Delivery of Human Immunodeficiency Virus Vaccine Vectors to the Intestine Induces Enhanced Mucosal Cellular Immunity

Vaccine Research Center, NIAID, National Institutes of Health, Bethesda, MD 20892-3005, USA.
Journal of Virology (Impact Factor: 4.44). 06/2009; 83(14):7166-75. DOI: 10.1128/JVI.00374-09
Source: PubMed


Effective vaccines for human immunodeficiency virus type 1 (HIV-1) will likely need to stimulate protective immunity in the
intestinal mucosa, where HIV-1 infection causes severe CD4+ T-cell depletion. While replication-competent recombinant adenovirus (rAd) vectors can stimulate adenovirus-specific mucosal
immunity after replication, oral delivery of replication-defective rAd vectors encoding specific immunogens has proven challenging.
In this study, we have systematically identified barriers to effective gut delivery of rAd vectors and identified sites and
strategies to induce potent cellular and humoral immunity. Vector-mediated gene transfer by rAd5 was susceptible to low-pH
buffer, gastric and pancreatic proteases, and extracellular mucins. Using ex vivo organ explants, we found that transduction
with rAd5 was highest in the ileum and colon among all intestinal segments. Transgene expression was 100-fold higher after
direct surgical introduction into the ileum than after oral gavage, with rAd5 showing greater potency than the rAd35 or the
rAd41 vector. A single immunization of rAd5 encoding HIV-1 gp140B to the ileum stimulated potent CD8+ T-cell responses in the intestinal and systemic compartments, and these responses were further enhanced by intramuscular
rAd5 boosting. These studies suggest that induction of primary immune responses by rAd5 gut immunization and subsequent systemic
boosting elicits potent antigen-specific gut mucosal responses.

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    • "A very high efficiency of transfection and specific translational discrimination between viral and cellular mRNA together facilitate the exceptional expression of adenovirus-vectored proteins from mammalian cells (Babich et al. 1983; Huang and Schneider 1990). We found this system capable of expressing the HIV-1 gp120 envelope glycoprotein, which has 9 disulfides and *20 sites of N-linked glycosylation, at a level of *50 mg/l for wild-type and various truncated variants (Zhou et al. 2007; Wang et al. 2009), a level of expression substantially better than achieved by transient transfection or from transformed drosophila cells (Kwong et al. 2010). As precise measurement of the flexibility of HIV-1 gp120 may provide insight into its immunogenicity, we sought to produce an isotopically labeled fragment of HIV-1 gp120 that contained the epitope for broadly neutralizing antibodies and that was sufficiently small and well behaved to be analyzed by NMR spectroscopy. "
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    ABSTRACT: NMR spectroscopic characterization of the structure or the dynamics of proteins generally requires the production of samples isotopically enriched in 15N, 13C, or 2H. The bacterial expression systems currently in use to obtain isotopic enrichment, however, cannot produce a number of eukaryotic proteins, especially those that require post-translational modifications such as N-linked glycosylation for proper folding or activity. Here, we report the use of an adenovirus vector-based mammalian expression system to produce isotopically enriched 15N or 15N/13C samples of an outer domain variant of the HIV-1 gp120 envelope glycoprotein with 15 sites of N-linked glycosylation. Yields for the 15N- and 15N/13C-labeled gp120s after affinity chromatography were 45 and 44 mg/l, respectively, with an average of over 80% isotope incorporation. Recognition of the labeled gp120 by cognate antibodies that recognize complex epitopes showed affinities comparable to the unlabeled protein. NMR spectra, including 1H-15N and 1H-13C HSQCs, 15N-edited NOESY-HSQC, and 3D HNCO, were of high quality, with signal-to-noise consistent with an efficient level of isotope incorporation, and with chemical shift dispersion indicative of a well-folded protein. The exceptional protein yields, good isotope incorporation, and ability to obtain well-folded post-translationally modified proteins make this mammalian system attractive for the production of isotopically enriched eukaryotic proteins for NMR spectroscopy. Electronic supplementary material The online version of this article (doi:10.1007/s10858-011-9506-4) contains supplementary material, which is available to authorized users.
    Full-text · Article · Jun 2011 · Journal of Biomolecular NMR
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    • "While some interesting results have been reported for these oral delivery systems, immune responses against the delivery bacteria eventually predominated over time [148]. Oral delivery of recombinant viruses such as adenoviruses (Ad), poxviruses, and polioviruses encoding specific HIV antigens has also been tested in several oral vaccine studies [91] [149] [150]. While these viral vectors showed promising results, pre-exposure to these viruses may result in an undesirable outcome marked by a gradually elevated response against such carrier viruses. "
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    ABSTRACT: The mucosal immune system appears to be a major target of the HIV infection. Therefore, a strong pre-existing anti-HIV immune response in mucosal compartments might be able to prevent HIV infection. Conflicting views regarding the mechanisms of protection at mucosal sites, inferred by the contradictory results of mucosal vaccines in human clinical trials, attests to our lack of knowledge in understanding the human mucosal immune system. In this article, we briefly review the function of innate and adaptive immune responses and discuss current strategies and potential adjuvants in designing and delivering HIV vaccines through mucosal routes.
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    ABSTRACT: Abstract Gastrointestinal dysfunction has been recognised as a major manifestation of the human immunodeficiency virus (HIV) infection usually presenting as diarrhoea which may or may not be due to the presence of an opportunistic infection of the GIT. Contrary to earlier assumptions, there is now substantial evidence to demonstrate that there are significant changes in the gut in the acute phase of HIV infection; the most significant of these being the substantial loss of the CD4+ T-cells in the GIT. Delays in the initiation of HAART (that is, once the CD4+ T-cell count drops below 200 cells/uL), is associated with a greater severity of HIV-associated GIT enteropathy, and poor clinical outcome. S Afr J Clin Nutr 2010;23(1) Supplement:S65-S68
    Full-text · Article · Feb 2010 · South African Journal of Clinical Nutrition
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