Anti-P30-52 monoclonal antibody cross-reacted to Env V3 and inhibited the viral multiplication of HIV-1-infected MT-4 cells.

It is well known that the anti-p17 antibody titer decreases with the disease progression among human immunodeficiency virus type 1 (HIV-1) carriers. We previously established several murine anti-p17 monoclonal antibodies (MAbs) to investigate the immunological role of p17, and to further characterize these MAbs, we examined the anti-p17 antibody titer in serum of a patient who was a long-term nonprogressor with hemophilia, and found that the antibody for the p17-derivative peptide from amino acid residues 30 to 52 (P30-52) cross-reacted to the third variable region of the envelope glycoprotein of HIV-1, Env V3. In the present study, we primed mice with P30-52 to establish anti-P30-52 MAbs (P30-52 MAbs), and examined their affinity and whether they suppressed the viral multiplication of HIV-1-infected MT-4 (HTLV-1-transformed CD4+ T-cell line) cells, in a TCID50 assay. At the same time, an anti-Env V3 MAb (Env V3 MAb) was also established and examined as above. The IgM-type P30-52 MAb and Env V3 MAb showed heteroclitic binding, and the IgM-type P30-52 MAb inhibited the viral multiplication. We also found that an increase of fragmented DNA of HIV-1-infected MT-4 cells co-cultured with P30-52 MAbs. Because DNA fragmentation is one of the features of programmed cell death, the viral multiplication may be suppressed by the apoptosis of HIV-1-infected MT-4 cells co-cultured with P30-52 MAbs. Though the relationship between cross-reactivity and the inhibition mechanism of multiplication of HIV-1 is unclear, P30-52 of p17 may well be a useful region of viral proteins for the development of therapeutic and vaccination strategies.