Development of Mycoplasma hyopneumoniae Recombinant Vaccines
Mycoplasma hyopneumoniae is the etiological agent of swine enzootic pneumonia (EP), a disease that affects swine production worldwide. Vaccination is the most cost-effective strategy for the control and prevention of the disease. Research using genome-bas
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Introduction Respiratory diseases are among the most important health problems associated with swine production. Mycoplasma hyopneumoniae is the principal etiological agent responsible for enzootic pneumonia (EP), a chronic respiratory disease in pigs. This infection is highly prevalent (ranging between 38 and 100 %), in almost all areas of pig production worldwide, and M. hyopneumoniae infections cause significant economic losses [1]. The control of EP should focus on the optimization of management practices and housing conditions [2], the use of antimicrobial medication [3], and vaccination. Several commercial vaccines consisting of the inactivated adjuvanted whole cell lysates of M. hyopneumoniae are available and used worldwide. Though these vaccines have been proven to be effective in reducing the clinical signs, they provide only partial protection against the development of lesions [4]. Recombinant DNA technology could be employed to overcome problems encountered with conventional vaccines. The small genome of this pathogen, as well as the limited number of secreted or surface proteins, favors the use of reverse vaccinology approach [5]. However, Mycoplasma sp. uses an unusual genetic code. The amino acid tryptophan is not encoded by TGG, as in most organisms, but by TGA, which is a stop codon [6]. This difference has hampered the expression of genes of M. hyopneumoniae containing TGA codons in Escherichia coli, the most attractive system used for production of recombinant proteins [7]. However, mutations that can replace TGA codons with TGG have been used to solve this problem [8].
Sunil Thomas (ed.), Vaccine Design: Methods and Protocols, Volume 2: Vaccines for Veterinary Diseases, Methods in Molecular Biology, vol. 1404, DOI 10.1007/978-1-4939-3389-1_2, © Springer Science+Business Media New York 2016
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Silvana Beutinger Marchioro et al.
Constant effort is being directed toward the investigation of new vaccines that may offer a better protection against M. hyopneumoniae infections. Several studies have evaluated recombinant proteins of M. hyopneumoniae, in different forms of administration and formulations, seeking to develop more effective vaccines against EP. Some of them were evaluated individually [9, 10], and others were associated with attenuated bacterial or viral vectors [11–18], fused to mucosal adjuvants [19, 20], and also evaluated as a cocktail of antigens [21, 22]. Only a few of these recombinant proteins were used in challenge experiments in pigs; most of them were evaluated only in mice. Differences in the immunity induced by these antigens were observed, which can be influenced by differences in the vaccine construction, the route of immunization, the correct folding, and/or other posttranslational modification that may contribute to the ability to generate antibodies by the antigens [23]. However, these evaluations suggest that these new vaccine approaches may represent promising new strategies and may be economically feasible to control EP.
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Materials
2.1 Strains and Plas
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