Authors:G. Kulcsár, P. Soós, L. Kucsera, R. Glávits and V. Pálfi
The biological properties of bovine viral diarrhoea virus (BVDV) strain Oregon C24V were studied after intranasal and subcutaneous infection of pregnant sows. This virus strain is widely used in Hungary for immunising cattle against bovine viral diarrhoea (BVD). Based upon the results of the clinical, gross pathological, histopathological and virological examinations it can be established that the given strain caused asymptomatic infection and serological conversion in sows that were in the second third of gestation. The virus caused clinically apparent disease in some of the piglets born at term, which indicates that it had crossed the placenta. More than half (57%) of the live-born piglets died within 60 days of birth. The sows and their progeny did not shed the virus. BVDV infection has great differential diagnostic importance in pigs, as classical swine fever (CSF) virus strains of reduced virulence cause similar clinical symptoms and gross and histopathological changes.
Authors:Angela Lacombe-Antoneli, S. Píriz and S. Vadillo
The present study reports on the location of major foci of footrot in goats in the Extremadura region of Spain by the determination of locally occurring strictly anaerobic microorganisms involved in the pathogenesis and development of this disease. The most commonly isolated microorganisms belonged to the genera Dichelobacter, Fusobacterium, Porphyromonas and Prevotella; these were found in conjunction with other species of minor importance. The species most frequently isolated were Fusobacterium necrophorum (40%), Dichelobacter nodosus (31.7%), Porphyromonas asaccharolytica (21.1%) and Prevotella melaninogenica (12.9%). Virulence factors identified in the isolated microorganisms included haemolysins, elastases and lecithinases, which enabled the organisms involved to initiate and/or aggravate the disease. Serotyping was performed for Dichelobacter nodosus isolates, since this species is responsible for triggering the process of infection. A and C were the most frequently isolated serovarieties (representing 40.7% and 25.9% of the cases, respectively).
The possible role of fusariotoxin-fusaproliferin in Fusarium disease was investigated with respect to ultrastructure responses in the cells of maize leaves. The seedlings of resistant (Lucia) and susceptible (Pavla) maize cultivars were grown on two fusaproliferin concentrations (5 and 35 µg/mL
). Only the higher concentration caused appearance of visible symptoms on the leaves. Structural changes of chloroplasts such as dilatation of grana thylakoids in the mesophyll chloroplasts, thylakoid disorganization, and an increased number of osmiophilic globules (plastoglobuli) in the stroma were observed in mesophyll and bundle sheath chloroplasts of both cultivars. The higher toxin concentration sporadically induced severe damage to the outer chloroplast membrane. The extent of ultrastructure disturbances depended on toxin concentration and it was greater in the susceptible cultivar Pavla. Fusaproliferin may be involved in Fusarium pathogenesis as a virulence factor or, by enhancing activity of some other toxins that might be concomitantly present in the diseased plants.
Authors:Ágnes Szabó, Zoltán Sipák, András Miczák and Ildikó Faludi
Better vaccines and new therapeutic drugs could be a successful breakthrough against intracellular bacteria. M. tuberculosis ABC transporter ATPase (Rv0986) plays a role in mycobacterial virulence by inhibiting phagosome-lysosome fusion. Thus, it could be a potential vaccine candidate. C. pneumoniae another important intracellular bacterium possesses a protein named CpB0255, which is homologous with the mycobacterial Rv0986. The aim of this study was the cloning, over-expression and purification of CpB0255 ABC transporter ATPase protein to study its biological properties. The immunogenicity and protective effect of recombinant chlamydial ATPase protein combined with Alum adjuvant were investigated in mice. The immunization resulted in the reduction of the number of viable C. pneumoniae in the lungs after challenge. Our results confirm that chlamydial ATPase induces protective immunity in mice.
Authors:L. Makrai, K. Kira, A. Kono, Y. Sasaki, T. Kakuda, S. Tsubaki, L. Fodor, J. Varga and S. Takai
virulence plasmids in the isolates from infected foals, dog and monkey. Onderstepoort J. Vet. Res. 68 ,105-110.
Prevalence of virulent Rhodococcus equi in isolates from soil collected from 2 horse farms in South Africa and
Authors:Ivan Dobrosavljević, Dejan Vidanović, Maja Velhner, Biljana Miljković and Branislav Lako
Infectious bursal disease virus is an important poultry pathogen. It is distributed worldwide and causes significant economic losses. In this study, a system was adopted for the simultaneous monitoring of vaccine and virulent strains using reverse transcription polymerase chain reaction (RT-PCR). After the decay of maternal antibodies, chickens were vaccinated at the age of 37 days with a virus of intermediate virulence and challenged at 5, 10 and 14 days post vaccination (dpv). The challenge was done with IBDV strain CH/99. Sequencing of the hypervariable region of VP2 has shown that CH/99 belongs to the very virulent group of viruses. The vaccine virus could be found in the bursa of Fabricius, spleen, thymus and bone marrow until 24 dpv. The CH/99 challenge virus was found in the bursa and lymphoid organs when chickens were challenged at 5 and 10 dpv. When challenge was performed at 14 dpv, the pathogenic virus could not be found in the bursa and other lymphoid organs.
Some wild species of the genus Oryza such as O. rufipogon and O. longistaminata show a high level of resistance to pests and diseases including rice blast (caused by Magnaporthe grisea). To transfer blast resistance from wild species into cultivatedvarieties (O. sativa), interspecific hybrids were produced and anther culture was used toaccelerate the procedure of resistance breeding. Anther culture efficiency depended onboth the medium and the genotype of the cultivated varieties and the wild species. Afterinoculation with a mixture of six strains with wide spectrum virulence, all the F1 hybridswere resistant to blast; the F2 plants segregated, from high resistance to susceptibility, anda similar result was obtained for the H1 and H2 plants. At the H3 stage, blast resistancetended to be stable and almost 100% of inoculated H5 plants were highly resistant to riceblast. For agronomic characteristics, the F2 and H1 showed segregation, but no significantdifferences were seen between the cultivated parents and the H2 to H5 generations. Theresults demonstrate that blast resistance genes can be transferred from wild rice speciesinto cultivated varieties through crossing and anther culture, and the H5 can be used asstable lines in future breeding programmes.
Authors:Doris Lucyshyn, Shamsozoha Abolmaali, Hanna Weindorfer, Mehrdad Shams, Gerlinde Wiesenberger, Eva Wilhelm, Marc Lemmens and Gerhard Adam
The production of the trichothecene mycotoxin deoxynivalenol (DON) is an important virulence factor of the plant pathogenic fungus
on wheat. We have engineered a DON sensitive yeast strain and constructed a cDNA library from DON treated wheat suspension culture cells in a yeast expression vector. The library was used to select DON resistance conferring clones. Besides ORFs of unknown function, we found 3 classes of cDNAs that in addition to DON resistance conferred hypersensitivity to hygromycin and canavanine. The predicted functions of several of the wheat cDNAs (putative E3 ligase, ubiquitin specific protease, proteasome subunit) suggested a role for ubiquitin-proteasome mediated protein degradation in DON resistance. Results with a coupled wheat germ
translation system and a GUS-luciferase fusion gene showed that DON is a powerful translation elongation inhibitor. The truncated proteins formed in the presence of DON most likely lead to ubiquitin depletion and consequently growth inhibition in yeast. Ubiquitin is essential for many processes in plants, including plant defense. Our results warrant the re-evaluation of the relevance of proteasome system components found to be differentially regulated during
Authors:L. Kredics, Zsuzsanna Antal, A. Szekeres, L. Hatvani, L. Manczinger, Cs. Vágvölgyi and Erzsébet Nagy
Cellulolytic, xylanolytic, chitinolytic and b-1,3-glucanolytic enzyme systems of species belonging to the filamentous fungal genus Trichoderma have been investigated in details and are well characterised. The ability of Trichoderma strains to produce extracellular proteases has also been known for a long time, however, the proteolytic enzyme system is relatively unknown in this genus. Fortunately, in the recent years more and more attention is focused on the research in this field. The role of Trichoderma proteases in the biological control of plant pathogenic fungi and nematodes has been demonstrated, and it is also suspected that they may be important for the competitive saprophytic ability of green mould isolates and may represent potential virulence factors of Trichoderma strains as emerging fungal pathogens of clinical importance. The aim of this review is to summarize the information available about the extracellular proteases of Trichoderma. Numerous studies are available about the extracellular proteolytic enzyme profiles of Trichoderma strains and about the effect of abiotic environmental factors on protease activities. A number of protease enzymes have been purified to homogeneity and some protease encoding genes have been cloned and characterized. These results will be reviewed and the role of Trichoderma proteases in biological control as well as their advantages and disadvantages in biotechnology will be discussed.