The Open Toxinology Journal 

About: The Open Toxinology Journal is an academic journal. The journal publishes majorly in the area(s): Pore-forming toxin & Clostridium botulinum. It has an ISSN identifier of 1875-4147. Over the lifetime, 27 publications have been published receiving 622 citations.

Clostridium Perfringens Toxins Involved in Mammalian Veterinary Diseases.

Abstract: Clostridium perfringens is a gram-positive anaerobic rod that is classified into 5 toxinotypes (A, B, C, D, and E) according to the production of 4 major toxins, namely alpha (CPA), beta (CPB), epsilon (ETX) and iota (ITX). However, this microorganism can produce up to 16 toxins in various combinations, including lethal toxins such as perfringolysin O (PFO), enterotoxin (CPE), and beta2 toxin (CPB2). Most diseases caused by this microorganism are mediated by one or more of these toxins. The role of CPA in intestinal disease of mammals is controversial and poorly documented, but there is no doubt that this toxin is essential in the production of gas gangrene of humans and several animal species. CPB produced by C. perfringens types B and C is responsible for necrotizing enteritis and enterotoxemia mainly in neonatal individuals of several animal species. ETX produced by C. perfringens type D is responsible for clinical signs and lesions of enterotoxemia, a predominantly neurological disease of sheep and goats. The role of ITX in disease of animals is poorly understood, although it is usually assumed that the pathogenesis of intestinal diseases produced by C. perfringens type E is mediated by this toxin. CPB2, a necrotizing and lethal toxin that can be produced by all types of C. perfringens, has been blamed for disease in many animal species, but little information is currently available to sustain or rule out this claim. CPE is an important virulence factor for C. perfringens type A gastrointestinal disease in humans and dogs; however, the data implicating CPE in other animal diseases remains ambiguous. PFO does not seem to play a direct role as the main virulence factor for animal diseases, but it may have a synergistic role with CPA-mediated gangrene and ETX-mediated enterotoxemia. The recent improvement of animal models for C. perfringens infection and the use of toxin gene knock-out mutants have demonstrated the specific pathogenic role of several toxins of C. perfringens in animal disease. These research tools are helping us to establish the role of each C. perfringens toxin in animal disease, to investigate the in vivo mechanism of action of these toxins, and to develop more effective vaccines against diseases produced by these microorganisms.

Insecticidal Toxins from the Photorhabdus and Xenorhabdus Bacteria

Abstract: Insect pathogens are an excellent source of novel insecticidal agents with proven toxicity. In particular, bacteria from the genera Photorhabdus and Xenorhabdus are proving to be a genomic goldmine, encoding a multitude of insecticidal toxins. Some are highly specific in their target species, whilst others are more generalist, but all are of potential use in crop protection against insect pests. These astounding bacterial species are also turning out to be equipped to produce a vast range of anti-microbial compounds which could be of use to medical science. This review will cover the current knowledge of the lifecycles of the two genera and the potential role of the toxins in their biology, before a more in depth exploration of some of the best studied toxins and their potential use in agriculture.

Overview of the Basic Biology of Bacillus thuringiensis with Emphasis on Genetic Engineering of Bacterial Larvicides for Mosquito Control

Abstract: The insecticidal bacterium, Bacillus thuringiensis, consists of a wide variety of subspecies, most of which are insecticidal for either lepidopteran, coleopteran, or dipteran insect larvae. Subspecies such as B. thuringiensis subsp. kurstaki have been used with remarkable safety for more than forty years to control lepidopteran pests in agriculture and forestry, and over the past thirty years, B. thruingeinsis subsp. israelensis, has proven to be a safe and effective larvicide for controlling mosquito and black fly larvae. Studies of the basic biology of B. thuringiensis have shown that it produces a variety of insecticidal proteins produced during vegetative growth and sporulation that determines its activity for insect species belonging to different orders, with the most important of these being the Cry proteins active against lepidopteran and coleopteran pests, and a combination of Cry and Cyt proteins for mosquitoes and blackflies. After intoxication by these proteins, spores typically germinate and invade larvae, contributing to insect mortality. Whereas strains of many wild type isolates have been commercialized and are now used worldwide, the use of recombinant DNA techniques, i.e., genetic engineering, has been used over the past decade to recombine the proteins of different B. thuringiensis strains with those of B. sphaericus to generate recombinant larvicides as much as ten-fold more toxic than the parental strains. In this chapter, we begin with a general overview of the basic biology of B. thuringiensis and B. sphaericus, then show how studies of its molecular genetics combined with recombinant DNA techniques have been used to generate highly improved bacterial larvicides for control of nuisance and vector mosquitoes.

Mosquito Resistance to Bacterial Larvicidal Toxins

Abstract: Insecticide resistance to the microbial insecticides Bacillus thuringiensis subsp. israelensis (Bti) and Bacillus sphaericus (Bs) represents a serious threat to their success. Available evidence indicates that the risk for resistance to Bti is low due to the makeup of its parasporal crystal, which contains Cyt1A, Cry4A, Cry4B, and Cry11A toxic proteins. Disrupting the toxin complex in Bti enables resistance to evolve, especially in the absence of the key factor, the cytolytic toxin, Cyt1A. Cross-resistance is widespread among mosquitocidal Bacillus thuringiensis Cry toxins and the mechanisms of Cry resistance in mosquitoes are not known. Bacillus sphaericus (Bs) is at higher risk for resistance due to its single- site action and field cases have been reported from a number of locations worldwide. Cross-resistance is reported among the various Bs isolates, although some isolates produce additional toxic proteins that can reduce cross-resistance and slow resistance evolution. Field and lab evolved resistant populations consistently show recessive and monofactorial inheritance of resistance. Resistant populations, however, have evolved a variety of molecular mechanisms causing that resistance. Traditional resistance management strategies with promise include rotations and mixtures of Bti and Bs, as well as untreated areas that provide natural refuges for susceptible alleles. Promising new strategies include genetic engineering to increase the toxin complexity targeted toward mosquito larvae, to enhance the host range of the mosquito control product, and to avoid the evolution of insecticide resistance. Regardless of the control strategy, a resistance- monitoring program alongside an integrative pest management approach is the best strategy to delay insecticide resistance.