ABSTRACT
Brucella is a facultative intracellular pathogen that causes infection in domestic animal and humans,mainly parasitizing in cells and macrophages of hosts.Brucella can lead to abortion and sterility in animals.Meanwhile,it also causes arthralgia,weakness,undulat fever,hepatosplenomegaly and other symptoms in humans.Brucella relies on immune escape mechanism in the confrontation with the host.It can help Brucella "camouflage" to evade the identification of the immune system of the hosts and replicate within cells to persist to establish a long-term infection in the host.As a result of the existence of this mechanism,the treatment of Brucella infection is quite difficult.Type Ⅳ secretion system (T4SS) is a key virulence factor and it is essential for Brucella to survive in host cells.The effector proteins secreted by T4SS can help regulate the immune response against Brucella.In this article,we reviewed the studies on related proteins of the type Ⅳ secretion system of Brucella and its immune response,especially the relationship between the secretions of effector proteins mediated by VirB operon and immunity of the host.