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...

Chronic or hard to heal wounds are very susceptible to infections. Due to the biofilm mode of growth in these wound, conventional therapies, such as antibiotics, do not eradicate the bacteria. New therapeutics must be developed to be able to combat these infections and one way might be to control or inhibit bacterial communication, so called quorum sensing. Possible quorum sensing inhibitors ca...

Virulent, avirulent, and attenuated hybrid strains of Shigella flexneri 2a are equally susceptible to phagocytosis by cultured mouse peritoneal macrophages. The virulent strain is highly lethal for the macrophages, whereas the avirulent is not and is killed. The attenuated hybrid strain is intermediate in its lethality. Comparable results were obtained by using virulent and avirulent S. flexner...

Two strains of Drosophila melanogaster (resistant and susceptible) were parasitized by a virulent or avirulent strain of the parasitoid wasp Leptopilina boulardi. The success of encapsulation depends on both the genetic status of the host strain and the genetic status of the parasitoid strain: the immune cellular reaction (capsule) is observed only with the resistant strain-avirulent strain com...

INTRODUCTION Streptococcus suis serotype 2 is an important swine pathogen and emerging zoonotic agent causing meningitis and septicemia/septic shock. Strains are usually virulent (Eurasia) or of intermediate/low virulence (North America). Very few data regarding human and swine isolates from South America are available. CASE PRESENTATION Seventeen new human S. suis cases in Argentina (16 sero...

OBJECTIVES We compared the reactivity of IgG1 and IgG2a antibodies in mouse sera after infection with virulent RH and low-virulent S273 and Beverley strains of Toxoplasma gondii against RH SAG1 recombinant p30 (rp30) and synthetic SAG1 peptides. METHODS Infected mouse serum samples were collected 9 days after infection, and the level of total IgG, IgG1 and IgG2a against the RH SAG1 rp30 prote...

Newcastle disease is one of the main concerns of poultry farmers. Detection of virulent strains of Newcastle disease virus (NDV) has a great impact on control measures against the disease. In this study RT-PCR was optimized in high sensitivity in order to differentiate the virulent from non-virulent NDV isolates directly in tissue homogenates. The vaccinal NDV strain and known field isolates we...

We propose that the 70-kDa heat shock protein (HSP70) protects virulent Toxoplasma gondii from the effects of the host by immunomodulation. This hypothesis was tested using quercetin and antisense oligonucleotides targeting the start codon of the virulent T. gondii HSP70 gene. Oligonucleotides were transiently transfected into two virulent (RH, ENT) and two avirulent (ME49, C) strains of T. gon...

Transmission experiments were conducted to compare the transmissibility of genetically different Trypanosoma congolense (Savannah subgroup) strains isolated from cattle in a trypanosomiasis endemic area of eastern Zambia. A total of 17 strains were compared. Three strains were extremely virulent with a short pre-patent period, high parasitaemia and a short median survival time (between 5 and 9 ...

Yersinia pestis, the highly virulent agent of plague, is a biological weapon. Strategies that prevent plague have been sought for centuries, and immunization with live, attenuated (nonpigmented) strains or subunit vaccines with F1 (Caf1) antigen is considered effective. We show here that immunization with live, attenuated strains generates plague-protective immunity and humoral immune responses...