-classic non-viscous isolates of M. viscosa, demonstrate that the isolates from the classic clade that are included in current commercial multivalent core vaccines, provide limited cross protection against the emerging non-viscous strains. However, a vaccine recently approved for marketing authorization in Norway, containing inactivated antigen of a variant M. viscosa strain, demonstrates reduced mortality as well as clinical signs caused by infections with the classic non-viscous M. viscosa isolated from outbreaks in Norwegian salmon farms. The study shows that there are antigenic similarities between variant and classic non-viscous types of M. viscosa, and these similarities are mirrored in the observed cross-protection in vaccination-challenge trials.

The multidimensional role of the principal in post-apartheid-South-Africa

The end of apartheid in 1994 brought about radical changes in the South African education system, especially for school principals to manage their own affairs as promulgated in the South African Schools Act. These developments have changed the principal's position irrevocably. However, these changes did not result in the expected outcome in the majority of schools for a number of reasons. Teachers are frequently unsure whether the anticipated changes will have the desired impact in schools. Moreover, principals and teachers have different views on how these changes will affect schools and their work. This paper adopts a conceptual approach that draws on various theories and concepts from the literature on school leadership and management. Understanding the challenges of the school principal's job after apartheid was the aim of the research. The Standards for School Principalship (2015) provided the theoretical framework and basis for this conceptual paper. It should be noted that principals are the most crucial persons in education since they serve as managers and major delivery agents in the educational system. They are the driving force behind improved educational outcomes in South Africa after apartheid. However, it is increasingly uncommon for principals to carry out their multifaceted tasks alone because of how significantly their positions have altered since 1994. All the parties concerned with running a school should receive training and orientation in this respect. The main findings of this paper are that, since the end of apartheid, principals face various challenges in their role, such as lack of resources, support, autonomy, accountability, collaboration, diversity, equity, quality, innovation, and professionalism.

Deficiency of dltD contributes to increased autolysis in Streptococcus mutans

ABSTRACTStreptococcus mutans (S. mutans) is one of the major etiological agents of dental caries. Interfering with the expression of genes associated with cariogenicity of S. mutans is an effective ecological approach for caries prevention. Thus, understanding the role of genes related to cariogenicity in S. mutans is important. dltD is a conserved gene in Gram-positive bacteria, which is involved in D-alanylation of lipoteichoic acid to modify cell surface charge. In vivo caries experiments have shown significant decreases in the caries severity in rats infected with S. mutans dltD-deficient strain. Although the impact of dltD on bacterial surface charge and division in other Gram-positive bacteria is known, its role in S. mutans biological functions remains unclear. This study aimed to investigate the biological functions of dltD in S. mutans. We examined growth curves, morphology, autolysis, biofilm formation, and cell membrane properties of S. mutans wild strain and dltD-deficient strain. Our results revealed that dltD plays a key role in the growth and autolysis of S. mutans. dltD deletion increased biofilm autolysis, thereby reducing the number of viable bacteria within the biofilm. Furthermore, dltD may have an epistatic effect on cell division and surface charge. Its regulatory network needs to be further elucidated. This study shed light on therole of dltD in the growth of S. mutans, thereby enhancing our understanding of its function.

In Vitro Leishmanicidal Activity of Copaiba Oil and Kojic Acid Combination on the Protozoan Leishmania (Leishmania) amazonensis and Host Cell.

(1) Background: Leishmaniasis refers to a group of anthropozoonotic diseases caused by Leishmania. The major chemotherapeutic agent used for its treatment is Glucantime®®, but the search continues for new compounds that are economically viable and act on the protozoan without causing damage to the host cell. As an alternative approach, this study used a combination of copaiba oil (CO) and kojic acid (KA) to determine their in vitro action on host cells, on the Leishmania (Leishmania) amazonensis protozoan and its interaction with macrophages. (2) Methods: In vitro culture, analysis of cytokine release and microscopy assays were performed. Statistical analysis was performed with ANOVA (GraphPad Prism). (3) Results: The combination did not induce cytotoxic effects on macrophages after treatment but promoted morphological changes in the protozoan, such as nuclear alterations (apoptotic characteristics), alterations in the cellular body and an increase in the number of electrodense structures and acidocalcisomes, observed mainly at the concentrations of CO20KA50 and CO30KA50 μg/mL. We observed reductions in the intracellular amastigote number and in the production of proinflammatory cytokines, such as IL-6 and TNF-α, after treatment with CO30KA at 50 µg/mL. (4) Conclusions: We report here, for the first time, that the combination of CO and KA may be a promising approach against Leishmania (Leishmania) amazonensis.