A procedure was developed for direct detection, isolation, and maintenance of plasmid-bearing virulent serotypes of Yersinia enterocolitica from different food sources. Plasmid-bearing virulent strains of Y. enterocolitica representing five serotypes were simultaneously detected and isolated from enriched swab samples of artificially contaminated pork chops, ground pork, cheese, and zucchini, u...

Four strains of Salmonella typhimurium avirulent for mice were found to be capable of acting as gene acceptors in transduction experiments. An attempt was made to transduce virulence to three strains, using a typical mouse-virulent strain of S. typhimurium as donor. Two of the strains which are adenine-dependent were successfully made virulent by transduction and simultaneously became adeninein...

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...

Streptococcus suis serotype 2 is an important porcine bacterial pathogen and emerging zoonotic agent mainly responsible for sudden death, septic shock, and meningitis, with exacerbated inflammation being a hallmark of the infection. However, serotype 2 strains are genotypically and phenotypically heterogeneous, being composed of a multitude of sequence types (STs) whose virulence greatly varies...

Listeria monocytogenes lineage III strains belonging to subgroups IIIA (n = 8), IIIB (n = 5), and IIIC (n = 6) were examined along with other known serotype strains (n = 11) by PCR and Southern hybridization using several recently described species-, virulence-, and serotype-specific primers and probes. The virulence of seven representative lineage III strains was then evaluated in mice via the...

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...

The purpose of this study is investigate Differentiation Between Vaccinal and Iranian Virulent Isolates of Newcastle Disease Virus based on F Region Genotyping by HRM Analysis. Discrimination of circulating virulent strains of Newcastle Disease Virus (NDV) from low pathogenic and vaccine stains is the basis for implementation of strategies to control and eradication of that aims at the eradicat...

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...

Could some vaccines drive the evolution of more virulent pathogens? Conventional wisdom is that natural selection will remove highly lethal pathogens if host death greatly reduces transmission. Vaccines that keep hosts alive but still allow transmission could thus allow very virulent strains to circulate in a population. Here we show experimentally that immunization of chickens against Marek's ...

Preventing disease outbreaks in cultured turbot Psetta maxima L. caused by Aeromonas salmonicida subsp. salmonicida (ASS) requires a better understanding of how this pathogen colonizes its host. Distribution of 1 virulent and 2 avirulent ASS strains in turbot tissues was investigated during early and late stages of infection following an immersion challenge. To track bacteria within the turbot,...