Enhanced exposure of human immunodeficiency virus type 1 primary isolate neutralization epitopes through binding of CD4 mimetic compounds.
N-(4-Chlorophenyl)-N'-(2,2,6,6-tetramethyl-piperidin-4-yl)-oxalamide (NBD-556) is a low-molecular-weight compound that reportedly blocks the interaction between human immunodeficiency virus type 1 (HIV-1) gp120 and its receptor CD4. We investigated whether the enhancement of binding of anti-gp120 monoclonal antibodies (MAbs) toward envelope (Env) protein with NBD-556 are similar to those of soluble CD4 (sCD4) by comparing the binding profiles of the individual MAbs to Env-expressing cell surfaces. In flow cytometric analyses, the binding profiles of anti-CD4-induced epitope (CD4i) MAbs toward NBD-556-pretreated Env-expressing cell surfaces were similar to the binding profiles toward sCD4-pretreated cell surfaces. To investigate the binding position of NBD-556 on gp120, we induced HIV-1 variants that were resistant to NBD-556 and sCD4 in vitro. At passage 21 in the presence of 50 microM NBD-556, two amino acid substitutions (S375N in C3 and A433T in C4) were identified. On the other hand, in the selection with sCD4, seven mutations (E211G, P212L, V255E, N280K, S375N, G380R, and G431E) appeared during the passages. The profiles of the mutations after the selections with NBD-556 and sCD4 were very similar in their three-dimensional positions. Moreover, combinations of NBD-556 with anti-gp120 MAbs showed highly synergistic interactions against HIV-1. We further found that after enhancing the neutralizing activity by adding NBD-556, the contemporaneous virus became highly sensitive to antibodies in the patient's plasma. These findings suggest that small compounds such as NBDs may enhance the neutralizing activities of CD4i and anti-V3 antibodies in vivo.
Yoshimura
Kazuhisa
K
Division of Clinical Retrovirology and Infectious Diseases, Center for AIDS Research, Kumamoto University, Kumamoto, Japan.
Harada
Shigeyoshi
S
Shibata
Junji
J
Hatada
Makiko
M
Yamada
Yuko
Y
Ochiai
Chihiro
C
Tamamura
Hirokazu
H
Matsushita
Shuzo
S
D057134:Antibodies, Neutralizing / Q000276:immunology*; D000998:Antiviral Agents / Q000378:metabolism*; D000939:Epitopes / Q000276:immunology; D015483:HIV Antibodies / Q000276:immunology*; D015699:HIV Envelope Protein gp120 / Q000276:immunology* / Q000378:metabolism*; D015497:HIV-1 / Q000276:immunology*; D006801:Humans; D010070:Oxalates / Q000378:metabolism*; D010880:Piperidines / Q000378:metabolism*; D011485:Protein Binding; D053585:Virus Attachment
D057134:Antibodies, Neutralizing; D000998:Antiviral Agents; D000939:Epitopes; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; C514246:N-(4-chlorophenyl)-N'-(2,2,6,6-tetramethylpiperidin-4-yl)oxalamide; D010070:Oxalates; D010880:Piperidines; C514793:gp120 protein, Human immunodeficiency virus 1