A virulent isolate of Pseudomonas aeruginosa PAO1, which had been obtained from eight sequential intraperitoneal infections in mice compromised with iron and methotrexate, expressed greater lethality than the avirulent parent strain when both strains were injected into mice treated with iron. The present study demonstrates that pyochelin, a siderophore produced by P. aeruginosa, also increases ...

Tuberculosis is caused by Mycobacterium tuberculosis infection, and it remains major life-threatening infectious diseases worldwide. Although, M. tuberculosis has infected one-third of the present human population, only 5-10% of immunocompetent individuals are genetically susceptible to tuberculosis. All inbred strains of mice are susceptible to tuberculosis; however, some mouse strains are muc...

BACKGROUND There is increasing evidence of a strain-related variation in the virulence in Mycobacterium tuberculosis that may afford a selective advantage to certain strains. The W-Beijing strain family is globally distributed, highly virulent in animal models, associated with human immunodeficiency virus infection and drug resistance, and may be an emerging strain family. Our goal was to deter...

Newcastle disease is a viral disease of birds caused by avian paramyxovirus 1 (APMV-1). For official control purposes, this disease is currently defined as the most severe form of the illness, which is caused only by certain viral strains. Many less virulent strains of APMV-1 also circulate among domesticated and wild birds. These viruses usually cause much milder clinical signs or infect birds...

It is becoming increasingly clear that many diseases are the result of infection from multiple genetically distinct strains of a pathogen. Such multi-strain infections have the capacity to alter both disease and pathogen dynamics. Infection with multiple strains of human cytomegalovirus (HCMV) is common and has been linked to enhanced disease. Suggestions that disease enhancement in multi-strai...

The aim of this study was to compare invasive and non-invasive strains of Shigella flexneri isolated from Tehran by a 120 kDa protein band by SDS-PAGE, electron microscopy of cell culture and Congo red dye methods. Methods: S. flexneri strains were isolated by standard bacterial methods from fecal specimens of children attending to the 3 children’s hospitals. Phenotype analysis for screening v...

The objectives of this study were to compare generation and lag times of virulent Bacillus anthracis strains with those of other Bacillus strains, to identify possible surrogates for growth studies, and to determine if the B. cereus module of the U.S. Department of Agriculture Pathogen Modeling Program (PMP) had predictive value for B. anthracis. Growth characteristics of B. anthracis, B. cereu...

BACKGROUND Leptospirosis is caused by pathogenic spirochetes of the genus Leptospira. The bacteria enter the human body via abraded skin or mucous membranes and may disseminate throughout. In general the clinical picture is mild but some patients develop rapidly progressive, severe disease with a high case fatality rate. Not much is known about the innate immune response to leptospires during h...

A comparison of extracellular proteins of virulent and avirulent Edwardsiella tarda strains revealed several major, virulent-strain-specific proteins. Proteomic analysis identified two of the proteins in the virulent strain PPD130/91 as flagellin and SseB, which are virulence factors in bacterial pathogens. PCR amplification and DNA sequencing confirmed the presence of the genes that encode the...

The objective of this study was the in vitro differentiation of isolates of Salmonella enteritidis whose virulences differed in a chick model. A total of 14 strains of S. enteritidis were isolated from either the environment, dairy products, or infected patients. The isolates could be divided into two groups on the basis of their virulence (50% lethal dose) in chickens infected intraperitoneall...