The virulence of Pasteurella multocida (P. multocida) serotype A1 for chickens and mice was determined. Groups of chicken and mice were exposed intramuscularly and intraperitoneally to various concentration of P. multocida broth culture, respectively. This strain was highly virulent for chickens so that those exposed to only 7 c.f.u. of the organism died in less than 24 hours. Groups of mice ex...

The Brucella abortus strain S19, a spontaneously attenuated strain, has been used as a vaccine strain in vaccination of cattle against brucellosis for six decades. Despite many studies, the physiological and molecular mechanisms causing the attenuation are not known. We have applied pyrosequencing technology together with conventional sequencing to rapidly and comprehensively determine the comp...

We investigated the susceptibility of virulent and avirulent strains of Haemophilus ducreyi to the bactericidal activity of normal human serum and to phagocytosis and killing by human polymorphonuclear leukocytes (PMNL). Strains were defined as virulent if intradermal inoculation into a rabbit produced a typical necrotic lesion. Nonvirulent strains produced no cutaneous lesions in rabbits. Viru...

The pectic enzymes produced in vitro by 8 isolates (5 Highly virulent and 3 Weakly virulent) of Fusarium oxysporum , were detected by spectrophotometry, and characterized by polyacrylamide gel electrophoresis with substrate-containing gels (zymogram). Analysis of the polygalacturonase (PG) isozyme banding patterns (zymogram) identified two distinct phenotypes among the isolates from chickpea (C...

Aeromonas hydrophila is the most common Aeromonas species causing infections in human and other animals such as amphibians, reptiles, fish and crustaceans. Pathogenesis of Aeromonas species have been reported to be associated with virulence factors such as lipopolysaccharides (LPS), bacterial toxins, bacterial secretion systems, flagella, and other surface molecules. Several mutant strains of A...

Recent reports have demonstrated that Bordetella pertussis has invasive behavior in vivo and in vitro. In this study, we investigated the ability of a virulent strain, avirulent mutants, and mutants deficient in specific virulence factors to enter and survive intracellularly in human macrophages in vitro. Uptake of virulent B. pertussis was dose dependent and occurred in the absence of serum or...

background: diarrhea, caused by enteroaggregative escherichia coli (eaec), is an important cause of illness and death. numerous virulent factors have been described in eaec. however, their prevalence was highly variable among eaecs of distinct geographic locations. studies have shown that dispersin (antiaggregation protein, aap) is one of the important and abundant virulent factors in eaec. in ...