Temporal evolution of anti- Clostridium antibody responses in sheep after vaccination with polyvalent clostridial vaccines

Immunogenicity of a pentavalent recombinant Escherichiacoli bacterin against enterotoxemia and botulism in sheep

INTRODUCTION

Producing commercial bacterins/toxoids against Clostridium spp. is laborious and hazardous. Conversely, developing prototype vaccines using purified recombinant toxoids, though safe and effective, is both laborious and costly for application in production animals.

OBJECTIVE

Considering that inactivated recombinant Escherichiacoli (bacterin) is a simple, cost-effective, and to be safe solution, we evaluated, for the first time, a pentavalent formulation of recombinant bacterins containing the alpha, beta, and epsilon toxins of Clostridiumperfringens and C and D neurotoxins of Clostridiumbotulinum in sheep.

METHODS

Subcutaneously, 18 Texel sheep received two doses (200 μg of each antigen) of recombinant bacterin (n = 7) or purified recombinant antigens (n = 6) on days 0 and 28, while the control group (n = 5) did not receive an immunization. Sera samples from days 0 (before the 1st dose), 28 (before the 2nd dose), and 56, 84, and 112 were used for measuring IgG (indirect ELISA) and neutralizing antibodies (mouse serum neutralization).

RESULTS

Both formulations induced significant levels of IgG against all five toxins (p < 0.05) up to day 112, with peaks at days 28 and 56 post-immunization. The expected booster effect occurred only for the botulinum toxins. The neutralizing antibody titers were satisfactory against ETX (≥2 IU/ml for both formulations) and BoNT-D [5 IU/ml (bacterin) and 10 IU/ml (purified)].

CONCLUSION

While adjustments are required, the recombinant bacterin platform holds great potential for polyvalent vaccines due to its straightforward, safe, and cost-effective production, establishing it as a user-friendly technology for the veterinary immunobiological industry.

Antibody levels following vaccination of beef calves with a tetanus toxoid

Tetanus is a preventable, yet often fatal, disease affecting many species, including beef cattle. Vaccination for tetanus is recommended for calves at high risk of disease, but typical beef cattle management practices often make adherence to vaccine manufacturers' guidance for a second (booster) dose of vaccine difficult. This study examined the antibody response following a single dose of tetanus toxoid, as well as following booster vaccination at various intervals. Anti-tetanus IgG antibodies were detectable 25 days (D25) after a single dose, and rose following booster at either D25 D109 after initial vaccination. Antibody levels then declined numerically from D109 to D179 for calves boostered at D25 but rose on D179 for those receiving a second dose on D109. The relatively rapid response in IgG production, even in the absence of a booster vaccine, may suggest value in vaccinating calves for tetanus at time of greatest risk, even if a booster cannot be administered. The study also provides support for priming of the immune response lasting at least until D109 after primary immunization.

Clostridium haemolyticum, a review of beta toxin and insights into the antigen design for vaccine development

Phospholipases C (PLCs) represent an important group of lethal toxins produced by pathogenic bacteria of the Clostridium genus, including the beta toxin of C. haemolyticum. Bacillary hemoglobinuria in cattle and sheep is the main disease caused by this pathogen and its incidence can be reduced by annual vaccination of herds. Currently, widely used vaccines depend on cultivating the pathogen and obtaining high concentrations of the toxin, disadvantages that can be overcome with the use of recombinant vaccines. In the development of this new generation of immunizing agents, identifying and understanding the structural and immunological aspects of the antigen are crucial steps, but despite this, the beta toxin is poorly characterized. Fortunately, the time and resources required for these investigations can be reduced using immunoinformatics. To advance the development of recombinant vaccines, in addition to a brief review of the structural and immunological aspects of beta toxin, this work provides in silico mapping of immunodominant regions to guide future vaccinology studies against C. haemolyticum. A review of alternatives to overcome the limitations of beta toxin vaccines (conventional or recombinant) is also proposed.

Blackleg in Cattle in the Irkutsk Region

Blackleg is an acute, toxic, infectious, non-contagious disease of domestic and wild ruminants that occurs while the animals are pastured. This article describes an outbreak of blackleg on a farm in Siberia (Russia) in 2019. We provide a detailed description of the cases based on the results of comprehensive diagnostic and epidemiological investigations. For description of case and evaluation, we used the following methods: owner observations, descriptive epidemiology, clinical diagnostics, pathological examination and bacteriology. The distinctive features (in addition to the characteristic features) were as follows: the outbreak of the disease occurred in early spring when there was abundant snow cover and under unfavorable living conditions of animals and traumas; the disease appeared in both vaccinated and unvaccinated cattle; the characteristic clinical signs were low-grade fever, the absence of crepitus, and the presence of haematomas containing erythrocytes with basophilic granularity; thrombs in vessel and vacuolization in tissue of the adrenal gland. This paper aimed to present classical and new clinical and pathology changes in cattle with blackleg in winter conditions of Russian Siberia.

Fleece rot and dermatophilosis (lumpy wool) in sheep: opportunities and challenges for new vaccines

During prolonged wetting of the fleece, proliferation of bacterial flora often dominated by Pseudomonas aeruginosa or Dermatophilus congolensis can induce dermatitis and fleece damage termed fleece rot and dermatophilosis respectively, which predispose sheep to blowfly strike. A large research effort in the 1980s and 1990s on vaccines to control fleece rot and dermatophilosis met with limited success. This review examines theoretical and technological advances in microbial ecology, pathogenesis, immunology, vaccine development and the characterisation of microbial virulence factors that create new opportunities for development of vaccines against these diseases. Genomic technologies have now created new opportunities for examining microbial dynamics and pathogen virulence in dermatitis. An effective vaccine requires the combination of appropriate antigens with an adjuvant that elicits a protective immune response that ideally provides long-lasting protection in the field. A clinical goal informed by epidemiological, economic and animal welfare values is needed as a measure of vaccine efficacy. Due to dependence of fleece rot and dermatophilosis on sporadic wet conditions for their expression, vaccine development would be expedited by in vitro correlates of immune protection. The efficacy of vaccines is influenced by genetic and phenotypic characteristics of the animal. Advances in understanding vaccine responsiveness, immune defence in skin and immune competence in sheep should also inform any renewed efforts to develop new fleece rot and dermatophilosis vaccines. The commercial imperatives for new vaccines are likely to continue to increase as the animal welfare expectations of society intensify and reliance on pharmacotherapeutics decrease due to chemical resistance, market pressures and societal influences. Vaccines should be considered part of an integrated disease control strategy, in combination with genetic selection for general immune competence and resistance to specific diseases, as well as management practices that minimise stress and opportunities for disease transmission. The strategy could help preserve the efficacy of pharmacotherapeutics as tactical interventions to alleviate compromised welfare when adverse environmental conditions lead to a break down in integrated strategic disease control. P. aeruginosa and D. congolensis are formidable pathogens and development of effective vaccines remains a substantial challenge.

Measurement over 1 Year of Neutralizing Antibodies in Cattle Immunized with Trivalent Vaccines Recombinant Alpha, Beta and Epsilon of Clostridium perfringens

The alpha (CPA), beta (CPB) and epsilon (ETX) toxins of Clostridium perfringens are responsible for causing diseases that are difficult to eradicate and have lethal potential in production animals. Vaccination of herds is still the best control strategy. Recombinant clostridial vaccines have shown good success at inducing neutralizing antibody titers and appear to be a viable alternative to the conventional production of commercial clostridial toxoids. Research is still needed on the longevity of the humoral immune response induced by recombinant proteins in immunized animals, preferably in target species. The objective of this study was to measure the humoral immune response of cattle immunized with trivalent vaccines containing the recombinant proteins alpha (rCPA), beta (rCPB) and epsilon (rETX) of C. perfringens produced in Escherichia coli at three different concentrations (100, 200, and 400 µg) of each protein for 12 months. The recombinant vaccines containing 200 (RV2) and 400 µg (RV3) yielded statistically similar results at 56 days. They performed better throughout the study period because they induced higher neutralizing antibody titers and were detectable for up to 150 and 180 days, respectively. Regarding industrial-scale production, RV2 would be the most economical and viable formulation as it achieved results similar to RV3 at half the concentration of recombinant proteins in its formulation. However, none of the vaccines tested induced the production of detectable antibody titers on day 365 of the experiment, the time of revaccination typically recommended in vaccination protocols. Thus, reiterating the need for research in the field of vaccinology to achieve greater longevity of the humoral immune response against these clostridial toxins in animals, in addition to the need to discuss the vaccine schedules and protocols adopted in cattle production.

Clostridium septicum: A review in the light of alpha-toxin and development of vaccines

Clostridium septicum (CS) is a pathogen that can cause the death of animals in livestock worldwide through its main virulence factor, alpha-toxin (ATX). The aspects involved in diseases caused by ATX, such as economic impact, prevalence, and rapid clinical course, require that animals should be systematically immunized. This review provides an overview of CS in livestock farming and discusses current immunization methods. Currently, commercial vaccines available against CS involve the cultivation and inactivation of microorganisms and toxins using a time-consuming, expensive, and high biological risk-carrying production platform, and some have been reported to be ineffective. An alternative to this process is the recombinant DNA technology, although recombinant ATX obtained thus far is no longer efficient in stimulating protective antibody titers despite improvements in the production methods. On the other hand, immunized animals have highly favorable levels of survival when subjected to challenge tests, suggesting that high titers of circulating serum antibodies may not be representative of protection after immunization and that the non-immune cellular defenses associated with the particularities of the mechanism of action of ATX may be involved in the immune response of the host. To contribute to the future of global livestock farming through the development of more efficient recombinant vaccines, we suggest novel perspectives and strategies, such as the location of immunodominant epitopes, expression of relevant functional domains, and construction of chimeras, in the rational design of recombinant ATX.

Vaccination against pathogenic clostridia in animals: a review

Clostridium is a Gram-positive, rod-shaped, anaerobic, and spore-forming bacterium, which is found in the surrounding environments throughout the world. Clostridium species cause botulism, tetanus, enterotoxaemia, gas gangrene, necrotic enteritis, pseudomembranous colitis, blackleg, and black disease. Clostridium infection causes severe economic losses in livestock and poultry industries. Vaccination seems to be an effective way to control Clostridial diseases. This review discusses the toxins and vaccine development of the most common pathogenic Clostridium species in animals, including Clostridium perfringens, Clostridium novyi, Clostridium chauvoei, and Clostridium septicum. In this comprehensive study, we will review different kinds of clostridial toxins and the vaccines that are experimentally or practically available and will give a short description on each vaccine focusing on its applications, advantages, and disadvantages.

Sheep and goat vaccines

The relatively low economic value of small ruminants places constraints upon vaccination in these species. In general, vaccination against clostridial diseases such as enterotoxemia and tetanus are most important. Enzootic pneumonia is a major cause of losses in intensively housed sheep. Footrot is a difficult disease to control because of the extreme antigenic diversity of its causal agent. In some areas soremouth vaccination is important. Bluetongue vaccination, even though complex, is also essential in some areas. Peste de petits ruminants is a growing cause for concern over much of Africa. Goats and llamas generally require the same vaccines as sheep.

Humoral responses in cattle to commercial vaccines containing Clostridium perfringens epsilon toxoid and C. botulinum types C and D toxoids last less than a-year

The aim of this study was to evaluate the titers of neutralizing antibodies in cattle inoculated with multivalent commercial clostridial vaccines containing C. botulinum type C (BoNTC), C. botulinum type D (BoNTD), and C. perfringens epsilon (ETX) toxoids for a period of one year. Cattle (Bos taurus), aged 4-6 months and not previously immunized, were vaccinated under four different protocols at days 0 and 30 and followed over one year. Individual serum titration was performed by a serum neutralization test in mice or in MDCK cells. The number of animals with detectable neutralizing antibodies ranged from 40.6% to 78.1%, but only 12.5% of animals showed neutralizing antibodies against all tested antigens. Neutralizing antibodies were found only until 60 days for ETX, 120 days for BoNTC, and 180 days for BoNTD. The absence of detectable neutralizing antibodies against the three antigens before 360 days, suggests that cattle remained unprotected for a long period before the recommended booster vaccination.