Lentivirus induced arthritis in animals

Retroviral arthritis in sheep and goats depends on persistent infection in the animals. Virus is latent in macrophage precursor cells and viral replication is initiated when these cells are induced to differentiate. Antiviral antibodies and cytokines modulate the efficiency of viral gene product expression. Specific cytokines induced during replication of the lentivirus in mononuclear cells are also responsible for directing infected cells from peripheral blood through the vascular endothelium to particular tissues. Cytokines induced by other infectious agents such as bacteria, mycoplasma or protozoa, may also contribute to this chemotactic process. Once in the tissue, macrophages interact with lymphocytes to induce an inflammatory cascade with further production of cytokines which enhances expression of class II major histocompatibility complex antigens and proliferation of B and CD8 lymphocytes. In addition, immune complexes between viral glycoproteins and immunoglobulins are produced locally and probably lead to further enhancement of pathological changes in the tissues.