Porcine parvovirus 1 (PPV1) is a major cause of reproductive failure in pigs. To date, six additional porcine parvoviruses (PPV2–PPV7) have been identified. In this study, we detected 11 PPV1 strains, five PPV3 three PPV4 PPV5 PPV6 and one PPV7 strain Korean wild boars. PPV1, -3, -5, from boars harbor conserved motifs within the Ca2+ binding loop catalytic center PLA1 motif. Intra-species recom...

Bursaphelenchus xylophilus is the pathogen of pine wilt disease. Bursaphelenchus mucronatus is similar to B. xylophilus in morphology. Both species share a common niche, but they are quite different in pathogenicity. Presently, the role of bacteria in pine wilt disease development has been widely speculated. The diversity of bacteria associated with B. xylophilus and B. mucronatus with differen...

The ecological mechanism of survival of Aeromonas salmonicida, the bacterial pathogen of fish furunculosis, in river water was investigated by laboratory-based experiments with two virulent strains (which were autoagglutinating) and two virulent strains (which were nonagglutinating). A difference in net electrical charge of A. salmonicida cells was detected by electrophoresis; cells of the viru...

Iransiflissi(n and scanniiing vlo-Ic n microm ollY wete used to study the phagocvtosis of virulent and avirulent strains of JLcgionella pneurnopiila. Tlhe interact ion between L. lincumnophila andl( peritoneal macrophages front normial guinea pigs or front animials that had survived infection was studied. The virulent strains survivedi and proliferated within the phagocyte after ingestion by ei...

This study was carried out to better understand factors that influenced the process of attenuation of Marek's disease (MD) virus by serial passage in cell cultures. Three virulent (v) pathotype and three very virulent plus (vv+) pathotype strains were passed by three techniques up to 131 times, and the passage level at attenuation was determined. The 18 attenuated or partially attenuated viruse...

Macrophages from the mouse peritoneal cavity were examined by electron microscopy at various time intervals up to 24 h after intraperitoneal administration of each of three strains of staphylococci different in virulence for mice: high-virulent, low-virulent, and avirulent strains. After engulfment, avirulent bacteria were highly liable to intracellular digestion, resulting in almost complete d...

Virulent and avirulent strains of swine vesicular disease virus (SVDV), a picornavirus, have been characterized previously. The major determinants for attenuation have been mapped to specific residues in the 1D-2A-coding region. The properties of the 2A proteases from the virulent and avirulent strains of SVDV have now been examined. Both proteases efficiently cleaved the 1D/2A junction in vitr...

The experiments reported in this paper indicate that a pure culture of a virulent Type I pneumococcus as transferred under ordinary conditions is made up of individuals which are not identical in virulence for animals,-in bile solubility, or in their power to multiply under unfavorable conditions. By mechanical analysis alone no avirulent strains were obtained from the virulent strain, but one,...

The nucleotide sequences of the fusion (F) and haemagglutinin-neuraminidase (HN) glycoprotein genes of the extremely avirulent Newcastle disease virus (NDV) strain Ulster have been determined by sequencing cDNA clones derived from viral genomic RNA. Open reading frames, assumed to encode the F0 and HN0 glycoprotein precursors, were 553 and 616 amino acids long, respectively. Comparisons of the ...