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Association of enhanced HIV-1 neutralization by a single Y681H substitution in gp41 with increased gp120-CD4 interaction and macrophage infectivity.

Ringe R, Bhattacharya J - PLoS ONE (2012)

Bottom Line: In the present study, we found that presence of a naturally occurring H681 in gp41 membrane proximal external region (MPER) of a clade C envelope (Env) obtained from a recently infected Indian patient conferred increased sensitivity to autologous and heterologous plasma antibodies.Furthermore, Env-pseudotyped viruses expressing H681 showed increased sensitivity to soluble CD4, b12 and 4E10 monoclonal antibodies both in related and unrelated Envs and was corroborated with increased Env susceptibility and binding to cellular CD4 as well as with prolonged exposure of MPER epitopes.In summary, our data indicate that Y681H substitution exposes neutralizing epitopes in CD4bs and MPER towards comprehensive interference in HIV-1 entry.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Virology, National AIDS Research Institute, Indian Council of Medical Research, Bhosari, Pune, India.

ABSTRACT
HIV-1 variants that show unusual sensitivity to autologous antibodies due to presence of critical neutralization signatures would likely contribute towards rational envelope based HIV-1 vaccine design. In the present study, we found that presence of a naturally occurring H681 in gp41 membrane proximal external region (MPER) of a clade C envelope (Env) obtained from a recently infected Indian patient conferred increased sensitivity to autologous and heterologous plasma antibodies. Furthermore, Env-pseudotyped viruses expressing H681 showed increased sensitivity to soluble CD4, b12 and 4E10 monoclonal antibodies both in related and unrelated Envs and was corroborated with increased Env susceptibility and binding to cellular CD4 as well as with prolonged exposure of MPER epitopes. The increased gp120-CD4 interaction was further associated with relative exposure of CD4-induced epitopes and macrophage infectivity. In summary, our data indicate that Y681H substitution exposes neutralizing epitopes in CD4bs and MPER towards comprehensive interference in HIV-1 entry.

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Effect of presence of H681 on gp120-CD4 interaction.A. Neutralization sensitivity of Env-pseudotyped viruses to sCD4 was carried out in TZM-bl cells. Percent neutralization was measured by scoring RLU as indicated on Y-axis at various concentrations of sCD4 plotted on X-axis. B. Competition between Env-pseudotyped viruses (carrying H681 and Y681) and anti-CD4 MAb QS1420 for binding to cellular CD4. Env pseudotyped virus was expected to compete with QS1420 to bind with the cellular CD4 on TZM-bl cells for productive infection. Percent infection of Env pseudotyped virus on Y-axis in presence of various concentration of QS1420 on X-axis was recorded in comparison with infectivity of virus in absence of QS1420 which was considered as 100%. Percent infectivity was assessed by measuring RLU in a luminometer. The result in the graph is representative of a single experiment performed in duplicate. The assay was performed at three independent time points using an independent virus preparation.
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pone-0037157-g004: Effect of presence of H681 on gp120-CD4 interaction.A. Neutralization sensitivity of Env-pseudotyped viruses to sCD4 was carried out in TZM-bl cells. Percent neutralization was measured by scoring RLU as indicated on Y-axis at various concentrations of sCD4 plotted on X-axis. B. Competition between Env-pseudotyped viruses (carrying H681 and Y681) and anti-CD4 MAb QS1420 for binding to cellular CD4. Env pseudotyped virus was expected to compete with QS1420 to bind with the cellular CD4 on TZM-bl cells for productive infection. Percent infection of Env pseudotyped virus on Y-axis in presence of various concentration of QS1420 on X-axis was recorded in comparison with infectivity of virus in absence of QS1420 which was considered as 100%. Percent infectivity was assessed by measuring RLU in a luminometer. The result in the graph is representative of a single experiment performed in duplicate. The assay was performed at three independent time points using an independent virus preparation.

Mentions: Neutralization of wild type Envs 4.J2 (containing N668, H681) and 4.J22 (containing S668, Y681) with soluble CD4 showed that 4.J2 was sensitive while 4.J22 being completely resistant at 25 µg/ml. Next we wanted to know what domain has modulated this sensitivity to sCD4. We assessed the neutralization sensitivity of chimeric clones made between 4.J2 and 4.J22, mutant clones of 4.J2 where we substituted H681Y and N668S, and wild type Envs. As shown in Figure 4A, 4.J2 (H681) conferred significantly higher sensitivity to sCD4 over 4.J2 (Y681) by >40-folds, N668S moderately decreased the sensitivity to sCD4. All the Envs which contained H681 showed higher sensitivity to sCD4 in the panel of Envs while those containing Y681 were completely resistant at 10 µg/ml. This data shows that N668 and H681 act in cooperation to enhance the sensitivity of Env to sCD4, although H681 exerts more influence than N668 for sensitivity. The results were quite intriguing as the same H681 which modulated the neutralization sensitivity to 4E10 was found to alter sCD4 sensitivity-the phenotype which is supposedly more relevant to changes in gp120. The data imply that the change in MPER does not only exert its effect at local site in gp41 subunit but also traverse through transmembrane subunit to surface protein gp120 to alter the conformation at CD4 binding site as supported by CD4-Ig and IgG1b12 binding with Env trimers (Figure 5).


Association of enhanced HIV-1 neutralization by a single Y681H substitution in gp41 with increased gp120-CD4 interaction and macrophage infectivity.

Ringe R, Bhattacharya J - PLoS ONE (2012)

Effect of presence of H681 on gp120-CD4 interaction.A. Neutralization sensitivity of Env-pseudotyped viruses to sCD4 was carried out in TZM-bl cells. Percent neutralization was measured by scoring RLU as indicated on Y-axis at various concentrations of sCD4 plotted on X-axis. B. Competition between Env-pseudotyped viruses (carrying H681 and Y681) and anti-CD4 MAb QS1420 for binding to cellular CD4. Env pseudotyped virus was expected to compete with QS1420 to bind with the cellular CD4 on TZM-bl cells for productive infection. Percent infection of Env pseudotyped virus on Y-axis in presence of various concentration of QS1420 on X-axis was recorded in comparison with infectivity of virus in absence of QS1420 which was considered as 100%. Percent infectivity was assessed by measuring RLU in a luminometer. The result in the graph is representative of a single experiment performed in duplicate. The assay was performed at three independent time points using an independent virus preparation.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3351407&req=5

pone-0037157-g004: Effect of presence of H681 on gp120-CD4 interaction.A. Neutralization sensitivity of Env-pseudotyped viruses to sCD4 was carried out in TZM-bl cells. Percent neutralization was measured by scoring RLU as indicated on Y-axis at various concentrations of sCD4 plotted on X-axis. B. Competition between Env-pseudotyped viruses (carrying H681 and Y681) and anti-CD4 MAb QS1420 for binding to cellular CD4. Env pseudotyped virus was expected to compete with QS1420 to bind with the cellular CD4 on TZM-bl cells for productive infection. Percent infection of Env pseudotyped virus on Y-axis in presence of various concentration of QS1420 on X-axis was recorded in comparison with infectivity of virus in absence of QS1420 which was considered as 100%. Percent infectivity was assessed by measuring RLU in a luminometer. The result in the graph is representative of a single experiment performed in duplicate. The assay was performed at three independent time points using an independent virus preparation.
Mentions: Neutralization of wild type Envs 4.J2 (containing N668, H681) and 4.J22 (containing S668, Y681) with soluble CD4 showed that 4.J2 was sensitive while 4.J22 being completely resistant at 25 µg/ml. Next we wanted to know what domain has modulated this sensitivity to sCD4. We assessed the neutralization sensitivity of chimeric clones made between 4.J2 and 4.J22, mutant clones of 4.J2 where we substituted H681Y and N668S, and wild type Envs. As shown in Figure 4A, 4.J2 (H681) conferred significantly higher sensitivity to sCD4 over 4.J2 (Y681) by >40-folds, N668S moderately decreased the sensitivity to sCD4. All the Envs which contained H681 showed higher sensitivity to sCD4 in the panel of Envs while those containing Y681 were completely resistant at 10 µg/ml. This data shows that N668 and H681 act in cooperation to enhance the sensitivity of Env to sCD4, although H681 exerts more influence than N668 for sensitivity. The results were quite intriguing as the same H681 which modulated the neutralization sensitivity to 4E10 was found to alter sCD4 sensitivity-the phenotype which is supposedly more relevant to changes in gp120. The data imply that the change in MPER does not only exert its effect at local site in gp41 subunit but also traverse through transmembrane subunit to surface protein gp120 to alter the conformation at CD4 binding site as supported by CD4-Ig and IgG1b12 binding with Env trimers (Figure 5).

Bottom Line: In the present study, we found that presence of a naturally occurring H681 in gp41 membrane proximal external region (MPER) of a clade C envelope (Env) obtained from a recently infected Indian patient conferred increased sensitivity to autologous and heterologous plasma antibodies.Furthermore, Env-pseudotyped viruses expressing H681 showed increased sensitivity to soluble CD4, b12 and 4E10 monoclonal antibodies both in related and unrelated Envs and was corroborated with increased Env susceptibility and binding to cellular CD4 as well as with prolonged exposure of MPER epitopes.In summary, our data indicate that Y681H substitution exposes neutralizing epitopes in CD4bs and MPER towards comprehensive interference in HIV-1 entry.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Virology, National AIDS Research Institute, Indian Council of Medical Research, Bhosari, Pune, India.

ABSTRACT
HIV-1 variants that show unusual sensitivity to autologous antibodies due to presence of critical neutralization signatures would likely contribute towards rational envelope based HIV-1 vaccine design. In the present study, we found that presence of a naturally occurring H681 in gp41 membrane proximal external region (MPER) of a clade C envelope (Env) obtained from a recently infected Indian patient conferred increased sensitivity to autologous and heterologous plasma antibodies. Furthermore, Env-pseudotyped viruses expressing H681 showed increased sensitivity to soluble CD4, b12 and 4E10 monoclonal antibodies both in related and unrelated Envs and was corroborated with increased Env susceptibility and binding to cellular CD4 as well as with prolonged exposure of MPER epitopes. The increased gp120-CD4 interaction was further associated with relative exposure of CD4-induced epitopes and macrophage infectivity. In summary, our data indicate that Y681H substitution exposes neutralizing epitopes in CD4bs and MPER towards comprehensive interference in HIV-1 entry.

Show MeSH
Related in: MedlinePlus