Detection by polymerase chain reaction of Clostridium perfringens producing epsilon toxin in faeces and in gastrointestinal contents of goats

Detection of Clostridium perfringens alpha toxin gene in lambs by loop mediated isothermal amplification

Aim:

The loop mediated isothermal amplification (LAMP) was standardized for rapid detection of Clostridium perfringens.

Materials and Methods:

A total of 120 fecal samples were collected from enterotoxemia suspected lambs were used for screening of C. perfringens cpa gene by LAMP. The specificity of the LAMP amplified products was tested by digesting with restriction enzyme XmnI for alpha toxin gene.

Results:

Out of 120 samples screened 112 (93.3%) samples were positive by both LAMP and polymerase chain reaction (PCR) for detection of cpa gene which indicated the equal sensitivity of both the tests. The enzyme produced single cut in 162 base pair amplified product of alpha toxin gene at 81 base pair resulting in a single band in gel electrophoresis.

Conclusion:

Both LAMP and PCR for detection of cpa gene indicated the equal sensitivity of both the tests. Standardization of LAMP reaction for amplification of epsilon and beta toxin genes will help to identify the C. perfringens toxin types from the clinical samples. The test could be a suitable alternative to the PCR in detection of toxin types without the help of sophisticated machinery like thermal cycler. Considering its simplicity in operation and high sensitivity, there is the potential use of this technique in clinical diagnosis and surveillance of infectious diseases.

Molecular cloning and expression of epsilon toxin from Clostridium perfringens type D and tests of animal immunization

Epsilon toxin produced by Clostridium perfringens types B and D causes enterotoxemia in sheep, goats and calves. Enterotoxemia can cause acute or superacute disease, with sudden death of the affected animal. It provokes huge economic losses when large numbers of livestock are affected. Therapeutic intervention is challenging, because the disease progresses very rapidly. However, it can be prevented by immunization with specific immunogenic vaccines. We cloned the etx gene, encoding epsilon toxin, into vector pET-11a; recombinant epsilon toxin (rec-epsilon) was expressed in inclusion bodies and was used for animal immunization. Serum protection was evaluated and cross-serum neutralization tests were used to characterize the recombinant toxin. To analyze the potency of the toxin (as an antigen), rabbits were immunized with 50, 100 or 200 microg recombinant toxin, using aluminum hydroxide gel as an adjuvant. Titers of 10, 30 and 40 IU/mL were obtained, respectively. These titers were higher than the minimum level required by the European Pharmacopoeia (5 IU/mL) and by the USA Code of Federal Regulation (2 IU/mL). This rec-epsilon is a good candidate for vaccine production against enterotoxemia caused by epsilon toxin of C. perfringens type D.

DETECÇÃO DOS GENES DAS TOXINAS ALFA (α), BETA (β) E ÉPSILON (ε) EM AMOSTRAS DE CLOSTRIDIUM PERFRINGENS ISOLADAS DE BOVINOS PELA REAÇÃO EM CADEIA DA POLIMERASE (PCR)

RESUMO O Clostridium perfringens, microrganismo anaeróbio, está presente no solo e no trato intestinal dos mamíferos. Provoca gangrena gasosa e intoxicação alimentar nos seres humanos e doenças enterotoxêmicas nos animais domésticos. O C. perfringens é classificado em 5 tipos (A, B, C, D e E) mediante a produção de quatro toxinas principais (alfa-α, beta-β, gama-γ, delta-δ e épsilon-ε). A identificação destas toxinas é realizada através da reação de soroneutralização em animais utilizando anti-soros específicos, os quais, além do alto custo, são de difícil obtenção em laboratórios de referência internacionais. Visando contribuir para a tipificação de amostras de C. perfringens, em nosso meio, o presente trabalho teve como objetivo avaliar a reação em cadeia da polimerase (PCR) na detecção dos genes que codificam as toxinas alfa (cpa), beta (cpb) e épsilon (etx) em isolamentos provenientes de bovinos. A sensibilidade analítica da técnica de PCR padronizada a partir do DNA total bacteriano foi de 2,27 ng/?L para o gene cpa e 227 pg/?L para os genes cpb e etx. Das 35 amostras de C. perfringens isoladas e tipificadas por PCR, 16 (45,7%) foram do tipo A, 18 (51,4%) foram do tipo C e 1 (2,9%) foi do tipo B.

The demonstration of Pasteurella multocida in the alimentary tract of chickens after experimental oral infection

A selective medium containing polymyxin B, crystal violet, thallous acetate, bacitracin and cycloheximide in 10% sheep blood dextrose starch agar, and a modified Pasteurella multocida-specific polymerase chain reaction (PCR) assay were developed for the respective isolation and detection of P. multocida from chicken alimentary tract. The selective medium and the PCR assay were highly sensitive, detecting 100 cfu from colon contents. These techniques were used to follow the localisation of an orally administered virulent P. multocida in chickens. Pasteurellae could be isolated from the crop of some birds up to 30 h, occasionally from other sites after 28 h. It was concluded that the crop was a likely site for colonisation and that infection was most likely to occur through the mucosa of the jejunum or ileum.

PCR detection of Clostridium perfringens type D in formalin-fixed, paraffin-embedded tissues of goats and sheep

A polymerase chain reaction (PCR) was used to identify the genes encoding the alpha, epsilon and beta toxins of Clostridium perfringens in formalin-fixed, paraffin-embedded intestinal tissues of goats and sheep. When pure cultures of Cl. perfringens types B and D were used as control templates in the PCR, products of the following sizes were observed on the agarose gel: 247 bp (alpha primers), 1025 bp (beta primers) and 403 bp (epsilon primers). When used to identify Cl. perfringens type D in formalin-fixed, paraffin-embedded intestinal tissues of goats and sheep, the PCR technique resulted in the detection of this micro-organism in 11 out of 13 samples known to be infected with Cl. perfringens. No false positive results were obtained when 13 culturally negative samples were analysed by the PCR technique.

Experimental Clostridium perfringens type D enterotoxemia in goats

The effects of intraduodenal administration of Clostridium perfringens cultures and culture products in goats were evaluated to develop a reliable experimental model of enterotoxemia in this species. Five conventionally reared, 11-16-week-old Angora goat kids were dosed intraduodenally with whole cultures of C. perfringens type D; five similar animals were dosed with C. perfringens type D filtered culture supernatant; and a third group of five kids was dosed with C. perfringens type D washed cells. Two kids were used as controls and received sterile, nontoxic culture medium intraduodenally. All animals received starch solution into the abomasum. All five kids inoculated with whole culture and three of five dosed with culture supernatant and with washed cells developed central nervous system signs. Diarrhea was observed in two of five kids inoculated with whole culture, in all five of those dosed with culture supernatant, and in three of five of those that received washed cells. The most striking postmortem findings consisted of lung edema, necrotizing pseudomembranous colitis, and cerebral vasogenic edema. The protocol thus provided a reasonable model of naturally occurring enterotoxemia in goats, producing a range of clinical signs and postmortem changes similar to those observed in the natural disease.