Abstract
Strategies to induce potent and broad antibody responses against the human immunodeficiency virus type 1 (HIV-1) envelope glycoproteins (Env) at both systemic and mucosal sites represent a central goal for HIV-1 vaccine development. Here, we show that the non-toxic CTA1-DD adjuvant promoted mucosal and systemic humoral and cell-mediated immune responses following intranasal (i.n.) immunizations with trimeric or monomeric forms of HIV-1 Env in mice and in non-human primates. Env-specific IgG subclasses in the serum of immunized mice reflected a balanced Th1/Th2 type of response. Strikingly, i.n. immunizations with Env and the CTA1-DD adjuvant induced substantial levels of mucosal anti-Env IgA in bronchial alveolar lavage and also detectable levels in vaginal secretions. By contrast, parenteral immunizations of Env formulated in Ribi did not stimulate mucosal IgA responses, while the two adjuvants induced a similar distribution of Env-specific IgG-subclasses in serum. A single parenteral boost with Env in Ribi adjuvant into mice previously primed i.n. with Env and CTA1-DD, augmented the serum anti-Env IgG levels to similar magnitudes as those observed after three intraperitoneal immunizations with Env in Ribi. The augmenting potency of CTA1-DD was similar to that of LTK63 or CpG oligodeoxynucleotides (ODN). However, in contrast to CpG ODN, the effect of CTA1-DD and LTK63 appeared to be independent of MyD88 and toll-like receptor signalling. This is the first demonstration that CTA1-DD augments specific immune responses also in non-human primates, suggesting that this adjuvant could be explored further as a clinically safe mucosal vaccine adjuvant for humoral and cell-mediated immunity against HIV-1 Env.
Highlights
Because the majority of natural human immunodeficiency virus type 1 (HIV-1) transmissions occur via mucosal membranes an effective prophylactic vaccine should stimulate immune responses that are active at the portal site for viral entry (Gupta & Klasse, 2006; Mestecky et al, 2005)
In the present study we document the adjuvant effects of CTA1-DD for mucosal and systemic immune responses following i.n. immunizations using trimeric or monomeric forms of the HIV-1 envelope glycoproteins (Env) proteins in both mice and nonhuman primates
Though, is highly likely with mutant derivatives of cholera toxin (CT) or labile toxin (LT), such as i.n. vaccines adjuvanted by LTR192R or the LTK63 mutant (Dickinson & Clements, 1995; Stephenson et al, 2006)
Summary
Because the majority of natural human immunodeficiency virus type 1 (HIV-1) transmissions occur via mucosal membranes an effective prophylactic vaccine should stimulate immune responses that are active at the portal site for viral entry (Gupta & Klasse, 2006; Mestecky et al, 2005). Vaccine-induced neutralizing antibodies (NAbs) that interfere with viral entry have been found to be the protective correlates of many other prophylactic antiviral. An HIV-1 vaccine that prevents or limits virus replication in the mucosa should reduce the risk of systemic viral dissemination (Haase, 2005; Maher et al, 2005; Mazanec et al, 1992) and may reduce the risk of human-to-human transmission (Kozlowski & Neutra, 2003; Mascola, 2003; Neutra & Kozlowski, 2006).
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