Comparison of four techniques for the detection of Clostridium perfringens type D epsilon toxin in intestinal contents and other body fluids of sheep and goats

Enterotoxemia produced by lambda toxin-positive Clostridium perfringens type D in 2 neonatal goat kids

Enterotoxemia caused by Clostridium perfringens type D usually affects sheep and goats ≥ 2-wk-old. The main clinical signs and lesions of the disease are produced by the epsilon toxin (ETX) elaborated by this microorganism. However, ETX is produced in the form of a mostly inactive prototoxin that requires protease cleavage for activation. It has traditionally been believed that younger animals are not affected by type D enterotoxemia given the low trypsin activity in the intestinal content associated with the trypsin-inhibitory action of colostrum. Two Nigerian dwarf goat kids, 2- and 3-d-old, with a history of acute diarrhea followed by death, were submitted for postmortem examination and diagnostic workup. Autopsy and histopathology revealed mesocolonic edema, necrosuppurative colitis, and protein-rich pulmonary edema. Alpha toxin and ETX were detected in intestinal content, and C. perfringens type D was isolated from the colon of both animals. The isolates encoded the gene for lambda toxin, a protease that has been shown previously to activate ETX in vitro. Type D enterotoxemia has not been reported previously in neonatal kids, to our knowledge, and we suggest that lambda toxin activated the ETX.

Bacteriological and serological investigation of Clostridium perfringens in lambs

Clostridium perfringens is one of the most common and important pathogens in livestock due to its ability to produce a diverse arsenal of toxins. Owing to C. perfringens economic importance, this study aimed to determine the types and toxins of C. perfringens in newly born lambs. A total of 200 lambs of less than one-month old were examined, including 100 lambs suffered from diarrhea, 60 freshly dead and 40 apparent healthy. C. perfringens was identified morphologically and biochemically using bacteriological culture in 103 of 200 samples (51.5%). Moreover, serological typing of C. perfringens isolates revealed three serotypes, C. perfringens type A (54.2%), C. perfringens type B (28.8%) and C. perfringens type D (16.9%). The highest prevalence rate for C. perfringens infection was observed in winter (58.25%) in comparison with other seasons. The findings of the present study confirm the presence of enterotoxmia among lambs in localities under study, causing economic losses. The proper vaccination schedule particularly against C. perfringens type A and B is highly recommended.

Pathology and Pathogenesis of Brain Lesions Produced by Clostridium perfringens Type D Epsilon Toxin

Clostridium perfringens type D epsilon toxin (ETX) produces severe, and frequently fatal, neurologic disease in ruminant livestock. The disorder is of worldwide distribution and, although vaccination has reduced its prevalence, ETX still causes substantial economic loss in livestock enterprises. The toxin is produced in the intestine as a relatively inactive prototoxin, which is subsequently fully enzymatically activated to ETX. When changed conditions in the intestinal milieu, particularly starch overload, favor rapid proliferation of this clostridial bacterium, large amounts of ETX can be elaborated. When sufficient toxin is absorbed from the intestine into the systemic circulation and reaches the brain, two neurologic syndromes can develop from this enterotoxemia. If the brain is exposed to large amounts of ETX, the lesions are fundamentally vasculocentric. The neurotoxin binds to microvascular endothelial receptors and other brain cells, the resulting damage causing increased vascular permeability and extravasation of plasma protein and abundant fluid into the brain parenchyma. While plasma protein, particularly albumin, pools largely perivascularly, the vasogenic edema becomes widely distributed in the brain, leading to a marked rise in intracranial pressure, coma, sometimes cerebellar herniation, and, eventually, often death. When smaller quantities of ETX are absorbed into the bloodstream, or livestock are partially immune, a more protracted clinical course ensues. The resulting brain injury is characterized by bilaterally symmetrical necrotic foci in certain selectively vulnerable neuroanatomic sites, termed focal symmetrical encephalomalacia. ETX has also been internationally listed as a potential bioterrorism agent. Although there are no confirmed human cases of ETX intoxication, the relatively wide species susceptibility to this toxin and its high toxicity mean it is likely that human populations would also be vulnerable to its neurotoxic actions. While the pathogenesis of ETX toxicity in the brain is incompletely understood, the putative mechanisms involved in neural lesion development are discussed.

Intramural Vascular Edema in the Brain of Goats With Clostridium perfringens Type D Enterotoxemia

Enterotoxemia caused by Clostridium perfringens type D is an important disease of sheep and goats with a worldwide distribution. Cerebral microangiopathy is considered pathognomonic for ovine enterotoxemia and is seen in most cases of the disorder in sheep. However, these lesions are poorly described in goats. In this article, we describe the vasculocentric brain lesions in 44 cases of caprine spontaneous C. perfringens type D enterotoxemia. Only 1 goat had gross changes in the brain, which consisted of mild cerebellar coning. However, 8 of 44 (18%) cases showed microscopic brain lesions, characterized by intramural vascular proteinaceous edema, a novel and diagnostically significant finding. The precise location of the edema was better observed with periodic acid–Schiff, Gomori’s, and albumin stains. Glial fibrillary acidic protein and aquaporin 4 immunostaining revealed strong immunolabeling of astrocyte foot processes surrounding microvessels. The areas of the brain most frequently affected were the cerebral cortex, corpus striatum (basal ganglia), and cerebellar peduncles, and both arterioles and venules were involved. Most of the goats of this study showed lesions in the intestine (enteritis, colitis, and typhlitis), although pulmonary congestion and edema, hydrothorax, hydropericardium, and ascites were also described. Although the intramural edema described, for the first time, in these caprine cases is useful for the diagnosis of enterotoxemia when observed, its absence cannot exclude the disease.

A Novel Panel of Rabbit Monoclonal Antibodies and Their Diverse Applications Including Inhibition of Clostridium perfringens Epsilon Toxin Oligomerization

The pore-forming epsilon toxin (ETX) produced by Clostridium perfringens is among the most lethal bacterial toxins known. Sensitive antibody-based reagents are needed to detect toxin, distinguish mechanisms of cell death, and prevent ETX toxicity. Using B-cell immuno-panning and cloning techniques, seven ETX-specific monoclonal antibodies were generated from immunized rabbits. ETX specificity and sensitivity were evaluated via western blot, ELISA, immunocytochemistry (ICC), and flow cytometry. ETX-neutralizing function was evaluated both in vitro and in vivo. All antibodies recognized both purified ETX and epsilon protoxin via western blot with two capable of detecting the ETX-oligomer complex. Four antibodies detected ETX via ELISA and three detected ETX bound to cells via ICC or flow cytometry. Several antibodies prevented ETX-induced cell death by either preventing ETX binding or by blocking ETX oligomerization. Antibodies that blocked ETX oligomerization inhibited ETX endocytosis and cellular vacuolation. Importantly, one of the oligomerization-blocking antibodies was able to protect against ETX-induced death post-ETX exposure in vitro and in vivo. Here we describe the production of a panel of rabbit monoclonal anti-ETX antibodies and their use in various biological assays. Antibodies possessing differential specificity to ETX in particular conformations will aid in the mechanistic studies of ETX cytotoxicity, while those with ETX-neutralizing function may be useful in preventing ETX-mediated mortality.

Highly sensitive sandwich immunoassay and immunochromatographic test for the detection of Clostridial epsilon toxin in complex matrices

Epsilon toxin is one of the four major toxins of Clostridium perfringens. It is the third most potent clostridial toxin after botulinum and tetanus toxins and is thus considered as a potential biological weapon classified as category B by the Centers for Disease Control and Prevention (CDC). In the case of a bioterrorist attack, there will be a need for a rapid, sensitive and specific detection method to monitor food and water contamination by this toxin, and for a simple human diagnostic test. We have produced and characterized five monoclonal antibodies against common epitopes of epsilon toxin and prototoxin. Three of them neutralize the cytotoxic effects of epsilon toxin in vitro. With these antibodies, we have developed highly sensitive tests, overnight and 4-h sandwich enzyme immunoassays and an immunochromatographic test performed in 20 min, reaching detection limits of at least 5 pg/mL (0.15 pM), 30 pg/mL (0.9 pM) and 100 pg/mL (3.5 pM) in buffer, respectively. These tests were also evaluated for detection of epsilon toxin in different matrices: milk and tap water for biological threat detection, serum, stool and intestinal content for human or veterinary diagnostic purposes. Detection limits in these complex matrices were at least 5-fold better than those described in the literature (around 1 to 5 ng/mL), reaching 10 to 300 pg/mL using the enzyme immunoassay and 100 to 2000 pg/mL using the immunochromatographic test.

Clostridium perfringens type-D enterotoxaemia in cattle: the diagnostic significance of intestinal epsilon toxin

The aims of this study were to describe 42 cases of Clostridium perfringens type-D enterotoxaemia in cattle seen between 2003 and 2014 and to determine the diagnostic value of detecting epsilon toxin in bovine intestinal content. All cases in the series had histological brain changes considered pathognomonic for C. perfringens type-D enterotoxaemia in sheep and goats and the epsilon toxin of C. perfringens was concurrently detected in the intestinal contents of 15 (36 per cent) cases. The data from the case series indicate that intestinal epsilon toxin has a sensitivity of 56 per cent compared with histology of the brain for diagnosis of bovine C. perfringens type-D enterotoxaemia. The diagnostic specificity of detecting epsilon toxin in bovine intestinal content was investigated by screening intestinal contents of 60 bovine carcases submitted for postmortem examination. Epsilon toxin was detected in 11 (18 per cent) carcases but no pathognomonic histological brain change was found in any. The specificity of intestinal epsilon toxin was estimated to be 80.4 per cent. These studies demonstrate that for a definitive diagnosis of C. perfringens type-D enterotoxaemia in cattle histological examination of the brain is essential as the presence of epsilon toxin in the intestinal contents alone is neither sensitive nor specific enough.

The Myelin and Lymphocyte Protein MAL Is Required for Binding and Activity of Clostridium perfringens ε-Toxin

Clostridium perfringens ε-toxin (ETX) is a potent pore-forming toxin responsible for a central nervous system (CNS) disease in ruminant animals with characteristics of blood-brain barrier (BBB) dysfunction and white matter injury. ETX has been proposed as a potential causative agent for Multiple Sclerosis (MS), a human disease that begins with BBB breakdown and injury to myelin forming cells of the CNS. The receptor for ETX is unknown. Here we show that both binding of ETX to mammalian cells and cytotoxicity requires the tetraspan proteolipid Myelin and Lymphocyte protein (MAL). While native Chinese Hamster Ovary (CHO) cells are resistant to ETX, exogenous expression of MAL in CHO cells confers both ETX binding and susceptibility to ETX-mediated cell death. Cells expressing rat MAL are ~100 times more sensitive to ETX than cells expressing similar levels of human MAL. Insertion of the FLAG sequence into the second extracellular loop of MAL abolishes ETX binding and cytotoxicity. ETX is known to bind specifically and with high affinity to intestinal epithelium, renal tubules, brain endothelial cells and myelin. We identify specific binding of ETX to these structures and additionally show binding to retinal microvasculature and the squamous epithelial cells of the sclera in wild-type mice. In contrast, there is a complete absence of ETX binding to tissues from MAL knockout (MAL-/-) mice. Furthermore, MAL-/- mice exhibit complete resistance to ETX at doses in excess of 1000 times the symptomatic dose for wild-type mice. We conclude that MAL is required for both ETX binding and cytotoxicity.

ELISA and modified toxin-binding inhibition test for quality control of the clostridial vaccine processes

This study aimed to assess and standardize the ELISA and modified ToBI test in vitro methods in order to verify the potency of epsilon toxicoid in comparison with the in vivo TCP method. The following epsilon toxoids were used: NIBSC standard from batches 375/07, 532/08, 551/08, 373/07 and 378/07. These were evaluated using a TCP test, ELISA and ToBI tests. The results indicate that the correlation ratio between the dilutions of standard NIBSC toxicoid and absorbance values of 89.44% obtained with the ELISA method support the use of the curve to evaluate epsilon toxoids. However, it was observed that the absorbance values were similar for all toxoids, thus presenting no significant difference between higher and lower concentration toxoids. For the ToBI test, the correlation ratio of 96.76, obtained in the curve pattern, demonstrates the effectiveness of the curve to be used in the epsilon toxoid evaluation. The correlation ratio between the titration degrees of toxoids obtained through TCP and ToBI tests was higher than 90%. It is concluded that the type of ELISA test used does present discriminative power for toxoids with different concentrations, which does not support the use of this technique for such a purpose. The ToBI test can be used as a screening method for it is sensitive and effective to detect epsilon toxicoid produced by C. perfringens type D.

Clostridium perfringens epsilon toxin: a malevolent molecule for animals and man?

Clostridium perfringens is a prolific, toxin-producing anaerobe causing multiple diseases in humans and animals. One of these toxins is epsilon, a 33 kDa protein produced by Clostridium perfringens (types B and D) that induces fatal enteric disease of goats, sheep and cattle. Epsilon toxin (Etx) belongs to the aerolysin-like toxin family. It contains three distinct domains, is proteolytically-activated and forms oligomeric pores on cell surfaces via a lipid raft-associated protein(s). Vaccination controls Etx-induced disease in the field. However, therapeutic measures are currently lacking. This review initially introduces C. perfringens toxins, subsequently focusing upon the Etx and its biochemistry, disease characteristics in various animals that include laboratory models (in vitro and in vivo), and finally control mechanisms (vaccines and therapeutics).

Diagnosis of Clostridium perfringens intestinal infections in sheep and goats

Clostridium perfringens produces enteric diseases, generically called enterotoxemias, in sheep, goats, and other animals. This microorganism can be a normal inhabitant of the intestine of most animal species, including humans, but when the intestinal environment is altered by sudden changes in diet or other factors, C. perfringens proliferates and produces potent toxins that act locally or are absorbed into the general circulation with usually devastating effects on the host. History, clinical signs, and gross postmortem findings are useful tools for establishing a presumptive diagnosis of clostridial enterotoxemia in sheep and goats. Definitive diagnosis requires laboratory confirmation. Isolation of some types of C. perfringens (e.g., B and C) can be of diagnostic value, but other types (e.g., A) are so commonly found in the intestine of normal animals that isolation is meaningless from a diagnostic point of view. The most accepted criterion in establishing a definitive diagnosis of enterotoxemia is detection of C. perfringens toxins in intestinal contents. Also, histopathological examination of brain is very useful for diagnosis of type D disease, as lesions produced by epsilon toxin in the brains of sheep and goats are pathognomonic for type D enterotoxemia. Ancillary tests, such as measuring urine glucose or observing Gram-stained smears of intestinal mucosa, can be used. However, although such tests have a presumptive diagnostic value when positive, they cannot be used to rule out a diagnosis of enterotoxemia when negative.

Diagnosis of Clostridium perfringens intestinal infections in sheep and goats

Clostridium perfringens produces disease in sheep, goats and other animal species, most of which are generically called enterotoxemias. This micro-organism can be a normal inhabitant of the intestine of most animal species including humans, but when the intestinal environment is altered by sudden changes in diet or other factors, C. perfringens proliferates in large numbers and produces several potent toxins that are absorbed into the general circulation or act locally with usually devastating effects on the host. History, clinical signs and gross post-mortem findings are useful tools for establishing a presumptive diagnosis of enterotoxaemia by C. perfringens in sheep and goats, although no definitive diagnosis of these diseases can be made without laboratory confirmation. Because all types of C. perfringens can be normal inhabitants of the intestine of most animals, culture of this micro-organism from intestinal contents of animals has no diagnostic value unless a colony count is performed and large numbers (usually more than 10(4)-10(7)CFU/g) of C. perfringens are found. The most accepted criterion in establishing a definitive diagnosis of enterotoxaemia by C. perfringens is the detection of its toxins in intestinal contents. However, some of the major toxins of C. perfringens (i.e. epsilon toxin) can also be found, albeit in small amounts, in the small intestine of clinically normal sheep, and this poses a diagnostic challenge. In such cases the histopathology of the brain must be used as an alternative diagnostic tool, since the lesions produced by epsilon toxin in the brains of sheep and goats are unique and pathognomonic for C. perfringens type D enterotoxaemia. Ancillary tests, such as measurement of urine glucose or observation of Gram stained smears of intestinal mucosa can be used and, although they have a presumptive diagnostic value when positive, they cannot be used to rule out a diagnosis of enterotoxaemia if they are negative. In conclusion, the diagnosis of C. perfringens infections in animals is complex and it is appropriate to rely on a combination of diagnostic techniques rather than one singe test.

Evaluation of different fluids for detection of Clostridium perfringens type D epsilon toxin in sheep with experimental enterotoxemia

Enterotoxemia caused by Clostridium perfringens type D is a highly lethal disease of sheep, goats and other ruminants. The diagnosis of this condition is usually confirmed by detection of epsilon toxin, a major exotoxin produced by C. perfringens types B and D, in the intestinal content of affected animals. It has been suggested that other body fluids can also be used for detection of epsilon toxin. This study was performed to evaluate the usefulness of intestinal content versus other body fluids in detecting epsilon toxin in cases of sheep enterotoxemia. Samples of duodenal, ileal and colon contents, pericardial and abdominal fluids, aqueous humor and urine from 15 sheep with experimentally induced enterotoxemia, were analysed for epsilon toxin using a capture ELISA. Epsilon toxin was detected in 92% of the samples of ileal content, 64% of the samples of duodenal content, 57% of the samples of colon content and in 7% of the samples of pericardial fluid and aqueous humor. No epsilon toxin was found in samples of abdominal fluid or urine from the animals with enterotoxemia or in any samples from six clinically healthy sheep used as negative controls. The results of this study indicate that with the diagnostic capture ELISA used, intestinal content (preferably ileum) should be used for C. perfringens type D epsilon toxin detection in suspected cases of sheep enterotoxemia.

The pathology of peracute experimental Clostridium perfringens type D enterotoxemia in sheep

The pathological findings in sheep with peracute experimental Clostridium perfringens type D enterotoxemia are described. Of 16 animals inoculated intraduodenally with a whole culture of this microorganism and a starch solution in the abomasum, 12 developed clinical signs including increased respiratory efforts, recumbency, paddling, bleating, convulsions, blindness, and opisthotonus. Diarrhea was not observed in any of the animals. The time lapse between the beginning of intraduodenal infusion and onset of clinical signs varied between 30 minutes and 26 hours, and the clinical course varied between 1 and 9 hours. Gross postmortem changes were observed in these 12 animals and included pulmonary edema; excess pericardial, peritoneal, or pleural fluid with or without strands of fibrin; liquid small intestinal contents; leptomeningeal edema; cerebellar coning; and subcapsular petechiae on kidneys. Histological changes consisted of severe edema of pleura and interlobular septa and around blood vessels and airways and acidophilic, homogeneous, proteinaceous perivascular edema in the brain. Five of 12 animals (42%) with clinical signs consistent with enterotoxemia lacked specific histological lesions in the brain. None of the intoxicated or control animals developed nephrosis. Glucose was detected in the urine of 3 of 6 animals that were tested for this analyte. These results stress the importance of the use of histological examination of the brain, coupled with epsilon toxin detection, for a definitive diagnosis of C. perfringens type D enterotoxemia in sheep.

Enterotoxemia em caprinos no Rio Grande do Sul

São descritos surtos de enterotoxemia em caprinos em cinco propriedades no Estado do Rio Grande do Sul. Os animais afetados eram, normalmente, encontrados mortos ou apresentavam evolução aguda de 2 a 3 horas com acentuada depressão, cólicas abdominais e diarréia profusa com fibrina. Em duas propriedades relataram-se casos com a evolução de até 12 horas. Em treze animais necropsiados observaram-se aumento de líquidos nas cavidades abdominal, torácica e pericárdica, congestão e hiperemia da serosa e mucosa do intestino, conteúdo do cólon líquido com fibrina além de hemorragias de serosa e fibrina. Em um animal constatou-se microangiopatia cerebral caracterizada por acúmulo de material homogêneo e eosinofílico no espaço perivascular. No conteúdo intestinal, colônias com bastonetes morfológica e bioquimicamente sugestivos de Clostridium perfringens foram caracterizadas no estudo bacteriológico. A soroneutralização em camundongos com conteúdo intestinal dos animais afetados, revelou a presença da toxina épsilon. Estes achados evidenciam a enterotoxemia como doença de importância para criação de caprinos no Rio Grande do Sul.