Host-specific virulence

Wraight, S. P., Ramos, M., Williams, J. E., Avery, S., Jaronski, S., and Vandenberg, J. (2003). Comparative virulence and host specificity of Beauveria bassiana isolates assayed against lepidopteran pests of vegetable crops. Proceedings of the Annual Meeting of the Society for Invertebrate Pathology, pp. 36. 

Altemaria altemata apple pathotype (previously described as A. mali Roberts) causes Altemaria blotch of susceptible apple cultivars through production of a cyclic peptide host-selective toxin, AM-toxin, whose complete structure has been determined for the first time among host-specific toxins.298 Disruption of AM-toxin synthetase (AMT) gene resulted in toxin-minus mutants, which were also unable to cause disease symptoms in susceptible apple cultivars, indicating that AMT is a primary determinant of virulence and specificity in the A. altemata apple pathotype309 (Figure 33). 

Puccinia chondrillina Bubak. Syd., a rust fungus from Europe, determined to be a virulent, host-specific, and safe biocontrol agent, was introduced into Australia in 1971 to control Chondrilla iuncea L., rush skeletonweed (27. 28). In 1976 it was introduced into California and later into other western states in the U.S. (29-31). The biology of this pathogen, weed control success, and assessment of the economic impact of controlling rush skeletonweed in Australia have been reviewed (23, 27-31). In summary, the... 

Staib P, Kretschmar M, Nichterlein T, Kohler G, Michel S, Hof H, Hacker J, Morschhauser J Host induced, stage specific virulence gene activation in Candida albicans during infection. Mol Microbiol 1999 533-546. 

All animals infected in the pathogenesis study were found to have a positive serologic response typical of a smooth Brucella-strain infection. Region E is reported to be a putative hemagglutinin and may be a virulence factor for B. melitensis 16M. It also may be evaluated as a possible host specificity factor for B. melitensis 16M in goats. 

If host invasion is a dead-end for trophozoites of E. histolytica, what has maintained the invasive phenotype in a fairly competitive population of intestinal microorganisms One possibility is that the invasive phenotype confers other adaptive advantages. The release of proteolytic enzymes and cytolytic factors may enhance degradation and uptake of nutritional molecules from host or bacteria. Pathogenicity and invasiveness not only correlate with the release of specific virulence factors but also enhanced phagocytosis. With controversial exceptions, only pathogenic (potentially invasive) isolates have been successfully weaned to long-term and stable axenic culture. 

The economic importance of nitrogen-fixation by leguminous plants has led to extensive study of the process of nodulation and in particular the nature of the host specificity of Rhizobium. Antiserum raised to clover tissue reacts with virulent strains of R. trifolii and to a lesser extent with avirulent strains of the same organism. If the antiserum is pretreated with avirulent cells a purified antibody, specific for the virulent strain, can be prepared. The purified antisera will bind to R. trifolii virulent strains and clover cells, but not to incompatible Rhizobium species. Immunofluorescence can be used to demonstrate that antisera raised against the capsular polysaccharide of R. trifolii binds to the surface of clover root cells, in particular to the tips of the root hairs. Chemical analysis of this capsule shows that it... 

---