A B-cell mitogen involved in immunomodulation and chronicity in Brucellosis

SPERA, J. M.; DIEGO JOSE COMERCI; UGALDE, J. E.; UGALDE, R. A.

San Miguel de Tucumán

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB).; 2009

SAIBBM

One of the outstanding characteristics of Brucella as well as other pathogens, is the ability to establish a chronic infection that persists over the host lifespan. The fact that a pathogen can survive in a host with an ongoing immune response, depicts the existence of mechanisms capable of subverting or avoiding it. One common way of manipulating the immune response is by interfering with the fine tuned balance of cytokines and thus affecting the number and function of immune effector cells. Understanding this cross-talk could result promising for the development of new strategies for vaccination, immunotherapy and drug design. We have characterized a B. abortus protein (PrpA) with strong immunomodulating abilities. We have demonstrated that recombinant PrpA stimulates B-cell polyclonal activation and IL-10 and IFNg secretion in vitro. By conducting experimental infections, we characterized the immune response of mice infected with B. abortus prpA mutant and its parental strain (2308). We observed that B-cell number, IgG titers, IFNg, IL-10 and IL-4 levels were manipulated by Brucella in a prpA dependent manner. We also show that prpA is responsible for a transient and reversible anergic state during the course of the infection. Finally, mutation of prpA resulted in a 100-fold reduction in bacterial number recovered from mice spleens during the chronic phase of infection