Immunogenicity and protection efficacy of monovalent and polyvalent poxvirus vaccines that include the D8 antigen.

Recent studies have established the feasibility of subunit-based experimental vaccines to protect animals from lethal poxvirus infection. Individual outer membrane proteins from intracellular and extracellular virions of vaccinia virus, when delivered in the form of either DNA vaccines or recombinant protein vaccines produced from baculovirus-infected insect cells, were able to protect mice from the vaccinia virus challenge and rhesus macaques from the monkeypox virus challenge. The polyvalent formulations with various combinations of the four poxvirus antigens (A27, L1, B5 and A33) achieved better protection than the monovalent formulation using only one of these antigens.

Polyvalent HIV-1 Env vaccine formulations delivered by the DNA priming plus protein boosting approach are effective in generating neutralizing antibodies against primary human immunodeficiency virus type 1 isolates from subtypes A, B, C, D and E.

A major challenge in developing an HIV-1 vaccine is to identify immunogens and their delivery methods that can elicit broad neutralizing antibodies against primary isolates of different genetic subtypes. Recently, we demonstrated that priming with DNA vaccines expressing primary HIV-1 envelope glycoprotein (Env) followed by recombinant Env protein boosting was successful in generating positive neutralizing antibody responses against a clade B primary HIV-1 isolate, JR-FL, that was not easily neutralized. In the current study, we examined whether the DNA priming plus recombinant protein boosting approach delivering a polyvalent primary Env formulation was able to generate neutralizing antibodies against primary HIV-1 viral isolates from various genetic subtypes.

Preclinical evaluation of cellular immune responses elicited by a polyvalent DNA prime/protein boost HIV-1 vaccine.

While DNA vaccines have been shown to prime cellular immune responses, levels are often low in nonhuman primates or humans. Hence, efforts have been directed toward boosting responses by combining DNA with different vaccination modalities. To this end, a polyvalent DNA prime/protein boost vaccine, consisting of codon optimized HIV-1 env (A, B, C, E) and gag (C) and homologous gp120 proteins in QS-21, was evaluated in rhesus macaques and BALB/c mice.

Relative contributions of codon usage, promoter efficiency and leader sequence to the antigen expression and immunogenicity of HIV-1 Env DNA vaccine.

Optimized antigen expression is critical to the immunogenicity of DNA vaccines. A number of approaches have been proposed to enhance the antigen expression and/or immunogenicity of DNA vaccines, but their relative contributions have not been compared in a same antigen system. In the current study, optimization of codon usage, enhancement of viral promoter function and selection of secretary leader sequences were evaluated for their roles in improving the immunogenicity of a same model antigen, the HIV-1 envelope glycoprotein.

Novel DNA vaccine based on hepatitis B virus core gene induces specific immune responses in Balb/c mice.

Aim: To investigate the immunogenicity of a novel DNA vaccine, pSW3891/HBc, based on HBV core gene in Balb/c mice.

Methods: A novel DNA vaccine, pSW3891/HBc, encoding HBV core gene was constructed using a vector plasmid pSW3891. Balb/c mice were immunized with either pSW3891/HBc or empty vector DNA via gene gun.

Application of the polyvalent approach to HIV-1 vaccine development.

One major obstacle to the design of a global HIV-1 vaccine is viral diversity. Presently, data suggest that a single antigen will not suffice to generate broadly reactive neutralizing antibodies to protect all individuals against all subtypes of HIV-1 infection. While some of the neutralizing epitopes are identified in the constant regions of the HIV-1 envelope (Env) glycoprotein, many are localized to variable regions and differ conformationally from one virus to the next.

Enhanced immunogenicity of gp120 protein when combined with recombinant DNA priming to generate antibodies that neutralize the JR-FL primary isolate of human immunodeficiency virus type 1.

Strategies are needed for human immunodeficiency virus type 1 vaccine development that improves the neutralizing antibody response against primary isolates of the virus. Here we examined recombinant DNA priming followed by subunit protein boosting as a strategy to generate neutralizing antibodies. Both plasmid-based and recombinant protein envelope (Env) glycoprotein immunogens were derived from a primary viral isolate, JR-FL.

Assays for the assessment of neutralizing antibody activities against Severe Acute Respiratory Syndrome (SARS) associated coronavirus (SCV).

Accurate assessment of neutralizing antibody activities is important either for patients infected with Severe Acute Respiratory Syndrome (SARS) or for animals and volunteers immunized with the experimental vaccines against the SARS associated coronavirus (SCV). However, the current assay based on the cytopathic effect (CPE) which has been frequently cited in literature has several limitations. The CPE assay relies on the visual observation on the damage of SCV infected target cells under a microscope.

Epitope mapping and biological function analysis of antibodies produced by immunization of mice with an inactivated Chinese isolate of severe acute respiratory syndrome-associated coronavirus (SARS-CoV).

Inactivated severe acute respiratory syndrome-associated coronavirus (SARS-CoV) has been tested as a candidate vaccine against the re-emergence of SARS. In order to understand the efficacy and safety of this approach, it is important to know the antibody specificities generated with inactivated SARS-CoV. In the current study, a panel of twelve monoclonal antibodies (mAbs) was established by immunizing Balb/c mice with the inactivated BJ01 strain of SARS-CoV isolated from the lung tissue of a SARS-infected Chinese patient.

Identification of two neutralizing regions on the severe acute respiratory syndrome coronavirus spike glycoprotein produced from the mammalian expression system.

The Spike (S) protein of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) plays important roles in viral pathogenesis and potentially in the development of an effective vaccine against this virulent infectious disease. In this study, the codon-optimized S gene of SARS-CoV was synthesized to construct DNA vaccine plasmids expressing either the full-length or segments of the S protein. High titer S-specific immunoglobulin G antibody responses were elicited in rabbits immunized with DNA against various segments of the S protein.

Independent but not synergistic enhancement to the immunogenicity of DNA vaccine expressing HIV-1 gp120 glycoprotein by codon optimization and C3d fusion in a mouse model.

The ability to elicit humoral and cell-mediated immune (CMI) responses from DNA immunization by combinational use of codon optimization and C3d component of complement was evaluated in this study. DNA vaccines that express either the wild type or the codon optimized gp120 gene coding for the envelope (Env) glycoprotein of human immunodeficiency virus (HIV-1) from the primary isolate JR-FL strain were compared to the same forms fused to three tandem copies of the murine C3d genes. Either codon optimization or C3d fusion alone was effective at generating early appearance, higher binding and neutralizing antibody responses.