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Viral escape from neutralizing antibodies in early subtype A HIV-1 infection drives an increase in autologous neutralization breadth.

Murphy MK, Yue L, Pan R, Boliar S, Sethi A, Tian J, Pfafferot K, Karita E, Allen SA, Cormier E, Goepfert PA, Borrow P, Robinson JE, Gnanakaran S, Hunter E, Kong XP, Derdeyn CA - PLoS Pathog. (2013)

Bottom Line: Crystal structures of the antigen-binding fragments (Fabs) revealed flat epitope contact surfaces, where minimal light chain mutation in 19.3H-L3 allowed for additional antigenic interactions.Our data demonstrate that this subject's first recognized nAb epitope elicited strain-specific mAbs, which incrementally acquired autologous breadth, and directed later B cell responses to target distinct portions of Env.This immune re-focusing could have triggered the evolution of cross-clade antibodies and suggests that exposure to a specific sequence of immune escape variants might promote broad humoral responses during HIV-1 infection.

View Article: PubMed Central - PubMed

Affiliation: Immunology and Molecular Pathogenesis Graduate Program, Emory University, Atlanta, Georgia, United States of America.

ABSTRACT
Antibodies that neutralize (nAbs) genetically diverse HIV-1 strains have been recovered from a subset of HIV-1 infected subjects during chronic infection. Exact mechanisms that expand the otherwise narrow neutralization capacity observed during early infection are, however, currently undefined. Here we characterized the earliest nAb responses in a subtype A HIV-1 infected Rwandan seroconverter who later developed moderate cross-clade nAb breadth, using (i) envelope (Env) glycoproteins from the transmitted/founder virus and twenty longitudinal nAb escape variants, (ii) longitudinal autologous plasma, and (iii) autologous monoclonal antibodies (mAbs). Initially, nAbs targeted a single region of gp120, which flanked the V3 domain and involved the alpha2 helix. A single amino acid change at one of three positions in this region conferred early escape. One immunoglobulin heavy chain and two light chains recovered from autologous B cells comprised two mAbs, 19.3H-L1 and 19.3H-L3, which neutralized the founder Env along with one or three of the early escape variants carrying these mutations, respectively. Neither mAb neutralized later nAb escape or heterologous Envs. Crystal structures of the antigen-binding fragments (Fabs) revealed flat epitope contact surfaces, where minimal light chain mutation in 19.3H-L3 allowed for additional antigenic interactions. Resistance to mAb neutralization arose in later Envs through alteration of two glycans spatially adjacent to the initial escape signatures. The cross-neutralizing nAbs that ultimately developed failed to target any of the defined V3-proximal changes generated during the first year of infection in this subject. Our data demonstrate that this subject's first recognized nAb epitope elicited strain-specific mAbs, which incrementally acquired autologous breadth, and directed later B cell responses to target distinct portions of Env. This immune re-focusing could have triggered the evolution of cross-clade antibodies and suggests that exposure to a specific sequence of immune escape variants might promote broad humoral responses during HIV-1 infection.

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Identification of R880F nAb escape variants.Twenty-two single-genome amplified subtype A HIV-1 Envs were cloned out of R880F plasma collected at 0-months (A), 2-months (B), 5-months (C), 7-months (D), and 10-months (E) post-seroconversion, pseudotyped, and assayed against autologous plasma contemporaneous to their respective dates of isolation. Two 0-month Envs (0-A6/B24) representative of the transmitted/founder sequence are included in each panel. To demonstrate that humoral escape variants were neutralized during the course of infection, all 22 longitudinal Envs were assayed for neutralization with 16-month plasma (F); it was from PBMC collected at this time point that the two autologous R880F mAbs, 19.3H-L1 and 19.3H-L3, were derived. Percent viral infectivity, as adjusted against wells containing no test plasma, is depicted on the vertical axis; reciprocal plasma dilutions are plotted along the horizontal axis in a logarithmic fashion. Each curve represents a single Env-plasma combination, and error bars demonstrate the standard error of the mean of two independent experiments using duplicate wells (0-month Envs = circles, 2-month Envs = triangles, 5-month Envs = inverted triangles, 7-month Envs = squares, 10-month Envs = diamonds). Colored lines (2-A9/2-A13 in magenta, 2-B31 in red, 2-B12 in cyan, and 5-B52 in green) indicate Envs that succumbed to neutralization, in varying combinations, by the isolated R880F mAbs.
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ppat-1003173-g001: Identification of R880F nAb escape variants.Twenty-two single-genome amplified subtype A HIV-1 Envs were cloned out of R880F plasma collected at 0-months (A), 2-months (B), 5-months (C), 7-months (D), and 10-months (E) post-seroconversion, pseudotyped, and assayed against autologous plasma contemporaneous to their respective dates of isolation. Two 0-month Envs (0-A6/B24) representative of the transmitted/founder sequence are included in each panel. To demonstrate that humoral escape variants were neutralized during the course of infection, all 22 longitudinal Envs were assayed for neutralization with 16-month plasma (F); it was from PBMC collected at this time point that the two autologous R880F mAbs, 19.3H-L1 and 19.3H-L3, were derived. Percent viral infectivity, as adjusted against wells containing no test plasma, is depicted on the vertical axis; reciprocal plasma dilutions are plotted along the horizontal axis in a logarithmic fashion. Each curve represents a single Env-plasma combination, and error bars demonstrate the standard error of the mean of two independent experiments using duplicate wells (0-month Envs = circles, 2-month Envs = triangles, 5-month Envs = inverted triangles, 7-month Envs = squares, 10-month Envs = diamonds). Colored lines (2-A9/2-A13 in magenta, 2-B31 in red, 2-B12 in cyan, and 5-B52 in green) indicate Envs that succumbed to neutralization, in varying combinations, by the isolated R880F mAbs.

Mentions: Each Env-pseudotyped virus was assayed against autologous plasma contemporaneous to its date of isolation in the Tzm-bl neutralization assay. Plasma samples from 2-, 5-, 7-, and 10-months, but not 0-months, potently neutralized the founder Envs 0-A6 and 0-B24 (Figure 1). All longitudinal Envs were at least one log less sensitive to neutralization by contemporaneous plasma than the founder Envs and were, therefore, considered humoral escape variants (Figure 1B–E). These 0-, 2-, 5-, 7-, and 10-month Envs all succumbed to neutralization by plasma collected at 16-months post-seroconversion (Figure 1F). Hence, the induction of de novo nAbs against contemporaneous escape variants, which we and others have previously described [26]–[30], also occurred during the first year and a half of infection in R880F. In this subtype A HIV-1 infected subject, a potent nAb response was detected by 2-months following the first antibody positive time point and initiated repeated rounds of neutralization and viral escape.


Viral escape from neutralizing antibodies in early subtype A HIV-1 infection drives an increase in autologous neutralization breadth.

Murphy MK, Yue L, Pan R, Boliar S, Sethi A, Tian J, Pfafferot K, Karita E, Allen SA, Cormier E, Goepfert PA, Borrow P, Robinson JE, Gnanakaran S, Hunter E, Kong XP, Derdeyn CA - PLoS Pathog. (2013)

Identification of R880F nAb escape variants.Twenty-two single-genome amplified subtype A HIV-1 Envs were cloned out of R880F plasma collected at 0-months (A), 2-months (B), 5-months (C), 7-months (D), and 10-months (E) post-seroconversion, pseudotyped, and assayed against autologous plasma contemporaneous to their respective dates of isolation. Two 0-month Envs (0-A6/B24) representative of the transmitted/founder sequence are included in each panel. To demonstrate that humoral escape variants were neutralized during the course of infection, all 22 longitudinal Envs were assayed for neutralization with 16-month plasma (F); it was from PBMC collected at this time point that the two autologous R880F mAbs, 19.3H-L1 and 19.3H-L3, were derived. Percent viral infectivity, as adjusted against wells containing no test plasma, is depicted on the vertical axis; reciprocal plasma dilutions are plotted along the horizontal axis in a logarithmic fashion. Each curve represents a single Env-plasma combination, and error bars demonstrate the standard error of the mean of two independent experiments using duplicate wells (0-month Envs = circles, 2-month Envs = triangles, 5-month Envs = inverted triangles, 7-month Envs = squares, 10-month Envs = diamonds). Colored lines (2-A9/2-A13 in magenta, 2-B31 in red, 2-B12 in cyan, and 5-B52 in green) indicate Envs that succumbed to neutralization, in varying combinations, by the isolated R880F mAbs.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3585129&req=5

ppat-1003173-g001: Identification of R880F nAb escape variants.Twenty-two single-genome amplified subtype A HIV-1 Envs were cloned out of R880F plasma collected at 0-months (A), 2-months (B), 5-months (C), 7-months (D), and 10-months (E) post-seroconversion, pseudotyped, and assayed against autologous plasma contemporaneous to their respective dates of isolation. Two 0-month Envs (0-A6/B24) representative of the transmitted/founder sequence are included in each panel. To demonstrate that humoral escape variants were neutralized during the course of infection, all 22 longitudinal Envs were assayed for neutralization with 16-month plasma (F); it was from PBMC collected at this time point that the two autologous R880F mAbs, 19.3H-L1 and 19.3H-L3, were derived. Percent viral infectivity, as adjusted against wells containing no test plasma, is depicted on the vertical axis; reciprocal plasma dilutions are plotted along the horizontal axis in a logarithmic fashion. Each curve represents a single Env-plasma combination, and error bars demonstrate the standard error of the mean of two independent experiments using duplicate wells (0-month Envs = circles, 2-month Envs = triangles, 5-month Envs = inverted triangles, 7-month Envs = squares, 10-month Envs = diamonds). Colored lines (2-A9/2-A13 in magenta, 2-B31 in red, 2-B12 in cyan, and 5-B52 in green) indicate Envs that succumbed to neutralization, in varying combinations, by the isolated R880F mAbs.
Mentions: Each Env-pseudotyped virus was assayed against autologous plasma contemporaneous to its date of isolation in the Tzm-bl neutralization assay. Plasma samples from 2-, 5-, 7-, and 10-months, but not 0-months, potently neutralized the founder Envs 0-A6 and 0-B24 (Figure 1). All longitudinal Envs were at least one log less sensitive to neutralization by contemporaneous plasma than the founder Envs and were, therefore, considered humoral escape variants (Figure 1B–E). These 0-, 2-, 5-, 7-, and 10-month Envs all succumbed to neutralization by plasma collected at 16-months post-seroconversion (Figure 1F). Hence, the induction of de novo nAbs against contemporaneous escape variants, which we and others have previously described [26]–[30], also occurred during the first year and a half of infection in R880F. In this subtype A HIV-1 infected subject, a potent nAb response was detected by 2-months following the first antibody positive time point and initiated repeated rounds of neutralization and viral escape.

Bottom Line: Crystal structures of the antigen-binding fragments (Fabs) revealed flat epitope contact surfaces, where minimal light chain mutation in 19.3H-L3 allowed for additional antigenic interactions.Our data demonstrate that this subject's first recognized nAb epitope elicited strain-specific mAbs, which incrementally acquired autologous breadth, and directed later B cell responses to target distinct portions of Env.This immune re-focusing could have triggered the evolution of cross-clade antibodies and suggests that exposure to a specific sequence of immune escape variants might promote broad humoral responses during HIV-1 infection.

View Article: PubMed Central - PubMed

Affiliation: Immunology and Molecular Pathogenesis Graduate Program, Emory University, Atlanta, Georgia, United States of America.

ABSTRACT
Antibodies that neutralize (nAbs) genetically diverse HIV-1 strains have been recovered from a subset of HIV-1 infected subjects during chronic infection. Exact mechanisms that expand the otherwise narrow neutralization capacity observed during early infection are, however, currently undefined. Here we characterized the earliest nAb responses in a subtype A HIV-1 infected Rwandan seroconverter who later developed moderate cross-clade nAb breadth, using (i) envelope (Env) glycoproteins from the transmitted/founder virus and twenty longitudinal nAb escape variants, (ii) longitudinal autologous plasma, and (iii) autologous monoclonal antibodies (mAbs). Initially, nAbs targeted a single region of gp120, which flanked the V3 domain and involved the alpha2 helix. A single amino acid change at one of three positions in this region conferred early escape. One immunoglobulin heavy chain and two light chains recovered from autologous B cells comprised two mAbs, 19.3H-L1 and 19.3H-L3, which neutralized the founder Env along with one or three of the early escape variants carrying these mutations, respectively. Neither mAb neutralized later nAb escape or heterologous Envs. Crystal structures of the antigen-binding fragments (Fabs) revealed flat epitope contact surfaces, where minimal light chain mutation in 19.3H-L3 allowed for additional antigenic interactions. Resistance to mAb neutralization arose in later Envs through alteration of two glycans spatially adjacent to the initial escape signatures. The cross-neutralizing nAbs that ultimately developed failed to target any of the defined V3-proximal changes generated during the first year of infection in this subject. Our data demonstrate that this subject's first recognized nAb epitope elicited strain-specific mAbs, which incrementally acquired autologous breadth, and directed later B cell responses to target distinct portions of Env. This immune re-focusing could have triggered the evolution of cross-clade antibodies and suggests that exposure to a specific sequence of immune escape variants might promote broad humoral responses during HIV-1 infection.

Show MeSH
Related in: MedlinePlus