Assessment of methodological quality and sources of variation in the magnitude of vaccine efficacy: A systematic review of studies from 1960 to 2005 reporting immunization with Moraxella bovis vaccines in young cattle

Department of Veterinary Diagnostics and Production Animal Medicine, Iowa State University College of Veterinary Medicine, 1715 Veterinary Medicine Building, Ames, IA 50011, USA.
Vaccine (Impact Factor: 3.62). 02/2008; 26(2):144-52. DOI: 10.1016/j.vaccine.2007.10.014
Source: PubMed


A review was conducted of all identified literature evaluating Moraxella bovis vaccines efficacy in preventing pinkeye in beef calves. From 292 publications identified by the search, data on 123 unique vaccine-to-control comparisons were extracted from 38 studies published in English from 1960 to 2005. Descriptive analysis was performed and an analysis of sources of variation evaluated. Use of methods to control bias such as randomization and blinding were associated with decreased vaccine efficacy. Only 15 trials reported using randomization and blinding. The authors conclude that when designing and reporting veterinary vaccination studies, researchers must include methodological quality information necessary to judge the evidence produced from the study.

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    • "(Olivry and Mueller, 2003); What is the efficacy of vaccines for the prevention of pinkeye in cattle? (Burns and O'Connor, 2008); What is the evidence for the effectiveness of acupuncture in veterinary medicine? (Habacher et al., 2006); and What is the evidence for efficacy of selected pre-harvest interventions to reduce faecal shedding of Escherichia coli O157 in ruminants? "
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    ABSTRACT: This article is the first in a series of six articles related to systematic reviews in animal agriculture and veterinary medicine. In this article, we overview the methodology of systematic reviews and provide a discussion of their use. Systematic reviews differ qualitatively from traditional reviews by explicitly defining a specific review question, employing methods to reduce bias in the selection and inclusion of studies that address the review question (including a systematic and specified search strategy, and selection of studies based on explicit eligibility criteria), an assessment of the risk of bias for included studies and objectively summarizing the results qualitatively or quantitatively (i.e. via meta-analysis). Systematic reviews have been widely used to address human healthcare questions and are increasingly being used in veterinary medicine. Systematic reviews can provide veterinarians and other decision-makers with a scientifically defensible summary of the current state of knowledge on a topic without the need for the end-user to read the vast amount of primary research related to that topic.
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    • "Therefore, induction of protective immunity with pili-based vaccines is serogroup specific. A recent review regarding the current status of vaccine efficacy against pinkeye reported that the effectiveness of the vaccines varies a great deal, likely depending on the vaccine type, and the similarity of the vaccine organism to the challenge organism [5]. Besides, vaccine efficacy also depends on the inclusion of the appropriate strains regarding the regional serogroups and microbial diversity [6] [7], and on an adequate control of the components in the vaccine formulation [6] [8]. "
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    ABSTRACT: Pili are the principal antigens and virulence factors of Moraxella bovis, the etiological agent of infectious bovine keratoconjunctivitis (IBK). Although it has been reported that the low efficacy of whole cell vaccines against IBK is mainly due to the difficulties in keeping the cellular piliation level of M. bovis during the growth of bacteria in stirred bioreactors, the problem has not yet been overcome because the mechanisms involved in the loss of piliation are still not fully clarified. In this work we found that during the culture of M. bovis in liquid media, around 15% of the cells changed from piliated to non-piliated phenotypes at the end of the growth. Nevertheless, we demonstrated that the main cause of cellular piliation loss in M. bovis growing in stirred and/or sparged bioreactors is due to shear forces, which are a function of the volumetric gassed power drawn (P(g)V(-1)). Therefore, we tested here the use of bubble column bioreactors to protect M. bovis cell-bound pili from mechanical agitation damage effects. These bioreactors operated at a superficial air velocity of 0.0065 m s(-1) yielded a cellular piliation level of 25%, in contrast to 1% obtained for stirred bioreactors. The addition of carboxymethylcellulose (CMC) at 0.10% (w v(-1)) to culture medium proved to be suitable to improve the final piliation level (65%). We demonstrated by FT-IR spectroscopy and ELISA technique, that this chemical additive has a pili protective role interacting with the cells but without affecting pili antigenic properties.
    Full-text · Article · Nov 2008 · Vaccine
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