부산대학교 도서관

Rhodococcus equiis a Gram‐positive, facultative intracellular bacterium which infects macrophages and causes rhodococcal pneumonia and enteritis in foals. Recently, this agent has been recognized as an opportunistic pathogen for immunocompromised humans. Several murine experimental models have been used to study R. equiinfection. High (HIV‐A) and Low (LIV‐A) antibody (Ab)‐producers mice were obtained by bi‐directional genetic selections for their ability to produce antibodies against sheep and human erythrocytes (Selection IV‐A). These lines maintain their phenotypes of high and low responders also for other antigens than those of selection (multispecific effect). A higher macrophage activity in LIV‐Amice has been described for several intracellular infectious agents, which could be responsible for their intense macrophage antigens (Ag)‐handling and low Ab production. Due to these differences, LIV‐Amice were found to exhibit a better performance to trigger an effective immune response towards intracellular pathogens. The objective of this work was to characterize the immune response of Selection IV‐A against R. equi. HIV‐Aand LIV‐Amice were infected with 2.0 ×106CFU of ATCC 33701+R. equiby intravenous route. With regards to bacterial clearance and survival assays, LIV‐Amice were more resistant than HIV‐Amice to virulent R. equi. LIV‐Amice presented a higher hydrogen peroxide (H2O2) and nitric oxide (NO) endogenous production by splenic macrophages than HIV‐Amice. LIV‐Aexpressed the most intense cellular response, available by the Delayed‐Type Hypersensitivity (DTH) reaction, which activated macrophages and produced more H2O2and NO. The three times higher specific antibodies titres in HIV‐Aindicated that Selection IV‐A maintained the multispecific effect and the polygenic control of humoral and cellular responses also to R. equi.