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...

Marek's disease virus (MDV), a herpesvirus that causes a lymphoproliferative disorder in chickens, encodes a number of microRNAs derived primarily from two locations in the MDV genome. One cluster of microRNA genes flanks the meq oncogene, and a second cluster is found within the latency-associated transcript (LAT) region. The sequences of MDV microRNAs from a collection of field and reference ...

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...

Introduction Marek’s disease, an economically-important lymphoid neoplasm of chickens, is caused by oncogenic strains of Marek’s disease herpesvirus (MDV). The virus replicates in lymphocytes and the epithelia of the skin and feather tissues (1). Despite very successful vaccination with attenuated virus strains, vaccine failures do occur as field viruses evolve towards greater virulence. In the...

Outer membrane proteins (OMPs) are the major virulent factors of Haemophilus parasuis. PCR-RFLP targeting the ompA gene was conducted to investigate the possibility of genotyping H. parasuis in this study. Fifteen reference strains and 49 isolates from pig farms in northwest China were genotyped by PCR-RFLP with a pair of specific primers. The results indicated that both the 15 reference strain...

A new character, the A marker, for polioviruses is described. In the presence of Al(+++) (1 to 100 mM) attenuated, but not virulent, strains of type 1 and type 2 polioviruses are stabilized so that they resist thermal inactivation at 50 degrees C. Differences between the attenuated and virulent type 3 strains studied were of the opposite character and less marked. By the use of optimal concentr...