Chapter 22 - Immune responses and vaccination

Abstract

This chapter discusses the immune responses and vaccination of the organism infected with brucellosis. Brucella spp. are facultative intracellular bacteria capable of survival and multiplication within phagocytes of the host. In this environment, they are protected from humoral antibody. Infection usually results in both humoral and cell-mediated responses. The magnitude and duration of these responses depends upon many factors such as the virulence of the infecting strain, exposure numbers, age, sex, pregnancy status, species of animals, and previous exposure to Brucella antigens. In food-producing animals most research on the immunology of brucellosis has been in cattle. As many diagnostic tests detect antibody to the S (smooth)-lipopolysaccharide complex of the brucella cell, many studies have concerned antibody-mediated reactions to these antigens. However, it is generally accepted that cell-mediated immunity plays the major role in defense mechanisms against infection by Brucella. Following exposure to Brucella antigens, activation and multiplication of macrophages occur together with the formation of antibodies by plasma cells. The stimulation of cellular responses occurs concurrently but probably largely independent of specific humoral antibody production.