engleski

Immunity to equine infectious anemia virus: current knowledge

Equine infectious anemia (EIA) is a contagious viral disease that occurs only in members of family Equidae and induces a lifelong, persistent infection. Thus, all horses infected with EIA virus (EIAV) are thought to remain virus carriers for life, and are treated as if they pose the risk for transmission of the virus.The causative agent of EIA, EIAV is classified in the family Retroviridae, genus Lentivirus, based on its ultrastructure, genomic organization, reverse transcriptase activity, serologic cross-reactivity, and tropism for monocytes/macrophages. Like other lentiviruses, including human immunodeficiency virus-type 1 (HIV -1), immune-mediated hypersensitivity reactions and immunosuppression of host's immune responses are typical features of EIAV. The horse reaction to infection involves both humoral and cellular immune responses. EIAV-infected horses develop a marked antibody response to the major envelope and the transmembrane glycoprotein (gp 90 and gp45, respectively) antigens within few weeks following infection. Peripheral blood mononuclear cells of infected horses have been shown to selectively lyse virus-infected cells in direct cytolytic (DC) and antibody dependent cellular cytolytic (ADCC) assays. However, the immune controle of EIAV is ineffective due to the emerging mutants of the virus which escape immunological inactivation and exclusively infect cells of the monocyte/macrophage lineage. The changing epitopes on two virus-encoded glycosylated proteins, gp90 or gp45 are major obstacles in the development of an effective vaccine against myriad antigenic variants of the EIAV. Among lentiviruses, the persistent infection with EIAV represents a uniquely dynamic contest between a constantly changing virus that utilizes a complex system of biological diversity and variability in regulatory and antigenic phenotype and evolving horse immune responses that ultimately establish control over virus replication and disease.The purpose of this review is to summarize and revise the role of the immune response to EIAV in the light of our increased understanding of lentivirus immunopathogenesis.

equine infectious anemia; immunity; horse

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