Evaluation of Setaria cervi antigen in the diagnosis of human filariasis

Bovine filariid worm (Setaria cervi) antigen was evaluated for the immunodiagnosis of human filariasis. Patients with manifestations of filarial infection; [1) microfilaremia cases, (2) chronic clinical cases, (3) tropical pulmonary eosinophilia (TPE) cases) were taken for the investigations along with (4) normal endemic and non-endemic human subjects. CIEP, IFAT and ELISA tests were employed for detection of serum antibodies. There was a high degree of sensitivity shown by IFAT (1:64-1:256) and ELISA (1:200-1:20,800) in microfilaraemia cases and higher in chronic clinical cases with IFAT (1:128-1:1,024) and ELISA (1:12,800-1:102,400). Only one TPE case showed positive titre by IFAT (1:64) and ELISA (1:200) whereas sera from controls and patients with helminth infections did not show positive titres (1:100). In the case of CIEP, positive reaction was seen in only one case from group I.     

Experimental chemotherapy and chemoprophylaxis of filariasis

This paper describes some of the current methods used for the development of new chemotherapeutic agents against filarial parasites. These are based on the extensive previous experience of experimental chemotherapy of filariasis and of the development of new rodent and non-rodent filarial models. A review on the chemotherapeutic activity and micro- or macro-filaricidal potency of some well-known or recently developed filaricidal drugs is given, based on results obtained with Litomosoides carinii infection of Mastomys natalensis. Corresponding information on the chemo-prophylactic activity of filaricides is presented and discussed, with regard to the relevancy and need for the further development and evaluation of anthelmintics in filarial infections.     

Bancroftian filariasis in the Igwun basin, Nigeria: an epidemiological, parasitological, and clinical study in relation to the transmission dynamics

A 12-months study on bancroftian filariasis was carried out in the Igwun basin, Nigeria. A total of 1,418 individuals (768 males, and 650 females) were examined for microfilaremia and clinical filarial stigmata. There were 14.3% and 11.1% male and female point prevalence rates, respectively, and an overall prevalence of 12.8%. Prevalence rates and microfilarial density increased with age. The highest mff density of 35 mff/20 ml blood occurred in the 40-49 year old male individuals. Disease rates of 55.5 and 65.3% were recorded for males and females respectively. Chyluria (9.3% males, 16.7% females), hydrocele (17.8%), elephantiasis (15.9% males, 29.2% females), and enlarged groin glands (16.4% males, 19.4% females) were the major clinical signs, all associated with microfilaremia. Anopheles gambiae and Cules pipiens were the principal vectors. The estimated mean daily, weekly, and monthly per capita biting densities were 26, 161, and 753 respectively. The overall infection rate of mosquitoes was 22.3%, with a mean mff density of approximately 5 mff/mosquito. These vector parameters were indicative of active transmission in the area, and may be responsible for the high prevalence of infection, the diversity of clinical signs, and high morbidity rates.     

Spatial pattern analysis of citrus canker-infected plantings in são paulo, Brazil, and augmentation of infection elicited by the asian leafminer

ABSTRACT Eradication of Asiatic citrus canker (ACC) has become increasingly difficult over the last decade, following the introduction of the Asian leafminer into Brazil and Florida, which has led to changes in the eradication protocols. The present study, undertaken in Brazil, was aimed at characterizing the spatial patterns of ACC in commercial citrus plantings to gain better understanding of the dynamics of the disease subsequent to introduction of the leafminer. The spatial patterns of ACC were mapped in 326 commercial citrus plantings and statistically assessed at various spatial dimensions. The presence of "within-group" aggregation in each plot was examined via beta-binomial analysis for groups of trees parsed into three-by-three-tree quadrats. The relative intensity of aggregation was expressed as a binomial index of dispersion (D) and heterogeneity among plots expressed as the intracluster correlation coefficient, rho. The population of data sets was found to fall into three D categories, D < 1.3, 1.3 3.5. These categories then were related to other spatial characteristics. The binary form of Taylor's power law was used to assess the overdispersion of disease across plots and was highly significant. When the overall population of plots was parsed into D categories, the Taylor's R (2) improved in all cases. Although these methods assessed aggregation well, they do not give information on the number of foci or aggregations within each plot. Therefore, the number of foci per 1,000 trees was quantified and found to relate directly to the D categories. The lowest D category could be explained by a linear relationship of number of foci versus disease incidence, whereas the higher two categories were most easily explained by a generalized beta function for the same relationship. Spatial autocorrelation then was used to examine the spatial relationships "among groups" composed of three-by-three-tree quadrats and determine common distances between these groups of ACC-infected trees. Aggregation was found in >84% of cases at this spatial level and there was a direct relationship between increasing D category and increasing core cluster size, and aggregation at the among-group spatial hierarchy was generally stronger for the within-row than for the across-row orientation. Clusters of disease were estimated to average between 18 and 33 tree spaces apart, and the presence of multiple foci of infection was commonplace. The effectiveness of the eradication protocol of removing all "exposed" trees within 30 m surrounding each "ACC-infected tree" was examined, and the distance of subsequent infected trees beyond this 30-m zone from the original focal infected tree was measured for each plot. A frequency distribution was compiled over all plots to describe the distance that would have been needed to circumscribe all of these outliers as a theoretical alternative protocol to the 30-m eradication protocol. The frequency distribution was well described by a monomolecular model (R(2) = 0.98) and used to determine that 90, 95, and 99% of all newly infected trees occurred within 296, 396, and 623 m of prior-infected trees in commercial citrus plantings, respectively. These distances are very similar to previously reported distances determined for ACC in residential settings in Florida.     

Toxoplasmic antibodies in sera of HIV-infected persons.

The sera of 67 HIV-infected persons without clinical signs of Toxoplasma gondii infection and sera of 777 immunocompetent persons from three distinct regions of Czechoslovakia were examined for the presence of toxoplasmic antibodies using the complement-fixation test (CFT). Additionally Toxoplasma positive HIV+ individuals were re-examined for the presence of IgG and IgM toxoplasmic antibodies by ELISA methods. Results show that overall prevalence of toxoplasmic antibodies is not significantly greater in HIV-positive subjects (29.8%) than in the general population (26.1%). Similarities between these two tested groups were also documented by a close correlation of their geometrical means of titres (13.9 versus 14.5). All 20 HIV-infected patients who were positive in CFT were positive in ELISA IgG reaction, and none in ELISA IgM reaction. The detected antibody levels were suggestive of a latent Toxoplasma infection only. But because of the risk of the infection reactivation all of these patients should be attended to on a systematic basis.     

佛手山药线虫病害发生调查与病原鉴定

湖北省武穴市佛手山药是“农产品地理标志产品”, 近年佛手山药线虫病害严重, 为此在病源地采集山药土样进行了病害发生调查及病原鉴定?通过形态特征观察?形态特征测计值比较, 以及基于rDNA 28S D2/D3区序列构建短体线虫属线虫群体系统进化树并进行SCAR验证, 对引起佛手山药线虫病的病原线虫进行种类鉴定?结果表明:危害佛手山药的病原线虫的群体特征与咖啡短体线虫Pratylenchus coffeae相似?系统进化树显示:该病原群体与中国香港群体(HQ688677.1)聚类在一个分支上, 置信度达99%?因此, 将该群体线虫鉴定为咖啡短体线虫Pratylenchus coffeae?此外田间调查表明:线虫主要集中分布于10~20 cm深度的土层中, 线虫密度随土壤深度的增加而呈递减趋势, 且连作1年地较连作2年地的线虫数量少, 施用阿维菌素的地块较未施用的线虫数量少?上述结果表明, 在佛手山药生产中实行轮作和科学选择药剂防治, 避免连作, 可降低该线虫发生量?     

Evaluation of specific humoral immune responses in human filariasis

Using the antigens prepared from adult worms of B. malayi and D. immitis, a total of 37 malayan and 150 bancroftian serum samples were analysed for the presence of filarial specific antibodies by counterimmunoelectrophoresis and indirect enzyme linked immunosorbent assay. It was observed that microfilaraemic cases do show good specific humoral immune responses against homologous as well as heterologous antigen. Of the two antigens used, B. malayi adult antigen was found to be superior to D. immitis antigen in the detection of filarial antibodies.     

Quantitative trait loci for seedling and adult plant resistance to Stagonospora nodorum in wheat

Stagonospora nodorum blotch (SNB) caused by Stagonospora nodorum is a severe disease of wheat (Triticum aestivum) in many areas of the world. S. nodorum affects both seedling and adult plants causing necrosis of leaf and glume tissue, inhibiting photosynthetic capabilities, and reducing grain yield. The aims of this study were to evaluate disease response of 280 doubled haploid (DH) individuals derived from a cross between resistant (6HRWSN125) and susceptible (WAWHT2074) genotypes, compare quantitative trait loci (QTL) for seedling and adult plant resistance in two consecutive years, and assess the contribution of QTL on grain weight. Flag leaves and glumes of individuals from the DH population were inoculated with mixed isolates of S. nodorum at similar maturity time to provide accurate disease evaluation independent of morphological traits and identify true resistance for QTL analysis. Fungicide protected and inoculated plots were used to measure relative grain weight (RGW) as a yield-related trait under pathogen infection. The lack of similar QTL and little or no correlation in disease scores indicate different genes control seedling and adult plant disease and independent genes control flag leaf and glume resistance. This study consistently identified a QTL on chromosome 2DL for flag leaf resistance (QSnl.daw-2D) and 4BL for glume resistance (QSng.daw-4B) from the resistant parent, 6HRWSN125, explaining 4 to 19% of the phenotypic variation at each locus. A total of 5 QTL for RGW were consistently detected, where two were in the same marker interval for QSnl.daw-2D and QSng.daw-4B indicating the contribution of these QTL to yield related traits. Therefore, RGW measurement in QTL analysis could be used as a reliable indicator of grain yield affected by S. nodorum infection.     

Serologic examination of human population in South Moravia (Czechoslovakia) on the presence of antibodies to arboviruses of the Alfavirus, Flavivirus, Turlock groups and Bunyamwera supergroup.

A statistically representative group of human population from the South Moravian region (CSSR) was examined on the presence of antibodies against the following arboviruses: Lednice, Sindbis, tick-borne encephalitis, West Nile, Tahyna and Calovo. The ascertained absence of antibodies to the Lednice virus is an evidence that at present this virus is of no epidemiological importance in the region studied. No antibodies to Sindbis, West Nile and Calovo viruses were demonstrated. 17.8 to 42.0% of antibodies to Tahyna virus were detected in all age groups examined. The total infection rate was 26.0%. Antibodies to the tick-borne encephalitis virus occurred primarily in persons over 40 years. The total infection rate was 5.5%.     

Incorporation of temperature and solar radiation thresholds to modify a lettuce downy mildew warning system

ABSTRACT The effect of temperature on infection of lettuce by Bremia lactucae was investigated in controlled environment studies and in the field. In controlled conditions, lettuce seedlings inoculated with B. lactucae were incubated at 15, 20, 25, or 30 degrees C during a 4-h wet period immediately after inoculation or at the same temperatures during an 8-h dry period after the 4-h postinoculation wet period at 15 degrees C. High temperatures during wet and dry periods reduced subsequent disease incidence. Historical data from field studies in 1991 and 1992, in which days with or without infection had been identified, were analyzed by comparing average air temperatures during 0600 to 1000 and 1000 to 1400 Pacific standard time (PST) between the two groups of days. Days without infection had significantly higher temperatures (mean 21.4 degrees C) than days with infection (20.3 degrees C) during 1000 to 1400 PST (P < 0.01) but not during 0600 to 1000 PST. Therefore, temperature thresholds of 20 and 22 degrees C for the 3-h wet period after sunrise and the subsequent 4-h postpenetration period, respectively, were added to a previously developed disease warning system that predicts infection when morning leaf wetness lasts >/=4 h from 0600 PST. No infection was assumed to occur if average temperature during these periods exceeded the thresholds. Based on nonlinear regression and receiver operating characteristic curve analysis, the leaf wetness threshold of the previous warning system was also modified to >/=3-h leaf wetness (>/=0900 PST). Furthermore, by comparing solar radiation on days with infection and without infection, we determined that high solar radiation during 0500 to 0600 PST in conjunction with leaf wetness ending between 0900 and 1000 PST was associated with downy mildew infection. Therefore, instead of starting at 0600 PST, the calculation of the 3-h morning leaf wetness period was modified to start after sunrise, defined as the hour when measured solar radiation exceeded 8 W m(-2) (or 41 mumol m(-2) s(-1) for photon flux density). The modified warning system was compared with the previously developed system using historical weather and downy mildew data collected in coastal California. The modified system was more conservative when disease potential was high and recommended fewer fungicide applications when conditions were not conducive to downy mildew development.     

Variation in host range, systemic infection and epidemiology of Leptosphaeria maculans

The A and B groups (aggressive and non-aggressive) of Leptosphaeria maculans were compared in studies of host range, infection phenotypes and epidemiology. Isolates of both groups infected a wide range of cruciferous hosts including Brassica napus, B. rapa, B. oleracea, B. juncea, B. carinata. B. nigra, Thlaspi arvense and Raphanus sativus. On cotyledons, B-group isolates were generally more aggressive than A-group isolates, causing local lesions and subsequent systemic invasion of the majority of test species. On susceptible stems, A-group isolates caused cortical lesions; B-group isolates, if they reached the stem, usually caused pith lesions with no external symptoms. In a susceptible line of B. napus , CrGC5, systemic infections of the leaf and petiole were similar with both groups, but the B-group rarely entered the stem to form cortical lesions or cankers. At two different field locations, natural epidemics caused by the two groups on oilseed rape leaves were similar in overall pattern, B-group lesions occurred slightly later but the incidence increased more rapidly and reached a maximum slightly earlier than that of the A group. The two groups differed markedly in stem infection patterns. Infection of the cortex near the base of the stem and the development of a typical stem canker was caused entirely by the A group. However the B group often caused considerable damage to the pith. Superficial chlorotic lesions on stems and inflorescences were mainly attributable to the B group. In view of the stem pith infection by the B group without external symptoms, its importance on oilseed rape may have been underestimated previously.     

Endophytic-Host Selectivity of Discula umbrinella on Quercus alba and Quercus rubra Characterized by Infection, Pathogenicity and Mycelial Compatibility

The fungal endophytic–host relationships of Discula umbrinella and two oak species, Quercus alba and Quercus rubra, were characterized on the basis of endophytic infection, pathogenicity, and mycelial compatibility. Isolates of D. umbrinella were cultured from leaves of Q. alba and Q. rubra collected from a hardwood forest located in Patuxent Wildlife Research Center in Laurel, Maryland, USA. Endophytic infection was observed on sterile leaf discs and living 2-month-old seedlings of Q. alba and Q. rubra. Fungal-host reciprocal inoculations revealed the presence of conidiomata on both hosts but conidiomata production was more abundant on Q. alba. Isolates from Q. rubra produced milder disease symptoms on both oak species. Mycelial compatibility studies identified seven different MCG groups. MCG groups 1–3 contained isolates from both oak species whereas MCG groups 4–7 contained host specific isolates. Field studies monitored the seasonal appearance of the sexual fruiting structures, perithecia, as a possible source of new genetic variation that might alter host specificity/pathogenicity of the D. umbrinella isolates on Q. alba and Q. rubra hosts. Only 1–2% of the leaves contained perithecia throughout the sampling period (April–September). Isolates collected from Q. alba differed from those collected from Q. rubra in endophytic infection, pathogenic response, and perithecia production. The results of this study suggest that the endophyte–host relationship is one of host selective preference for Q. alba, but that the endophyte has the ability to maintain the endophytic/pathogenic life cycle on the less preferred host species, Q. rubra.     

Insecticide resistance in vector mosquitoes in China

Because of their special behaviour, physiology and close relationship with humans, mosquitoes act as one of the most important vectors of human diseases, such as filariasis, Japanese encephalitis, dengue and malaria. The major vector mosquitoes are members of the Culex, Aedes and Anopheles genera. Insecticides play important roles in agricultural production and public health, especially in a country with a huge human population, like China. Large quantities of four classes of insecticides, organochlorines, organophosphates, carbamates and pyrethroids, are applied annually to fields or indoors in China, directly or indirectly bringing heavy selection pressure on vector populations. The seven major species of vector mosquito in China are the Culex pipiens L. complex, C. tritaeniorhynchus Giles, Anopheles sinensis Wied., A. minimus Theobald, A. anthropophagus Xu & Feng, Aedes albopictus (Skuse) and Ae. aegypti L., and all have evolved resistance to all the above types of insecticide except the carbamates. The degree of resistance varies among mosquito species, insecticide classes and regions. This review summarizes the resistance status of these important vector mosquitoes, according to data reported since the 1990s, in order to improve resistance management and epidemic disease control, and to communicate this information from China to the wider community.     

The use of the random amplified polymorphic DNA technique to identify mating groups in the Fusarium section Liseola

The random amplified polymorphic DNA (RAPD) technique was used to determine the mating groups of several members of the Fusarium section Liseola recovered from maize, rice and sorghum collected from different locations in Ghana. Three mating groups were identified, A, D and F, of which all A and F isolates were confirmed by mating studies. Fertile crosses were also obtained in crosses involving two of the isolates identified as belonging to the D population. Variability within the A population isolated from seeds and stem-bases of maize was investigated to determine whether the sub-structuring of this population was related to the host tissue from which the isolates were obtained. The relative merits of the RAPD procedure, compared to the mating procedure, for determining the mating affiliations of isolates and for more detailed analyses of isolates within a population, as well as its possible advantages over established RFLP methodologies are discussed.     

Genome-wide association study for spot blotch resistance in Afghan wheat germplasm

Spot blotch (SB), caused by Bipolaris sorokiniana, is a devastating disease of wheat globally, especially in South Asia and South America. Understanding the genetics of resistance to SB is important for developing breeding strategies to improve resistance. A panel of 301 genotypes from Afghanistan was phenotyped over two crop seasons using a mixture of virulent B. sorokiniana isolates and genotyped using DArTSeq to obtain genome-wide markers. Fifty genotypes (16.6%) showed disease scores less than the resistant control. Principal component analysis using the genotypic data clustered the genotypes into five different groups. Among models used for genome-wide association mapping, the multilocus mixed model, and fixed and random model circulating probability unification algorithms were most effective in identifying significant marker-trait associations (MTA). Twenty-five MTAs at p ≤ .001 were identified on chromosomes 1A, 1B, 1D, 2B, 2D, 3A, 3B, 4A, 5A, 5B, 6A, 7A, and 7D, indicating the quantitative nature of resistance to SB. Phenotypic variation explained by these markers ranged from 2.0% to 17.7%, and genomic regions on the chromosomes 1D, 2D, 3A, 3B, 4A, 5A, and 5B coincided with loci identified in previous studies. Three single nucleotide polymorphism (SNP) markers on chromosomes 1B (SNP 1113207) and 5A (SNPs 5411867 and 998276) were significant in both crop seasons as well as in the combined analysis across seasons. Marker 5411867 is close to Vrn-A1, shown to be associated with SB in previous studies. Furthermore, among known SB resistance genes, Sb2 on chromosome 5B was predicted to be significant in this panel.     

Brugia malayi: status of host during different stages of infection

The status of glycogen, protein, lipid components, lipid peroxides and a few enzymes of energy metabolism was studied in liver of Mastomys natalensis during the development of Brugia malayi infection. Glycogen and lipid contents were decreased during the patent phase of infection while total protein was slightly altered in latent animals. Phospholipid and triglyceride contents declined at prepatent and patent phase of infection. The levels of lactate and malate dehydrogenases, as well as of adenosine triphosphatases (Na+K+, Mg2+, Ca2+), were significantly elevated and monoamine oxidase activity was decreased at patent phase of infection, while succinic dehydrogenase remained unaltered. The lipid peroxide formation was enhanced in liver during the development of filarial infection.     

Characteristics of the spread of apple proliferation by its vector Cacopsylla picta

The distribution and natural phytoplasma infection of Cacopsylla picta were investigated during a long-term field survey between 2002 and 2009 in commercial and abandoned apple proliferation-infected orchards throughout Germany, northern Switzerland, and eastern France. Comparable population dynamics were described for the different sites whereas considerable variations in the absolute population densities were observed among the years. Individual polymerase chain reaction (PCR) testing revealed, for each year, a rather stable natural infection rate with ?Candidatus Phytoplasma mali? of ?10% for overwintered adults of C. picta. Both genders were equally highly infected although more females were caught. The overall male/female ratio was 1:1.5. No direct correlation was found between the infection status of the orchard and the infection rate of overwintered C. picta. No influence of agricultural practices was seen. However, a relationship between the incidence of the disease and the vector population density became evident on a regional scale. Successful transmission of ?Ca. P. mali? occurred each year with overwintered individuals as well as with new adults. The transmission efficiency varied among the years within 8 to 45% for overwintered adults and 2 to 20% for individuals of the new generation. The load of single C. picta with ?Ca. P. mali? was determined by quantitative real-time PCR. High phytoplasma titers were measured in overwintered adults already at their first appearance in the orchards after remigration from their overwintering hosts. Thus, the data indicate the transmission of the disease on a regional scale by remigrant adults of C. picta and at a local scale within the same season by emigrant adults which developed on infected plants.     

In vitro analysis of host plant specificity in Rhizoctonia solani

Rhizoctonia solani is a plant pathogenic fungus with a wide host range. Host plant specificity within R. solani was analysed on seedlings grown aseptically on agar, which allowed continuous observation of both the fungus and the whole plant without disturbing the interaction. Symptom development on cauliflower, Arabidopsis , eggplant, tomato and potato by 32 R. solani isolates, belonging to six different anastomosis groups (AGs), was studied. Host plant specificity of isolates, as analysed by similarity clustering, was similar to AG-related host plant specificity as observed in the field, with AG3 isolates (except two avirulent strains) separating from the other isolates. Two R. solani isolates with a reciprocal pathogenicity on cauliflower and tomato were selected for further studies. These showed that in the pathogenic combination, R. solani isolates grew over the plant, adhered and formed infection structures, while in the nonpathogenic combination isolates grew over the plant, but neither adhesion nor the formation of infection structures occurred. From these data, it was concluded that host plant specificity is mediated in the early steps of the infection process.     

桑椹菌核病研究进展

桑椹菌核病是由3种子囊菌真菌引起的相似症状病害的统称,为果桑生产中的毁灭性真菌病害,严重制约果桑产业的发展。这3种病原菌同为死体营养型病原菌,其侵染手段多样,侵染机制复杂。由于3种病原菌在人工培养上存在不同程度的困难(桑实杯盘菌和肉阜状杯盘菌难培养,核地杖菌在人工培养基上不能完成生活史),在一定程度上限制了病原菌的研究。本文综述了桑椹菌核病的侵染循环、病原菌、病害流行、病原菌与寄主互作等方面的研究进展,并对未来的研究进行了展望,以期对桑椹菌核病的深入研究提供参考。