Effectiveness of bioactive compounds in amending the soil infested with soil-borne Ralstonia solanacearum of potato

Three natural bioactive compounds, viz. cow dung, bee propolis and turmeric powder were applied to amend the Ralstonia solanacearum infested soil of potato. Sun dried cow dung @ 30 t/ha, aqueous extraction of turmeric powder @ 30 kg/ha and propolis @ 5 lit/ha were applied to the inoculated soil by mixing with field soil in SAU (Dhaka) and BARI (Gazipur). Data on pH, organic matter, total cfu/ml and avirulent cfu/ml of the treatment applied soil and per cent disease index (PDI) of bacterial wilt of potato were recorded. Significant difference in soil pH and per cent organic matter (OM) occurred in all the amended soil as compared to control. A decreased total cfu/ml of R. solanacearum occurred in all the treated soil, but propolis (8.2 X 107) and cow dung (1.1 X 108) showed the lowest count. However, in increasing the avirulent count of R. solanacearum, turmeric powder (1.8 X 109) showed the highest count compared to other amended soil. Significant disease reduction over control was also observed in all the treatments, but propolis (45.65%) and turmeric powder (43.48%) showed the best results in wilt disease reduction. J. Biodivers. Conserv. Bioresour. Manag. 2021, 7(1): 43-50

In Tuber Biocontrol of Potato Late Blight by a Collection of Phenazine-1-Carboxylic Acid-Producing Pseudomonas spp.

Phenazine-1-carboxylic acid (PCA) produced by plant-beneficial Pseudomonas spp. is an antibiotic with antagonistic activities against Phytophthora infestans, the causal agent of potato late blight. In this study, a collection of 23 different PCA-producing Pseudomonas spp. was confronted with P. infestans in potato tuber bioassays to further understand the interaction existing between biocontrol activity and PCA production. Overall, the 23 strains exhibited different levels of biocontrol activity. In general, P. orientalis and P. yamanorum strains showed strong disease reduction, while P. synxantha strains could not effectively inhibit the pathogen’s growth. No correlation was found between the quantities of PCA produced and biocontrol activity, suggesting that PCA cannot alone explain P. infestans’ growth inhibition by phenazine-producing pseudomonads. Other genetic determinants potentially involved in the biocontrol of P. infestans were identified through genome mining in strains displaying strong biocontrol activity, including siderophores, cyclic lipopeptides and non-ribosomal peptide synthase and polyketide synthase hybrid clusters. This study represents a step forward towards better understanding the biocontrol mechanisms of phenazine-producing Pseudomonas spp. against potato late blight.

The efficacy of acibenzolar-S-methyl (ASM) in inducing resistance against Fusarium graminearum sensu stricto in wheat (Triticum aestivum L.)

Four ASM (acibenzolar-S-methyl) concentrations were applied on wheat plants at different growth stages prior to inoculation with 1x105 conidia/ml of Fusarium graminearum. Thereafter, disease severity was monitored and recorded over time. All ASM concentrations reduced disease severity compared to the control. The best treatment, providing the lowest Area Under the Disease Progress Curve (AUDPC) units, high average Hundred Seed Weight (HSW) and reduced average Percentage Seed Infection (PSI), was 0.075 g/L ASM applied at anthesis. A weak but significant positive correlation was observed between AUDPC and PSI (r = 0.33; p = 0.0001). However, a moderate and weak negative correlation was observed between AUDPC and HSW (r = - 0.41; p < 0.0001) and HSW and PSI (r = - 0.18; p = 0.04) respectively. Higher ASM concentrations were more effective when applied at anthesis and lower concentrations at late boot. Moreover, repeated applications (applied at both late boot and anthesis) did not improve disease reduction. A disease reduction and deoxynivalenol (DON) reduction of up to 28.97% (0.075 g/L ASM applied at anthesis) and 18.79% (0.0375 g/L ASM applied at anthesis) was observed. However, DON and zearalenone (ZEA) reduction did not always correspond with disease severity reduction of tested treatments. This accentuates the importance of the development of integrated control strategies for the improved and effective management of Fusarium head blight (FHB) in wheat.

Applications of bacteriophages in controlling rice bacterial grain rot caused by Burkholderia glumae

The study on the procedure of applicating bacteriophage (or phage) to prevent rice bacterial grain rot caused by Burkholderia glumae was conducted in the greenhouse conditions. The first experiment investigated the effect of different phage titers (i.e. 105 PFU/mL, 106 PFU/mL, 107 PFU/mL, 108 PFU/mL) in controlling bacterial grain rot of rice. The results showed that all four titers gave disease reduction with different levels, among these were the titer of 108PFU/mL expressed highest efficacy in disease reduction with the lowest percentage of infected grains compared to the rest treatments. The second experiment examined the effect of phage application times (i.e. spraying phage at 2 hours before pathogen inoculation, 2 hours before and 5 days after pathogen inoculation, and 5 days after pathogen inoculation) in suppressing bacterial grain rot disease. The results found that two treatments (i.e. one time spraying at 2 hours before pathogen inoculation, and two times spraying at 2 hours before and 5 days after pathogen inoculation) expressed high efficacy in reduction of grain rot disease through percentage of infected grains and improved yield parameter regarding rate of filled grains.

The Basics of Epidemiology

Epidemiology contributes to vaccine development and delivery by estimating disease burdens, identifying target populations for immunization, designing clinical trials to show vaccine-induced benefits and risks, and for formulating immunization policy. To estimate disease burden, a case definition is needed first. This may have several sets of criteria, depending on how definite the diagnosis is to be. Epidemiological studies to determine time, place, and person are referred to as descriptive epidemiology. Epidemiological studies to determine causes and effects are referred to as analytical epidemiology. Epidemiological studies may potentially be biased (systemic errors). Bias must be distinguished from confounding (interfering factors that are linked with both, exposure and outcome). Vaccine efficacy studies assess causality between vaccination and disease reduction in a prospective cohort design. Participants are assigned to receive vaccine or placebo usually in a double-blind, randomized fashion and efficacy is calculated from incidence reduction during the study period. Impact studies are observational studies and encompass e.g., describing disease reduction in a population over time after introduction of a vaccine, as well as cohort studies where vaccine effectiveness is calculated from cohorts in which vaccine administration is only observed. Observational studies are timesaving and less costly compared with prospective cohort studies. However, they are prone to various types of bias, e.g. recall bias if exposure status and outcome status are based on the participant's memory.

Anti-TRAP/SSP2 monoclonal antibodies can inhibit sporozoite infection and enhance protection of anti-CSP monoclonal antibodies

Vaccine-induced sterilizing protection from infection with the Plasmodium parasite, the pathogen that causes malaria, will be an essential tool in the fight against malaria as it would prevent both malaria-related disease and transmission. Stopping the relatively small number of parasites injected by the mosquito before they can migrate from the skin to the liver is an attractive goal. Antibody-eliciting vaccines have been used to pursue this objective by targeting the major parasite surface protein present during this stage, the circumsporozoite protein (CSP). While CSP-based vaccines have recently had encouraging success in disease reduction, this was only achieved with extremely high antibody titers and appeared less effective for a complete block of infection. While such disease reduction is important, these results also indicate that further improvements to vaccines based solely on CSP will likely yield diminishing benefits towards the goal of durable, infection-blocking immunity. Here, we show that monoclonal antibodies (mAbs) recognizing the sporozoite protein TRAP/SSP2 across the major protein domains exhibit a range of inhibitory capacity and that these mAbs can augment CSP-based protection despite delivering no sterile protection on their own. Therefore, pursuing a multivalent subunit vaccine immunization is a promising strategy for improving infection-blocking malaria vaccines.

Describing the burden of diphtheria in Canada from 2006 to 2017, using hospital administrative data and reportable disease data

Background: Canada has maintained a low incidence of toxigenic diphtheria since the 1990s, supported by continued commitment to publicly funded vaccination programs. Objective: To determine whether hospitalization data, complemented with notifiable disease data, can describe the toxigenic respiratory and cutaneous diphtheria burden in Canada, and to assess if Canada is meeting its diphtheria vaccine–preventable disease-reduction target of zero annual cases of locally transmitted respiratory diphtheria. Methods: Diphtheria-related hospital discharge data from 2006 to 2017 were extracted from the Discharge Abstract Database (DAD), and diphtheria case counts for the same period were retrieved from the Canadian Notifiable Disease Surveillance System (CNDSS), for descriptive analyses. As data from the province of Québec are not included in the DAD, CNDSS cases from Québec were excluded. Results: A total of 233 diphtheria-related hospitalizations were recorded in the DAD. Of these, diphtheria was the most responsible diagnosis in 23. Half the patients were male (52%), and 57% were 60 years and older. Central region (Ontario) accounted for the most discharge records (61%), followed by Prairie region (Alberta, Manitoba and Saskatchewan; 23%). Cutaneous diphtheria accounted for 43% of records, and respiratory diphtheria accounted for 3%, with the remainder being other diphtheria complications or site unspecified. Two records with diphtheria as the most responsible diagnosis resulted in inpatient deaths. Eighteen cases of diphtheria were reported through CNDSS. Cases occurred in all age groups, with the largest proportions among those aged 20 to 59 years (39%) and those aged 19 years and younger (33%). Cases were only reported in the Prairie (89%) and West Coast (British Columbia; 11%) regions. Conclusion: Hospital administrative data are consistent with the low incidence of diphtheria reported in CNDSS, and a low burden of respiratory diphtheria in Canada. Although Canada appears to be on track to meet its disease-reduction target, information on endemic transmission is not available.

Worldwide Vaccination Willingness for COVID-19: A Systematic Review and Meta-Analysis

Countries across the globe are currently experiencing a third or fourth wave of SARS-CoV-2 infections; therefore, the need for effective vaccination campaigns is higher than ever. However, effectiveness of these campaigns in disease reduction is highly dependent on vaccination uptake and coverage in susceptible populations. Therefore, this systematic review and meta-analysis estimated the vaccination intention and identified determinants of willingness and hesitancy. This study updates the existing body of literature on vaccination willingness, and was conducted according to the PRISMA guidelines. PubMed was searched for publications, selecting only studies published between 20 October 2020 and 1 March 2021, in English, with participants aged >16 years of age. The search identified 411 articles, of which 63 surveys were included that accounted for more than 30 countries worldwide. The global COVID-19 vaccination willingness was estimated at 66.01% [95% CI: 60.76–70.89% I2 = 99.4% [99.3%; 99.4%]; τ2 = 0.83]. The vaccination willingness varied within as well as between countries. Age, gender, education, attitudes and perceptions about vaccines were most frequently observed to be significantly associated with vaccine acceptance or refusal.

Screening of Tuberose Cultivars against Leaf Spot (Alternaria polyanthi) and its Management

Background: Tuberose flower has been found to be affected by various fungal and viral diseases which affect growth and cause loss in flower yield. Among them, leaf spot incited by Aternaria polianthi is an important fungal disease in tuberose. The incidence of the disease is common in the both single and double-type tuberose varieties due to prevalence of high rainfall and humid conditions. During survey it was found that the disease incidence was increasing gradually causing economic losses in Assam. Methods: The field trial was carried out during kharif seasons (2015 -18) to test the efficacy of six fungicides against leaf spot of tuberose (Var. Local single petal) caused by Alternaria polyantha. Four sprays with fungicides at an interval of seven days starting from the first appearance of the disease symptom were done. Per cent disease incidence (%) with growth parameters were recorded one week after the last spray. Another field experiment for screening the resistant genotypes was conducted using 11 tuberose genotypes during kharif seasons (2016-17 and 2017-18). Result: Eleven tuberose cultivars (Bidhan Ranjani-1, Bidhan Ranjani-2, Arka Nirantara, GK-TC-4, Prajwal, Phule Rajani, Local Single, Local Double, Vaibhav, Suhashini and Shringer) were screened against leaf spot caused by A.polyanthi under natural field condition. None of the cultivars were found to be immune or resistant, while three cultivars viz., GK-TC-4, Bidhan Rajani-1 and Arka Nirantara showed moderate resistant reaction with recorded per cent disease incidence of 16.11, 18.17 and 18.71, respectively. Spraying with azoxystrobin, difenoconazole and a combo fungicide consisting of iprodione (25%) + carbendazim (25%), at 0.1% recorded lowest per cent disease incidence of 7.91, 9.83 and 11.85% compared to control (33.62 PDI) with per cent disease reduction of 70.59%, 64.61% and 76.31%, respectively.