• A B-cell mitogen involved in immunomodulation and chronicity in brucellosis

SPERA JM, COMERCI DJ, UALDE JE, UGALDE RA

Congreso; SAIB XLV; 2009

One of the outstanding characteristics of Brucella as well as otherpathogens, is the ability to establish a chronic infection that persistsover the host lifespan. The fact that a pathogen can survive in a hostwith an ongoing immune response, depicts the existence of mechanismscapable of subverting or avoiding it. One common way of manipulating theimmune response is by interfering with the fine tuned balance of cytokinesand thus affecting the number and function of immune effector cells.Understanding this cross-talk could result promising for the developmentof new strategies for vaccination, immunotherapy and drug design.We have characterized a B. abortus protein (PrpA) with strongimmunomodulating abilities. We have demonstrated that recombinant PrpAstimulates B-cell polyclonal activation and IL-10 and IFNg secretion invitro.By conducting experimental infections, we characterized the immuneresponse of mice infected with B. abortus prpA mutant and its parentalstrain (2308). We observed that B-cell number, IgG titers, IFNg, IL-10 andIL-4 levels were manipulated by Brucella in a prpA dependent manner. Wealso show that prpA is responsible for a transient and reversible anergicstate during the course of the infection. Finally, mutation of prpAresulted in a 100-fold reduction in bacterial number recovered from micespleens during the chronic phase of infection.