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Antigenicity and immunogenicity of RV144 vaccine AIDSVAX clade E envelope immunogen is enhanced by a gp120 N-terminal deletion.

ABSTRACT: An immune correlates analysis of the RV144 HIV-1 vaccine trial revealed that antibody responses to the gp120 V1/V2 region correlated inversely with infection risk. The RV144 protein immunogens (A244-rp120 and MN-rgp120) were modified by an N-terminal 11-amino-acid deletion (?11) and addition of a herpes simplex virus (HSV) gD protein-derived tag (gD). We investigated the effects of these modifications on gp120 expression, antigenicity, and immunogenicity by comparing unmodified A244 gp120 with both ?11 deletion and gD tag and with ?11 only. Analysis of A244 gp120, with or without ?11 or gD, demonstrated that the ?11 deletion, without the addition of gD, was sufficient for enhanced antigenicity to gp120 C1 region, conformational V2, and V1/V2 gp120 conformational epitopes. RV144 vaccinee serum IgGs bound more avidly to A244 gp120 ?11 than to the unmodified gp120, and their binding was blocked by C1, V2, and V1/V2 antibodies. Rhesus macaques immunized with the three different forms of A244 gp120 proteins gave similar levels of gp120 antibody titers, although higher antibody titers developed earlier in A244 ?11 gp120-immunized animals. Conformational V1/V2 monoclonal antibodies (MAbs) gave significantly higher levels of blocking of plasma IgG from A244 ?11 gp120-immunized animals than IgG from animals immunized with unmodified A244 gp120, thus indicating a qualitative difference in the V1/V2 antibodies induced by A244 ?11 gp120. These results demonstrate that deletion of N-terminal residues in the RV144 A244 gp120 immunogen improves both envelope antigenicity and immunogenicity.

SUBMITTER: Alam SM

PROVIDER: S-EPMC3554162 | biostudies-literature | 2013 Feb

REPOSITORIES: biostudies-literature

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Antigenicity and immunogenicity of RV144 vaccine AIDSVAX clade E envelope immunogen is enhanced by a gp120 N-terminal deletion.

Alam S Munir SM Liao Hua-Xin HX Tomaras Georgia D GD Bonsignori Mattia M Tsao Chun-Yen CY Hwang Kwan-Ki KK Chen Haiyan H Lloyd Krissey E KE Bowman Cindy C Sutherland Laura L Jeffries Thomas L TL Kozink Daniel M DM Stewart Shelley S Anasti Kara K Jaeger Frederick H FH Parks Robert R Yates Nicole L NL Overman R Glenn RG Sinangil Faruk F Berman Phillip W PW Pitisuttithum Punnee P Kaewkungwal Jaranit J Nitayaphan Sorachai S Karasavva Nicos N Rerks-Ngarm Supachai S Kim Jerome H JH Michael Nelson L NL Zolla-Pazner Susan S Santra Sampa S Letvin Norman L NL Harrison Stephen C SC Haynes Barton F BF

Journal of virology 20121121 3

An immune correlates analysis of the RV144 HIV-1 vaccine trial revealed that antibody responses to the gp120 V1/V2 region correlated inversely with infection risk. The RV144 protein immunogens (A244-rp120 and MN-rgp120) were modified by an N-terminal 11-amino-acid deletion (Δ11) and addition of a herpes simplex virus (HSV) gD protein-derived tag (gD). We investigated the effects of these modifications on gp120 expression, antigenicity, and immunogenicity by comparing unmodified A244 gp120 with b ...[more]

PMID: 23175357

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Project description:Recombinant expression systems differ in the type of glycosylation they impart on expressed antigens such as the human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins, potentially affecting their biological properties. We performed head-to-head antigenic, immunogenic and molecular profiling of two distantly related Env surface (gp120) antigens produced in different systems: (a) mammalian (293 FreeStyle cells; 293F) cells in the presence of kifunensine, which impart only high-mannose glycans; (b) insect cells (Spodoptera frugiperda, Sf9), which confer mainly paucimannosidic glycans; (c) Sf9 cells recombinant for mammalian glycosylation enzymes (Sf9 Mimic), which impart high-mannose, hybrid and complex glycans without sialic acid; and (d) 293F cells, which impart high-mannose, hybrid and complex glycans with sialic acid. Molecular models revealed a significant difference in gp120 glycan coverage between the Sf9-derived and wild-type mammalian-cell-derived material that is predicted to affect ligand binding sites proximal to glycans. Modeling of solvent-exposed surface electrostatic potentials showed that sialic acid imparts a significant negative surface charge that may influence gp120 antigenicity and immunogenicity. Gp120 expressed in systems that do not incorporate sialic acid displayed increased ligand binding to the CD4 binding and CD4-induced sites compared to those expressed in the system that do, and imparted other more subtle differences in antigenicity in a gp120 subtype-specific manner. Non-sialic-acid-containing gp120 was significantly more immunogenic than the sialylated version when administered in two different adjuvants, and induced higher titers of antibodies competing for CD4 binding site ligand-gp120 interaction. These findings suggest that non-sialic-acid-imparting systems yield gp120 immunogens with modified antigenic and immunogenic properties, considerations that should be considered when selecting expression systems for glycosylated antigens to be used for structure-function studies and for vaccine use.

Project description:BackgroundPrevious clinical efficacy trials failed to support the continued development of recombinant gp120 (rgp120) as a candidate HIV vaccine. However, the recent RV144 HIV vaccine trial in Thailand showed that a prime/boost immunization strategy involving priming with canarypox vCP1521 followed by boosting with rgp120 could provide significant, although modest, protection from HIV infection. Based on these results, there is renewed interest in the development of rgp120 based antigens for follow up vaccine trials, where this immunization approach can be applied to other cohorts at high risk for HIV infection. Of particular interest are cohorts in Africa, India, and China that are infected with clade C viruses.Methodology/principal findingsA panel of 10 clade C rgp120 envelope proteins was expressed in 293 cells, purified by immunoaffinity chromatography, and used to immunize guinea pigs. The resulting sera were collected and analyzed in checkerboard experiments for rgp120 binding, V3 peptide binding, and CD4 blocking activity. Virus neutralization studies were carried out with two different assays and two different panels of clade C viruses. A high degree of cross reactivity against clade C and clade B viruses and viral proteins was observed. Most, but not all of the immunogens tested elicited antibodies that neutralized tier 1 clade B viruses, and some sera neutralized multiple clade C viruses. Immunization with rgp120 from the CN97001 strain of HIV appeared to elicit higher cross neutralizing antibody titers than the other antigens tested.Conclusions/significanceWhile all of the clade C antigens tested were immunogenic, some were more effective than others in eliciting virus neutralizing antibodies. Neutralization titers did not correlate with rgp120 binding, V3 peptide binding, or CD4 blocking activity. CN97001 rgp120 elicited the highest level of neutralizing antibodies, and should be considered for further HIV vaccine development studies.

Dataset Information

Antigenicity and immunogenicity of RV144 vaccine AIDSVAX clade E envelope immunogen is enhanced by a gp120 N-terminal deletion.

Publications

Antigenicity and immunogenicity of RV144 vaccine AIDSVAX clade E envelope immunogen is enhanced by a gp120 N-terminal deletion.

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