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The present study aimed at the molecular characterization of pathogenic and non pathogenic F. oxysporum f. sp. lycopersici strains isolated from tomato. The causal agent isolated from symptomatic plants and soil samples was identified based on morphological and molecular analyses. Pathogenicity testing of 69 strains on five susceptible tomato varieties showed 45% of the strains were highly viru...

A new class of pyrrolo[2,3-d] pyrimidine derivatives has been designed and synthesized, then examined and evaluated for their antiviral and antibacterial activity. New prophylactic therapeutic tools are needed for the treatment of highly pathogenic avian influenza (HPAI) H5N1 and highly virulent Newcastle disease virus (NDV). 3a, 3b, 3g, 3h have shown to posses highly potent against highly path...

Francisella tularensis is a highly virulent bacterium that is capable of causing severe disease (tularemia) in a wide range of species. This organism is characterized into two distinct subspecies: tularensis (type A) and holarctica (type B) which vary in several crucial ways, with some type A strains having been found to be considerably more virulent in humans and laboratory animals. Cottontail...

Virulence variability was investigated by analyzing the experimental pathogenicity of seven Leishmania tropica strains isolated from human lesions in Syria, through the evaluation of the infective ability, growth pattern and pathogenicity. Two of the strains presented higher levels of macrophage infection, increased promastigote replication in culture medium and as well as amastigote multiplica...

A new character, the A marker, for polioviruses is described. In the presence of Al(+++) (1 to 100 mM) attenuated, but not virulent, strains of type 1 and type 2 polioviruses are stabilized so that they resist thermal inactivation at 50 degrees C. Differences between the attenuated and virulent type 3 strains studied were of the opposite character and less marked. By the use of optimal concentr...

Previous studies have demonstrated that the four subspecies of the human pathogen Francisella tularensis, despite showing marked variations in their virulence for mammals and originating from different regions in the Northern Hemisphere, display a very close phylogenetic relationship. This property has hampered the development of generally applicable typing methods. To overcome this problem, we...

The bacterial factors responsible for the variation in invasive potential between different clones and serotypes of Streptococcus pneumoniae are largely unknown. Therefore, the isolation of rare serotype 1 carriage strains in Indigenous Australian communities provided a unique opportunity to compare the genomes of non-invasive and invasive isolates of the same serotype in order to identify such...

A triple one-step RT-PCR was developed to screen and differentiate virulent from avirulent Newcastle disease virus (NDV) isolates. Three sets of oligonucleotides were designed, each specific for amplifying NDV fusion protein gene-specific RNA from virulent, avirulent or all isolates respectively. The sensitivity of one-step RT-PCR was determined using viral RNA extracted from serially diluted N...