HIV-1 integrase (IN) catalyzes integration of a DNA copy of the viral genome into the host genome. In contrast to canonical proteases (trypsin, chymotrypsin and proteinase K), IgGs and IgMs isolated from HIV-infected patients by affinity chromatography on immobilized IN specifically hydrolyzed only IN but not many other tested intact globular proteins. The sites of IN cleavage determined by MALDI mass spectrometry were localized mainly within seven known immunodominant regions of IN. Thin layer chromatography analysis has shown that the abzymes (Abzs) could also cleave 17 to 22-mer oligopeptides (OPs) corresponding to the immunodominant regions of IN sequence with a much higher rate than non-specific long peptides or three- and tetrapeptides of various sequence. Therefore, a prolonged incubation of IN with AIDS IgGs and IgMs having high catalytic activity usually produces many OPs of different length. Since anti-IN IgGs and IgMs can efficiently hydrolyze IN, a positive role of the Abzs in counteracting the infection is possible.