Role of the exoprotease InA in the pathogenicity of Bacillus thuringiensis in pupae of Hyalophora cecropia

Two geographical biotypes of Nomuraea rileyi (from Ecuador and the United States) were topically bioassayed against seven lepidopteran species, i.e., Anticarsia gemmatalis, Heliothis zea, Heliothis virescens, Heliothis subflexa, Pseudoplusia includens, Spodoptera exigua, and Trichoplusia ni. There was an average difference of 1.7-fold in mortality in how cultures of the same insect species from different sources responded to topical applications of either biotype of N. rileyi. Regression equations and LC₅₀ values were obtained for each insect species and fungal biotype combination. Larvae of S. exigua were equally susceptible to both biotypes of N. rileyi. Although larvae of A. gemmatalis were moderately susceptible to the Ecuadoran biotype, they were relatively nonsusceptible to the Mississippian biotype. Species of Heliothis (H. zea, H. virescens, and H. subflexa) were about equally susceptible to the Mississippian biotype. Larvae of H. subflexa and H. virescens, however, were significantly less susceptible than H. zea to the Ecuadoran biotype. When the integumental barrier was breached via intrahemocoelic injections, larvae of H. virescens were as susceptible as H. zea larvae to blastospores of either biotype of N. rileyi.     

Origins and development of peptide antibiotic research

That cationic proteins might be factors on the antimicrobial defenses of mammalian hosts and are apparently associated with the cytoplasmic granules of phagocytic leukocytes first became evident on the late nineteenth century. It remained, however, for development of sophisticated microanalytic techniques in microbiology, cell biology and protein biochemistry to place these hypotheses in the realm of established theory. This article is a brief summary of singificant steps in the development of this theory. It also attempts to outline the firmly established scope and significance of these developments both for the theory of immunity to infection in the different phyla and for the now global quest for new antibiotics.