bluuebunny/crossref_metadata_2025 huggingface dataset:
Association of the pitch canker fungus,Fusarium subglutinansf.sp.pini, with Monterey pine seeds and seedlings in California
Authors: Storer  , Gordon  , Clark
Published: March 2003

The causal agent of pitch canker disease of pines,Fusarium subglutinansf.sp.pini, is a recent introduction to California. The work presented here demonstrates that this pathogen is seed‐borne in Monterey pine (Pinus radiata). The pathogen was isolated from up to 83% of seeds collected from cones on recently infected branches. Seedling emergence from infested Monterey pine seeds was 9%, compared with 67% for uninfested seeds. The fungus was isolated more frequently from seedlings originating from diseased branches than from symptomless branches. However, more than 50% of seeds from symptomless Monterey pine branches produced symptomless seedlings from which the pathogen was isolated. It is hypothesized thatF. s.piniis carried within the seeds, where it may remain dormant until germination. The implications of these findings for the regeneration of native and landscape‐planted Monterey pines, and for the transport of this non‐native pathogen in pine seeds and seedlings to previously uninfested areas, are discussed.
Effects of climatic factors on native arbuscular mycorrhizae and Meloidogyne exigua in a Brazilian rubber tree (Hevea brasiliensis) plantation
Authors: Schwob  , Ducher  , Coudret
Published: March 2003

The root‐knot nematode Meloidogyne exigua and arbuscular mycorrhizal (AM) fungi may both occur in the roots of Brazilian rubber trees (Hevea brasiliensis). AM fungi may stimulate plant growth whereas nematodes usually reduce it. Variations of native AM fungi and M. exigua populations in soil and roots of rubber trees were studied for one year in a Brazilian plantation. The number of AM spores in the soil was generally greater in the rainy season than in the dry season, although AM colonization of roots was unaffected by season. During the dry season, numbers of juveniles and eggs of M. exigua in roots were lower than in the rainy season. A site without nematodes in the soil or roots showed the greatest numbers of AM spores in soil and highest AM colonization of roots. A negative correlation was observed between the percentage of AM colonization and the number of second‐stage juveniles in soil and second‐stage juveniles and eggs in roots. Microscope observations revealed (i) tissue specificity for each of the microorganisms in the roots, with a cortical location of mycorrhizae and a mainly vascular cylinder location of nematodes, and (ii) that Gigaspora was the most abundant AM genus in the plantation soil.
Identification of volatiles generated by potato tubers (Solanum tuberosum CV: Maris Piper) infected by Erwinia carotovora, Bacillus polymyxa and Arthrobacter sp.
Authors: De Lacy Costello  , Evans  , Ewen  , Gunson  , Ratcliffe  , Spencer‐Phillips
Published: March 2003

Bacteria were isolated from internal tissues of surface sterilized healthy tubers of Solanum tuberosum cv. Maris Piper (8 different isolates) and from tubers inoculated with Erwinia carotovora ssp. carotovora showing soft‐rot symptoms (3 different isolates), and identified by fatty acid profiling. Bacillus polymyxa and an Arthrobacter sp. were isolated from both sources, E. carotovora only from the soft‐rotted tubers. The volatile organic compounds (VOCs) generated by tubers inoculated with E. carotovora, B. polymyxa and the Arthrobacter sp. were identified. Inoculated tubers of cv. Maris Piper were incubated under controlled humidity (95% relative humidity) and temperature (10°C) to simulate typical storage conditions. B. polymyxa and Arthrobacter sp. did not cause symptoms, whilst E. carotovora caused limited soft‐rot infections after 4 weeks at the low temperatures typically associated with potatoes in storage. The VOCs released to the headspace around these tubers were collected using an adsorbent system and analysed by Gas Chromatography‐Mass Spectrometry (GC‐MS). Twenty‐two volatiles unique to E. carotovora infection of potato tubers were found, including 10 alkanes, four alkenes, two aldehydes, one sulphide, one ketone, one alcohol, one aromatic, one acid and one heterocyclic compound. B. polymyxa generated three unique volatiles: N,N‐dimethylformamide, 1‐pentadecene and 1‐hexadecane. Only one volatile, 2,3‐dihydrofuran, was unique to the Arthrobacter infection. Production of volatile nitrogen species from E. carotovora‐infected tubers increased with time, whereas none were detected in the headspace above uninfected tubers. Further analysis using a modified GC‐MS method established that ammonia, trimethylamine and several volatile sulphides were evolved from tubers infected by E. carotovora. No specific volatile was useful as a marker associated with any of the three bacterial species but in the case of E. carotovora‐infected potato tubers a significant increase in the volume of compounds evolved was clearly observed. The results are discussed in relation to the use of sensors to detect VOCs evolved from infected tubers in order to provide an early warning system for the control of soft rot in potato stores.
Winter oilseed rape with high levels of resistance to Pyrenopeziza brassicae derived from wild Brassica species
Authors: Bradburne  , Majer  , Magrath  , Werner  , Lewis  , Mithen
Published: March 2003

Oilseed rape cultivars possess inadequate levels of resistance to light leaf spot disease, caused by the ascomycete Pyrenopeziza brassicae Sutton & Rawlinson. High levels of resistance to this disease were found within wild accessions of Brassica oleracea and B. rapa. This resistance was introgressed into agronomically acceptable winter oilseed rape breeding lines. Seedling resistance was determined by two genes. One of these, derived from B. rapa and positioned on linkage group N1, resulted in no apparent symptoms following infection, while the other, derived from B. oleracea and positioned on N16, resulted in black necrotic flecks and a reduced amount of sporulation compared with standard cultivars. Several agronomically acceptable double haploid lines were developed which expressed very high levels of adult plant resistance.
Inheritance of partial resistance to race 2 of Albugo candida in canola‐quality mustard (Brassica juncea) and its role in resistance breeding
Authors: Bansal  , Thiagarajah  , Stringam  , Tewari
Published: March 2003

The inheritance of partial resistance to race 2 of Albugo candida was studied in a canola‐quality line of Brassica juncea. This partially resistant line was crossed with the susceptible B. juncea cultivar Commercial Brown. F1, F1(reciprocal), F2, BC and doubled haploid generations from the cross were inoculated with a zoospore suspension of race 2 to study segregation of partial resistance. The partially resistant phenotype appeared to be controlled by a single dominant gene that has variable expression. This partial resistance can have implications in breeding for disease resistance against white rust, as adult plants did not develop hypertrophic growth or stagheads under greenhouse and field conditions.
Characterization by conventional techniques and PCR of Rhizoctonia solani isolates causing banded leaf sheath blight in maize
Authors: Pascual  , Toda  , Raymondo  , Hyakumachi
Published: March 2003

Rhizoctonia‐diseased specimens were collected from various host species growing in or near maize fields in different geographic regions of the Philippines. A greater range of host species, with varying types of disease symptoms, was found in Mindanao than in Luzon. Fifty‐two isolates belonged to anastomosis group AG1‐IA and caused banded leaf and sheath blight in maize (Zea mays), but they showed considerable variation in virulence. The most and least virulent isolates recovered from maize were both collected from Mindanao. Isolates from necrotic spots/foliar blight of durian and coffee, which were collected from the same region, showed the lowest lesion heights. UPGMA‐SAHN clustering analysis from RAPD fingerprint data of 30 haplotypes of R. solani AG1‐IA isolates from the Philippines and Japan resolved seven groups of AG1‐IA at the 75% similarity level. Variation among isolates from upland crops seemed to be partially correlated with geographical origin and virulence. In the case of paddy rice isolates from Japan and the Philippines, some were closely related, with over 75% similarity, suggesting a common origin. In PCR‐RFLP analysis of the rDNA internal transcribed spacer region, no polymorphism was observed among the AG1‐IA isolates but they were differentiated from subgroups AG1‐IB and AG1‐IC using the endonucleases EcoRI, MboI and HinfI.
A general model of plant‐virus disease infection incorporating vector aggregation
Authors: Zhang X.‐S. , Holt J. , Colvin J.
Published: March 2003

In plant‐virus disease epidemiology, dynamical models have invariably incorporated a bilinear inoculation rate that is directly proportional to both the abundance of healthy (susceptible) hosts and the abundance of infective vectors. Similarly, the acquisition rate is usually assumed to be directly proportional to the abundance of nonviruliferous vectors and that of infectious hosts. These bilinear assumptions have been questioned for certain human diseases, and infection rates that incorporate power parameters of the variables have been proposed. Here, infection rates for plant‐virus diseases that are of a more general form than the familiar bilinear terms are examined. For such diseases, the power parameter can be regarded as a measure of the spatial aggregation of the vectors or as a coefficient of interference between them, depending on the context.

Field data of cassava mosaic virus disease (CMD) incidence were examined. When vector population density and disease incidence were high, disease progress curves over the first 6 months from planting could not be explained using models with bilinear infection rates. Incorporation of the new infection terms allowed the range of observed disease progress curve types to be described. New evidence of a mutually beneficial interaction between the viruses causing CMD and the whitefly vector, Bemisia tabaci, has shown that spatial aggregation of the vectors is an inevitable consequence of infection, particularly with a severe virus strain or a sensitive host. Virus infection increases both vector fecundity and the density of vectors on diseased plants. It is postulated that this enhances disease spread by causing an increased emigration rate of infective vectors to other crops. Paradoxically, within the infected crop, vector aggregation reduces the effective contact rate between vector and host and therefore the predicted disease incidence is less than when a bilinear contact rate is used.
The effect of dose and mobility on the strength of selection for DMI fungicide resistance in inoculated field experiments
Authors: Metcalfe R. J. , Shaw M. W. , Russell P. E.
Published: March 2003

Plots of spring wheat cv. Baldus were inoculated at GS 13 with four Mycosphaerella graminicola isolates, two relatively susceptible and two relatively resistant to DMI fungicides. Changes in the ratio of relatively susceptible to resistant types following fungicide or water sprays were measured. Three fungicides were compared: flutriafol, which is very mobile within leaves, fluquinconazole, which is less so, and prochloraz, which is almost immobile. All are inhibitors of sterol demethylation. In 1996, fungicide‐treated plots were sprayed once with half the recommended dose at GS 39–47. In 1997, three doses were used: one‐quarter and one‐eighth of the recommended dose and a dual application of two one‐eighth recommended doses, a week apart. Isolates were classified using a discriminating dose assay and the ratio of relatively susceptible to relatively resistant isolates in each field plot before and after fungicide application calculated. In both years, the numbers of relatively susceptible and relatively resistant isolates were equal just before fungicide application. All fungicides caused significant selection towards resistance, but the strength of selection varied with fungicide, dose and position in the crop canopy. Fluquinconazole selected most strongly and gave the best control of disease. Interactions between fungicide and dose were not significant. Selection was equally strong all along leaves sprayed with prochloraz, but increased smoothly from base to tip of leaves sprayed with fluquinconazole or flutriafol. Averaged over fungicides, reducing the dose of a single fungicide application from one‐quarter to one‐eighth slightly reduced selection towards resistance on both leaf layers. The dual one‐eighth dose caused twice the change of the single one‐eighth dose on the flag leaf, but was similar to a single spray on leaf 2.
Development of phoma lesions on oilseed rape leaves inoculated with ascospores of A‐group or B‐groupLeptosphaeria maculans(stem canker) at different temperatures and wetness durations
Authors: Toscano‐Underwood C. , West J. S. , Fitt B. D. L. , Todd A. D. , Jedryczka M.
Published: March 2003

In controlled‐environment experiments, ascospores of both A‐group and B‐groupLeptosphaeria maculanswere able to infect leaves of oilseed rape and produce phoma leaf spot lesions at temperatures from 5 to 20°C and wetness durations from 8 to 72 h after inoculation. Lesions formed on leaves inoculated with B‐group ascospores had few pycnidia and were darker, smaller and less noticable than the larger, pale grey lesions with many pycnidia produced by A‐group ascospores. Lesions formed by A‐group or B‐groupL. maculanson naturally infected winter oilseed rape experimental crops were similar to lesions produced by the two groups on inoculated plants. The greatest numbers of lesions were produced with a leaf wetness duration of 48 h and at temperatures of 15–20°C for both A‐group and B‐group ascospores. As leaf wetness duration and temperature decreased below the optimal values, the number of lesions decreased. The incubation period, estimated as the time from inoculation to the appearance of the first lesions (t1), or the time to the appearance of 50% of the lesions (t50), of B‐group was often shorter than that of A‐groupL. maculans. As temperature decreased below 20°C, the length of the incubation period of both A‐group and B‐groupL. maculansincreased.
Comparative aggressiveness of standard and variant hybrid alder phytophthoras, Phytophthora cambivora and other Phytophthora species on bark of Alnus, Quercus and other woody hosts
Authors: Brasier C. M. , Kirk S. A.
Published: March 2003

Pathogenicity tests were carried out on the bark of Alnus glutinosa with 19 isolates of the standard (near‐tetraploid) hybrid alder phytophthora, nine isolates representing its known heteroploid variants and 11 isolates of P. cambivora, a probable parent species of the hybrid. Over a 4‐year period, 12 experiments were conducted on living alder logs incubated at 20°C. Most isolates of the standard hybrid and those of the ‘Dutch variant’ were highly aggressive to alder bark. Isolates of the ‘Swedish’, ‘UK’ and ‘German variants’, and of P. cambivora, were only weakly pathogenic. Also, isolates of P. fragariae, P. cinnamomi, P. sp. ‘O‐group’, P. cryptogea, P. megasperma, P. gonapodyides and P. citricola were either weakly or nonpathogenic. Rates of lesion development were greatest on logs cut during July–October, slower on logs cut between November and March and zero on logs cut during April, indicating a strong seasonal effect. Other evidence indicated that lesion development was subject to critical thresholds of host resistance. The standard hybrid was nonpathogenic to the bark of four other hardwood and two conifer species, indicating that it is relatively host specific. In contrast, P. cambivora was an aggressive pathogen on live bark of Quercus and Castanea. The significance of these results is discussed.
Metalaxyl sensitivity of isolates of Phytophthora erythroseptica in Prince Edward Island
Authors: Peters R. D. , Sturz A. V. , Matheson B. G. , Arsenault W. J. , Malone A.
Published: March 2003

Isolates of Phytophthora erythroseptica, causal agent of pink rot of potato, were obtained from diseased tubers collected in Prince Edward Island (PEI), Canada. In an in vitro assay of field and single‐zoospore isolates, all isolates of the pathogen from PEI were sensitive to metalaxyl (EC50 < 0·5 µg mL−1), unlike moderately or highly resistant reference isolates obtained from Maine, USA. Allozyme‐banding patterns at the glucose‐6‐phosphate isomerase (Gpi) locus were identical (91/91) for all isolates of P. erythroseptica examined from PEI and Maine, but could be used to distinguish isolates of P. erythroseptica from local isolates of Phytophthora infestans. Inoculation of potato tubers from plants treated with foliar applications of metalaxyl in the field indicated that compounds inhibitory to metalaxyl‐sensitive isolates of P. erythroseptica were present in the periderm, even after 4 months' storage. By contrast, moderately or highly resistant isolates of the pathogen caused significantly (P ≤ 0·05) more disease than sensitive isolates in tubers from plants treated with metalaxyl. The effectiveness of metalaxyl in controlling pink rot in a particular region will depend on resistance levels of local populations of P. erythroseptica. Preventing the development and spread of resistant strains of P. erythroseptica will be critical in maintaining metalaxyl as an effective chemical for control of this pathogen.
Seasonal patterns of dispersal of ascospores ofCryphonectria parasitica(chestnut blight)
Authors: Guerin L. , Froidefond G. , Xu X.‐M.
Published: March 2003

Infected barks of chestnut blight cankers, caused byCryphonectria parasitica, were collected from a naturally infected orchard and incubated at different temperatures. Cankers started to discharge ascospores about a week after incubation at 15–25°C; most ascospores were collected at 20 and 25°C. When incubated at 5, 10 or 30°C, only a few cankers released a small number of ascospores and only during the later stages of incubation. However, the rate of formation of perithecia was not affected by the incubation temperature. The number of airborne ascospores was monitored using a volumetric spore trap in a chestnut orchard during 1996 and 1997. In both years, the number of ascospores trapped daily varied greatly, but in general it increased sharply from March onwards, reached a peak in May, and then declined steeply. There was a significant correlation between daily counts of ascospores and air temperature. Time‐series transfer function (TF) analysis showed a positive association of the daily number of ascospores with increasing temperature, rain events and wet/humid conditions. In general, values predicted by the TF model agreed well with the observed pattern. However, a multiple regression equation based on TF analysis failed to provide a satisfactory prediction of the daily number of ascospores.
Root infection by Phytophthora cinnamomi in seedlings of three oak species
Authors: Robin C. , Capron G. , Desprez‐Loustau M. L.
Published: March 2003

The combination of soil infestation with Phytophthora cinnamomi and repetitive flooding was studied on 1‐year‐old plants of Quercus ilex (holm oak) and Q. suber (cork oak). In a second experiment, using 2‐year‐old plants of the same species and of red oak (Q. rubra), the soil infestation was followed by two drought‐rewatering cycles. Oak predawn leaf water potential (PLWP) and stomatal conductance (gs) were monitored during both experiments. Root infection, root loss, wilting and mortality were assessed at the end of the experiments. Q. ilex exhibited the highest susceptibility to P. cinnamomi, and Q. rubra the lowest. Root infections caused by P. cinnamomi were more severe in the flooding than in the drought experiment. The most noticeable effect of the infection on plant water relations was a decrease in stomatal conductance. This occurred at different times after inoculation, varying with species susceptibility and experiment. Inoculation with P. cinnamomi induced a decrease of PLWP in Q. ilex plants, and in some Q. suber plants exhibiting a severe root loss. The results further showed that the relationship between PLWP and gs was modified by infection with P. cinnamomi. The combination of flooding and infection with P. cinnamomi acted synergistically on the water relations of Q. ilex. By contrast, there was no significant increase in disease severity due to the postinoculation water stress imposed on the oaks.
Bacterial leaf blight of strawberry (Fragaria (x) ananassa) caused by a pathovar of Xanthomonas arboricola, not similar to Xanthomonas fragariae Kennedy & King. Description of the causal organism as Xanthomonas arboricola pv. fragariae (pv. nov., comb. nov.)
Authors: Janse J. D. , Rossi M. P. , Gorkink R. F. J. , Derks J. H. J , Swings J. , Janssens D. , Scortichini M.
Published: March 2003

A new bacterial disease of strawberry is described. This disease, called bacterial leaf blight of strawberry, is characterized by dry, brown necrotic leaf spots and large brown V‐shaped lesions along the leaf margin, midrib and major veins. Symptoms are different from angular leaf spot of strawberry caused by the bacterium Xanthomonas fragariae. Strains of the bacterial leaf blight pathogen were characterized in a polyphasic approach by biochemical tests, fatty acid analysis, protein electrophoresis, serology, PCR, pigment analysis, ice‐nucleation activity, AFLP analysis, DNA:DNA hybridization, pathogenicity and host range tests, and compared with a number of reference strains of X. fragariae and other Xanthomonas species. Bacterial leaf blight strains formed a homogeneous group in all tests, completely different from X. fragariae. They were the only strains causing leaf blight of strawberry upon artificial inoculation into strawberry. Fatty acid and protein electrophoretic analysis showed that the strains belong to the phenon X. campestris (sensu latu, including pathovars now classified as belonging to X. arboricola). AFLP analysis and DNA:DNA hybridization further clarified their taxonomic position as belonging to X. arboricola. The name X. arboricola pv. fragariae is proposed for the bacterium causing leaf blight of strawberry with strain PD2780 (LMG 19145) as pathovar type strain. Criteria for routine identification are given and the taxonomic status is discussed.
Symptom severity of cassava mosaic disease in relation to concentration of African cassava mosaic virus in different cassava genotypes
Authors: Ogbe F. O. , Atiri G. I. , Dixon A. G. O. , Thottappilly G.
Published: March 2003

The concentration of African cassava mosaic virus (ACMV) was assessed by enzyme‐linked immunosorbent assay in relation to symptom severity among resistant, moderately resistant and susceptible cassava genotypes. Resistant genotype NR 8083 had significantly lower symptom severity scores (P < 0·05) than the susceptible genotype TMS 91934, but the two genotypes contained similar levels of virus concentration. The moderately resistant genotypes TMS 30572 and NR 8082 expressed significantly lower symptom severities (P < 0·05) than the susceptible genotypes TMS 91934 and TME 117, but they contained significantly higher virus concentrations (P < 0·05) than TMS 91934 and similar virus concentration as in TME 117. However, two other resistant genotypes, TME 1 and TME 8, had low symptom severity scores and virus concentrations. There was significant interaction (P ≤ 0·05) between cropping season and virus concentration in all the genotypes except TMS 30572. The resistant and moderately resistant genotypes that had high virus concentrations sustained storage root yield losses. The severity of symptoms expressed was not necessarily a reflection of the virus concentration in some of the genotypes. In addition to the use of symptom severity scores to group genotypes into resistant classes, it is recommended that virus concentration should also be considered. Genotypes displaying mild symptoms, but with high levels of virus accumulation, could be an important source of inoculum in the spread of ACMV by the whitefly vectors. This suggests that each genotype should be tested for virus accumulation prior to its release to the farmers.
Lack of Polarized Type 1 or Type 2 Cytokine Profile in Asymptomatic HIV‐1‐Infected Patients During a Two‐Year Bimonthly Follow‐Up
Authors: Canaris  , Caruso  , Licenziati  , Cantalamessa  , De Francesco  , Fallacara  , Fiorentini  , Dima  , Martinelli  , Manca  , Balsari  , Turano
Published: March 2003

The production of type 1 (interferon or IFN‐γ) and type 2 (interleukin or IL‐4 and IL‐10) cytokines by mitogen‐stimulated peripheral blood mononuclear cells (PBMCs) obtained from asymptomatic human immunodeficiency virus‐seropositive (HIV+) patients untreated with any antiviral, antibacterial or antimycotic drugs, and from healthy individuals, was evaluated by quantitative ELISA. Patients who were HIV+ were characterized by the absence of abnormal cytokine production. The level of each cytokine differed among individuals in the same group with intersubject variations greater for HIV+ patients than for healthy individuals. The longitudinal evaluation of IFN‐γ, IL‐4 and IL‐10 production showed intrasubject variations which were particularly marked in HIV+ patients. Accordingly, HIV+ patients and, to a lesser extent, healthy individuals were characterized by a wide spectrum of possible profiles, which were confined to type 0 phenotype. In HIV+ patients no correlation was found between each cytokine level and the number of CD4+ T cells, not even in those with a falling CD4+ T‐cell count and clinical symptoms.
Characterization of the T‐Cell Receptor V‐β Repertoire in Kawasaki Disease
Authors: Mancia  , Wahlström  , Schiller  , Chini  , Elinder  , D'argenio  , Gigliotti  , Wigzell  , Rossi  , Grunewald
Published: March 2003

Kawasaki disease (KD) is a paediatric multisystem necrotizing vasculitis constituting the most frequent cause of acquired heart disease in childhood. Conflicting data have been reported regarding expanded T‐cell populations using particular T‐cell receptor (TCR) β‐chain variable (BV) gene segments, suggesting either a superantigen‐ or a conventional antigen‐mediated immune response in this disease. In order to further investigate the role of T lymphocytes, cells were stained with an extensive panel of 21 different TCRBV specific monoclonal antibobies (MoAbs) covering almost 70% of all T‐cells. Flow cytometry was employed to analyse the expression of the TCRBV repertoire in the CD4+ and CD8+ subsets separately, and of activation markers, in freshly isolated peripheral blood lymphocytes of 25 Kawasaki disease patients during the acute and convalescent phases of the disease. No abnormal usage of any TCRBV family was found, neither acutely nor during convalescence, compared with a control group of healthy children. However, a significant increase in interleukin‐2 receptor (IL‐2R)‐expressing T lymphocytes restricted to the CD4+ subset was observed in KD patients. Our data confirm a strong immune activation in KD that might be of importance in the pathogenesis of the disease.
Costimulatory Function of CD28 in Avian γδ T Cells is Evolutionarily Conserved
Authors: Koskela  , Arstila  , Lassila
Published: March 2003

CD28 costimulatory signals are required for T‐cell proliferation and lymphokine production. In this work, the functional conservation of CD28 was studied in avian γδ T cells. The avian CD28 molecule is expressed on all αβ T cells and is capable of giving a costimulatory signal. Most peripheral γδ T cells are CD28 negative; however, we identified a CD28‐positive γδ T‐cell subset from peripheral blood comprising about 12% of γδ T cells. The peripheral CD28+γδ T‐cell subset included all CD8+γδ T cells known to be a responding subset during activation. After polyclonal activation, the frequency of CD28+γδ T cells was increased and the activation also up‐regulated CD5, CD25 and major histocompatibility complex (MHC) class II molecules. These changes were detected after both polyclonal and antigen‐specific T‐cell activation. In addition, we also showed that CD28 can give a costimulatory signal to γδ T cells and that this signal leads to up‐regulation of IL‐2 and bcl‐x transcripts. These results indicate that the function of CD28 is evolutionarily conserved and can already be detected in avian γδ T cells.
Irregular Cytokine Pattern of CD4+ T Lymphocytes in Response to Staphylococcus aureus in Patients with Wegener's Granulomatosis
Authors: MAYET  , MÄRKER‐HERMANN  , SCHLAAK  , MEYER ZUM BÜSCHENFELDE
Published: March 2003

The initial stage of Wegener's Granulomatosis (WG) is often marked by symptoms of infection and it has been postulated that a bacterial infection could be the aetiologic factor of this disease. The objective of our work was to investigate T‐cell‐mediated immunity in WG by testing proliferative responses on bacterial antigens and particularly Staphylococcus aureus. We investigated the bulk proliferative response of peripheral blood lymphocytes (PBL) from patients with clinically active WG to gram‐positive bacteria and purified proteinase 3 (PR‐3), the major target antigen of c‐ANCA. We generated S. aureus‐specific PBL‐derived T‐cell lines and T‐cell clones (TLC). In two WG patients 27 TLC were characterized in terms of reactivity to bacterial antigens/PR‐3, phenotype, HLA class II restriction and pattern of cytokine secretion. Compared to coagulase‐negative Staphylococci and beta‐haemolytic Streptococci A, reactivity to S. aureus was significantly increased in all patients with WG. Using purified PR‐3, we found a PBL proliferation in five out of 25 WG patients. The TLC were S. aureus‐specific and did not cross‐recognize Streptococci or coagulase‐negative Staphylococci. The S. aureus‐specific TLC were of the αβ‐TCR+ CD4+ phenotype and HLA‐DR‐restricted. These TLC predominantly showed a Th2‐type of cytokine secretion. Interestingly, seven of the S. aureus‐reactive TLC also recognized the PR‐3 antigen. From these data we conclude that Staphylococci‐specific HLA‐DR‐restricted CD4+ T cells may play a key role in the initial triggering of immune responses in WG.
Interleukin‐10 Produced by the Innate Immune System Masks In Vitro Evidence of Acquired T‐Cell Immunity to E. coli
Authors: Hessle  , Hanson  , Wold
Published: March 2003

Bacteria trigger stimulation of antigen‐specific, as well as innate, immune responses. Cytokines and other products of cells belonging to the innate immune system may interfere with the detection of acquired immunity to whole bacteria in vitro. Proliferation and cytokine production by human blood mononuclear cells in response to a whole UV‐killed Escherichia coli was compared with the response to commonly used antigen preparations: purified protein derivative (PPD), Candida albicans and influenza proteins. E. coli induced a weaker proliferative response with later onset than did the other antigens, and production of interferon (IFN)‐γ comparable with that in response to C. albicans and influenza vaccine, but lower than that induced by PPD. Both proliferation and IFN‐γ production were abolished by removal of CD4 cells or blocking of HLA‐D, but not CD1 antigen‐presenting molecules. Purified lipopolysaccharide (LPS) induced neither proliferation nor IFN‐γ production. None of the antigen preparations stimulated interleukin (IL)‐4 production but, in contrast to the other antigens, whole E. coli, as well as purified O6 LPS, induced large quantities of IL‐10. IL‐10 production was independent of CD4 cells or HLA‐D molecules. Blocking of IL‐10 by neutralizing antibodies increased both E. coli‐induced proliferation and IFN‐γ production markedly. Conversely, the addition of whole E. coli or LPS to cultures stimulated with other antigens (C. albicans or Staphylococcus aureus) down‐regulated proliferative and IFN‐γ responses, an effect which was at least partly IL‐10 dependent. The results indicate a substantial T‐cell memory to commensal E. coli, but suggest that the evidence of such memory, e.g. proliferation and IFN‐γ production, is effectively prevented by IL‐10 and perhaps other factors produced by monocytes in response to bacteria. Thus, the innate immune responses must be taken into account when acquired immune responses to microbes are measured.
Evaluation of Diagnostic Tests for Antinuclear Antibodies in Rheumatological Practice
Authors: Ulvestad  , KanestrøM  , Madland  , Thomassen  , Haga  , Vollset
Published: March 2003

To investigate and compare the accuracy and usefulness of diagnostic tests for antinuclear antibodies (ANA) a cross‐sectional study of sera derived from patients admitted to the Department of Rheumatology was tested for the presence of ANA using either indirect immunofluorescence on HEp‐2 cells, indirect immunoperoxidase techniques on HEp‐2 cells and mouse kidney, or two commercial enzyme‐linked immunosorbent assays (ELISA). The diagnostic sensitivity and predictive values of the tests were calculated and compared. The accuracy of tests was compared using receiver‐operating characteristics (ROC) methodology. All ANA‐positive sera were further analysed for the presence of antibodies against extractable nuclear antigens (anti‐ENA) and anti‐DNA. A moderate to good agreement was found between tests, with κ ranging from 0.469 to 0.659. Highest sensitivity for systemic lupus erythematosus (SLE; 93.3%) and primary Sjögren's syndrome (SS; 70%) was found using immunofluorescence on HEp‐2 cells. Immunofluorescence on HEp‐2 cells performed statistically better than the other tests in predicting SLE but not SS. All tests except mouse kidney showed good and comparable performance in detecting sera with anti‐ENA and anti‐DNA. At the given cut‐off values indirect immunofluorescence on HEp‐2 cells performed best. All assays except mouse kidney showed performance characteristics sufficient for use in routine analysis of ANA.
In Search of the Origin of the Thymus: the Thymus and GALT May Be Evolutionarily Related*
Authors: Matsunaga T. , Rahman A.
Published: March 2003

The thymus is the major primary immune tissue for the production of functional T lymphocytes in vertebrates. However, its evolutionary origin is unknown. It has recently been shown that the generation of local T cells also occurs in gut‐associated lymphoid tissues (GALT). This suggests that the thymus and GALT have similar functions and that they might be evolutionarily related. We discuss the possibility that the thymus may have evolved from mucosa‐associated lymphoid tissues (MALT) located in the gill region in early vertebrates. Various facts supporting this proposal are summarized.
Activation of T Cells in the Blood of Patients with Acute Malaria: Proliferative Activity as Indicated by Ki‐67 Expression
Authors: Worku S. , Troye‐Blomberg M. , Christensson B. , Björkman A. , Fehniger T.
Published: March 2003

The expression of the proliferation‐associated nuclear antigen Ki‐67 in peripheral blood mononuclear cells was studied in 30 patients with acute malarial illness and 11 healthy controls from Addis Ababa or Nazareth in Ethiopia. Seventeen patients had Plasmodium falciparum infections and 13 had Plasmodium vivax. Two‐colour immunoenzymatic staining was developed in order to simultaneously detect the expression of the nuclear antigen Ki‐67 and determine the surface phenotype of the cell. The median percentage of proliferating, Ki‐67 positive lymphocytes was significantly higher in patients with acute P. falciparum (11.8%) and P. vivax (15.6%) illnesses compared to the controls (4.3%). The majority of Ki‐67 positive cells were T cells (CD3+) while the relative increase of Ki‐67 expressing cells was similar for both the CD4+ and CD8+ T‐cell subsets. Our data show an increased number of activated cells driven to proliferation in the peripheral blood of patients during acute malaria illness.
Intranasal Administration of One Alpha Gliadin Can Downregulate the Immune Response to Whole Gliadin in Mice
Authors: Maurano F. , Siciliano R. A. , De Giulio B. , Luongo D. , Mazzeo M. F. , Troncone R. , Auricchio S. , Rossi M.
Published: March 2003

The mucosal lesion present in coeliac disease is an immune‐mediated injury triggered by gliadin and restricted by a particular assortment of major histocompatibility complex genes. In view of this, an immunomodulatory approach that induces tolerance to this antigen appears to be a possible alternative to a strict gluten‐free diet in treating coeliac disease. We have shown that intranasal administration of multiple doses of whole gliadin is required to specifically inhibit T helper 1‐like T‐cell reactivity in BALB/c mice immunized parenterally with whole gliadin. However, T‐cell activation to multiple antigens, as a consequence of the chemical complexity shown by the antigen gliadin, could hamper efforts to identify single component(s) useful for tolerance induction. In this study, gliadin fractions were purified and administered intranasally to study their ability to induce tolerance to whole gliadin in our animal model. We found that the alpha fraction was particularly effective in downregulating both the in vitro gliadin‐specific T‐cell proliferation and interferon‐γ production to whole gliadin. In particular, a purified α‐gliadin was able to suppress the immune response to the entire gliadin mixture. These results demonstrate how an immune response to a complex antigen may be controlled by treatment with a purified component and specifically indicate α‐gliadin to be a good candidate for further identification of short peptides to be used as tolerogens in this model.
Elevated Levels and Different Repertoire Profile of Colostral Anti‐LPS Antibodies May Have a Significant Role in Compensating Newborn Immunity
Authors: Nagao A. T. , Friedlander‐Del Nero D. , Arslanian C. , Carneiro‐Sampaio M. M. S.
Published: March 2003

A high prevalence of systemic infections caused by enterobacteria such as Escherichia coli is observed during the neonatal period. Lipopolysaccharide (LPS) is one of the major factors responsible for septic shock caused by these Gram‐negative bacteria. We have recently demonstrated the presence of anti‐LPS immunoglobulin (Ig)G antibodies in cord blood with a repertoire identical to that found in maternal serum. In the present study, we analyzed anti‐LPS O111 antibody isotypes in maternal serum and colostrum from mothers and in cord serum from their respective full‐term (n = 30) and preterm (n = 13) neonate infants. The main isotype found in serum samples from mothers of term infants was IgM (range between 28 and 54 mg/l), followed by IgA (1–2 mg/l) and IgG (2–3 mg/l). The range of IgG antibody concentrations in cord blood was between 2 and 3 mg/l, as a result of placental transfer. A novel observation in our study was that the LPS bands recognized by colostral antibodies were completely different from those recognized by IgG in serum. Colostral IgA antibodies recognized several bands not bound by serum IgG antibodies from the respective maternal serum, independently of the antibody quantity. In addition, we verified the pattern of LPS recognition by serum IgA and colostral IgA antibodies was identical, what suggested that the antibody isotype found in serum could probably be derived from differentiated IgA‐positive cells which were homing to the mucosa through the mucosal homing mechanism. Identical pattern of recognition was obtained comparing the IgA and IgM isotypes in colostrum. Slight differences in the pattern of recognition were found between colostral and serum IgM antibodies. The fact that colostral antibodies recognize much more bands than serum antibodies may be important for the host to mount an effective immune response in the intestinal lumen, in order to prevent excessive absorption of LPS, reducing possible systemic effects caused by the molecule.
Innate IFN‐γ Production in Cattle in Response to MPP14, a Secreted Protein from Mycobacterium avium subsp. Paratuberculosis
Authors: Olsen I. , Storset A. K.
Published: March 2003

Calves experimentally infected with Mycobacterium avium subsp. paratuberculosis and uninfected calves were tested for interferon(IFN)‐γ production after stimulation with purified protein derivative from M. avium subsp. paratuberculosis (PPDp) or a secreted 14 kDa protein (MPP14) specific for the M. avium‐intracellulare‐scrofulaceum (MAIS) complex. Several calves in both groups responded strongly up to about 5 months to both antigens. Two uninfected calves responded repeatedly, but not always, to MPP14 and PPDp throughout the study. The responses in the uninfected animals seemed to be independent of cell contact between the antigen presenting cells (APC) and the responding population. The supernatant from adherent cells stimulated with MPP14 induced similar levels of IFN‐γ production in CD14+/B‐cell depleted peripheral blood mononuclear cells (PBMC) as when the antigen was used directly on PBMC. In contrast, APC/T‐cell contact was necessary to induce the IFN‐γ production in infected animals, suggesting that both innate and adaptive IFN‐γ production in response to MPP14 could occur. CD8+ cells contributed to some of the IFN‐γ production in response to MPP14, but the rest could not be explained, while CD4+ cells were responsible for the adaptive response to PPDp. This study showed that secreted proteins could induce innate IFN‐γ production that interferes with diagnostic testing using the IFN‐γ‐test.
CD26: A Multifunctional Integral Membrane and Secreted Protein of Activated Lymphocytes
Authors: Gorrell M. D. , Gysbers V. , McCaughan G. W.
Published: March 2003

CD26 has proved interesting in the fields of immunology, endocrinology, cancer biology and nutrition owing to its ubiquitous and unusual enzyme activity. This dipeptidyl aminopeptidase (DPP IV) activity generally inactivates but sometimes alters or enhances the biological activities of its peptide substrates, which include several chemokines. CD26 costimulates both the CD3 and the CD2 dependent T‐cell activation and tyrosine phosphorylation of TCR/CD3 signal transduction pathway proteins. CD26 in vivo has integral membrane protein and soluble forms. Soluble CD26 is at significant levels in serum, these levels alter in many diseases and soluble CD26 can modulate in vitro T‐cell proliferation. CD26, being an adenosine deaminase binding protein (ADAbp), functions as a receptor for ADA on lymphocytes. The focus of this review is the structure and function of CD26 and the influence of its ligand binding activity on T‐cell proliferation and the T cell costimulatory activity of CD26.
A Heat‐Stable Component of Bartonella henselae Upregulates Intercellular Adhesion Molecule‐1 Expression on Vascular Endothelial Cells
Authors: Maeno N. , Yoshiie K. , Matayoshi S. , Fujimura T. , Mao S. , Wahid M. R. , Oda H.
Published: March 2003

Bartonella henselae upregulated the expression of intercellular adhesion molecule‐1 (ICAM‐1) on human umbilical vein endothelial cells (HUVECs). The induction level of ICAM‐1 depended on the inoculation bacterial dose. ICAM‐1 expression began increasing 4 h after infection and reached a sustained peak beginning at 12 h after B. henselae infection; this time course was similar to that of lipopolysaccharide (LPS) of Escherichia coli. The stimulatory effect was abolished when live B. henselae were separated from HUVECs by a filter membrane. The nonpiliated strain, which is unable to invade endothelial cells, induced ICAM‐1 expression to the same extent as the piliated strain. Inactivation of B. henselae by ultraviolet (UV) irradiation, heat (56 °C, 30 min), or sonication did not alter its stimulatory activity. Polymyxin B, which strongly inhibited the effect of LPS, did not exert any influence on the stimulatory activity of B. henselae. Furthermore, the effect of sonicated B. henselae was not inhibited even by boiling, which was also the case with LPS. Our data suggest that some heat‐stable component of B. henselae binds to the endothelial cell surface, inducing ICAM‐1 expression. Though the participation of LPS could not be completely ruled out, we suppose that some unidentified heat‐stable proteins, lipids, or polysaccharides may be the stimulatory factor(s). The ability of B. henselae to enhance the expression of adhesion molecules on endothelial cells may be an important mechanism in the pathogenesis of B. henselae infection.
Age‐Related Changes in Human Blood Dendritic Cell Subpopulations
Authors: Teig N. , Moses D. , Gieseler S. , Schauer U.
Published: March 2003

It is well known that the human immune system is functionally less mature at birth and, within the first years of life, undergoes a process of sequential development. Two subsets of dendritic cells (DCs) were identified in the blood: plasmacytoid and myeloid DCs. DCs stain negative for CD3, CD14, CD16, CD19, CD20 and CD56, and positive for human leucocyte antigen (HLA)‐DR. In addition, plasmacytoid DCs strongly express CD123 while myeloid DCs express CD11. The number of the two different subsets was measured by flow cytometry in the peripheral blood from 44 healthy infants and children, aged 8 months to 18 years. While the number of CD11c+ myeloid cells (mean 11 cells/µl) did not change with age, the proportion of CD123+ plasmacytoid DCs decreased significantly (P < 0.001) from about 20 cells/µl to 8 cells/µl with age. In addition, we found a direct correlation between the number of plasmacytoid DC and interferon (IFN)‐α production. As the two subsets of DC preferentially recognize different pathogens, age‐related changes may have an impact on the maturation of the immune response.
Differential Expression of Cytokines (IL‐2, IFN‐γ, IL‐10) and Adhesion Molecules (VCAM‐1, LFA‐1, CD44) Between Spleen and Lymph Nodes Associates with Remission in Chronic Relapsing Experimental Autoimmune Encephalomyelitis
Authors: YANG J. , LINDSBERG P. J. , HUKKANEN V. , SELJELID R. , GAHMBERG C. G. , MERI S.
Published: March 2003

We have recently established chronic relapsing experimental autoimmune encephalomyelitis (CR‐EAE) in SJL mice with a modified protocol. In this model, splenectomy aborts the relapsing–remitting course of the disease, and adoptive transfer of lymphocytes of the local draining lymph nodes (LNs) to naive recipients exacerbates the disease. Adoptive transfer of splenic cells converted acute EAE into CR‐EAE in the naive recipients. In light of the different roles of the spleen and LNs in the evolution of CR‐EAE, we examined by semiquantitative reverse‐transcription polymerase chain reaction (RT‐PCR) whether a differential mRNA expression profile of cytokines and cellular adhesion molecules (CAMs) in spleen versus LN was associated with relapse or remission in CR‐EAE. All the cytokines tested (interleukin‐1β (IL‐1β), IL‐2, IL‐4, IL‐7, IL‐10, interferon‐γ (IFN‐γ)) as well as CAMs (ICAM‐1, ICAM‐2, VCAM‐1, LFA‐1 and CD44) were expressed at substantial levels in both spleen and LNs. Interestingly, disease remission was found to be associated with an increased mRNA expression of IL‐2 and IFN‐γ in LNs and a decreased IL‐10 mRNA level in the spleen. On the other hand, an increased mRNA expression of VCAM‐1, LFA‐1 and CD44 was observed in the spleens in comparison with that in LNs of mice, with remission. During relapses, mRNA expression of the tested molecules did not significantly differ between spleens and LNs. Our results suggest that a differential and polarized expression profile of certain cytokines and CAMs in spleen versus LN could provide molecular correlates of the cyclic pathogenesis of CR‐EAE.
Neutralization Titres and Vertical HIV‐1 Transmission
Authors: Bongertz V. , Costa C. I. , Veloso V. G. , Grinsztejn B. , Filho E. C. J. , Calvet G. , Pilotto J. H.
Published: March 2003

Replication of the human immunodeficiency virus type 1 (HIV‐1) isolate MN in CEM cells was less neutralized by the plasma from the mothers of infected children (MIC) in comparison with the plasma from the mothers of uninfected children (MUC). Significantly higher neutralization titres were observed for the sera from MUCs compared with MICs, and only the sera from MUC showed 100% neutralization of the HIV‐1 MN strain. We suggest that a simple neutralization assay as described here could be useful in prognostic analyses.