Article

Influence of glycosylation on the efficacy of an Env-based vaccine against simian immunodeficiency virus SIVmac239 in a macaque AIDS model

AIDS Research Center, National Institute of Infectious Diseases, Tokyo, Japan.
Journal of Virology (Impact Factor: 4.65). 09/2005; 79(16):10386-96. DOI: 10.1128/JVI.79.16.10386-10396.2005
Source: PubMed

ABSTRACT The envelope glycoprotein (Env) of human immunodeficiency viruses (HIVs) and simian immunodeficiency viruses (SIVs) is heavily glycosylated, and this feature has been speculated to be a reason for the insufficient immune control of these viruses by their hosts. In a macaque AIDS model, we demonstrated that quintuple deglycosylation in Env altered a pathogenic virus, SIVmac239, into a novel attenuated mutant virus (delta5G). In delta5G-infected animals, strong protective immunity against SIVmac239 was elicited. These HIV and SIV studies suggested that an understanding of the role of glycosylation is critical in defining not only the virological properties but also the immunogenicity of Env, suggesting that glycosylation in Env could be modified for the development of effective vaccines. To examine the effect of deglycosylation, we constructed prime-boost vaccines consisting of Env from SIVmac239 and delta5G and compared their immunogenicities and vaccine efficacies by challenge infection with SIVmac239. Vaccination-induced immune responses differed between the two vaccine groups. Both Env-specific cellular and humoral responses were higher in wild-type (wt)-Env-immunized animals than in delta5G Env-immunized animals. Following the challenge, viral loads in SIVmac239 Env (wt-Env)-immunized animals were significantly lower than in vector controls, with controlled viral replication in the chronic phase. Unexpectedly, viral loads in delta5G Env-immunized animals were indistinguishable from those in vector controls. This study demonstrated that the prime-boost Env vaccine was effective against homologous SIVmac239 challenge. Changes in glycosylation affected both cell-mediated and humoral immune responses and vaccine efficacy.

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Available from: Kazuyasu Mori, Sep 01, 2015
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    • "Certain site specific deglycosylations or their combinations on HIV-1 Env have been suggested to enhance the induction of neutralizing activity (Bolmstedt et al., 1996). Similar results have also been observed with SIV Env (Mori et al., 2005; Reitter et al., 1998). In particular, multiple deglycosylation combinations in the V1V2 region of HIV- 1 89.6 Env induce neutralizing activity more effectively than the wild-type (WT) Env (Quinones-Kochs et al., 2002). "
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    ABSTRACT: Glycosylation plays important roles in gp120 structure and HIV-1 immune evasion. In the current study, we introduced deglycosylations into the 24 N-linked glycosylation sites of a R5 env MWS2 cloned from semen and systematically analyzed the impact on infectivity, antigenicity, immunogenicity and sensitivity to entry inhibitors. We found that mutants N156-T158A, N197-S199A, N262-S264A and N410-T412A conferred decreased infectivity and enhanced sensitivity to a series of antibodies and entry inhibitors. When mice were immunized with the DNA of wild-type or mutated gp160, gp140 or gp120; N156-T158A, N262-S264A and N410-T412A were more effective in inducing neutralizing activity against wild-type MWS2 as well as heterologous IIIB and CH811 Envs. In general, gp160 and gp140 induced higher neutralizing activity compared with gp120. Our study demonstrates for the first time that removal of individual glycan N156, N262 or N410 proximal to CD4-binding region impairs viral infectivity and results in enhanced capability to induce neutralizing activity.
    Virology 12/2011; 423(1):97-106. DOI:10.1016/j.virol.2011.11.023 · 3.28 Impact Factor
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    • "Certain site specific deglycosylations or their combinations on HIV-1 Env have been suggested to enhance the induction of neutralizing activity (Bolmstedt et al., 1996). Similar results have also been observed with SIV Env (Mori et al., 2005; Reitter et al., 1998). In particular, multiple deglycosylation combinations in the V1V2 region of HIV- 1 89.6 Env induce neutralizing activity more effectively than the wild-type (WT) Env (Quinones-Kochs et al., 2002). "
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    ABSTRACT: High-mannose N-linked glycans recognized by carbohydrate-binding agents (CBAs) are potential targets for topical microbicides. To better understand the mechanisms by which CBAs inhibit human immunodeficiency virus (HIV)-1 infection at the molecular level, we systematically analysed the contribution of site-specific glycans to the anti-HIV activity of CBAs by site-directed mutagenesis. Our results demonstrate that a single deglycosylation at N295 or N448 in a range of primary and T-cell-line-adapted HIV-1 isolates resulted in marked resistance to griffithsin (GRFT) but maintained the sensitivity to cyanovirin (CV-N), Galanthus nivalis agglutinin (GNA) and a range of neutralizing antibodies. Unlike CV-N and GNA, the interaction between GRFT and gp120 appeared to be dependent on the specific trimeric 'sugar tower' including N295 and N448. This was further strengthened by the results of GRFT-Env binding experiments. Our study identifies GRFT-specific gp120 glycans and may provide information for the design of novel CBA antiviral strategies.
    Journal of General Virology 06/2011; 92(Pt 10):2367-73. DOI:10.1099/vir.0.033092-0 · 3.53 Impact Factor
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    • "Anti-gp120 Ab ELISA and anti-Env peptide ELISA. Recombinant SIV239 gp120 and D5G gp120 were expressed utilizing a Sendai virus vector as described previously (Mori et al., 2005; Yu et al., 1997). Culture supernatant containing approximately 2 mg secreted SIV gp120 ml 21 was diluted with an equal amount of PBS, dispensed into each well of an ELISA plate and allowed to incubate at 4 uC overnight. "
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    ABSTRACT: Infection of rhesus macaques with a deglycosylation mutant, Delta5G, derived from SIV239, a pathogenic clone of simian immunodeficiency virus (SIV), led to robust acute-phase viral replication followed by a chronic phase with undetectable viral load. This study examined whether humoral responses in Delta5G-infected animals played any role in the control of infection. Neutralizing antibodies (nAbs) were elicited more efficiently in Delta5G-infected animals than in SIV239-infected animals. However, functional nAb measured by 90% neutralization was prominent in only two of the five Delta5G-infected animals, and only at 8 weeks post-infection (p.i.), when viral loads were already below 10(4) copies ml(-1). These results suggest a minimal role for nAbs in the control of the primary infection. In contrast, whilst Ab responses to epitopes localized to the variable loops V1/V2 were detected in all Delta5G-infected animals at 3 weeks p.i., this response was associated with a concomitant reduction in Ab responses to epitopes in gp41 compared with those in SIV239-infected animals. These results suggest that the altered surface glycosylation and/or conformation of viral spikes induce a humoral response against SIV that is distinct from the response induced by SIV239. More interestingly, whereas V1/V2-specific Abs were induced in all animals, these Abs were associated with vigorous Delta5G-specific virion capture ability in only two Delta5G-infected animals that exhibited a functional nAb response. Thus, whereas the deglycosylation mutant infection elicited early virion capture and subsequent nAbs, the responses differed among animals, suggesting the existence of host factors that may influence the functional humoral responses against human immunodeficiency virus/SIV.
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