Bovine IgG1 antibodies against Mycobacterium avium subsp. paratuberculosis protein p34-cx improve association of bacteria and macrophagesSilvia L. Mundo1, Adriana M. Fontanals1, Mariana García2, María Durrieu1, Elida Álvarez2, Elida R. Gentilini1 and Silvia E. Hajos2
1 Cátedra de Inmunología, Facultad de Ciencias Veterinarias, Universidad de Buenos Aires (UBA), Argentina
2 Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, IDEHU, UBA-CONICET, Argentina
(Received 17 October 2006; accepted 6 August 2007; published online 9 November 2007)
Abstract - Paratuberculosis, caused by Mycobacterium avium subsp. paratuberculosis (Map), is a chronic granulomatous enteric disease in cattle. Among molecular components of Map, protein p34 was identified as specific and immunodominant for bovine B cells. In order to determine if specific antibodies could influence the course of Map pathogenesis, the interaction between bacteria and bovine macrophages was studied. Bovine polyclonal antibodies from 3 calves vaccinated with protein p34-cx, 6 calves vaccinated with heat-killed Map, 8 naturally infected, and 3 healthy calves -as negative controls- were used. Specific anti-Map, -p34-cx and -PPA-3 antibodies were evaluated and isotype characterized. Infected and Map vaccinated animals showed similar IgG1 and IgG2 response against Map whole bacteria. When p34-cx was used as the antigen, mainly IgG1 and IgG3 were detected in infected and only IgG1 in p34-cx vaccinated animals. Bovine polyclonal antibodies from three animals of each category were isolated and affinity purified through Map and p34-cx columns. The effect of these antibodies in association with Map and a transformed bovine peritoneal macrophage's cell line (Bov-Mac) as well as activation of NF-B transcription factor was studied. Our results show that association of Map significantly increased in vitro after pretreatment with bovine anti-Map or anti-p34-cx antibodies obtained from vaccinated or infected cattle when compared with those of controls. Improved activation of NF-B was detected in macrophages that ingested Map opsonized with either anti-Map or anti-p34-cx specific antibodies of infected or vaccinated calves, suggesting that both anti-Map and IgG1 anti-p34-cx antibodies support Map-macrophage interactions.
Key words: Mycobacterium avium subsp. paratuberculosis / p34 / IgG1 / macrophages / cattle
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© INRA, EDP Sciences 2007