Oral vaccination of 1-day-old turkeys with<i>in vitro</i>attenuated<i>Histomonas meleagridis</i>protects against histomonosis and has no negative effect on performance

Liebhart, Dieter; Windisch, Manfred; Heß, Michael

doi:10.1080/03079457.2010.506906

Cited by 24 publications

(24 citation statements)

References 14 publications

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“…Unfortunately, to date, efficacy of these products could not be demonstrated under experimental conditions (van der Heijden & Landman, 2008a, 2008bThofner et al, 2012). In parallel, other scientists have chosen a more conventional approach, that is, vaccinology to solve the "histomonas problem" (Hess et al, 2008;Liebhart et al, 2010;Nguyen Pham et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Quantification of parasite shedding and horizontal transmission parameters inHistomonas meleagridis-infected turkeys determined by real-time quantitative PCR

et al. 2015

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To gain more insight into the within flock transmission of Histomonas meleagridis, the shedding of parasites was quantified by a newly developed real-time quantitative (q)PCR and the basic reproduction number (R 0 ) and the mean number of secondary infections per infectious bird per day in a susceptible population (β) of H. meleagridis in the absence of heterakis were assessed. Forty turkeys were divided into two groups of 10 and 30 birds at 14 days of age. Birds of the first group were inoculated with 200,000 histomonads each, the second group served as a susceptible contact group. Cloacal swabs were taken at −1, 1, 4, 7, 9, 11, 14, 18 and 21 days post inoculation (p.i.) to assess the shedding of the parasite by the qPCR (detection limit 330 histomonads/ml droppings). The experiment ended at 28 days p.i. Mortality was 100% in the inoculated birds and started at day 12 p.i., while in the contacts, it was 83% and started at 16 days p.i. Shedding started 1 day after the inoculation in both groups. The mean shedding levels (and 95% CI) expressed as parasite equivalents per gram cloacal content on a log 10 scale in the inoculated, contact birds that died and contact birds alive were 2.0 (1.6-2.4), 1.6 (1.4-1.9) and 1.2 (0.5-2.0), respectively. Birds that died shed histomonas more often and were infectious for 13.4 days; in contrast, those that recovered were infectious for 5.7 days. R 0 was estimated to be 8.4 and β 0.70. Simulations made with the parameters obtained were in agreement with the experimental results, confirming their validity.

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Section: Introductionmentioning

confidence: 99%

Quantification of parasite shedding and horizontal transmission parameters inHistomonas meleagridis-infected turkeys determined by real-time quantitative PCR

et al. 2015

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“…In contrast to this, we could achieve full protection from fatal histomonosis by vaccination using a well-defined clonal culture of in vitro attenuated histomonads in turkeys . In continuation, successful oral administration of attenuated histomonads to day-old turkeys was demonstrated successfully for the first time (Liebhart et al, 2010). The established vaccine candidate was further investigated for its safety, with the outcome that (i) no clinical signs or pathological lesions were found in chickens and turkeys that were vaccinated and (ii) the strain used for vaccination did not revert to virulence following consecutive passages in both host species, and only minimal lesions were noted (Sulejmanovic et al, 2013).…”

Section: Investigations On Vaccination Against Histomonosismentioning

confidence: 99%

Histomonosis in poultry: previous and current strategies for prevention and therapy

et al. 2016

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Histomonosis is a parasitic disease of poultry with worldwide prevalence. The disease can cause morbidity and mortality in chicken and turkey flocks entailing severe economic losses. In the first half of the last century, there was a high demand to control histomonosis as the turkey industry was severely affected by the disease. Consequently, numerous chemical compounds were tested for their efficacy against Histomonas meleagridis with varying outcomes, that are summarized and specified in this review. At the same time, preliminary attempts to protect birds with cultured histomonads indicated the possibility of vaccination. Several years ago antihistomonal drugs were banned in countries with tight regulations on pharmaceuticals in order to comply with the demand of consumer protection. As a consequence, outbreaks of histomonosis in poultry flocks increased and the disease became endemic again. New approaches to prevent and treat histomonosis are, therefore, needed and recently performed studies focused on various areas to combat the disease, from alternative chemotherapeutic substances to plant-derived compounds until vaccination, altogether reviewed here. Considering existing regulations and the overall outcome of experimental studies, it can be concluded that vaccination is very promising, despite the fact that various challenges need to be addressed until the first ever developed vaccine based upon live flagellates in human or bird medicine can be marketed.

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“…The vaccinal strain became attenuated when organisms were passaged every 2–3 days in axenic broth culture for 295 times. The vaccine is effective when administered into the crop or into the cloaca, and provides strong protection in challenge experiments, at least against low passage virulent organisms of the parent strain (Liebhart et al 2010, 2013). Histomoniasis is re-emerging as a cause of poultry losses, in part because the prophylactic use of effective antimicrobials has been restricted or banned.…”

Section: Experimental Protozoal Vaccinesmentioning

confidence: 99%

Successful vaccines for naturally occurring protozoal diseases of animals should guide human vaccine research. A review of protozoal vaccines and their designs

McAllister

2014

Parasitology

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SUMMARYEffective vaccines are available for many protozoal diseases of animals, including vaccines for zoonotic pathogens and for several species of vector-transmitted apicomplexan haemoparasites. In comparison with human diseases, vaccine development for animals has practical advantages such as the ability to perform experiments in the natural host, the option to manufacture some vaccines in vivo, and lower safety requirements. Although it is proper for human vaccines to be held to higher standards, the enduring lack of vaccines for human protozoal diseases is difficult to reconcile with the comparatively immense amount of research funding. Common tactical problems of human protozoal vaccine research include reliance upon adapted rather than natural animal disease models, and an overwhelming emphasis on novel approaches that are usually attempted in replacement of rather than for improvement upon the types of designs used in effective veterinary vaccines. Currently, all effective protozoal vaccines for animals are predicated upon the ability to grow protozoal organisms. Because human protozoal vaccines need to be as effective as animal vaccines, researchers should benefit from a comparison of existing veterinary products and leading experimental vaccine designs. With this in mind, protozoal vaccines are here reviewed.

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Oral vaccination of 1-day-old turkeys within vitroattenuatedHistomonas meleagridisprotects against histomonosis and has no negative effect on performance

Cited by 24 publications

References 14 publications

Quantification of parasite shedding and horizontal transmission parameters inHistomonas meleagridis-infected turkeys determined by real-time quantitative PCR

Quantification of parasite shedding and horizontal transmission parameters inHistomonas meleagridis-infected turkeys determined by real-time quantitative PCR

Histomonosis in poultry: previous and current strategies for prevention and therapy

Successful vaccines for naturally occurring protozoal diseases of animals should guide human vaccine research. A review of protozoal vaccines and their designs

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