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1.
J Viral Hepat ; 25(7): 791-801, 2018 07.
Article in English | MEDLINE | ID: mdl-29406608

ABSTRACT

Different strategies of DAAs treatment are currently possible both pre- and postliver transplantation (LT). Clinical and economic consequences of these strategies still need to be adequately investigated; this study aims at assessing their cost-effectiveness. A decision analytical model was created to simulate the progression of HCV-infected patients listed for decompensated cirrhosis (DCC) or for hepatocellular carcinoma (HCC). Three DAAs treatment strategies were compared: (i) a 12-week course of DAAs prior to transplantation (PRE-LT), (ii) a 4-week course of DAAs starting at the time of transplantation (PERI-LT) and (iii) a 12-week course of DAAs administered at disease recurrence (POST-LT). The population was substratified according to HCC presence and, in those without HCC, according to the MELD score at listing. Data on DAAs effectiveness were estimated using a cohort of patients still followed by 11 transplant centres of the European Liver and Intestine Transplant Association and by data available in the literature. In this study, PRE-LT treatment strategy was dominant for DCC patients with MELD<16 and cost-effective for those with MELD16-20, while POST-LT strategy emerged as cost-effective for DCC patients with MELD>20 and for those with HCC. Sensitivity analyses confirmed PRE-LT as the cost-effective strategy for patients with MELD≤20. In conclusion, PRE-LT treatment is cost-effective for patients with MELD≤20 without HCC, while treatments after LT are cost-effective in cirrhotic patients with MELD>20 and in those with HCC. It is worth reminding, though, that the final choice of a specific regimen at the patient level will have to be personalized based on clinical, social and transplant-related factors.


Subject(s)
Antiviral Agents/economics , Antiviral Agents/therapeutic use , Cost-Benefit Analysis , Hepatitis C, Chronic/drug therapy , Liver Transplantation , Adult , Aged , Carcinoma, Hepatocellular/surgery , Female , Hepatitis C, Chronic/complications , Humans , Liver Cirrhosis/surgery , Male , Middle Aged , Time Factors
2.
J Appl Microbiol ; 122(1): 180-187, 2017 Jan.
Article in English | MEDLINE | ID: mdl-27748552

ABSTRACT

AIMS: This study aimed to develop a new formulation of Cryphonectria parasitica hypovirulent mycelium suitable for inoculations of tall trees from the ground. Cryphonectria parasitica hypovirulent strains are widely used for biological control of chestnut blight. However, it is often inconsistent and ineffective not only for biological reasons but also because the current manual application of hypovirulent strains on adult plants is difficult, time-consuming and expensive. Here, we propose an improved formulation and more effective mode of application of hypovirulent strains, which could boost chestnut blight biocontrol. METHODS AND RESULTS: The Cp 4.2H hypovirulent strain was formulated as mycelium discs with polyethylene glycol and hydroxypropyl methylcellulose, loaded into lead-free pellets that are used as carriers to inoculate cankers on chestnut stems by shooting. The formulation of mycelium did not hamper its viability which was stable, with an estimated shelf life of 72 days at 6 ± 1°C. The inoculum effectiveness was confirmed ex planta and in planta in a small-scale pilot study in field, where formulated mycelium discs of hypovirulent strain Cp 4.2H were inoculated by airgun shot method into the chestnut bark. In planta, Cp 4.2H was recovered in 37% of bark samples taken around the inoculated points 1 year after the treatment. CONCLUSIONS: We demonstrated that the proposed airgun shooting inoculation method of C. parasitica hypovirulent strain formulated as mycelium discs is suitable for treatment of adult chestnut trees. SIGNIFICANCE AND IMPACT OF THE STUDY: The proposed method could be a valid alternative to the traditional manual technique of chestnut biocontrol. The main advantages are the cost-effectiveness and the ease to treat high-positioned, otherwise unreachable cankers both in orchards and forests.


Subject(s)
Agricultural Inoculants/physiology , Antibiosis , Ascomycota/physiology , Plant Diseases/microbiology , Agricultural Inoculants/chemistry , Agricultural Inoculants/growth & development , Ascomycota/chemistry , Ascomycota/growth & development , Mycelium/growth & development , Pilot Projects , Plant Diseases/prevention & control , Trees/microbiology
4.
Haemophilia ; 22(1): 96-102, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26278414

ABSTRACT

INTRODUCTION: Although immune tolerance induction (ITI) is considered the first choice treatment to eradicate inhibitors in haemophilia A patients, little is known about outcomes determinants and cost magnitude. AIM AND METHODS: A retrospective, multicentre study was conducted to assess the relationship between ITI outcome, clinical and treatment characteristics and cost of ITI treatment in haemophilia A patients. Data from 12 months before inhibitor diagnosis to 12 months after ITI completion were collected. Treatment cost was calculated in the third-party perspective and expressed as mean € per patient-month. Cox regression models were used to identify predictors of better outcome and the time taken to achieve tolerance. RESULTS: Seventy-one patients, aged 0.4-41 years (median: 3.8 years) at ITI start, were enrolled. Undetectable inhibitor was achieved in 84.5% of patients and inhibitor eradication with normal factor VIII (FVIII) pharmacokinetics in 74.2%. Median time to successful tolerance was 10.7 months (range 2.0-90.0 months). Peak inhibitor level on ITI was a significant predictor of ITI success. Breakthrough bleeding event incidence during ITI was associated with time to success. The mean cost of treatment for the time period between inhibitor diagnosis and ITI start was €3188 per patient-month (92.1% for bypassing agents), and €60 078 during ITI (76.8% for FVIII use in ITI). CONCLUSION: Immune tolerance induction in this patient cohort was successful in 84.5% of patients with a mean cost of €60 000 per patient-month. This high cost is dwarfed by comparison with the prospect of lifelong care of an inhibitor patient, in addition to gains in life expectancy and health-related quality of life.


Subject(s)
Antibodies, Neutralizing/immunology , Hemophilia A/drug therapy , Hemophilia A/immunology , Adolescent , Adult , Child , Child, Preschool , Cohort Studies , Costs and Cost Analysis , Europe , Factor VIII/economics , Factor VIII/immunology , Factor VIII/therapeutic use , Humans , Infant , Quality of Life , Retrospective Studies , Young Adult
5.
Am J Transplant ; 15(7): 1817-26, 2015 Jul.
Article in English | MEDLINE | ID: mdl-26086300

ABSTRACT

Preliminary studies on HCV-cirrhotics listed for transplant suggest that sofosbuvir in combination with ribavirin is very effective in promoting viral clearance and preventing disease recurrence. Unfortunately, the high cost of such treatment (€46 500 per 12 weeks of treatment) makes its cost-effectiveness questionable. A semi-Markov model was developed to assess the cost-effectiveness of sofosbuvir/ribavirin treatment in cirrhotic patients without HCC (HCV-CIRRH) and with HCC (HCV-HCC) listed for transplant. In the base-case analysis, the incremental cost-effectiveness ratio for 24 weeks of sofosbuvir/ribavirin was €44 875 per quality-adjusted life-year gained in HCV-CIRRH and €60 380 in HCV-HCC patients. Both results were above the willingness to pay threshold of €37 000 per quality-adjusted life-year. Our data also show that in order to remain cost-effective (with a 24-week treatment), any novel interferon-free treatment endowed with ideal efficacy should cost less than €67 224 or €95 712 in HCV-cirrhotics with and without HCC, respectively. The results shows that sofosbuvir/ribavirin therapy, given to patients listed for transplant, is not cost-effective at current prices despite being very effective, and new, more effective treatments will have little economic margins to remain cost-effective. New interferon-free combinations have the potential to revolutionize the treatment and prognosis of HCV-positive patients listed for transplant; however, without sustainable prices, this revolution is unlikely to happen.


Subject(s)
Antiviral Agents/economics , Cost-Benefit Analysis , Hepacivirus/pathogenicity , Hepatitis C/economics , Hepatitis C/prevention & control , Liver Transplantation/adverse effects , Postoperative Complications , Aged , Antiviral Agents/therapeutic use , Female , Follow-Up Studies , Hepatitis C/complications , Humans , Male , Middle Aged , Prognosis , Quality-Adjusted Life Years , Recurrence
6.
J Viral Hepat ; 22(2): 175-83, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25040391

ABSTRACT

New and more promising therapies for chronic hepatitis C (CHC) genotype 1 (G1) naive patients have recently been approved in the United States and Europe, and several more regimens are expected to become available within the next several years. While this scenario unfolds, it is necessary to develop a rational method to allocate current treatment in CHC G1 patients. We performed a cost-effectiveness analysis of boceprevir (BOC)- and telaprevir (TVR)-based triple therapy according to different patients' selection strategies. A semi-Markov model of CHC natural history and progression towards end-stage liver disease was built. We considered 3 selection strategies based on METAVIR fibrosis stage: (i) treat all patients with F1-F4 fibrosis, (ii) only F2-F4 and (iii) only F3-F4. For each strategy, TVR interleukin-28B-guided (IL28B-guided) and BOC rapid virologic response-guided (RVR-guided) therapies were applied. The model assessed the costs and outcomes, using a lifetime and 5-year time horizon, and adopting the Italian National Health System perspective. The incremental cost-effectiveness ratio (ICER) for F1-F4 strategy relative to F3-F4 was €5132 per quality-adjusted life years gained, across TVR IL-28B-guided therapy, and €7042 in the BOC RVR-guided therapy. Conversely, in the 5-year scenario, the ICER for F1-F4 strategy relative to F3-F4 was €1 818 679 (TVR IL28B-guided) and €1 866 437 (BOC RVR-guided) per end-stage liver disease or death (ESLD-D) avoided. In view of anticipated improvement in the efficacy of future regimens, selective treatment of only patients with advanced fibrosis and cirrhosis with TVR or BOC could represent the most cost-effective strategy to optimize resource utilization.


Subject(s)
Antiviral Agents/therapeutic use , Hepacivirus/classification , Hepatitis C, Chronic/drug therapy , Hepatitis C, Chronic/economics , Oligopeptides/therapeutic use , Proline/analogs & derivatives , Adult , Aged , Antiviral Agents/economics , Cost-Benefit Analysis , Drug Therapy, Combination/economics , Drug Therapy, Combination/methods , Genotype , Hepacivirus/genetics , Hepacivirus/isolation & purification , Humans , Italy , Middle Aged , Oligopeptides/economics , Proline/economics , Proline/therapeutic use , Prospective Studies
7.
Br J Dermatol ; 172(1): 187-95, 2015 Jan.
Article in English | MEDLINE | ID: mdl-24974982

ABSTRACT

BACKGROUND: Data on the epidemiological impact and clinical characteristics of chronic hand eczema in Southern Europe are lacking. OBJECTIVES: To estimate the prevalence of chronic hand eczema in its different stages of severity and refractoriness to standard therapy in patients accessing Italian dermatological reference centres, and to evaluate sociodemographic and clinical factors associated with each stage. METHODS: A cross-sectional multicentre study was conducted. Adult patients with hand eczema, consecutively accessing 14 centres over a 6-month period, were enrolled. Patients were classified according to disease duration, severity and response to standard therapy with potent topical corticosteroids. Logistical regression was performed to investigate the relationship between sociodemographic and clinical data with different stages of eczema. RESULTS: The total number of participants was 981. Hand eczema was chronic in 83·5% of patients; 21·3% had severe eczema, with 62·0% of these patients refractory to standard therapy. Food processing and related work, the health professions, craft and related trade works (building, plumbing, electrical), hairdressing/beauty and handicraft work were most frequently associated with chronic hand eczema. Severe chronic hand eczema was more likely to be seen in men, older patients and those with less education. Severe and refractory hand eczema was also more likely among the unemployed and patients with allergic rhinitis and/or atopic dermatitis. CONCLUSIONS: Chronic hand eczema is frequent among patients with hand eczema accessing dermatology centres. Many patients were severe and refractory to standard therapy. The appropriate identification of hand eczema is the first step in implementing effective and efficient treatments.


Subject(s)
Eczema/epidemiology , Hand Dermatoses/epidemiology , Adolescent , Adult , Age Distribution , Aged , Aged, 80 and over , Chronic Disease , Cross-Sectional Studies , Dermatitis, Occupational/epidemiology , Dermatitis, Occupational/therapy , Eczema/therapy , Female , Hand Dermatoses/therapy , Humans , Italy/epidemiology , Male , Middle Aged , Prevalence , Sex Distribution , Socioeconomic Factors , Young Adult
13.
Haemophilia ; 19(5): 736-43, 2013 Sep.
Article in English | MEDLINE | ID: mdl-23731246

ABSTRACT

Patients with haemophilia A and inhibitors are at high risk for severe bleeding, progression of joint disease and deterioration of health-related quality of life (HRQoL). To determine the impact of prophylaxis with an activated prothrombin complex concentrate (aPCC) on HRQoL, HRQoL was assessed using the Short-Form (SF)-36 Health Survey and the EQ-5D questionnaire in subjects ≥ 14 years participating in a prospective, randomized, crossover study comparing 6 months of aPCC prophylaxis with 6 months of on-demand therapy. Eighteen of 19 patients completed the survey or questionnaire before and after the on-demand therapy and prophylaxis periods. A general trend towards improved HRQoL after prophylaxis was observed for the 18 evaluable patients in all SF-36 dimensions except for vitality/energy and physical functioning. After prophylaxis, 'good responders,' defined as patients experiencing ≥ 50% reduction in bleeding, exhibited statistically and clinically significant differences in the physical component score (P = 0.021), role - physical (P = 0.042), bodily pain (P = 0.015), and social functioning (P = 0.036). Similarly, the EQ-5D health profile showed a trend towards improvement after prophylaxis in all evaluable patients. Among the good responders, improvements did not differ from those observed after on-demand treatment. EQ visual analogue scale values were slightly improved following prophylaxis for all evaluable patients and the EQ-5D utility index improved in the good responders only. During prophylaxis, patients missed significantly fewer days from school or work because of bleeding than during on-demand treatment (P = 0.01). In conclusion, by significantly reducing bleeding frequency in good responders, aPCC prophylaxis improved HRQoL compared with on-demand treatment.


Subject(s)
Factor VIII/immunology , Hemophilia A/drug therapy , Hemophilia A/psychology , Isoantibodies/immunology , Prothrombin/administration & dosage , Adolescent , Adult , Aged , Child , Child, Preschool , Cross-Over Studies , Female , Hemophilia A/immunology , Humans , Isoantibodies/biosynthesis , Male , Middle Aged , Prospective Studies , Quality of Life , Surveys and Questionnaires , Young Adult
14.
Acta Chir Belg ; 113(6): 406-14, 2013.
Article in English | MEDLINE | ID: mdl-24494467

ABSTRACT

OBJECTIVES: to investigate the utility of assessing Health-Related Quality of Life (HRQoL) in a large group of subjects participating in a screening program for aneurysm and the relationship between HRQoL, diagnosis of aneurysm and related risk factors. METHODS: subjects involved in this screening program were submitted the EQ-5D questionnaire to report their own HRQoL. HRQoL was reported also a second time by the subjects who were diagnosed with aneurysm during screening and who returned for a monitoring follow up visit a few months later. We evaluated compliance with HRQoL data collection and performed multiple regression analyses in order to investigate the possible relationship between demographic and clinical data with HRQoL. RESULTS: 1,633 subjects screened (6.1% diagnosed with aneurysm) and 125 subjects diagnosed with aneurysm and attending a follow-up visit reported their HRQoL. Completion of the EQ-5D questionnaire was well accepted by both physicians and subjects undergoing screening. HRQoL was not significantly different between the screening and followup visits, on adjusting for age and sex. At the screening visit, HRQoL was associated with ASA class, heart condition, BMI and respiratory diseases. No associations were found at the follow-up visit. CONCLUSION: Assessing HRQoL in screening programs is feasible and well accepted and add useful information on health of large numbers of subjects from general population. This could be considered as a routine approach to optimizing the informative role of screening programs in guiding other investigations or interventions.


Subject(s)
Health Status , Quality of Life , Aged , Aged, 80 and over , Aortic Aneurysm, Abdominal/epidemiology , Aortic Aneurysm, Abdominal/prevention & control , Female , Humans , Male , Mass Screening , Risk Factors , Surveys and Questionnaires
15.
Reumatismo ; 62(3): 210-4, 2010.
Article in Italian | MEDLINE | ID: mdl-21052568

ABSTRACT

OBJECTIVE: Health-related quality of life (HRQoL) in patients with systemic sclerosis (SSc), a chronic disabling disease associated to physical and psychological impairment, is often left behind in clinical practice and research. This is due to the use of tools that are not complete or mainly designed for the physical condition only. We tested EQ-5D, a valid, simple and brief questionnaire for HRQoL that has never been validated in SSc. METHODS: Thirty-three consecutive SSc patients referring to our Rheumatology Department and undergoing treatment have been asked to fulfill EQ-5D together with HAQ. RESULTS: EQ-5D demonstrated good acceptability, feasibility and validity in patients affected by SSc. Conceptually equivalent domains of EQ-5D demonstrated a good correlation with HAQ correspondent domains. CONCLUSIONS: We suggest the use of EQ-5D in SSc patients as a HRQoL measure in clinical practice, as well as an out come parameter in randomized clinical trials and/or in pharmaco-economic evaluations.


Subject(s)
Quality of Life , Scleroderma, Systemic/psychology , Adult , Aged , Aged, 80 and over , Awards and Prizes , Feasibility Studies , Female , Humans , Italy/epidemiology , Male , Middle Aged , Outcome Assessment, Health Care , Patient Acceptance of Health Care , Quality of Life/psychology , Rheumatology , Scleroderma, Systemic/epidemiology , Surveys and Questionnaires
16.
Heart ; 95(5): 370-6, 2009 Mar.
Article in English | MEDLINE | ID: mdl-18653571

ABSTRACT

OBJECTIVE: To assess the clinical impact of a regional network for the treatment of ST-segment elevation myocardial infarction (STEMI). METHODS: All patients with STEMI (n = 1823) admitted to any of the hospitals of an area with one million inhabitants during the year 2002 (n = 858)-that is, before the network was implemented, and in 2004 (n = 965), the year of full implementation of the network, were enrolled in this study. The primary evaluation was in-hospital mortality. Secondary outcomes included the incidence of major adverse cardiac and cerebrovascular events (MACCE), defined as death, myocardial infarction, stroke and coronary revascularisation procedures over 1-year follow-up. RESULTS: Between 2002 and 2004, there was a major change in reperfusion strategy: primary angioplasty increased from 20.2% to 65.6% (p<0.001), fibrinolytic therapy decreased from 38.2% to 10.7% (p<0.001) and the rate of patients not undergoing reperfusion was reduced from 41.6% to 23.7% (p<0.001). In-hospital mortality decreased from 17.0% to 12.3% (p = 0.005), and this reduction was sustained at 1-year follow-up (23.9% in 2002 and 18.8% in 2004, p = 0.009). Similarly, the 1-year incidence of all MACCE was reduced from 39.5% in 2002 to 34.3% in 2004 (p = 0.01). CONCLUSIONS: Organisation of a territorial network for STEMI is associated with increased rates of reperfusion therapy and reduction of in-hospital and 1-year mortality.


Subject(s)
Angioplasty, Balloon, Coronary/mortality , Coronary Angiography/mortality , Emergency Medical Services/organization & administration , Myocardial Infarction , Thrombolytic Therapy/mortality , Aged , Angioplasty, Balloon, Coronary/statistics & numerical data , Coronary Care Units/organization & administration , Female , Hospital Mortality , Humans , Italy/epidemiology , Male , Myocardial Infarction/mortality , Myocardial Infarction/therapy , Thrombolytic Therapy/statistics & numerical data , Time Factors , Treatment Outcome
17.
Phytopathology ; 98(2): 148-52, 2008 Feb.
Article in English | MEDLINE | ID: mdl-18943190

ABSTRACT

The population structure of the grape powdery mildew fungus, Erysiphe necator (formerly Uncinula necator), has been hypothesized to vary from being clonal to highly diverse and recombining. We report here on the structure of an E. necator population sampled during a 4-year period from an isolated vineyard in northern Italy (Voghera, Pavia Province). We obtained 54 isolates of E. necator that overwintered asexually as mycelium in grapevine buds and caused severe symptoms on the emerging shoots, known as flag shoots. All isolates were genotyped for mating type, four multilocus polymerase chain reaction (PCR)-based markers (a total of 64 loci were scored), and two single-copy loci designed to identify genetic subgroups in E. necator. All isolates had the same mating type and single-locus alleles that correlate to isolates from flag shoots in other areas. Only 2 of the 64 loci scored from multilocus markers were polymorphic; 46 of the 54 isolates had the same multilocus haplotype. Seven isolates had a second haplotype that was recovered over 3 years, and only a single isolate was found with a third haplotype. Both variant haplotypes differed from the main clonal haplotype by single loci. Spatial autocorrelation analyses showed that vines with flag shoots were not aggregated within years, but they were aggregated between consecutive years. These results demonstrate that this subpopulation of E. necator on flag shoots is composed of a single clonal lineage that has persisted for at least 4 years. We speculate that the lack of diversity in the flag shoot subpopulation in this vineyard is the result of restricted immigration from surrounding areas and genetic drift operating through founder effects and periodic bottlenecks. We propose a model that integrates epidemiology and population genetics to explain the variation observed in genetic structure of E. necator flag shoot subpopulations from different vineyards or viticultural regions.


Subject(s)
Ascomycota/genetics , Mycelium/genetics , Plant Diseases/microbiology , Vitis/microbiology , Ascomycota/isolation & purification , DNA, Fungal/genetics , Genes, Mating Type, Fungal/genetics , Genetic Variation/genetics , Genotype , Italy , Mycelium/isolation & purification , Polymerase Chain Reaction
18.
Chemosphere ; 73(3): 272-80, 2008 Sep.
Article in English | MEDLINE | ID: mdl-18657290

ABSTRACT

Chloramphenicol (CA) is a largely used antibiotic and it is an inhibitor of protein synthesis that also induces ROS production. In this work there were investigated activities and expressions in the Adriatic bivalve Chamelea gallina of some antioxidant and detoxification proteins like superoxide dismutase (Mn-SOD, Cu/Zn-SOD), catalase (CAT) and Cytochrome P450 (CYP1A). Clams exposed to 5mgl(-1) of chloramphenicol were sampled 2, 4 and 8 days after treatment (CA2, CA4 and CA8). SODs, CAT, and CYP1A activity and/or expression were detected in pooled digestive glands by Western blotting and by spectrophotometrical analysis. Enzymes activities increase during the entire antibiotic exposure. With respect to the control Cu/Zn-SOD expression increases, while Mn-SOD expression decreases significantly after 4 days. Two CYP1A immunopositive-proteins (57.7 and 59.8kDa) were detected. The lower band significantly decreases in CA8, the upper one also in CA4 condition. High levels of Mn-SOD, CAT activity and Cu/Zn-SOD expression, indicate intense ROS production while Mn-SOD expression inhibition might be ascribable to mitochondrial alterations due to CA and indirectly to ROS. CYP1A1 action determines H2O2 production that would contribute to a CYP1A1 gene promoter down regulation, a response to oxidative stress with the antioxidant enzymes activation as a final result. This study highlights the close association, in C. gallina, in presence of chloramphenicol, between SOD/CAT and CYP system, and it appear particularly interesting to the lack of similar researches on mollusc species.


Subject(s)
Anti-Bacterial Agents/pharmacology , Antioxidants/metabolism , Bivalvia/enzymology , Catalase/metabolism , Chloramphenicol/pharmacology , Cytochrome P-450 Enzyme System/metabolism , Microsomes/drug effects , Superoxide Dismutase/metabolism , Animals , Blotting, Western , Electrophoresis, Polyacrylamide Gel , Microsomes/enzymology
19.
Heredity (Edinb) ; 93(2): 189-95, 2004 Aug.
Article in English | MEDLINE | ID: mdl-15241462

ABSTRACT

As in plants, fungi exhibit wide variation in reproductive strategies and mating systems. Although most sexually reproducing fungi are either predominantly outcrossing or predominantly selfing, there are some notable exceptions. The haploid, ascomycete chestnut blight pathogen, Cryphonectria parasitica, has previously been shown to have a mixed mating system in one population in USA. In this report, we show that both selfing and outcrossing occur in 10 additional populations of C. parasitica sampled from Japan, Italy, Switzerland and USA. Progeny arrays from each population were assayed for segregation at vegetative incompatibility (vic) and DNA fingerprinting loci. Outcrossing rates (t(m)) were estimated as the proportion of progeny arrays showing segregation at one or more loci, corrected by the probability of nondetection of outcrossing (alpha). Estimates of t(m) varied from 0.74 to 0.97, with the lowest rates consistently detected in USA populations (0.74-0.78). Five populations (four in USA and one in Italy) had t(m) significantly less than 1, supporting the conclusion that these populations exhibit mixed mating. The underlying causes of variation in outcrossing rates among populations of C. parasitica are not known, but we speculate that--as in plants--outcrossing is a function of ecological, demographic and genetic factors.


Subject(s)
Ascomycota/genetics , Ascomycota/physiology , Genetics, Population , DNA Fingerprinting , Europe , Inbreeding , Japan , Reproduction/physiology , United States
20.
Genetics ; 159(1): 107-18, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11560890

ABSTRACT

Vegetative incompatibility in fungi has long been known to reduce the transmission of viruses between individuals, but the barrier to transmission is incomplete. In replicated laboratory assays, we showed conclusively that the transmission of viruses between individuals of the chestnut blight fungus Cryphonectria parasitica is controlled primarily by vegetative incompatibility (vic) genes. By replicating vic genotypes in independent fungal isolates, we quantified the effect of heteroallelism at each of six vic loci on virus transmission. Transmission occurs with 100% frequency when donor and recipient isolates have the same vic genotypes, but heteroallelism at one or more vic loci generally reduces virus transmission. Transmission was variable among single heteroallelic loci. At the extremes, heteroallelism at vic4 had no effect on virus transmission, but transmission occurred in only 21% of pairings that were heteroallelic at vic2. Intermediate frequencies of transmission were observed when vic3 and vic6 were heteroallelic (76 and 32%, respectively). When vic1, vic2, and vic7 were heteroallelic, the frequency of transmission depended on which alleles were present in the donor and the recipient. The effect of heteroallelism at two vic loci was mostly additive, although small but statistically significant interactions (epistasis) were observed in four pairs of vic loci. A logistic regression model was developed to predict the probability of virus transmission between vic genotypes. Heteroallelism at vic loci, asymmetry, and epistasis were the dominant factors controlling transmission, but host genetic background also was statistically significant, indicating that vic genes alone cannot explain all the variation in virus transmission. Predictions from the logistic regression model were highly correlated to independent transmission tests with field isolates. Our model can be used to estimate horizontal transmission rates as a function of host genetics in natural populations of C. parasitica.


Subject(s)
Ascomycota/genetics , Ascomycota/virology , Disease Transmission, Infectious , Gene Transfer, Horizontal , RNA Viruses/genetics , Trees/microbiology , Alleles , Ascomycota/pathogenicity , Epistasis, Genetic , Genetic Variation , Genotype , Models, Statistical , Pest Control, Biological , Plant Diseases/microbiology , Protein Binding , RNA Viruses/physiology , Virulence
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