CONTROL OF EQUINE INFECTIOUS-ANEMIA VIRUS IS NOT DEPENDENT ON ADCC MEDIATING ANTIBODIES

Horses infected with equine infectious anemia Virus (EIAV) have recurr ent episodes of viremia which are eventually controlled, but the immun e mechanisms have not been identified. Antibodies were detected to the surface of EIAV-infected cells within 1 month postinfection and remai ned for at least 3.5 years postinfection. These antibodies recognized cell surface-exposed envelope (Env) glycoproteins, but could not media te antibody dependent cellular cytotoxicity (ADCCJ using EIAV-WSU5-inf ected equine kidney (EK) cells as targets and peripheral blood mononuc lear cells (PBMC) or polymorphonuclear cells (PMN) as effector cells. Furthermore, purified IgG antibodies from horses infected with either EIAV-WSU5 or EIAV-Wyo did not mediate ADCC of infected target cells. A rmed effector cells could not be detected in infected horse blood nor could effector cells be prearmed by incubation with serum antibodies t o cell surface antigens. The use of EIAV-WSU5-infected equine macropha ges as target cells did not result in ADCC. In contrast, serum antibod y from EHV-1 vaccinated horses and PBMG or PMN as effector cells cause d ADCC of EHV-1-infected EK cells. These results indicate that ADCC is not involved in the control of EIAV in carrier horses. (C) 1997 Acade mic Press.