Monoclonal antibodies against HIV type 1 integrase: clues to molecular structure

Eleven murine hybridoma clones were selected for their ability to produce anti-HIV-1 integrase (IN) antibodies. Competition and epitope mapping studies allowed segregation of the monoclonal antibodies (MAbs) into four distinct classes. The five MAbs that comprise the first class showed high affinity for epitopes within an N-terminal domain of 58 amino acids that includes a conserved zinc finger motif. The second class, with two MAbs, showed high affinity for epitopes within 29 amino acids at the C terminus. Another two MAbs, which constitute the third class, displayed moderate affinities for epitopes that mapped to regions within the highly conserved catalytic core referred to as the D,D(35)E domain. One of these MAbs showed significant cross-reactivity with HIV-2 IN and weak, but detectable, cross-reactivity with RSV IN. The remaining two MAbs, which comprise the fourth class, exhibited fairly low binding affinities and appeared to recognize epitopes in the zinc finger motif domain as well as the C-terminal half of the IN protein. The MAbs can be used for immunoprecipitation and immunoblotting procedures as well as for purification of HIV-1 IN protein by affinity chromatography. We show that several can also be used to immunostain viral IN sequences in HIV-1-infected T cells, presumably as a component of Gag-Pol precursors. Finally, analysis of our mapping and competition data suggests a structure for mature IN in which the C terminus approaches the central core domain, and the N and C termini touch or are proximal to each other. These MAbs should prove useful for further analyses of the structure and function of IN both in vitro and in vivo.