Haemophilus parasuis is a commensal bacterium of the upper respiratory tract of healthy pigs. However, in conjunction with viral infections in immunocompromised animals H. parasuis can transform into a pathogen that is responsible for causing Glasser's disease which is typically characterized by fibrinous polyserositis, polyarthritis, meningitis and sometimes acute pneumonia and septicemia in p...

Classical swine fever (CSF), a highly contagious disease of pigs caused by the classical swine fever virus (CSFV), can lead to important economic losses in the pig industry. Numerous CSFV isolates with various degrees of virulence have been isolated worldwide, ranging from low virulent strains that do not result in any apparent clinical signs to highly virulent strains that cause a severe perac...

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...

Rhodococcus equi is an important bacterial pathogen in foals up to 6 months old, widespread in horse farms all over the world. It was found that only virulent R. equi strains expressing 15-17 kDa virulence-associated protein (VapA) and having large virulence plasmid of 85-90 kb containing vapA gene are pathogenic for horses. To date, 12 plasmid types have been reported in VapA positive strains ...

Toxoplasma gondii pathogenicity depends on the type derived from a clonal population. A genetic analysis of locus has been carried out to determine different genotypes T. (strain types I, II, and III) that are associated with human toxoplasmosis. The several linked toxoplasmosis have identified through study locus. In this investigation, PCR-RFLP was found be useful, simple method genotypic cha...

Ozaki, Yoshikatsu (Baylor University College of Medicine, Houston, Tex.), Arwin R. Diwan, Mizuho Takizawa, and Joseph L. Melnick. Chromatography of poliovirus on calcium phosphate and its application to the identification of vaccine progeny strains. J. Bacteriol. 89:603-610. 1965.-Virulent and attenuated polioviruses were studied chromatographically with calcium phosphate as adsorbent and neutr...

Full-length cDNA clones of two Theiler murine encephalomyelitis virus (TMEV) strains, one highly virulent and the other less virulent, were constructed in the bacterial plasmid pGEMR-3. Transfection of BHK-21 cells with RNA transcribed from these cDNAs yielded progeny viruses with the exact in vitro growth phenotype and mouse neurovirulence pattern of the respective parental virus strains. RNA ...

The influence of cultural conditions upon the loss of virulence in laboratory cultures of Pasteurella pestis has been noted in the literature. Devignat and Schoetter (1942) reported that 2 highly virulent strains became avirulent after 30 to 36 days when serially transferred in aerated broth at 37 C. Pollitzer (1954) summarized additional conditions under which loss in virulence occurred. These...

Comparison of immune responses induced in cattle by virulent and attenuated strains of Mycobacterium bovis will assist in identifying responses associated with resistance or susceptibility to disease. Four strains of M. bovis, one which is virulent in guinea pigs (WAg201) and three which are attenuated in guinea pigs (an isoniazid-resistant strain [WAg405], ATCC 35721, and BCG) were compared fo...