Comparison of the efficacy of Brucella suis strain 2 and Brucella melitensis Rev. 1 live vaccines against a Brucella melitensis experimental infection in pregnant ewes

Verger, Jean-Michel; Grayon, Maggy; Zundel, Etienne; Lechopier, Patrick; Olivier-Bernardin, Véronique

doi:10.1016/0264-410x(95)93135-v

Cited by 56 publications

(43 citation statements)

References 8 publications

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“…For instance, as consequence of high prevalence in domestic animal reservoirs (sheep) in Inner Mongolia, the R 0 for human infection corresponds to 1.8 (Hou et al, 2013). Under the prevailing control measures and use of low protective vaccines (Blasco et al, 1993; Verger et al, 1995) it was predicted that human brucellosis will continue to increase for the next decade in China.…”

Section: Discussionmentioning

confidence: 99%

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Retrospective and prospective perspectives on zoonotic brucellosis

2014

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Members of the genus Brucella are pathogenic bacteria exceedingly well adapted to their hosts. The bacterium is transmitted by direct contact within the same host species or accidentally to secondary hosts, such as humans. Human brucellosis is strongly linked to the management of domesticated animals and ingestion of their products. Since the domestication of ungulates and dogs in the Fertile Crescent and Asia in 12000 and 33000 ya, respectively, a steady supply of well adapted emergent Brucella pathogens causing zoonotic disease has been provided. Likewise, anthropogenic modification of wild life may have also impacted host susceptibility and Brucella selection. Domestication and human influence on wild life animals are not neutral phenomena. Consequently, Brucella organisms have followed their hosts’ fate and have been selected under conditions that favor high transmission rate. The “arm race” between Brucella and their preferred hosts has been driven by genetic adaptation of the bacterium confronted with the evolving immune defenses of the host. Management conditions, such as clustering, selection, culling, and vaccination of Brucella preferred hosts have profound influences in the outcome of brucellosis and in the selection of Brucella organisms. Countries that have controlled brucellosis systematically used reliable smooth live vaccines, consistent immunization protocols, adequate diagnostic tests, broad vaccination coverage and sustained removal of the infected animals. To ignore and misuse tools and strategies already available for the control of brucellosis may promote the emergence of new Brucella variants. The unrestricted use of low-efficacy vaccines may promote a “false sense of security” and works towards selection of Brucella with higher virulence and transmission potential.

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Section: Discussionmentioning

confidence: 99%

“…Of all the problems in control programs, the introduction of low protection rate vaccines stands as a major drawback (Blasco et al, 1993; Verger et al, 1995; Moriyón et al, 2004; Godfroid et al, 2011). Apart from their failure in controlling brucellosis, there are long-term consequences in the use vaccines with low efficacy.…”

Section: Coping With Brucellosismentioning

confidence: 99%

Retrospective and prospective perspectives on zoonotic brucellosis

2014

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“…Nevertheless, under well-standardized conditions the mouse model is a useful tool for screening vaccines, even though one vaccine that performs efficiently in mice may not work in the natural host. The opposite, however, has not been reported: vaccines that protect poorly in mice are useless in the natural hosts [85,198,199]. In any case, for vaccine evaluation it is always necessary to use controls vaccinated with the reference vaccine strains and to apply the correct statistical tests.…”

Section: Discussionmentioning

confidence: 99%

What have we learned from brucellosis in the mouse model?

Grilló

Blasco

Gorvel

et al. 2012

Vet Res

191

219

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Brucellosis is a zoonosis caused by Brucella species. Brucellosis research in natural hosts is often precluded by practical, economical and ethical reasons and mice are widely used. However, mice are not natural Brucella hosts and the course of murine brucellosis depends on bacterial strain virulence, dose and inoculation route as well as breed, genetic background, age, sex and physiological statu of mice. Therefore, meaningful experiments require a definition of these variables. Brucella spleen replication profiles are highly reproducible and course in four phases: i), onset or spleen colonization (first 48 h); ii), acute phase, from the third day to the time when bacteria reach maximal numbers; iii), chronic steady phase, where bacterial numbers plateaus; and iv), chronic declining phase, during which brucellae are eliminated. This pattern displays clear physiopathological signs and is sensitive to small virulence variations, making possible to assess attenuation when fully virulent bacteria are used as controls. Similarly, immunity studies using mice with known defects are possible. Mutations affecting INF-γ, TLR9, Myd88, Tγδ and TNF-β favor Brucella replication; whereas IL-1β, IL-18, TLR4, TLR5, TLR2, NOD1, NOD2, GM-CSF, IL/17r, Rip2, TRIF, NK or Nramp1 deficiencies have no noticeable effects. Splenomegaly development is also useful: it correlates with IFN-γ and IL-12 levels and with Brucella strain virulence. The genetic background is also important: Brucella-resistant mice (C57BL) yield lower splenic bacterial replication and less splenomegaly than susceptible breeds. When inoculum is increased, a saturating dose above which bacterial numbers per organ do not augment, is reached. Unlike many gram-negative bacteria, lethal doses are large (≥ 108 bacteria/mouse) and normally higher than the saturating dose. Persistence is a useful virulence/attenuation index and is used in vaccine (Residual Virulence) quality control. Vaccine candidates are also often tested in mice by determining splenic Brucella numbers after challenging with appropriate virulent brucellae doses at precise post-vaccination times. Since most live or killed Brucella vaccines provide some protection in mice, controls immunized with reference vaccines (S19 or Rev1) are critical. Finally, mice have been successfully used to evaluate brucellosis therapies. It is concluded that, when used properly, the mouse is a valuable brucellosis model.

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“…S2 was also evaluated for its ability to be delivered by the conjunctival route in rams and ewes for protection against wt B. ovis . The results showed that S2 was less protective than Rev-1 in rams (43.7% versus 78.6%, respectively) (Blasco et al, 1993), and in ewe abortion (71%–81% versus 20%–38% for S2 and Rev-1 aborted ewes, respectively) (Verger et al, 1995). This may imply that S2 is not appropriate for usage via conjunctival immunization route, or alternatively, S2 is not effective in protecting infections caused by the species B. ovis or B. melitensis .…”

Section: Live Vaccinesmentioning

confidence: 99%

Progress in Brucella vaccine development

et al. 2012

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Brucella spp. are zoonotic, facultative intracellular pathogens, which cause animal and human disease. Animal disease results in abortion of fetuses; in humans, it manifests flu-like symptoms with an undulant fever, with osteoarthritis as a common complication of infection. Antibiotic regimens for human brucellosis patients may last several months and are not always completely effective. While there are no vaccines for humans, several licensed live Brucella vaccines are available for use in livestock. The performance of these animal vaccines is dependent upon the host species, dose, and route of immunization. Newly engineered live vaccines, lacking well-defined virulence factors, retain low residual virulence, are highly protective, and may someday replace currently used animal vaccines. These also have possible human applications. Moreover, due to their enhanced safety and efficacy in animal models, subunit vaccines for brucellosis show great promise for their application in livestock and humans. This review summarizes the progress of brucellosis vaccine development and presents an overview of candidate vaccines.

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Comparison of the efficacy of Brucella suis strain 2 and Brucella melitensis Rev. 1 live vaccines against a Brucella melitensis experimental infection in pregnant ewes

Cited by 56 publications

References 8 publications

Retrospective and prospective perspectives on zoonotic brucellosis

Retrospective and prospective perspectives on zoonotic brucellosis

What have we learned from brucellosis in the mouse model?

Progress in Brucella vaccine development

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