Impact of amino acid substitutions in the V2 and C2 regions of human immunodeficiency virus type 1 CRF01_AE envelope glycoprotein gp120 on viral neutralization susceptibility to broadly neutralizing antibodies specific for the CD4 binding site.
BACKGROUND
The CD4 binding site (CD4bs) of envelope glycoprotein (Env) gp120 is a functionally conserved, important target of anti-human immunodeficiency virus type 1 (HIV-1) neutralizing antibodies. Two neutralizing human monoclonal antibodies, IgG1 b12 (b12) and VRC01, are broadly reactive neutralizing antibodies which recognize conformational epitopes that overlap the CD4bs of Env gp120; however, many CRF01_AE viruses are resistant to neutralization mediated by these antibodies. We examined the mechanism underlying the b12 resistance of the viruses using CRF01_AE Env (AE-Env)-recombinant viruses in this study.


RESULTS
Our results showed that an amino acid substitution at position 185 in the V2 region of gp120 played a crucial role in regulating the b12 susceptibility of AE-Env-recombinant viruses by cooperating with 2 previously reported potential N-linked glycosylation (PNLG) sites at positions 186 (N186) and 197 (N197) in the V2 and C2 regions of Env gp120. The amino acid residue at position 185 and 2 PNLG sites were responsible for the b12 resistance of 21 of 23 (>91%) AE-Env clones tested. Namely, the introduction of aspartic acid at position 185 (D185) conferred b12 susceptibility of 12 resistant AE-Env clones in the absence of N186 and/or N197, while the introduction of glycine at position 185 (G185) reduced the b12 susceptibility of 9 susceptible AE-Env clones in the absence of N186 and/or N197. In addition, these amino acid mutations altered the VRC01 susceptibility of many AE-Env clones.


CONCLUSIONS
We propose that the V2 and C2 regions of AE-Env gp120 contain the major determinants of viral resistance to CD4bs antibodies. CRF01_AE is a major circulating recombinant form of HIV-1 prevalent in Southeast Asia. Our data may provide important information to understand the molecular mechanism regulating the neutralization susceptibility of CRF01_AE viruses to CD4bs antibodies.
Piraporn
P
Utachee
Panasda
P
Isarangkura-na-ayuthaya
Kenzo
K
Tokunaga
Kazuyoshi
K
Ikuta
Naokazu
N
Takeda
Thailand-Japan Research Collaboration Center on Emerging and Re-emerging Infections (RCC-ERI), Nonthaburi, Thailand. mkameoka@port.kobe-u.ac.jp.
Masanori
M
Kameoka
D019943:Amino Acid Substitution; D057134:Antibodies, Neutralizing / Q000276:immunology*; D001210:Asia, Southeastern; D001665:Binding Sites; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D005838:Genotype; D015483:HIV Antibodies / Q000276:immunology*; D015699:HIV Envelope Protein gp120 / Q000235:genetics / Q000276:immunology* / Q000502:physiology; D015658:HIV Infections / Q000821:virology; D015497:HIV-1 / Q000145:classification / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D006801:Humans; D050505:Mutant Proteins / Q000235:genetics / Q000276:immunology; D020125:Mutation, Missense; D053585:Virus Attachment
D057134:Antibodies, Neutralizing; D015483:HIV Antibodies; D015699:HIV Envelope Protein gp120; D050505:Mutant Proteins; C514793:gp120 protein, Human immunodeficiency virus 1