Search

Pathogen adaptation can threaten the durability of partial resistance. Mixed plantings of susceptible and partially resistant varieties may prolong the effectiveness of partial resistance, but little is known about how continued exposure to a susceptible genotype can change the aggressiveness of pathogen isolates adapted to a source of partial resistance. The objective of this study was to examine the effects of continued exposure to a highly susceptible tobacco genotype on isolates of Phytophthora nicotianae that had been adapted to partial resistance. Isolates of P. nicotianae previously adapted to two sources of partial resistance were continually exposed to either the original host of adaptation or a susceptible host. After six generations of host exposure, isolates obtained from the partially resistant and the susceptible hosts were compared for their aggressiveness on the resistant host and for differences in expression of genes associated with pathogenicity and aggressiveness. Results suggested that exposure to the susceptible tobacco genotype reduced aggressiveness of isolates adapted to partial resistance in K 326 Wz/– but not of isolates adapted to partial resistance in Fla 301. Quantification of pathogenicity-associated gene expression using qRT-PCR suggested the rapid change in aggressiveness of isolates adapted to Wz-sourced partial resistance may have resulted from modification in gene expression in multiple genes.

The spread of COVID-19 to more than 200 countries has shocked the public. Therefore, understanding the dynamics of transmission is very important. In this paper, the COVID-19 mathematical model has been formulated, analyzed, and validated using incident data from West Java Province, Indonesia. The model made considers the asymptomatic and symptomatic compartments and decreased immunity. The model is formulated in the form of a system of differential equations, where the population is divided into seven compartments, namely Susceptible Population ( S 0 ) , Exposed Population ( E ) , Asymptomatic Infection Population ( I A ) , Symptomatic Infection Population ( Y S ) , Recovered Population ( Z ) , Susceptible Populations previously infected ( Z 0 ) , and Quarantine population ( Q ) . The results show that there has been an outbreak of COVID-19 in West Java Province, Indonesia. This can be seen from the basic reproduction number of this model, which is 3.180126127 ( R 0 > 1 ) . Also, the numerical simulation results show that waning immunity can increase the occurrence of outbreaks; and a period of isolation can slow down the process of spreading COVID-19. So if a strict social distancing policy is enforced like a quarantine, the outbreak will lessen.

As COVID-19 vaccines become available, different model-based approach have been developed to evaluate strategic priorities for vaccine allocation to reduce severe illness. One strategy is to directly prioritize groups that are likely to experience medical complications due to COVID-19, such as older adults. A second strategy is to limit community spread by reducing importations, for example by vaccinating members of the mobile labour force, such as rotational workers. This second strategy may be appropriate for regions with low disease prevalence, where importations are a substantial fraction of all cases and reducing the importation rate reduces the risk of community outbreaks, which can provide significant indirect protection for vulnerable individuals. Current studies have focused on comparing vaccination strategies in the absence of importations, and have not considered allocating vaccines to reduce the importation rate. Here, we provide an analytical criteria to compare the reduction in the risk of hospitalization and intensive care unit (ICU) admission over four months when either older adults or rotational workers are prioritized for vaccination. Vaccinating rotational workers (assumed to be 6,000 individuals and about 1% of the Newfoundland and Labrador (NL) population) could reduce the average risk of hospitalization and ICU admission by 42%, if no community spread is observed at the time of vaccination, because epidemic spread is reduced and vulnerable individuals are indirectly protected. In contrast, vaccinating all individuals aged 75 and older (about 43,300 individuals, or 8% of the NL population) would lead to a 24% reduction in the average risk of hospitalization, and to a 45% reduction in the average risk of ICU admission, because a large number of individuals at high risk from COVID-19 are now vaccinated. Therefore, reducing the risk of hospitalization and ICU admission of the susceptible population by reducing case importations would require a significantly lower number of vaccines. Benefits of vaccinating rotational workers decrease with increasing infection prevalence in the community. Prioritizing members of the mobile labour force should be considered as an efficient strategy to indirectly protect vulnerable groups from COVID-19 exposure in regions with low disease prevalence.

Medicinal plant is a major source of drug discovery for disease management. Over 85% of the population in Asia and in the Middle East use herbal medicine for disease management such as severe acute respiratory syndrome (SARS) caused by coronavirus. Infection from coronavirus is initiated by entry of the virus into a susceptible host cell. The two types of human coronaviruses of public health concern some years back were SARS-CoV and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) which appeared in 2003 and 2012 respectively, and now SARS-CoV-2 which appeared in 2019 known as COVID-19. These three viruses belong to the same class of beta coronavirus. They are characterized by club-like spikes on the surface, and a unique replication strategy after infecting a susceptible host cell. Indeed, they are somewhat similar in their genome sequence, life cycle, mode of entry into a host, mode of transmission and clinical manifestations. Since there is no specific treatment for COVID-19 yet, the search for medicinal plants with inhibitory bioactive compounds against coronaviruses could be a valuable supportive therapeutic option. This review identified twenty medicinal plants that possess key bioactive compounds having potential activity against coronaviruses. We postulate that combination of extracts or phytochemicals from these plants could be developed into various drug delivery systems for the management of the current COVID-19 pandemic.

Inflammatory bowel disease is the result of an inappropriate immune response to environmental factors in a genetically susceptible host. The intestinal microbiota has been considered one of the key environmental factors in this disease process, and early influences on the structure of the intestine’s bacterial communities may lead to a dysbiotic state. The complicated relationship between dysbiosis and the developing host immune system, including the innate and adaptive immune systems as well as the intestinal epithelial interface, can have profound effects on the health and disease of the host. Therapies targeted at the gut microbiota continue to be investigated as potential interventions for inflammatory bowel disease.

We introduce a system of differential equations to assess the impact of (self-)quarantine of symptomatic infectious individuals on disease dynamics. To this end we depart from using the classic bilinear infection process, but remain within the framework of the mass-action assumption. From the mathematical point of view, the model we propose is interesting due to the lack of continuous differentiability at disease-free steady states, which implies that the basic reproductive number cannot be computed following established mathematical approaches for certain parameter values. However, we parametrise our mathematical model using published values from the COVID-19 literature, and analyse the model simulations. We also contrast model simulations against publicly available COVID-19 test data, focusing on the first wave of the pandemic during March–July 2020 in the UK. Our simulations indicate that actual peak case numbers might have been as much as 200 times higher than the reported positive test cases during the first wave in the UK. We find that very strong adherence to self-quarantine rules yields (only) a reduction of 22% of peak numbers and delays the onset of the peak by approximately 30–35 days. However, during the early phase of the outbreak, the impact of (self)-quarantine is much more significant. We also take into account the effect of a national lockdown in a simplistic way by reducing the effective susceptible population size. We find that, in case of a 90% reduction of the effective susceptible population size, strong adherence to self-quarantine still only yields a 25% reduction of peak infectious numbers when compared to low adherence. This is due to the significant number of asymptomatic infectious individuals in the population.

In this paper, the mathematical model used is the host-vector model for transmission on of dengue hemorrhagic fever where the host population consists of three compartments, namely susceptible host, infected, and recovered, while the vector population consists of two compartments, namely susceptible vector and infected vector. From this model, an estimate of the basic reproduction number will be constructed with the assumption that the number or humans and mosquitoes infected with the dengue virus grows exponentially with the same growth rate. Applications using field data in the City of Bima obtained an basic reproduction number estimates of . Because the estimated values for the basic reproduction number are greater than one, it illustrates that the spread of dengue hemorrhagic fever in Bima City from 2018 to 2020 is categorized as an epidemic.

versión pre-print: 30 páginas, 5 figuras, Temperate bacteriophages (phages) are viruses of bacteria. Upon infection of a susceptible host, a temperate phage can establish either a lytic cycle that kills the host or a lysogenic cycle as a stable prophage. The life cycle pursued by an infecting temperate phage can have a significant impact not only on the individual host bacterium at the cellular level but also on bacterial communities and evolution in the ecosystem. Thus, understanding the decision processes of temperate phages is crucial. This review delves into the molecular mechanisms behind lysis-lysogeny decision-making in Gram-positive phages. We discuss a variety of molecular mechanisms and the genetic organization of these well-understood systems. By elucidating the strategies used by phages to make lysis-lysogeny decisions, we can improve our understanding of phage-host interactions, which is crucial for a variety of studies including bacterial evolution, community and ecosystem diversification, and phage therapeutics., The writing of this review was supported by grants MR/M003876/1 and MR/S00940X/1 from the UK Medical Research Council, grants BB/N002873/1 and BB/S003835/1 from the UK Biotechnology and Biological Sciences Research Council, grant 201531/Z/16/Z from the Wellcome Trust, and ERC-ADG-2014 proposal 670932 “DUT-signal” from the European Research Council to J.R.P., as well as by grants BIO2016-78571-P and PID2019-108541GB-I00 from the Spanish government and PROMETEO/2020/012 from the Valencian Government to A.M. A.F-R. is a recipient of a PhD fellowship from the FPU program of the Spanish Government (reference FPU19/00433). Figures were created with BioRender.com.

The bacterium Vibrio cholerae is the cause of cholera. Cholera is spread through the feces of an infected individual in a population. From a mathematical point of view, this problem can be brought into a mathematical model in the form of Susceptible-Infected-Recovered (SIR), which considers the birth rate. Because outbreaks that occur easily spread if not treated immediately, it is necessary to control the susceptible individual population by vaccination. The vaccine used is Oral Vibrio cholera. For this reason, the purposes of this study were to establish a model for the spread of cholera without vaccination, analyze the stability of the model around the equili­brium point, form a model for the spread of cholera with vaccination control, and describe the simulation results of numerical model completion. Based on the analysis of the stability of the equilibrium point of the model, it indicates that if the contact rate is smaller than the sum of the birth rate and the recovery rate, cholera will disappear over time. If the contact rate is grea­ter than the sum of the birth rate and the recovery rate, then cholera is still present, or in other words, the disease can still spread. Because the spread is endemic, optimal control of the popu­lation of susceptible individuals is needed, in this case, control by vaccination, so that the popu­lation of susceptible individuals becomes minimum and the population of recovered indivi­duals increases.

BACKGROUND: College students are one of the susceptible population of Hepatitis B virus (HBV) infection. We aim to delineate HBV infection seromarkers among college freshmen and to evaluate immunological response of vaccination immunization for hepatitis B vaccine (HepB). METHODS: A simple random sampling method was adopted to select subjects and who met the ”inclusion and exclusion criteria” and who with history of vaccination were selected as the observation objects. HBsAg and anti-HBs levels were detected before revaccination. Subjects with negative anti-HBs before immunization were inoculated with 20 ug HepB according to the 0-1-6 procedure and those with weak positive anti-HBs before immunization were inoculated with 1-dose 20 ug HepB. Anti-HBs levels were detected after HepB booster. Combined with the results of anti-HBs, their immune response to HepB and influencing factors in freshmen were investigated. Anti-HBs before immunization was negative and ≥10 m IU/ml after immunization was considered positive conversion; anti-HBs before immunization was weak positive and anti-HBs≥100 m IU/ml after immunization was also considered positive conversion. RESULTS: A total of 10645 freshmen were included. The total rate of HBsAg carriers was 0.6% (63/10645), and the strong positive rate of anti-HBs was 16.1% (1706/10645), the weak positive rate was 14.4% (1526/10645).1286 freshmen were vaccinated with HepB and completed the questionnaire survey. About 79.0% (154/195) of freshmen’s anti-HBs turned strong positive after receiving 1-dose HepB and 100.0% (1091/1091) turned positive after receiving 3-doses HepB. The Geometrical Mean Titer (GMT) of anti-HBs was significantly influenced by gender, registration and the immunization doses of HepB. CONCLUSION: The HBsAg carrying rate and anti-HBs positive rate of college freshmen were low, and the HepB has a good effect on the immunity of college freshmen. Increasing the immunization rate of HepB is very important for the prevention and control of hepatitis B.

A deterministic model was formulated and employed in the analysis of the dynamics of tuberculosis with a keen emphasis on vaccination and drug resistance as the first line of treatment. It was assumed that some of the susceptible population were vaccinated but with temporal immunity. This is due to the fact that vaccines do not confer permanent immunity. Moreover, part of the infected individual after treatment grows resistance to the drug. Infective immigrants were also considered to be part of the population. The basic reproductive number for the model is estimated using the next-generation matrix method. The equilibrium points of the TB model and their local and global stability were determined. It was established that if the basic reproductive number was less than unity R 0 < 1 , then the disease free equilibrium is stable and unstable if R 0 > 1 . Furthermore, we investigated the optimal prevention, treatment, and vaccination as control measures for the disease. As the objective functional was optimised, there have been a significant reduction in the number of infections and an increase in the number of recovery. The best control measure in combating tuberculosis infections is prevention and vaccination of the susceptible population.

The rapid and widespread global pandemic of 2019 coronavirus disease (COVID-19) has had unprecedented negative health and economic impacts. Immune responses play a key role in the development of COVID-19, including the disruption of immune balance and cytokine storms caused by excessive inflammatory responses. Due to the effects of cancer itself and treatment, patients often accompanied by immunosuppression appear to be a susceptible population for COVID-19. Worryingly, COVID-19 with cancer is associated with a poor prognosis. Cancer patients are a vulnerable group, threatened by COVID-19, finding a way to combat COVID-19 for them is urgent. Immunonutrition is closely related to balance and strong immune function. Supplementary immunonutrition can improve the immune function and inflammatory response of cancer patients after surgery, which provides evidence for the role of immunonutrition in combating COVID-19. We reviewed possible mechanisms of immunonutrition against COVID-19, including enhancing immune cell function, increasing immune cell count, ameliorating excessive inflammatory response, and regulating gut microbiota. Immunonutrition supplementation in cancer patients may be beneficial to enhance immune function in the early stage of COVID-19 infection and control excessive inflammatory response in the late stage. Therefore, immunonutrition is a potential strategy for the prevention and treatment of COVID-19 in cancer.

Coronavirus diseases (COVID-19) is a respiratory disease. Most infected people are known to develop mild to moderate symptoms and recover without requiring special treatment except for those who have underlying medical conditions and the elderly have a higher risk of developing severe disease. This research is aimed at studying the probable spread of the COVID-19 virus within a completely susceptible density-dependent population using a modified exponential distribution function. The modified exponential distribution function was extended to include the Basic Reproduction Number which was computed using the Nigerian COVID-19 index cases from 27th February to 18th April, 2020 to be. Various interesting results were obtained for the including the time period for the spread for different population sizes. The duration of the spread of the virus is from 4 to 7 hours with an average of 5.5 hours. This indicates that, for one infectious person with to enter a completely susceptible population of size , the virus can spread through the entire population in about hours if no control measures are in place.

Heterosporis sutherlandae is an invasive microsporidian parasite in the Great Lakes region of North America that infects the skeletal muscle of numerous fish species, rendering the fillet unfit for human consumption. Although H. sutherlandae has been identified as a pathogen of concern by state management agencies, there is little information to inform regulation and intervention. We sampled fishes over 1 year from three lakes in northern Minnesota with known infected populations to determine the importance of host demographic and environmental variables for influencing H. sutherlandae infection prevalence. Heterosporis sutherlandae was present during all sampling periods, ranging in prevalence from 1% to 11%. The prevalence of H. sutherlandae among Yellow Perch Perca flavescens varied significantly according to season, with winter having the lowest prevalence (1%) and summer having the highest prevalence (11%). For other fish species, the prevalence of H. sutherlandae also varied significantly with season: the lowest prevalence occurred during spring (1%) and the highest prevalence occurred in fall (9%). Rates of pathogen transmission were estimated by exposing Fathead Minnows Pimephales promelas in the laboratory. Transmission rates were 23% when naïve fish were fed infected tissues and only 2% when naïve fish were held in cohabitation with tissue-fed fish. Exposure method and exposure duration (d) increased the probability that a fish was infected with H. sutherlandae. These findings suggest that H. sutherlandae transmission is greater when a susceptible host consumes infected tissue than when the fish is exposed to spores present in the water column. The current rates of infection in wild fishes are in stark contrast to the prevalence documented in 2004 (28%), suggesting a reduction in H. sutherlandae prevalence within at least one Yellow Perch population in the Laurentian Great Lakes region since the early 2000s.

Host-parasite interactions may often be subject to opposing evolutionary forces, which likely influence the evolutionary trajectories of both partners. Natural selection and genetic drift are two major evolutionary forces that act in host and parasite populations. Further, population size is a significant determinant of the relative strengths of these forces. In small populations, drift may undermine the persistence of beneficial alleles, potentially impeding host adaptation to parasites. Here, we investigate two questions: (a) can selection pressure for increased resistance in small, susceptible host populations overcome the effects of drift and (b) can resistance be maintained in small host populations? To answer these questions, we experimentally evolved the host Caenorhabditis elegans against its bacterial parasite, Serratia marcescens, for 13 host generations. We found that strong selection favouring increased host resistance was insufficient to counteract drift in small populations, resulting in persistently high host mortality. Additionally, in small populations of resistant hosts, we found that selection for the maintenance of resistance is not always sufficient to curb the loss of resistance. We compared these results with selection in large host populations. We found that initially resistant, large host populations were able to maintain high levels of resistance. Likewise, initially susceptible, large host populations were able to gain resistance to the parasite. These results show that strong selection pressure for survival is not always sufficient to counteract drift. In consideration of C. elegans natural population dynamics, we suggest that drift may often impede selection in nature.

Multiple resistance to different herbicides used for management of Phalaris minor Retz. in Northern India was quantified for its two populations—one susceptible and the other resistant to acetyl-CoA carboxylase (ACCase) inhibitor herbicide clodinafop-propargyl. Clodinafop-propargyl and pinoxaden at their recommended dose recorded complete control of clodinafop-propargyl susceptible P. minor population, whereas sulfosulfuron and mesosulfuron plus iodosulfuron at their recommended dose exhibited 48.5 and 51.5% control of this population. In clodinafop-propargyl-resistant P. minor population, sulfosulfuron and mesosulfuron plus iodosulfuron even at 4X dose did not cause any mortality; however, pinoxaden at 4X dose caused complete mortality at 30 DAS. Metribuzin plus clodinafop-propargyl applied at all the doses (0.25X, 0.5X, X, 2X and 4X) recorded complete mortality of both the populations. Application of different herbicides caused reduction in chlorophyll fluorescence and chlorophyll content index in leaves of both the populations in a dose-dependent manner. But the magnitude of reduction was higher in susceptible population as compared to the resistant population.

Meloidogyne paranaensis is an important root-knot nematode species for several crops in Brazil, especially coffee. Despite such notoriety, studies with this pathosystem are time and space consuming. Although Arabidopsis thaliana is widely used for genetics, physiological and biotic/abiotic stress studies, no information was found regarding M. paranaensis relationships with this model plant. The objective of this study was to optimize methodologies to study the interactions between M. paranaensis and plants, using A. thaliana as model plant. Columbia-0 (Col-0) ecotype was challenged with M. paranaensis to evaluate the penetration rates and nematode reproduction factor. Besides, nematode initial populations and plant ages for inoculation were tested to evaluate the parasitism, in different evaluation times. Substrate types and ideal number of plants were also evaluated. Once A. thaliana hosts M. paranaensis and showed to be a susceptible and reliable tool for studies with this nematode, the methodology optimization conditions were tested by the screening of 29 ecotypes, and variation on susceptibility among these genotypes was observed, indicating the adequacy of the methodology suggested and genetic variability to this trait. The optimization of the experimental conditions using A. thaliana here reported can provide a range of research lines to reach data faster, besides the possibility of increasing the knowledge of plant-M. paranaensis interactions.

Challenging wild plant accessions with pathogens is an initial approach for finding resistance genes for breeding programs. Viruses can be transmitted artificially by mechanical or arthropod-borne inoculation, but these experimental assays do not always reproduce natural conditions in the field. In this study, 56 wild Capsicum spp. accessions from Ecuador that were under natural inoculum pressure for six months were screened for virus infections by RNA sequencing. These plants exhibited low virus diversity in comparison to a commercial pepper cultivar that was used as a susceptible host. Subjecting numerous plants to natural infection prior to artificial assays may indicate promising accessions to track within virus/vector resistance breeding programs.

A novel predictive modeling framework for the spread of infectious diseases using high dimensional partial differential equations is developed and implemented. A scalar function representing the infected population is defined on a high-dimensional space and its evolution over all directions is described by a population balance equation (PBE). New infections are introduced among the susceptible population from non-quarantined infected population based on their interaction, adherence to distancing norms, hygiene levels and any other societal interventions. Moreover, recovery, death, immunity and all aforementioned parameters are modeled on the high-dimensional space. To epitomize the capabilities and features of the above framework, prognostic estimates of Covid-19 spread using a six-dimensional (time, 2D space, infection severity, duration of infection, and population age) PBE is presented. Further, scenario analysis for different policy interventions and population behavior is presented, throwing more insights into the spatio-temporal spread of infections across disease age, intensity and age of population. These insights could be used for science-informed policy planning., 9 pages, 4 figures

Novel switched HIV/AIDS (human immunodeficiency virus/acquired immune deficiency syndrome) epidemic models with distributed time delay and bounded noise and Gaussian white noise are developed and investigated using stochastic Itô’s lemma and the Lyapunov–Razumikhin method. New criteria depending on these factors are established to confirm that the disease-free equilibrium of the model is stochastically asymptotically stable as the threshold parameter is less than unity, which implies that the disease eventually disappears theoretically. Otherwise, the disease persists weakly. Further, the main results show that the threshold values are related to two types of noise and time delay. Pulse control strategies are then applied to two types of the infected population, the susceptible population, and the infected population, respectively. More precisely, the effects of each control strategy on the stochastic solution of the model are evaluated to justify the relation between control parameters and threshold parameters of the model. In comparison with the basic reproduction number of the model with pulse control, it is easily found that the main results in these references are improved and extended. Finally, four examples are presented to support the main results, and one future research direction is suggested.

Global change is shifting the timing of biological events, leading to temporal mismatches between biological events and resource availability. These temporal mismatches can threaten species’ populations. Importantly, temporal mismatches not only exert strong pressures on the population dynamics of the focal species, but can also lead to substantial changes in pairwise species interactions such as host–pathogen systems. We adapted an established individual‐based model of host–pathogen dynamics. The model describes a viral agent in a social host, while accounting for the host's explicit movement decisions. We aimed to investigate how temporal mismatches between seasonal resource availability and host life‐history events affect host–pathogen coexistence, that is, disease persistence. Seasonal resource fluctuations only increased coexistence probability when in synchrony with the hosts’ biological events. However, a temporal mismatch reduced host–pathogen coexistence, but only marginally. In tandem with an increasing temporal mismatch, our model showed a shift in the spatial distribution of infected hosts. It shifted from an even distribution under synchronous conditions toward the formation of disease hotspots, when host life history and resource availability mismatched completely. The spatial restriction of infected hosts to small hotspots in the landscape initially suggested a lower coexistence probability due to the critical loss of susceptible host individuals within those hotspots. However, the surrounding landscape facilitated demographic rescue through habitat‐dependent movement. Our work demonstrates that the negative effects of temporal mismatches between host resource availability and host life history on host–pathogen coexistence can be reduced through the formation of temporary disease hotspots and host movement decisions, with implications for disease management under disturbances and global change., Global change is shifting the timing of biological events away from their optima, resulting in temporal mismatches between these biological events and resource availability. We used a spatially explicit individual‐based host–pathogen model to investigate how temporal mismatches of seasonal resource availability and host life‐history events affect host–pathogen coexistence. Our Work demonstrated that host movement decisions and the formations of diseases hotspots can reduce the negative effects of temporal mismatches on host–pathogen coexistence.

Can Tu,1,2 Ming Niu,2 Ai-Wu Wei,3 Jin-Fa Tang,3 Le Zhang,2 Jing Jing,2 Xiao-He Xiao,2 Jia-Bo Wang2,4 1Beijing Research Institute of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, 100029, People’s Republic of China; 2China Military Institute of Chinese Medicine, Fifth Medical Center of Chinese PLA General Hospital, Beijing, 100039, People’s Republic of China; 3The First Affiliated Hospital of Henan University of Chinese Medicine, Zhengzhou, 450000, People’s Republic of China; 4School of Traditional Chinese Medicine, Capital Medical University, Beijing, 100069, People’s Republic of ChinaCorrespondence: Jia-Bo WangSchool of Traditional Chinese Medicine, Capital Medical University, Beijing, 100069, People’s Republic of ChinaEmail pharm_sci@126.comXiao-He XiaoChina Military Institute of Chinese Medicine, Fifth Medical Center of Chinese PLA General Hospital, Beijing, 100039, People’s Republic of ChinaEmail pharmacy302xxh@126.comBackground: Drug-induced liver injury is a common adverse effect in clinical practice, with severe cases resulting in liver failure and even death. Identification and prediction of individuals susceptible to idiosyncratic DILI continues to remain a challenge.Methods: In this study, we report that cytokines in human serum can be used to identify and predict individuals susceptible to Polygonum multiflorum-induced DILI (PM-DILI) in retrospective and prospective cohort studies.Findings: In the retrospective pilot study, we compared serum cytokine expression profiles of the PM-DILI group (n=10) and the PM-Tolerant group (n=12) and found 10 cytokines with significant differences. In the replication cohort study, differences in the 10 cytokines between PM-DILI (n =11) and PM-Tolerant (n=13) groups were verified. Among them, 6 cytokines showed no significant differences at two time points, including liver injury and recovery stage of PM-DILI, suggesting that these 6 cytokines have no correlation with PM-DILI, however, they may be related to susceptibility. Furthermore, all the retrospective cohorts were combined, and a PM-DILI susceptibility prediction model was built by screening the 6 cytokines. The combination of (TNF-α and CCL-2) or VEGF showed the highest sensitivity and specificity. Finally, the efficacy of the above 3 cytokine combination models in predicting PM-DILI-susceptible individuals was verified before PM exposure in another independent prospective cohort (n=24), with sensitivity and specificity of 66.7% and 83.3%, respectively.Conclusion: This proof-of-concept study demonstrates that the serum cytokine combination reflecting dysimmunity could be used as a new method to predict PM-DILI, thus providing a new perspective for improving the clinical management of IDILI.Keywords: drug-induced liver injury, Polygonum multiflorum, cytokine, prediction, susceptible individual

A population of Haemonchus contortus that was highly resistant to benzimidazoles and avermectin/milbemycins with a subpopulation that was resistant to levamisole, was replaced with a susceptible laboratory isolate of H. contortus in a flock of sheep. The anthelmintic susceptibility and population genetics of the newly established population were evaluated for 3.5 years using in vivo, in vitro, and molecular methods. Successful replacement of the resistant population with a susceptible population was confirmed using phenotypic and genotypic measurements; larval development assay indicated full anthelmintic susceptibility; albendazole treatment yielded 98.7% fecal egg count reduction; pyrosequence genotyping of single nucleotide polymorphisms in positions 167 and 200 of the isotype-1 beta tubulin gene were present at 0.0 and 1.7%, respectively; microsatellite genotyping indicated the background haplotype was similar to the susceptible isolate; and haplotypes of the isotype-1 beta tubulin gene were similar to the susceptible isolate. To sustain the susceptibility of the new population, targeted selective treatment was implemented using albendazole. Surprisingly, within 1.5 years post-replacement, the population reverted to a resistant phenotype. Resistance to albendazole, ivermectin, and moxidectin was confirmed via fecal egg count reduction test, larval development assay, and pyrosequencing-based genotyping. Targeted selective treatment was then carried out using levamisole. However, within one year, resistance was detected to levamisole. Population genetics demonstrated a gradual change in the genetic structure of the population until the final population was similar to the initial resistant population. Genetic analyses showed a lack of diversity in the susceptible isolate, suggesting the susceptible isolate had reduced environmental fitness compared to the resistant population, providing a possible explanation for the rapid reversion to resistance. This work demonstrates the power of combining molecular, in vitro, and in vivo assays to study phenotypic and genotypic changes in a field population of nematodes, enabling improved insights into the epidemiology of anthelmintic resistance., Graphical abstract Image 1

In this paper we consider a mathematical model of two host species competing for a single -limited resource mediated by parasites. Each host population is divided into susceptible and infective population. We assume that species 1 has the lowest break-even concentration with respect to nutrient, when there is no parasite. Thus species 1 is a superior competitor that outcompetes species 2. When parasites present, the competitive outcome is determined by the contact rate of the superior competitor. We analyze the model by finding the conditions for the existence of various equilibria and doing their stability analysis. Two bifurcation diagrams are presented. The first one is in $\beta_1$-$\beta_2$ plane (See Figure 3) and the second one is in $R^{(0)}$-line (See Figure 4).

Herd Immunity is a brilliant solution to tackle and control global pandemics, if taken proper route for immunization such as through vaccination. It is defined as the number of immune individuals against a transmissible virus in a completely susceptible population. The term herd protection or herd effect is the protection to the whole population due to herd immunity. Herd immunity threshold is the minimum proportion of immune population required for herd effect or herd protection. To calculate the threshold, we use basic reproduction number (R0) to measure the rate of transmission of pathogen, in this case SARS-CoV-2. However, a better measure is effective reproduction number (Re). India is major example of herd immunity. Despite strict lockdown and other Covid measure, due to already crowded area the virus could spread fast and to vast majority of people if one of them were to catch it. This explains the steady decline in the number of coronavirus cases in India. At the end, until an approved effective vaccination available, public will still need to follow all the CDC guidelines in order to avoid the large deaths along with natural infection.

Climate is a critical factor considered in predicting the potential distributions of species. However, the distribution of susceptible host plants is another important constraint in retrospective and predictive analyses of invasive insect pests, particularly for wood-boring insects. In the present study, we first modeled the geographic distribution of the invasive emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), and its susceptible host trees using MaxEnt. We then compared the differences between the predicted and actual distribution of EAB in its native (China) and invaded (the United States and Canada) ranges by incorporating the distribution of its susceptible host plants. Results from our models indicate that: (1) in addition to climatic factors, the presence of susceptible host tree species plays a major role in delineating the pest’s distribution; (2) it is more accurate to project EAB’s potential range distribution by considering the suitability of potential areas for its susceptible host plants; and (3) there is a high risk of EAB expanding its current distribution areas in both its native and invasive ranges. The inclusion of susceptible host plant presence as a factor enables more effective predictive modeling and risk assessment for biological invasions, especially for oligophagous insects.

After a major outbreak of the coronavirus disease (COVID-19) starting in late December 2019, there were no new cases reported in mainland China for the first time on March 18, 2020, and no new cases reported in Hong Kong Special Administrative Region on April 20, 2020. However, these places had reported new cases and experienced a second wave since June 11, 2020. Here we develop a stochastic discrete-time epidemic model to evaluate the risk of COVID-19 resurgence by analyzing the data from the beginning of the outbreak to the second wave in these three places. In the model, we use an input parameter to represent a few potential risks that may cause a second wave, including asymptomatic infection, imported cases from other places, and virus from the environment such as frozen food packages. The effect of physical distancing restrictions imposed at different stages of the outbreak is also included in the model. Model simulations show that the magnitude of the input and the time between the initial entry and subsequent case confirmation significantly affect the probability of the second wave occurrence. Although the susceptible population size does not change the probability of resurgence, it can influence the severity of the outbreak when a second wave occurs. Therefore, to prevent the occurrence of a future wave, timely screening and detection are needed to identify infected cases in the early stage of infection. When infected cases appear, various measures such as contact tracing and quarantine should be followed to reduce the size of susceptible population in order to mitigate the COVID-19 outbreak.

The global pandemic scenario has definitely pushed the scientific community to develop COVID-19 vaccines at unprecedented speed. Nevertheless, a worldwide vaccination campaign is still far from being achieved, making the usual precautionary measures as necessary as at the beginning of the outbreak. Many aspects of the SARS-CoV-2 infectious potential and disease severity do not solely rely on interactions at the molecular level but also on physical-chemical parameters that often involve nanoscale effects. Here the SARS-CoV-2 journey to infect a susceptible host is reviewed, focusing on the nanoscale aspects that play a role in the viral infectivity and disease progression. These nanoscale-driven interactions are essential to establish mitigation-related strategies.

Spodoptera littoralis (Lepidoptera noctuidae) (Boisd) is the most economic and series pest in Egypt with highly fecundity and dangerous attacking many crops. Insecticide efficiency trials showed failure and need more investigation periodically by many subject area. Susceptible laboratory reared population and field collected batches were subjected to bioassay of time mortality of the life survivors recording is the data producer by treating larvae with sublethal dose (LC30) of insecticides candidates for this testing. Time-mortality data are improved method involves proportional survival and hazards modeling, known as Cox regression. The survival analysis of S. littoralis treated with sublethal dose of some insecticides exhibit slight differences in the median survival time (LT50) observed for each insecticide, where the higher values was 224.4 hour for metaflumezone and the smallest was 170.1 for pyridalyl in susceptible population while in field, the higher was 336 for indoxacarb and the smallest was 144 hour for imidacloprid. The median survival time was 265 for susceptible control and 375 hour for field control. Log rank test exhibit significant differences among treatments for susceptible (Log-rank test, Z = 259.91, d.f. = 4, p

Pandemic influenza, typically caused by the reassortment of human and avian influenza viruses, can result in severe or fatal infections in humans. Timely identification of potential pandemic viruses must be a priority in influenza virus surveillance. However, the range of host species responsible for the generation of novel pandemic influenza viruses remains unclear. In this study, we conducted serological surveys for avian and human influenza virus infections in farmed mink and determined the susceptibility of mink to prevailing avian and human virus subtypes. The results showed that farmed mink were commonly infected with human (H3N2 and H1N1/pdm) and avian (H7N9, H5N6, and H9N2) influenza A viruses. Correlational analysis indicated that transmission of human influenza viruses occurred from humans to mink, and that feed source was a probable route of avian influenza virus transmission to farmed mink. Animal experiments showed that mink were susceptible and permissive to circulating avian and human influenza viruses, and that human influenza viruses (H3N2 and H1N1/pdm), but not avian viruses, were capable of aerosol transmission among mink. These results indicate that farmed mink could be highly permissive “mixing vessels” for the reassortment of circulating human and avian influenza viruses. Therefore, to reduce the risk of emergence of novel pandemic viruses, feeding mink with raw poultry by-products should not be permitted, and epidemiological surveillance of influenza viruses in mink farms should be urgently implemented.

Inflammatory bowel disease (IBD) is a chronic immune-mediated disease that affects the gastrointestinal tract. It is argued that environment, microbiome, and immune-mediated factors interact in a genetically susceptible host to trigger IBD. Recently, there has been increased interest in the development, progression, and treatment of IBD because of our understanding of the microbiome. Researchers have proved that some factors can alter the microbiome and the pathogenesis of IBD. As a result, there has been increasing interest in the application of probiotics, prebiotics, antibiotics, fecal microbiota transplantation, and gene manipulation in treating IBD because of the possible curative effect of microbiome-modulating interventions. In this review, we summarize the findings from human and animal studies and discuss the effect of the gut microbiome in treating patients with IBD.

The rapid spread of the SARS-CoV-2 in the COVID-19 pandemic had raised questions on the route of transmission of this disease. Initial understanding was that transmission originated from respiratory droplets from an infected host to a susceptible host. However, indirect contact transmission of viable virus by fomites and through aerosols has also been suggested. Herein, we report the involvement of fine indoor air particulates with a diameter of ≤ 2.5 µm (PM2.5) as the virus’s transport agent. PM2.5 was collected over four weeks during 48-h measurement intervals in four separate hospital wards containing different infected clusters in a teaching hospital in Kuala Lumpur, Malaysia. Our results indicated the highest SARS-CoV-2 RNA on PM2.5 in the ward with number of occupants. We suggest a link between the virus-laden PM2.5 and the ward’s design. Patients’ symptoms and numbers influence the number of airborne SARS-CoV-2 RNA with PM2.5 in an enclosed environment.

The COVID-19 global health crisis has had a significant impact on societies worldwide. To evaluate the effectiveness of transmission prevention strategies, infectivity modeling can be used to interpret and analyze various virus responses. In this study, compartmental modeling approaches are used to model and quantify the success of various control techniques, such as social behaviors. Newfoundland and Labrador (NL), a province in Canada, is a relatively isolated and easily-monitored region that can be used to study the characterization and effectiveness of infectivity model coefficients. The province has few points of entry and a lower contact frequency than densely populated urban districts. Based on the results, the implications of social distancing removed an estimated 85% of the susceptible population from potential exposure to a viral transmission. The modeling also determined a basic COVID-19 reproductive number of 3.7 in NL, higher than the globalized average of 2.3. Compartmental models are used to determine the validity of alternative pandemic responses, such as nonvaccine social practices to fight the wave of infection. The overall impact of COVID-19 in NL is concluded to have been effectively controlled by the implementation of social distancing behaviors, allowing for accurate quantification of modeling parameters.

Purpose of review To summarize recent evidence regarding the presence and potential role of the microbiome in systemic vasculitides. Recent findings Microbiomic descriptions are now available in patients with small, medium and large vessel vasculitis. The majority of studies have evaluated gastrointestinal inhabitants, with a smaller number of studies describing the nasal, pulmonary or vascular microbiomes. Most published studies are observational and cross-sectional. Dysbiosis is seen frequently in vasculitis patients with reduced microbial diversity observed in nasal, fecal and vascular samples compared with disease and/or healthy controls. Predominant bacteria vary, but overall, patients with vasculitis tend to have more pathogenic and less commensal bacteria in active disease. In the few longitudinal studies available, improvement or resolution of dysbiosis has been observed following vasculitis treatment and improved disease activity. Summary Dysbiosis and reduced microbial diversity has been identified in patients with small, medium and large vessel vasculitis. Although limited data suggests microbiomes may 'normalize' following immunosuppression, cause or effect cannot be determined. It is hypothesized that microbial disruption in a genetically susceptible individual may trigger excessive host immune activation and vasculitis; however, larger studies with longitudinal and translational design are needed to further our current understanding.

The amphibian chytrid fungal pathogen (Batrachochytrium dendrobatidis, henceforth Bd) has had a devastating impact on biodiversity, causing the decline or extinction of over 500 amphibian species. Yet, our understanding of Bd transmission pathways remains incomplete, in particular for host species with weak aquatic associations, and between reservoir and susceptible host species. We examined Bd transmission from a potential reservoir host to a potentially susceptible critically endangered host; directly assessing the capacity of the former to transmit Bd, and the susceptibility of the latter as a Bd host. Using cohousing versus sequential use of the same enclosure by the two species, we distinguished the effects of direct versus indirect (environmental) transmission. Our study provides clear evidence that both direct and indirect terrestrial transmission from a reservoir to susceptible host species results in fatal chytridiomycosis. Transmission mode had no effect on overall morbidity or disease progression in the susceptible species. Our results demonstrate that reservoir and susceptible hosts do not need to be in the same place at the same time, or within an aquatic environment for transmission to occur. Our demonstration of indirect terrestrial transmission from a reservoir to susceptible host identifies mechanisms by which Bd may drive ongoing declines in populations where the pathogen is now endemic. Identifying these transmission pathways is important for understanding long-term extinction vulnerability of remnant populations of declining species challenged by disease.

BACKGROUND Phosphine-susceptible or resistant populations of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults were exposed to 0 (control), 1000 and 3000 ppm of phosphine for 15 or 90 min, to estimate behavioral and mobility responses after exposure to phosphine. Knockdown of the exposed individuals after exposure was recorded visually. The total distance moved and velocity of movement were assessed immediately after exposure to phosphine, 2 or 24 h later using a camera coupled with automated video tracking software (i.e. Ethovision®). RESULTS For both species tested, the highest percentage of dead adults was noted at the highest concentration (3000 ppm) for both exposure times. For T. castaneum, total distance moved and velocity decreased as the concentration increased for the susceptible population, whereas there was significant variation among individuals in the resistant population. For R. dominica, the distance moved was reduced at the highest concentrations. Individuals of R. dominica moved less than those of T. castaneum and there were significant differences in mobility between susceptible and resistant populations for both species tested. Recovery was much faster in the case of the resistant populations. CONCLUSIONS Changes in movement parameters can be further exploited in assessing the efficacy of different management tactics, such as trapping and sampling. Automated video tracking systems such as Ethovision® can be used to track and record insect behavioral response, providing a more objective measure of insecticide efficacy than visual categorizations. These data shed light on insect mobility and behavioral responses to fumigation treatments in relation to resistance. © 2020 Society of Chemical Industry.

In epidemiology, the basic reproduction number (R0) is a term that describes the expected number of infections generated by 1 case in a susceptible population. At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, R0 was frequently referenced by the public health community and the wider public. However, this metric is often misused or misinterpreted. Moreover, the complexity of the process of estimating R0 has caused difficulties for a substantial number of researchers. In this article, in order to increase the accessibility of this concept, we address several misconceptions related to the threshold characteristics of R0 and the effective reproduction number (Rt). Moreover, the appropriate interpretation of the metrics is discussed. R0 should be considered as a population-averaged value that pools the contact structure according to a stochastic transmission process. Furthermore, it is necessary to understand the unavoidable time lag for Rt due to the incubation period of the disease.

Baseline susceptibility of neonicotinoid insecticide viz., imidacloprid 17.8% SL was carried out in rice whitebacked planthopper during 2019-20 at Tamil Nadu Agricultural university, Coimbatore. F3 generation of TNAU susceptible WBPH population was taken as base population and preliminary range tests were conducted to determine 50% mortality (LC50). Initially doses were fixed from wider to narrow range. Different concentrations of insecticides giving the mortality range from 20-80% were taken for the study. Each concentration of insecticides was replicated thrice by releasing 15 adult female insects per mylar cages. After fixing the X dose for susceptible population, dose for the other population were fixed at different concentration. Laboratory cultured TNAU susceptible population and populations from Coimbatore, Bhavani and Nagapattinam regions were treated. The results revealed that Nagapattinam populations showed higher LC50 and higher resistance level followed by Bhavani and Coimbatore population against the imidacloprid 17.8 SL. The resistance ratio varied from 2.8 - 6.2 fold among the populations against imidacloprid 17.8% SL.