RESUMO
In this work two cytokines were used in combination with inactivated bacteria (bacterin) to test the bovine conjuctival immune response to the pathogen Moraxella bovis, the causative agent of Infectious bovine keratoconjunctivitis (IBK). Treatments using the bacterin vaccine combined with interleukin-2 and interferon-α as adjuvants (Group A), the bacterin vaccine only (Group B), and controls without treatment (Group C), were applied by ocular spraying to evaluate the local immune response in the corneal structure of cattle experimentally infected with M. bovis. Six weeks after infection, 14 out of a total of 34 animals presented different corneal lesions; 9 corresponding to the control group C, 4 to the group B and only one to the group A. According to the clinical manifestations, a numeric score was calculated. Control animals presented the highest score value (12 points), followed by group B (7.5 points) and group A (1 point). These results suggest that the addition of cytokines to M. bovis treatments can reduce not only eye injuries caused by IBK but also the number of diseased animals.
Assuntos
Adjuvantes Imunológicos/uso terapêutico , Vacinas Bacterianas/uso terapêutico , Doenças dos Bovinos/prevenção & controle , Citocinas/uso terapêutico , Ceratoconjuntivite Infecciosa/prevenção & controle , Moraxella bovis , Infecções por Moraxellaceae/veterinária , Animais , Bovinos , Doenças dos Bovinos/imunologia , Doenças dos Bovinos/microbiologia , Interferon-alfa/uso terapêutico , Interleucina-2/uso terapêutico , Ceratoconjuntivite Infecciosa/imunologia , Ceratoconjuntivite Infecciosa/microbiologia , Moraxella bovis/imunologia , Infecções por Moraxellaceae/imunologia , Infecções por Moraxellaceae/prevenção & controleRESUMO
Infectious bovine keratoconjunctivitis (IBK) is a highly contagious ocular disease of cattle caused by Moraxella bovis (Mb). Parenterally administered immunogens used to prevent the disease do not offer complete protection possibly because they stimulate a poor ocular mucosal secretory response, in which locally secreted immunoglobulin-A (sIgA) is one of the main components. The principal aim of this study was to evaluate by an indirect enzyme linked immunosorbent assay (ELISA), the local ocular mucosal sIgA response against Mb purified pili, produced after intranasal inoculation of experimental vaccines. Pili were adjuvanted by several different adjuvants (QuilA, Marcol Arlacel, Marcol Span, microencapsulated pili with PLGA polymers). Results were compared to sIgA response produced by adjuvant placebo inoculations and by IBK natural infection. Significantly higher anti-pili IgA response (p<0.05) was detected in calves vaccinated intranasally with pili QuilA and pili Marcol Span compared to control calves, although this specific immune response did not seem to be related to protection against Mb infection or typical IBK lesion development.
Assuntos
Anticorpos Antibacterianos/análise , Vacinas Bacterianas/imunologia , Fímbrias Bacterianas/imunologia , Imunoglobulina A/análise , Moraxella bovis/imunologia , Infecções por Moraxellaceae/veterinária , Lágrimas/imunologia , Administração Intranasal , Animais , Anticorpos Antibacterianos/imunologia , Vacinas Bacterianas/administração & dosagem , Vacinas Bacterianas/uso terapêutico , Bovinos , Relação Dose-Resposta Imunológica , Ensaio de Imunoadsorção Enzimática/veterinária , Imunoglobulina A/imunologia , Infecções por Moraxellaceae/imunologia , Infecções por Moraxellaceae/prevenção & controle , Vacinação/métodos , Vacinação/veterináriaRESUMO
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.