Contribution of Virus-Like Particles to the Immunogenicity of Human Immunodeficiency Virus Type 1 Gag-Derived Vaccines in Mice

Wong, Soon Boon Justin; Siliciano, Robert F.

doi:10.1128/jvi.79.3.1701-1712.2005

Cited by 15 publications

(12 citation statements)

References 63 publications

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“…Indeed, it has been reported that the assembly of HIV-1 Gag, and the generation of Gag VLP, is blocked in murine cells [39,40]. However, Nabel and colleagues (who provided the Gag construct used in our experiments) have shown that a plasmid which encoded both HIV-1 Gag and Env efficiently generated VLP in mouse cells [41].…”

Section: Discussionmentioning

confidence: 78%

Effect of promoter strength on protein expression and immunogenicity of an HSV-1 amplicon vector encoding HIV-1 Gag

Santos¹,

Duke²,

Rodríguez-Colón³

et al. 2007

Vaccine

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Helper-free herpes simplex virus type-1 (HSV-1) amplicon vectors elicit robust immune responses to encoded proteins, including human immunodeficiency virus type-1 (HIV-1) antigens. To improve this vaccine delivery system, seven amplicon vectors were constructed, each encoding HIV-1 Gag under the control of a different promoter. Gag expression levels were analyzed in murine and human cell lines, as well as in biopsied tissue samples from injected mice; these data were then compared with Gag-specific T cell responses in BALB/c mice. The magnitude of the amplicon-induced immune response was found to correlate strongly with the level of Gag production both in vitro and in vivo. Interestingly, the best correlation of the strength of the amplicon-induced immune response was with antigen expression in cultured DC rather than expression at the tissue site of injection or in cultured cell lines. These findings may have implications for the generation of improved HSV-1 amplicon vectors for HIV-1 vaccine delivery.

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Section: Discussionmentioning

confidence: 78%

Effect of promoter strength on protein expression and immunogenicity of an HSV-1 amplicon vector encoding HIV-1 Gag

Santos¹,

Duke²,

Rodríguez-Colón³

et al. 2007

Vaccine

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“…It has been shown that VLPs that did not display HIV-1 Env were unable to induce immune responses that were stronger than a DNA vaccine that produced soluble polypeptides [86]. In addition, HIV VLPs displaying HIV-gp120 taken up by monocyte-derived dendritic cells (MDDC) [87] showed enhanced Th1- and Th2-cytokine production and were able to activate autologous naïve CD4 + T-cells and drive them towards a Th-1 response [87].…”

Section: Discussionmentioning

confidence: 99%

Abrogation of contaminating RNA activity in HIV-1 Gag VLPs

Valley‐Omar

Meyers

Shephard

et al. 2011

Virol J

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BackgroundHIV-1 Gag virus like particles (VLPs) used as candidate vaccines are regarded as inert particles as they contain no replicative nucleic acid, although they do encapsidate cellular RNAs. During HIV-1 Gag VLP production in baculovirus-based expression systems, VLPs incorporate the baculovirus Gp64 envelope glycoprotein, which facilitates their entry into mammalian cells. This suggests that HIV-1 Gag VLPs produced using this system facilitate uptake and subsequent expression of encapsidated RNA in mammalian cells - an unfavourable characteristic for a vaccine.MethodsHIV-1 Gag VLPs encapsidating reporter chloramphenicol acetyl transferase (CAT) RNA, were made in insect cells using the baculovirus expression system. The presence of Gp64 on the VLPs was verified by western blotting and RT-PCR used to detect and quantitate encapsidated CAT RNA. VLP samples were heated to inactivate CAT RNA. Unheated and heated VLPs incubated with selected mammalian cell lines and cell lysates tested for the presence of CAT protein by ELISA. Mice were inoculated with heated and unheated VLPs using a DNA prime VLP boost regimen.ResultsHIV-1 Gag VLPs produced had significantly high levels of Gp64 (~1650 Gp64 molecules/VLP) on their surfaces. The amount of encapsidated CAT RNA/μg Gag VLPs ranged between 0.1 to 7 ng. CAT protein was detected in 3 of the 4 mammalian cell lines incubated with VLPs. Incubation with heated VLPs resulted in BHK-21 and HeLa cell lysates showing reduced CAT protein levels compared with unheated VLPs and HEK-293 cells. Mice inoculated with a DNA prime VLP boost regimen developed Gag CD8 and CD4 T cell responses to GagCAT VLPs which also boosted a primary DNA response. Heating VLPs did not abrogate these immune responses but enhanced the Gag CD4 T cell responses by two-fold.ConclusionsBaculovirus-produced HIV-1 Gag VLPs encapsidating CAT RNA were taken up by selected mammalian cell lines. The presence of CAT protein indicates that encapsidated RNA was expressed in the mammalian cells. Heat-treatment of the VLPs altered the ability of protein to be expressed in some cell lines tested but did not affect the ability of the VLPs to stimulate an immune response when inoculated into mice.

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“…Gag p55 , is expressed as a polyprotein, which is cleaved into matrix (p17), capsid (p24), nucleocapsid (p7) and a C-terminal p6 domain [43,65]. Each of these Gag gene products elicits robust immune responses [1,3,10,11,15,17,22,26,39,46,47,58,59,75,94,97,98,100]. Expressing lentiviral antigens from codon-optimized gene sequences is an attractive strategy since this process by-passes the dependence of these mRNAs for Rev-mediated nuclear translocation [7,25,28,34,36,51,52,54,56,70,78,79,90], and therefore has been widely applied to DNA vaccine immunizations [4,6,12,16,53,55,77,99].…”

Section: Introductionmentioning

confidence: 99%

Reduction of Anti-HIV-1 Gag Immune Responses During Co-Immunization: Immune Interference by the HIV-1 Envelope

Toapanta

Craigo²,

Montelaro³

et al. 2007

CHR

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Immunization with more than one immunogen (co-immunization) is an efficient regimen to induce immunity to multiple antigens. However, immune interference has been reported using multi-plasmid DNA immunizations. HIV-1 envelope (Env) and Gag gene products are the predominant immunogens used in current AIDS vaccines, although, few studies have evaluated possible immune interference when these two antigens are co-administered. Therefore, in this study, immune interference during co-inoculation was examined using DNA vaccines expressing lentiviral Envs and Gag from gene sequences optimized for efficient expression in mammalian cells (codon-optimized). BALB/c mice vaccinated in separate hind legs with each plasmid individually elicited high titer immune responses, however, when HIV-1 Env(gp120) and HIV-1 Gag(p55) DNA plasmids were co-inoculated, there was a reduction in the immune responses elicited to HIV-1 Gag(p55). To determine if the anti-HIV-1 Gag(p55) immune interference was specific to HIV-1 Env(gp120), mice were co-immunized with plasmids expressing the surface envelope protein from two additional lentiviruses, Env(gp130)-SIV or Env(gp90)-EIAV, or a soluble form of hemagglutinin (sHA) from influenza virus and HIV-1 Gag(p55)- or SIV Gag(p55)-DNA. Interestingly, there was no reduction in anti-HIV-1 Gag(p55) immune responses using other lentiviral envelopes or the influenza sHA. Also, none of the lentiviral envelopes reduced anti-SIV Gag(p55) immune responses during co-immunization. Therefore, anti-HIV-1 Gag immune interference appears specific to co-immunizations with HIV-1 Env(gp120) and may involve a yet undefined immunological mechanism(s).

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Contribution of Virus-Like Particles to the Immunogenicity of Human Immunodeficiency Virus Type 1 Gag-Derived Vaccines in Mice

Cited by 15 publications

References 63 publications

Effect of promoter strength on protein expression and immunogenicity of an HSV-1 amplicon vector encoding HIV-1 Gag

Effect of promoter strength on protein expression and immunogenicity of an HSV-1 amplicon vector encoding HIV-1 Gag

Abrogation of contaminating RNA activity in HIV-1 Gag VLPs

Reduction of Anti-HIV-1 Gag Immune Responses During Co-Immunization: Immune Interference by the HIV-1 Envelope

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