background and aims: infectious laryngotracheitis virus (iltv) infection causes a highly contagious respiratory disease in poultry leads to significant economic losses in the poultry industry. the genomic and antigenic characteristics between virulent and vaccine strains of iltv are very similar. the ability of embryonated chicken neural stem (cns) cell for differential diagnosis of iltv strain...

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...

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...

Virulent strains of Shiga toxin-producing Escherichia coli (STEC) serogroups O103 and O121 are considered adulterants in beef. Two high-resolution melting (HRM) real-time PCR assays were standardized for the specific detection discrimination potentially virulent avirulent E. O121. The HRM assay offered possibility to distinguish clearly STEC O103:H2 from O103:H25. two extensively validated usin...

Virulence variability was investigated by analyzing the experimental pathogenicity of seven Leishmania tropica strains isolated from human lesions in Syria, through the evaluation of the infective ability, growth pattern and pathogenicity. Two of the strains presented higher levels of macrophage infection, increased promastigote replication in culture medium and as well as amastigote multiplica...

BACKGROUND Newcastle disease (ND) is one of the most contagious and devastating diseases to poultry in the world. The causative agents are virulent strains of Newcastle disease virus (NDV), which belong to the genus Avulavirus, sub-family Paramyxoviridae, family Paramyxovirinae. Knowing the genomic and antigenic characteristics of virulent NDVs might contribute to ND control in China. RESULTS...