The ability of virulent strains of Aeromonas salmonicida to resist the bactericidal activity of serum was quantitated. The A. salmonicida strains tested included virulent strains, mutants lacking the major surface A-protein, and mutants lacking A-protein and having a modified lipopolysaccharide structure. The sera evaluated included normal human, rabbit, and trout sera, immune trout serum, and ...

The ecology of virulent strains of Rhodococcus equi on horse farms is likely to influence the prevalence and severity of R. equi pneumonia in foals. This study examined the association between the ecology of virulent R. equi and the epidemiology of R. equi pneumonia by collecting air and soil samples over two breeding seasons (28 farm-year combinations) on Thoroughbred breeding farms with diffe...

The pathogenicity of different birnavirus strains to turbot was determined by challenge experiments. The reference strains of IPNV (Sp, Ab and VR-299) were not pathogenic for turbot (Scophthalmus maximus). The Norwegian serotype (N1) and two selected birnavirus strains isolated from turbot and related to the Ab serotype of IPNV (TB-306 and TB-390) were virulent to different degrees for turbot a...

Based on nucleotide sequence analysis of the hemagglutinin (HA) gene from the virulent and avirulent A/chicken/Pennsylvania/83 influenza viruses, it was previously postulated that acquisition of virulence was associated with a point mutation that resulted in loss of a glycosylation site. Since there are two potential glycosylation sites in this region of the HA molecule and since all Asn-Xaa-Th...

Infectious bursal disease virus (IBDV) is classified according to the antigenicity and virulence into classical virulent (cv), very virulent (vv), and antigenic variant strains. The molecular basis for the IBDV antigenic variation is well established and is associated to the capsid protein, VP2 (gene VP2 of segment A), whereas both VP2 and the RNA-dependent RNA polymerase, VP1 (gene VP1 of segm...

to isolate and detect anthrax spores form soil in different regions of iran in order to find the anthrax foci‚ a total of 668 environmental specimens were collected during 2003-2004. bacterial endospores were extracted from soil specimens via flotation in distilled water, incubation at room temperature, filtration, heat shock and culture on blood agar and selective plet media. bacillus anthraci...

In vivo infection studies in Japanese flounder (Paralichthys olivaceus) demonstrated that the number of viable cells of the virulent strain (NUF251) of Edwardsiella tarda increased gradually in kidney and hepato-pancreas after intraperitoneal injection, but the low virulent strain (NUF194) did not. To gain insight into the virulence factors of E. tarda, in vitro responses of Japanese flounder (...

Highly pathogenic avian influenza H5N1 and Newcastle disease viral infections cause severe illness in chickens and vaccination is a strategic tool of controlling these diseases. Hence, this study was conducted to evaluate the efficacy of using both recombinant herpesvirus of turkey (rHVT-H5 and rHVT-F) vector vaccines at day-old, in the hatchery, under field conditions. Vaccinated chickens were...

Many selective enrichment methods for the isolation of Yersinia enterocolitica from foods have been described. However, no single isolation procedure has been described for the recovery and identification of various plasmid-bearing serotypes. A single improved procedure for selective enrichment, isolation, identification, and maintenance of plasmid-bearing virulent serotypes of Y. enterocolitic...