PROTECTION OF RATS FROM ADJUVANT ARTHRITIS BY IMMUNIZATION WITH NAKEDDNA ENCODING FOR MYCOBACTERIAL HEAT-SHOCK PROTEIN-65

Objective. To assess the feasibility of vaccination with naked DNA enc oding for mycobacterial heat shock protein 65 (hsp65) in the modulatio n of experimental arthritis. Methods. Adjuvant arthritis (AA) was indu ced in Lewis rats preimmunized, intramuscularly, with a plasmid encodi ng for hsp65 (pCMV3.65), Clinical scores were recorded for 3-4 weeks, and histologic and radiologic parameters were evaluated. Cellular and antibody reactivity to hsp65 was assessed, The expression of the hsp65 gene was investigated in injected muscles. Results. The pCMV3.65-trea ted rats were significantly protected from disease development in comp arison with the control groups, This finding correlated with the resul ts of histologic and radiologic examinations of the involved joints. T he message for hsp65 was detected in injected muscles, T cell prolifer ation and antibodies to this protein were found to be elevated in pCMV 3.65-treated rats when compared with both the arthritic control (AA-in duced) and the naive (did not receive adjuvant) animals. Conclusion. W e have demonstrated for the first time that naked DNA delivery is feas ible in controlling experimental autoimmune disease. Although the actu al mechanism of protection has not been fully elucidated.