A Novel Prime and Boost Regimen of HIV Virus-Like Particles with TLR4 Adjuvant MPLA Induces Th1 Oriented Immune Responses against HIV

Abstract

HIV virus-like particles (VLPs) present the HIV envelope protein in its native conformation, providing an ideal vaccine antigen. To enhance the immunogenicity of the VLP vaccine, we sought to improve upon two components; the route of administration and the additional adjuvant. Using HIV VLPs, we evaluated sub-cheek as a novel route of vaccine administration when combined with other conventional routes of immunization. Of five combinations of distinct prime and boost sequences, which included sub-cheek, intranasal, and intradermal routes of administration, intranasal prime and sub-cheek boost (IN+SC) resulted in the highest HIV-specific IgG titers among the groups tested. Using the IN+SC regimen we tested the adjuvant VesiVax Conjugatable Adjuvant Lipid Vesicles (CALV) + monophosphoryl lipid A (MPLA) at MPLA concentrations of 0, 7.5, 12.5, and 25 μg/dose in combination with our VLPs. Mice that received 12.5 or 25 μg/dose MPLA had the highest concentrations of Env-specific IgG2c (20.7 and 18.4 μg/ml respectively), which represents a Th1 type of immune response in C57BL/6 mice. This was in sharp contrast to mice which received 0 or 7.5 μg MPLA adjuvant (6.05 and 5.68 μg/ml of IgG2c respectively). In contrast to IgG2c, MPLA had minor effects on Env-specific IgG1; therefore, 12.5 and 25 μg/dose of MPLA induced the optimal IgG1/IgG2c ratio of 1.3. Additionally, the percentage of germinal center B cells increased significantly from 15.4% in the control group to 31.9% in the CALV + 25 μg MPLA group. These mice also had significantly more IL-2 and less IL-4 Env-specific CD8+ T cells than controls, correlating with an increased percentage of Env-specific central memory CD4+ and CD8+ T cells. Our study shows the strong potential of IN+SC as an efficacious route of administration and the effectiveness of VLPs combined with MPLA adjuvant to induce Env specific Th1-oriented HIV-specific immune responses.

Powerful Complex Immunoadjuvant Based on Synergistic Effect of Combined TLR4 and NOD2 Activation Significantly Enhances Magnitude of Humoral and Cellular Adaptive Immune Responses

“…In fact, it has now been shown for a variety of PRR agonists that inclusion of the agonist as an adjuvant component in a vaccine (i) increases the magnitude of the specific immune response against the vaccine antigen, (ii) increases the longevity of the response, and (iii) steers polarization of the immune response. In particular, when administered as vaccine adjuvants, agonists of TLR-3, -4, -7/8, and -9 caused predominately Th1 response stimulation [ 5 , 6 , 7 , 8 ], agonists of TLR5 (e.g., flagellin) produced mixed Th1 and Th2 responses [ 9 ], and agonists of TLR2 (e.g., Pam 2 CSK 4 ) showed a strong Th2-biased humoral immune response [ 10 ]. It was also shown that stimulation of a non-TLR PRR, the C-type lectin Mincle receptor, by the synthetic agonist trehalose-6,6-dibehenate (TDB) induced a strong Th1/Th17 immune response [ 11 ].…”

In Vitro Evaluation of the Biological Responses of Canine Macrophages Challenged with PLGA Nanoparticles Containing Monophosphoryl Lipid A

“…MPLA is a derivative of lipid A from gram negative bacteria, considerably less toxic than LPS whilst maintaining immunostimulatory activity in vivo and in vitro [17]. When tested in animal models as a vaccine adjuvant, MPLA facilitated inducing strong Th1 immune responses, which is desirable for effective immune-elimination of intracellular pathogens and neoplastic cells [18]. Subsequent aims for this project were to standardize the generation of monocyte-derived macrophages from dogs and to evaluate selected biological responses of macrophages when exposed to PLGA NP containing MPLA.…”

Chemically Synthesized Alcaligenes Lipid A Shows a Potent and Safe Nasal Vaccine Adjuvant Activity for the Induction of Streptococcus pneumoniae-Specific IgA and Th17 Mediated Protective Immunity

“…Recently, a lipid A-based vaccine adjuvant has been developed. For example, 3-O-desacyl-4 -monophosphoryl lipid A (MPLA), a derivative of lipid A derived from Salmonella minnesota R595 LPS, is used for enhancement of the efficacy of Hepatitis B virus; human papillomavirus vaccine [26][27][28]. S. minnesota is a pathogenic bacteria, so its lipid A needs to be chemically modified to reduce its pathogenicity by deficient of phosphoryl group.…”