Cloning and Characterization of a Unique Cytotoxic Protein Parasporin-5 Produced by Bacillus thuringiensis A1100 Strain

Parasporin is the cytocidal protein present in the parasporal inclusion of the non-insecticidal Bacillus thuringiensis strains, which has no hemolytic activity but has cytocidal activities, preferentially killing cancer cells. In this study, we characterized a cytocidal protein that belongs to this category, which was designated parasporin-5 (PS5). PS5 was purified from B. thuringiensis serovar tohokuensis strain A1100 based on its cytocidal activity against human leukemic T cells (MOLT-4). The 50% effective concentration (EC₅₀) of PS5 to MOLT-4 cells was approximately 0.075 μg/mL. PS5 was expressed as a 33.8-kDa inactive precursor protein and exhibited cytocidal activity only when degraded by protease at the C-terminal into smaller molecules of 29.8 kDa. Although PS5 showed no significant homology with other known parasporins, a Position Specific Iterative-Basic Local Alignment Search Tool (PSI-BLAST) search revealed that the protein showed slight homology to, not only some B. thuringiensis Cry toxins, but also to aerolysin-type β-pore-forming toxins (β-PFTs). The recombinant PS5 protein could be obtained as an active protein only when it was expressed in a precursor followed by processing with proteinase K. The cytotoxic activities of the protein against various mammalian cell lines were evaluated. PS5 showed strong cytocidal activity to seven of 18 mammalian cell lines tested, and low to no cytotoxicity to the others.     

czcD gene from Bacillus megaterium and Microbacterium liquefaciens as a potential nickel–vanadium soil pollution biomarker

Metals are among the most prevalent pollutants released into the environment. For these reasons, the use of biomarkers for environmental monitoring of individuals and populations exposed to metal pollution has gained considerable attention, offering fast and sensitive detection of chemical stress in organisms. There are different metal resistance genes in bacteria that can be used as biomarkers, including cation diffusion facilitators carrying metal ions; the prototype is the cobalt–zinc–cadmium transporter (czcD). The present study reports the expression changes in the czcD gene in Bacillus megaterium and Microbacterium liquefaciens under nickel and vanadium exposure by real-time polymerase chain reaction. The nickel–vanadium-resistant strains of B. megaterium and M. liquefaciens used in this study were isolated from mine tailings in Guanajuato, Mexico. The czcD gene showed high expression under exposure to 200 ppm of Ni and 200 ppm of V during the logarithmic growth phase of M. liquefaciens in PHGII liquid media. In contrast, no changes were observed in B. megaterium during logarithmic and stationary growth, perhaps due to the gene having differential expression during the growth phases. The expression profiles obtained for czcD show the possibility of using this gene from M. liquefaciens as a biomarker of nickel and vanadium pollution in microorganisms.     

Bacillus Calmette–Guérin strains with defined resistance mutations: a new tool for tuberculosis laboratory quality control

ObjectiveLaboratory quality control (QC) is essential to assess the reliability of tuberculosis diagnostic testing. To provide safe QC reagents for the detection of drug-resistant Mycobacterium tuberculosis, we generated antibiotic-resistant mycobacterial strains of attenuated virulence (M. bovis bacillus Calmette–Guérin (BCG)).MethodsSeven mono-resistant BCG strains were developed by introducing resistance-conferring mutations into wild-type BCG strains. Mutations were confirmed by dideoxynucleotide sequencing. Phenotypic resistance was quantified by microbroth dilution to determine the MIC₉₀. The capacity of two commercial tests (GeneXpert TB/RIF and Genotype MTBDRplus) to detect resistance-conferring mutations was evaluated independently.ResultsOur panel included BCG strains with mutations in rpoB (S450L, I491F), katG (deletion at AA428), gyrA (D94G), rpsL (K43R) and Rv0678c (S63R). These mutations translated respectively into phenotypic resistance to rifampin (MIC ≥8 mg/L), isoniazid (MIC ≥8 mg/L), moxifloxacin (MIC 4 mg/L) and streptomycin (MIC ≥8 mg/L); the Rv0678c mutant showed decreased susceptibility to both clofazimine (MIC 4 mg/L) and bedaqualine (MIC 1 mg/L). GeneXpert (Cepheid) and Genotype MTBDRplus (Hain Lifesciences) both called the rpoB S450L strain rifampin-resistant and the I491F mutant rifampin-susceptible, as expected based on single nucleotide polymorphism positions. Likewise, MTBDRplus called the novel katG deletion mutant isoniazid susceptible despite phenotypic resistance.ConclusionBCG strains engineered to be mono-resistant to anti-tuberculosis drugs can be used as safe QC reagents for tuberculosis diagnostics and drug susceptibility testing.     

Progression of clinical tuberculosis is associated with a Th2 immune response signature in combination with elevated levels of SOCS3

In this study, we explored the local cytokine/chemokine profiles in patients with active pulmonary or pleural tuberculosis (TB) using multiplex protein analysis of bronchoalveolar lavage and pleural fluid samples. Despite increased pro-inflammation compared to the uninfected controls; there was no up-regulation of IFN-γ or the T cell chemoattractant CCL5 in the lung of patients with pulmonary TB. Instead, elevated levels of IL-4 and CCL4 were associated with high mycobacteria-specific IgG titres as well as SOCS3 (suppressors of cytokine signaling) mRNA and progression of moderate-to-severe disease. Contrary, IL-4, CCL4 and SOCS3 remained low in patients with extrapulmonary pleural TB, while IFN-γ, CCL5 and SOCS1 were up-regulated. Both SOCS molecules were induced in human macrophages infected with Mycobacterium tuberculosis in vitro. The Th2 immune response signature found in patients with progressive pulmonary TB could result from inappropriate cytokine/chemokine responses and excessive SOCS3 expression that may represent potential targets for clinical TB management.     

Current intravesical therapy for non-muscle invasive bladder cancer

Introduction: Transurethral resection of the bladder tumour (TURBT) is still the standard initial treatment for non-muscle invasive bladder cancer (NMIBC). However, even after a radical resection, recurrence (30 – 80%) and progression (1 – 45%) are commonly seen. Intravesical therapy provides direct contact of the agent with the bladder mucosa and clearly has improved the outcome, especially in high-risk disease.

Areas covered: The role of a good initial TURBT is emphasized. Risk assessment tools are discussed. Different intravesical therapies are enumerated according to the latest literature, with the emphasis on Bacillus Calmette–Guérin (BCG), including the discussion on the optimal dose and schedule. New developments are mentioned.

Expert opinion: A radical TURBT is essential for good prognosis. For optimal visualisation of tumours, fluorescence techniques should be used with low threshold, especially in case of suspicion of carcinoma in situ (CIS). Increased completeness of the resection will lead to less persisting disease and less need for adjuvant treatment. A re-TURBT should be done when in doubt of radical resection (judged by the pathologist or the surgeon). Risk assessment is essential, but the available tools are outdated. A single post-operative instillation (SPI) with chemotherapy is only indicated in low-risk disease. BCG is the treatment of choice for high-grade disease. BCG should be given as maintenance. Awareness of deterioration of the prognosis after progression is of great importance. In BCG failures, cystectomy should be strongly advised. Chemotherapy in combination with hyperthermia seems to be a new promising treatment.     

Attendance and vaccination at immunization clinics in rural Gambia before and during the COVID-19 pandemic

IntroductionThe COVID-19 pandemic has affected the delivery of essential health services, such as routine immunization. We assessed the impact of the pandemic on the uptake of routine immunization in rural Gambia.MethodsWe collected real-time vaccine administration data in the Basse and Fuladu West Health & Demographic Surveillance Systems from September 01, 2019, to December 31, 2020. We assessed the monthly number of Expanded Program on Immunization (EPI) clinic attendances and vaccines administered, comparing data during the baseline period (September 01, 2019–March 31, 2020), COVID-19 interruption period (April 01–June 30, 2020), initial recovery period (Jul 01–September 30, 2020) and the late recovery period (October 01–December 31, 2020).ResultsCompared to the baseline period, there was an overall average monthly decline of 13.4% in EPI attendance and 38.3% reduction in average monthly immunizations during the interruption period. This decrease was particularly noticeable for Bacille Calmette-Guérin (BCG) (47.2%), birth dose hepatitis B (Hep B) (46.9%), 1st dose pentavalent (Penta1) (43.1%), 1st dose pneumococcal conjugate vaccine (PCV1) (42.4%), and measles vaccines (15.5%). Comparing the late recovery to baseline period, average monthly EPI attendance was 5.3% higher, with 1.9% increase in average monthly immunizations. Monthly immunizations for BCG were 3.0% greater, 2.5% greater for Hep B, 22.7% greater for oral polio vaccine (OPV1), 2.0% less for Penta1, 19.2% less for Penta2, and 2.6% less for PCV1.ConclusionThe reduced EPI attendance during the pandemic interruption period lasted only 3 months. Significant recovery in EPI attendance occurred during the late recovery period, while rates of monthly immunization returned to pre-pandemic levels for most antigens. EPI programmes should implement strategies to deliver missed antigens when infants do present to EPI clinics, aware that missed doses may be age dependent.     

A 90-day safety study of genetically modified rice expressing Cry1Ab protein (Bacillus thuringiensis toxin) in Wistar rats.

An animal model for safety assessment of genetically modified foods was tested as part of the SAFOTEST project. In a 90-day feeding study on Wistar rats, the transgenic KMD1 rice expressing Cry1Ab protein was compared to its non-transgenic parental wild type, Xiushui 11. The KMD1 rice contained 15mg Bt toxin/kg and based on the average feed consumption the daily intake was 0.54mg Bt toxin/kg body weight. No adverse effects on animal behaviour or weight gain were observed during the study. Blood samples collected one week prior to sacrifice were analyzed and compared for standard haematological and biochemical parameters. A few parameters were significantly different, but all within the normal reference intervals for rats of this breed and age and not in relation to any other findings, thus not considered treatment related. Upon sacrifice a large number of organs were weighed, macroscopic and histopathological examinations were performed with only minor changes to report. The aim of the study was to use a known animal model in performance of safety assessment of a GM crop, in this case KMD1 rice. The results show no adverse or toxic effects of KMD1 rice when tested in the design used in this 90-day study. Nevertheless the experiences from this study lead to the overall conclusion that safety assessment for unintended effects of a GM crop cannot be done without additional test group(s).     

微生物发酵法生产利巴韦林的初步研究

以枯草芽孢杆菌（Bacillus subtilis）TM903（Ade^- ＋8-AG^t＋MSO^t）为生产菌株，考察了前体物1，2，4-三唑-3-甲酰胺（TCA）、MnSO4、温度、pH及培养基装量对发酵法生产利巴韦林的影响，确定了其摇瓶发酵工艺：培养至24h时添加10g／LTCA及10mg／LMnSO4，24h后每6h升温2℃，采用磷酸缓冲液调节pH，在500ml挡板三角瓶中培养基装液量为25ml。该工艺条件下经60h发酵，利巴韦林的摇瓶发酵水平达5．11g／L。