Brian McCluskey

Background: Brucella melitensis is recognized as one of the predominant zoonotic pathogens globally. Live-attenuated vaccine Rev 1 is currently the most effective vaccine for controlling B. melitensis in small ruminants. While Brucella inactivated, nanoparticle, and subunit vaccines are less effective and require multiple doses, live-attenuated vaccines are less expensive and more efficacious. Several drawbacks are associated with the administration of current attenuated B. melitensis vaccines, including interference with serological diagnostic tests, inducing abortion in pregnant animals, shedding in milk, and zoonotic infections in humans. In this systematic review, we summarize the current literature (1970–2022) on B. melitensis vaccines and review their advantages and disadvantages in order to support the rationale for a need for new or improved small ruminant brucellosis vaccines. Methods: A systematic search was carried out in Web of Science, CAB Abstracts, and PubMed. The original articles describing the B. melitensis vaccines were included. Review articles, articles not published in English, articles that did not offer full text, editorials, correspondences, case reports, case series, diagnostic tests, duplicate publications, and other Brucella vaccines (e.g., B. abortus and B. suis) were excluded. Results: Out of 3700 studies, we identified 18 articles that evaluated B. meltensis vaccines, including recombinant B. melitensis strains (16MΔhfq, 16MΔTcfSR, M5-90ΔmanB, LVM31, M5-90ΔvjbR, 16MΔmucR, ΔznuA, M5-90Δpgm, M5-90ΔwboA), live B. melitensis strain (Rev 1), nanoparticle vaccines (B. melitensis 16M, B. melitensis OMP 31, FliC protein—Mannosylated Chitosan Nanoparticles (FliC and FliC-MCN), B. melitensis and B. abortus combined, and B. melitensis 16M nanoparticles combined with oligopolysaccharide), subunit vaccines (outer membrane vesicles or outer membrane proteins), and a DNA vaccine based on B. melitensis outer membrane proteins (Omp25 and Omp31). The results from these studies revealed that these vaccines can induce humoral and cellular responses and reduce macrophage survival. However, most of these vaccines were evaluated only in murine models, which may not accurately reflect how they work in natural hosts. Conclusions: The high prevalence of B. melitensis in humans and animals remains an issue in many parts of the world. Human brucellosis can be prevented by controlling brucellosis in livestock using vaccination and test-and-removal strategies. Prospective vaccines have limitations, including interference with serodiagnostics after vaccination, virulence in humans and animals, the requirement of booster vaccinations, and insufficient efficacy in preventing infection or abortion. Moreover, most of these vaccines have been assessed in mice models, which have failed to predict immunogenicity or efficacy in natural hosts. Because of these limitations and the re-emergence of B. melitensis worldwide with a high incidence of human infection, our review suggests a need for additional research into the molecular pathology and immunological properties of B. melitensis infection and the identification of protective epitopes or genes that would allow for the development of improved vaccines for small ruminants.

Biosurveillance defines the process of gathering, integrating, interpreting, and communicating essential information related to all-hazards threats or disease activity affecting human, animal, or plant health to achieve early detection and warning, contribute to overall situational awareness of the health aspects of an incident, and to enable better decision making for action at all levels. Animal health surveillance is an important component within biosurveillance systems comprising a continuum of activities from detecting biological threats, to analyzing relevant data, to managing identified threats, and embracing a One Health concept. The animal health community can strengthen biosurveillance by adopting various developments such as increasing the alignment, engagement, and participation of stakeholders in surveillance systems, exploring new data streams, improving integration and analysis of data streams for decision-making, enhancing research and application of social sciences and behavioral methods in animal health surveillance, and performing timely evaluation of surveillance systems. The aim of this paper is to explore components of a biosurveillance system from an animal health perspective and identify opportunities for the animal health surveillance community to enhance biosurveillance. Structural and operational diagrams are presented to demonstrate the required components and relevant data of animal health surveillance as an effective part within a biosurveillance system.