Parasitic Bacteria Research Articles

Berberine ameliorates dextran sulfate sodium -induced colitis through tuft cells and bitter taste signalling

BackgroundInflammatory bowel disease (IBD), a persistent gastrointestinal disease, is featured with impaired gut immunity. Previous studies have demonstrated that tuft cells can regulate the intestinal type 2 immune response by activating downstream ILC2 and Th2 cells and repair gut barrier upon invasion of parasitic helminths, bacteria, protozoans, and enteritis through different chemo-sensing receptors, such as bitter taste receptors. Berberine is a widely used in the treatment of diarrhea in clinic, however the mechanism underlying this effect is not clear. In this study, we aim to explore the relationship between berberine and tuft cells in dextran sulfate sodium (DSS) -induced colitis.ResultsOur data showed that berberine significantly ameliorated DSS-induced colitis and regulating type 2 innate immune lymphocytes (ILC2) and Th2 immune cells via tuft cells in the gut. Furthermore, the effect of berberine on colitis was partially abolished by U73122, a bitter taste receptor inhibitor, suggesting that bitter taste signalling pathway played an important role in the effect of berberine on relieving colitis.ConclusionsBerberine ameliorates dextran sulfate sodium -induced colitis through tuft cells and bitter taste signalling. Our study reveals the unique pharmacological mechanisms of berberine in the context of colitis, laying the foundation for further clinical applications of this compound.

Penerapan Metode Clustering pada Penyakit Abses Berdasarkan Faktor Penyebab

An abcess is a collection of pus in an indefinite space in the body, an abscess can appear on the surface of the skin and can appear in the tissues of an organ. Abscesses occur due to an infectious process or from parasitic bacteria due to foreign bodies, such as splinters, bullet wounds, needles. Many patients come with complaints of pain, swelling, redness, fever and others. Therefore, to overcome this problem, it is necessary to take quick action to help reduce and deal with the problem of abscess disease among the community by using the clustering method do that it can help agencies in conducting socialization so that the communinty knows more about the factors that cause abscess disease and how to handle it. From this research courced at tha Binjai estate Health Center which consists of several variables, namely age, type of abscess disease data that often appears, the abscess disease data that often appears after doing the 2 cluster process is with age is 26-35 years, with the type of abscess disease is dental abscess, and the casual factor is not maintaining dental hygiene.

Deletion of the alr gene in Brucella suis S2 attenuates virulence by enhancing TLR4-NF-κB-NLRP3- mediated host inflammatory responses

Brucella is an intracellular parasitic bacterium lacking typical virulence factors, and its pathogenicity primarily relies on replication within host cells. In this study, we observed a significant increase in spleen weight in mice immunized with a Brucella strain deleted of the gene for alanine racemase (Alr), the enzyme responsible for alanine racemization (Δalr). However, the bacterial load in the spleen markedly decreased in the mutant strain. Concurrently, the ratio of white pulp to red pulp in the spleen was increased, serum IgG levels were elevated, but no significant damage to other organs was observed. In addition, the inflammatory response was potentiated and the NF-κB-NLRP3 signaling pathway was activated in macrophages (RAW264.7 Cells and Bone Marrow-Derived Cells) infect ed with the Δalr mutant. Further investigation revealed that the Δalr mutant released substantial amounts of protein in a simulated intracellular environment which resulted in heightened inflammation and activation of the TLR4-NF-κB-NLRP3 pathway in macrophages. The consequent cytoplasmic exocytosis reduced intracellular Brucella survival. In summary, cytoplasmic exocytosis products resulting from infection with a Brucella strain deleted of the alr gene effectively activated the TLR4-NFκB-NLRP3 pathway, triggered a robust inflammatory response, and reduced bacterial survival within host cells. Moreover, the Δalr strain exhibits lower toxicity and stronger immunogenicity in mice.

Prevalence of Hemoplasma spp. positivity in potential feline blood donors and study of the association with selected clinical variables.

Hemotropic mycoplasmas, hemoplasmas, are epi-erythrocytic parasitic bacteria that can be transmitted through blood transfusion. To study the prevalence of hemoplasma infection of potential feline blood donors and investigate the association between Hemoplasma spp. quantitative polymerase chain reaction (qPCR) positivity in blood units and selected variables. Seven thousand five hundred seventy-three blood units from 4121 privately-owned potential donor cats. Retrospective observational cross-sectional study. The Banco Sangue Animal (BSA)-Animal Blood Bank medical database was reviewed for all feline donations performed in 2022 in Portugal, Spain, and Belgium. Baseline characteristics and results of blood-borne pathogens screening tests were extracted from the medical records. Two hundred twelve of 4034 Portuguese donor cats and 2 of 70 Spanish donor cats tested positive for Hemoplasma spp. qPCR in 2022 leading to an overall estimated prevalence of 5.2% (95% CI: 4.5%-5.9%) in potential blood donors. Using multivariable generalized estimation equation models, Hemoplasma spp. qPCR was more often positive among blood units issued from male cats (OR = 1.9, 95% CI: 1.4-2.6, P < .0001), units positive for FeLV (OR = 2.8, 95% CI: 1.4-5.6, P = .0023), and units collected in winter months (OR = 2.5, 95% CI: 1.7-3.6, P < .0001). This study underscores the importance of Hemoplasma spp. and other relevant blood-borne pathogens screening at every donation. Implementing stringent screening protocols is crucial to mitigate the risk of hemoplasma transmission via blood transfusions, thereby safeguarding the health and welfare of cats receiving transfusions.

Molecular Detection and Characterization of Hemotropic Mycoplasma in Assamese Macaques (Macaca assamensis) of Northern Thailand.

Hemotropic mycoplasmas, also known as hemoplasmas, are parasitic bacteria that infect red blood cells, potentially leading to varying degrees of anemia across numerous mammalian species, including nonhuman primates. The present study aims to investigate the prevalence of hemoplasma infection and identify the species involved among free-ranging Assamese macaques (Macaca assamensis) inhabiting northern Thailand. A total of 133 blood samples were collected from Assamese macaques in Chiang Rai province, Thailand, and subjected to screening for hemoplasma infection utilizing nested PCR amplification targeting the 16S rRNA gene. Positive samples were subsequently analyzed through nucleotide sequencing and phylogenetic analysis for putative species identification. Current study results revealed that 17.3% (23/133; 95% CI 11.29-24.81) of Assamese macaques tested positive for hemoplasma infection using the nested PCR assay. Partial 16S rRNA sequences derived from hemoplasma isolates in Assamese macaques exhibited 99% homology, forming a cluster within the same phylogenetic clade as "Candidatus Mycoplasma haematomacacae," previously identified in long-tailed macaques, rhesus macaques, and Japanese macaques. These findings suggest the presence of "Ca. M. haematomacacae" not only in long-tailed macaques and rhesus macaques but also in Assamese macaques in Thailand. To our knowledge, this marks the first molecular detection of "Ca. M. haematomacacae" in Assamese macaques in Thailand. These results hold significance as they enhance our understanding of hemoplasma infection distribution among macaque populations in Thailand.

Predatory Bdellovibrio-and-like organism mixtures on efficient MBR in-situ membrane fouling diminishment and mechanisms

ABSTRACT Membrane fouling is a major hindrance that restricts the application of membrane bioreactors (MBRs). Bdellovibrio-and-like organisms (BALOs), as obligatory parasitic bacteria, prey upon various bacteria. In this study, the BALO mixtures were screened and found more effective in membrane fouling mitigation compared to the single BALO species and extended the membrane filtration period by as long as 33.3%. The higher BALO diversity reduced the potential foulants generation in the activated sludge by decreasing the sludge viscosity as high as 13.8 ± 0.6% than the pure culture of BALO. Meanwhile, the mixed BALOs demonstrated superior biofilm predation capabilities, with the content of soluble microbial products and extracellular polymeric substances on the biofilm decreasing by 26.1 ± 0.5% and 38.3 ± 0.2% as the most compared to the single BALO species involved system. Additionally, the BALO mixtures expanded the single strains’ host lysis spectrum of both the activated sludge and biofilm. The abundance of membrane-fouling-related bacteria such as Flavobacterium, Rhodobacter, and Labilithrix and pioneer bacteria such as Sphingorhabdus and Pseudomonas was significantly reduced. In summary, this study disclosed the significantly better membrane fouling mitigation effects of the BALOs with higher diversity, suggesting that the expansion of the host range is crucial for the further application of BALOs to enhance the anti-fouling performance of the MBR system.

Comparison of Methods Between the Multitube Fermentation Method and The Filter Membrane Method for Escherichia Coli in Drinking Water

Escherichia coli is a normal parasitic bacterium in the intestinal tract and is an important indicator of the degree of contamination and hygienic quality of water bodies. In this study, 78 samples of domestic drinking water were tested for Escherichia coli by filter membrane method and multi-tube fermentation method. The results showed that the passing rate of water samples tested by the multi-tube fermentation method was higher than that of the filter membrane method, which was statistically significant (P &lt; 0.05). In the untreated water samples test, the detection rate of Escherichia coli was 92.31% in the multi-tube fermentation method compared to 71.79% in the filter membrane method, and the difference was statistically significant. The results of the study showed that the detection rate and sensitivity of the multi-tube fermentation method in the microbiological testing of domestic drinking water were higher and better than that of the filter membrane method. The selection of testing methods should consider its applicability and the accuracy of the test results. Meanwhile, factors affecting the quality of microbiological testing include the quality of laboratory personnel, specimen handling, and the quality of instruments and reagents, which need to be carefully managed and trained. This study can provide a practical reference for microbiological testing of domestic drinking water.

Molecular basis of SAP05-mediated ubiquitin-independent proteasomal degradation of transcription factors

SAP05, a secreted effector by the obligate parasitic bacteria phytoplasma, bridges host SPL and GATA transcription factors (TFs) to the 26 S proteasome subunit RPN10 for ubiquitination-independent degradation. Here, we report the crystal structures of SAP05 in complex with SPL5, GATA18 and RPN10, which provide detailed insights into the protein-protein interactions involving SAP05. SAP05 employs two opposing lobes with an acidic path and a hydrophobic path to contact TFs and RPN10, respectively. Our crystal structures, in conjunction with mutagenesis and degradation assays, reveal that SAP05 targets plant GATAs but not animal GATAs dependent on their direct salt-bridged electrostatic interactions. Additionally, SAP05 hijacks plant RPN10 but not animal RPN10 due to structural steric hindrance and the key hydrophobic interactions. This study provides valuable molecular-level information into the modulation of host proteins to prevent insect-borne diseases.

FIRST DATA ON BACTERIAL, FUNGAL AND PARASITIC INFECTIONS OF BLACK RATS (RATTUS RATTUS) FROM THE PALM GROVES OF THE ALGERIAN SAHARA

The present study aimed to detect the parasitic fauna associated with black rats (Rattus rattus) from southeastern Algeria. It showed the presence of seven species of parasitic fungi namely Penicillium sp. (Prevalence Pr=91.3%), Aspergillus niger (Pr=91.3%), Alternaria sp. (Pr=58.7%), Cladosporium sp. (Pr=87%), Microsporum sp. (Pr=19.6%), Trichophyton sp. (Pr=21.7%) and Chrysosporium sp. (Pr=10.9%), noting that saprophytic fungi were the most recorded. On the other hand, according to the richness (S), adults (S = 7) and sub-adults (S = 7) of black rats were the most infested, with leaning for males compared to females, considering all the isolated species as satellites except the Chrysosporium sp. (2.9%) which is presented as a rare species. Concerning parasitic bacteria, aged rats were the most infected followed by adults and sub-adults where total coliforms were present in all individuals of the three classes tested. However, fecal streptococci were noted with a similar infestation rate in all age groups. Unlike this, clostridium sulfite-reducer (CSR) was mostly recorded on aged rats. Concerning the endoparasites found in the intestines of black rats, the pinworms (Syphacia muris, Syphacia obvelata, and Aspiculuris tetraptera) were more abundant than the other species. Hence, the current study allowed us to demonstrate that black rats can be considered an important reservoir of several microorganisms that can hold germs and represent a threat to biomedical and veterinary public health.

Internal structure of Mycoplasma mobile gliding machinery analyzed by negative staining electron tomography.

Mycoplasma mobile is a parasitic bacterium that forms gliding machinery on the cell pole and glides on a solid surface in the direction of the cell pole. The gliding machinery consists of both internal and surface structures. The internal structure is divided into a bell at the front and chain structure extending from the bell. In this study, the internal structures prepared under several conditions were analyzed using negative-staining electron microscopy and electron tomography. The chains were constructed by linked motors containing two complexes similar to ATP synthase. A cylindrical spacer with a maximum diameter of 6 nm and a height of 13 nm, and anonymous linkers with a diameter of 0.9-8.3 nm and length of 14.7±6.9 nm were found between motors. The bell is bowl-shaped and features a honeycomb surface with a periodicity of 8.4 nm. The chains of the motor are connected to the rim of the bell through a wedge-shaped structure. These structures may play roles in the assembly and cooperation of gliding machinery units.

Vitamin D effects on Chlamydia trachomatis infection: a case-control and experimental study.

Vitamin D deficiency is the most common nutritional deficiency worldwide. Chronic vitamin D deficiency causes immune system dysfunction, which increases susceptibility to pathogens such as bacteria, especially intracellular parasites, and viruses. Chlamydia trachomatis (C. t) is an obligate intracellular parasitic bacterium that causes a variety of sequelae. We speculated that vitamin D might be associated with C. t infection. This study aimed to address this gap in knowledge by investigating the relationship between vitamin D and C. t infection using both in vitro and in vivo models. The addition of calcitriol to McCoy cell culture in vitro delayed and reduced the quantity and volume of inclusions compared to the control group. Macrophages of peritoneally lavaged mice co-cultured with McCoy decreased the infection rate and delayed the appearance of inclusions. In mice models of vitamin D deficiency, mice in the VD-group exhibited more severe genital tract inflammation and a longer duration of infection after inoculation with C. t in the genital tract. Supplementing these mice with vitamin D3 during treatment enhanced the therapeutic effect of antibiotics. We also conducted a case-control study involving 174C. t-positive patients (95 males and 79 females) and 380 healthy volunteers (211 males and 169 females) aged 20-49 from January 2016 to March 15, 2017. Serum 25-(OH)D concentration was measured by assessing morning fasting blood samples of healthy volunteers and C. t-positive patients 1 day before antibiotic treatment and the next day after one course of treatment. The patients were followed up for 1 month and evaluated for recovery. The results showed that vitamin D deficiency was a risk factor for C. t infection and treatment failure. In summary, findings from experimental and clinical studies indicate a close association between vitamin D levels and C. t infection and treatment outcomes. Given the affordability and safety of vitamin D, both healthy individuals and patients should focus on vitamin D intake. Vitamin D supplementation could enhance treatment success and should be used as an adjunctive therapy alongside antibiotic therapy for C. t infections, pending confirmation in larger, prospective, randomized controlled trials.

Distribution characteristics of the Legionella CRISPR-Cas system and its regulatory mechanism underpinning phenotypic function.

Legionella is a common intracellular parasitic bacterium that infects humans via the respiratory tract, causing Legionnaires' disease, with fever and pneumonia as the main symptoms. The emergence of highly virulent and azithromycin-resistant Legionella pneumophila is a major challenge in clinical anti-infective therapy. The CRISPR-Cas acquired immune system provides immune defense against foreign nucleic acids and regulates strain biological functions. However, the distribution of the CRISPR-Cas system in Legionella and how it regulates gene expression in L. pneumophila remain unclear. Herein, we assessed 915 Legionella whole-genome sequences to determine the distribution characteristics of the CRISPR-Cas system and constructed gene deletion mutants to explore the regulation of the system based on growth ability in vitro, antibiotic sensitivity, and intracellular proliferation of L. pneumophila. The CRISPR-Cas system in Legionella was predominantly Type II-B and was mainly concentrated in the genome of L. pneumophila ST1 strains. The Type II-B CRISPR-Cas system showed no effect on the strain's growth ability in vitro but significantly reduced resistance to azithromycin and decreased proliferation ability due to regulation of the lpeAB efflux pump and the Dot/Icm type IV secretion system. Thus, the Type II-B CRISPR-Cas system plays a crucial role in regulating the virulence of L. pneumophila. This expands our understanding of drug resistance and pathogenicity in Legionella, provides a scientific basis for the prevention of Legionnaires' disease outbreaks and the rational use of clinical drugs, and facilitates effective treatment of Legionnaires' disease.

Effect of predatory bacterial mixtures on biolysis of waste activated sludge to improve dewatering performance

ABSTRACT The generation of surplus sludge during biological wastewater treatment has become a prevalent issue, necessitating the development of a dewatering approach that is efficient, economically feasible, and ecologically sound. Bdellovibrio-and-like-organisms (BALOs) are obligatory parasitic bacteria that prey on an array of bacteria. In this study, different BALO strains were isolated and purified from waste activited sludge (WAS). Anti-predation host strains were applied to screen the BALO strains with different host-range to minimize the overlap of the biolysis prey spectrum. In addition, the BALO strains with different host preferences were mixed for sludge biolysis treatment efficiency comparison. The results indicated that the capillary suction time and the bound water content in the WAS treated with the mixed BALOs were significantly decreased by 25.9% ± 1.7% and 5.2% ± 1.2%, respectively, compared to those treated with the single BALO strain. The soluble chemical oxygen demand concentration in the mixed BALOs treated group was increased by 31.2% ± 0.7% than that treated with the single strain. The findings indicate that the mixed strains used in the treatment process resulted in a notable enhancement of both sludge dewatering performance and lysis degree. In addition, the abundance of Proteobacteria treated with the BALO mixtures decreased by 69.1% than the single strain treated one which demonstrated that the BALO mixture expanded the sludge host lysis spectrum. This study revealed the different effects of single and mixed strains on sludge community structure, suggesting that the BALO host-range expansion is crucial to further improve sludge dewatering performances.

Brucella abortus Rough-Type Mutant Induces Ferroptosis and More Oxidative Stress in Infected Macrophages.

Brucella is an intracellular parasitic bacterium that uses multiple strategies to evade the host's defense mechanisms. However, how Brucella manipulates the host-induced oxidative stress and relevant biological processes are still poorly understood. In this study, a comparative transcriptome assay of macrophages infected with Brucella abortus S2308 and its rough mutant RB14 was performed to investigate the differentially expressed genes which might be associated with the pathogenic mechanism of Brucella. Our results showed that numerous host pro-oxidative and antioxidative stress genes were differentially expressed in macrophages infected with B. abortus S2308 and mutant RB14 at 4, 8, 24, and 48 h post-infection. Interestingly, we found that several ferroptosis-associated genes were differentially expressed during B. abortus RB14 infection. Moreover, we found that the rough mutant RB14-induced macrophage death was associated with reduced levels of host glutathione and glutathione peroxidase 4, together with increased free iron, lipid peroxidation, and ROS, all of which are important hallmarks of ferroptosis. The ferroptosis occurring during infection with RB14 was reduced by treatment with the inhibitor ferrostatin-1. However, B. abortus S2308 infection did not induce these hallmarks of ferroptosis. Taken together, our results demonstrate that ferroptosis is involved in rough B. abortus infection. Investigating how Brucella manipulates oxidative stress and ferroptosis in its host will be helpful to clarify the pathogenicity of B. abortus.

Erythronate utilization activates VdtR regulating its metabolism to promote Brucella proliferation, inducing abortion in mice.

Brucella is a facultative intracellular pathogen that preferentially colonizes reproductive organs and utilizes erythritol as a preferred carbon source for its survival and proliferation. In this study, we identified a virulence-related DeoR-family transcriptional regulator (VdtR) and an erythronate metabolic pathway responsible for four-carbon acid sugar metabolism of D-erythronate and L-threonate in Brucella. We found that VdtR plays an important role in Brucella intracellular survival and trafficking to the endoplasmic reticulum in RAW 264.7 macrophages and in virulence in a mouse model. More importantly, we found that VdtR negatively regulates the erythronate metabolic pathway to promote extracellular proliferation of Brucella, depending on utilization of D-erythronate, an oxidative product of erythritol in the host. In a pregnant mouse model, the erythronate metabolic pathway was shown to cooperate with erythritol metabolism and play a crucial role in Brucella proliferation in the placenta, inducing placentitis and finally resulting in abortion or stillbirth. Our results demonstrate that, in addition to erythritol, erythronate is a preferred carbon source for Brucella utilization to promote its extracellular proliferation. This discovery updates the information on the preferential colonization of reproductive organs by Brucella and provides a novel insight into the Brucella-associated induction of abortion in pregnant animals. IMPORTANCE Brucella is an intracellular parasitic bacterium causing zoonosis, which is distributed worldwide and mainly characterized by reproductive disorders. Erythritol is found in allantoic fluid, chorion, and placenta of aborted animals, preferentially utilized by Brucella to cause infertility and abortion. However, the erythritol metabolism-defected mutant was unable to function as a vaccine strain due to its residual virulence. Here, we found that erythronate, an oxidative product of erythritol in the host, was also preferentially utilized by Brucella relying on the function of a deoxyribonucleoside regulator-family transcriptional regulator VdtR. Erythronate utilization activates VdtR regulation of the erythronate metabolic pathway to promote Brucella extracellular proliferation, inducing placentitis/abortion in mice. Double mutations on Brucella erythritol and D-erythronate metabolisms significantly reduced bacterial virulence. This study revealed a novel mechanism of Brucella infection-induced abortion, thus providing a new clue for the study of safer Brucella attenuated vaccines.

Metabolic implications for predatory and parasitic bacterial lineages in activated sludge wastewater treatment systems

Deciphering unclear microbial interactions is key to improving biological wastewater treatment processes. Microbial predation and parasitism in wastewater treatment ecosystems are unexplored survival strategies that have long been known and have recently attracted attention because these interspecies interactions may contribute to the reduction of excess sludge. Here, microbial community profiling of 600 activated sludge samples taken from six industrial and one municipal wastewater treatment processes (WWTPs) was conducted. To identify the shared lineages in the WWTPs, the shared microbial constituents were defined as the family level taxa that had ≥ 0.1% average relative abundance and detected in all processes. The microbial community analysis assigned 106 families as the shared microbial constituents in the WWTPs. Correlation analysis showed that 98 of the 106 shared families were significantly correlated with total carbon (TC) and/or total nitrogen (TN) concentrations, suggesting that they may contribute to wastewater remediation. Most possible predatory or parasitic bacteria belonging to the phyla Bdellovibrionota, Myxococcota, and Candidatus Patescibacteria were found to be the shared families and negatively correlated with TC/TN; thus, they were frequently present in the WWTPs and could be involved in the removal of carbon/nitrogen derived from cell components. Shotgun metagenome-resolved metabolic reconstructions indicated that gene homologs associated with predation or parasitism are conserved in the Bdellovibrionota, Myxococcota, and Ca. Patescibacteria genomes (e.g., host interaction (hit) locus, Tad-like secretion complexes, and type IV pilus assembly proteins). This study provides insights into the complex microbial interactions potentially linked to the reduction of excess sludge biomass in these processes.

Rheotaxis in Mycoplasma gliding.

This review describes the upstream-directed movement in the small parasitic bacterium Mycoplasma. Many Mycoplasma species exhibit gliding motility, a form of biological motion over surfaces without the aid of general surface appendages such as flagella. The gliding motility is characterized by a constant unidirectional movement without changes in direction or backward motion. Unlike flagellated bacteria, Mycoplasma lacks the general chemotactic signaling system to control their moving direction. Therefore, the physiological role of directionless travel in Mycoplasma gliding remains unclear. Recently, high-precision measurements under an optical microscope have revealed that three species of Mycoplasma exhibited rheotaxis, that is, the direction of gliding motility is lead upstream by the water flow. This intriguing response appears to be optimized for the flow patterns encountered at host surfaces. This review provides a comprehensive overview of the morphology, behavior, and habitat of Mycoplasma gliding, and discusses the possibility that the rheotaxis is ubiquitous among them.

Nature's Needles: Adapting Bacterial “Syringes” into Programmable Protein Delivery Devices

Nature's Needles: Adapting Bacterial “Syringes” into Programmable Protein Delivery Devices

Nano-Encapsulation Of Neem Based Pesticide Formulations

Neem based pesticide formulations are reported to control plant parasitic fungi, bacteria, virus, nematodes, insects and mites. Despite its many promising properties, low stability under field conditions, mainly due to a high rate of photo-degradation, as well as a short residence time and slow killing rates, compared to conventional pesticides hinder effective large-scale use of Neem. Although when two lines of Myzus persicae Were exposed to pure azadirachtin and refined Neem seed extract at the same concentration, it was found that after forty generations, the line treated with azadirachtin had developed ninefold greater resistance compared to a control line, whereas the line treated with the extract did not show resistance. To overcome these limitations, nanotechnology has emerged as a novel tool for agricultural sustainability. Many studies have shown that the encapsulation of agrochemicals in nanoparticulate systems can enhance the efficacy of the active ingredient, decrease toxicity toward the environment and humans, and reduce losses due to volatilization, leaching, and photobleaching. Thus, the use of nanoparticles provides an effective means of protecting neem oil against premature degradation, resulting in prolongation of its effect on the target pest. Due to nano encapsulation sustained release of the active component is achieved. Furthermore, the number of applications of neem oil can be reduced, bringing substantial economic benefits. Therefore, nano-encapsulation of neem oil may enable the production of more stable formulations for control of diseases and pests. Further, the use of nanotechnology is an excellent way to combat development of resistance in insects and pathogens due to indiscriminate use of neem oil.

Out of the 'host' box: extreme off-host conditions alter the infectivity and virulence of a parasitic bacterium.

Disease agents play an important role in the ecology and life history of wild and cultivated populations and communities. While most studies focus onthe adaptation of parasites to their hosts, the adaptation of free-living parasite stages to their external (off-host) environment may tell us a lot about the factors that shape the distribution of parasites. Pasteuria ramosa is an endoparasitic bacterium of the water flea Daphnia with a wide geographical distribution. Its transmission stages rest outside of the host and thus experience varying environmental regimes. We examined the life history of P. ramosa populations from four environmental conditions (i.e.groups of habitats): the factorial combinations of summer-dry water bodies or not, and winter-freeze water bodies or not. Our goal was to examine how the combination of winter temperature and summer dryness affectsthe parasite's ability to attach to its host and to infect it. We subjected samples of the four groups of habitats to temperatures of 20, 33, 46 and 60°C in dry and wet conditions, and exposed a susceptible clone of Daphnia magna to the treated spores. We found that spores which had undergone desiccation endured higher temperatures better than spores kept wet, both regarding attachment and subsequent infection. Furthermore, spores treated with heightened temperatures were much less infective and virulent. Even under high temperatures (60°C), exposed spores from all populations were able to attach to the host cuticle, albeit they were unable to establish infection. Our work highlights the sensitivity of a host-free resting stage of a bacterial parasite to the external environment. Long heatwaves and harsh summers, which are becoming more frequent owing to recent climate changes, may therefore pose a problem for parasite survival. This article is part of the theme issue 'Infectious disease ecology and evolution in a changing world'.