Phase I/II vaccination study of recombinant peptide F46 corresponding to the HIV-1 transmembrane protein coupled with 2.4 dinitrophenyl (DNP) Ficoll

Optimization, Production, and Characterization of a CpG-Oligonucleotide-Ficoll Conjugate Nanoparticle Adjuvant for Enhanced Immunogenicity of Anthrax Protective Antigen

We have synthesized and characterized a novel phosphorothioate CpG oligodeoxynucleotide (CpG ODN)-Ficoll conjugated nanoparticulate adjuvant, termed DV230-Ficoll. This adjuvant was constructed from an amine-functionalized-Ficoll, a heterobifunctional linker (succinimidyl-[(N-maleimidopropionamido)-hexaethylene glycol] ester) and the CpG-ODN DV230. Herein, we describe the evaluation of the purity and reactivity of linkers of different lengths for CpG-ODN-Ficoll conjugation, optimization of linker coupling, and conjugation of thiol-functionalized CpG to maleimide-functionalized Ficoll and process scale-up. Physicochemical characterization of independently produced lots of DV230-Ficoll reveal a bioconjugate with a particle size of approximately 50 nm and covalent attachment of more than 100 molecules of CpG per Ficoll. Solutions of purified DV230-Ficoll were stable for at least 12 months at frozen and refrigerated temperatures and stability was further enhanced in lyophilized form. Compared to nonconjugated monomeric DV230, the DV230-Ficoll conjugate demonstrated improved in vitro potency for induction of IFN-α from human peripheral blood mononuclear cells and induced higher titer neutralizing antibody responses against coadministered anthrax recombinant protective antigen in mice. The processes described here establish a reproducible and robust process for the synthesis of a novel, size-controlled, and stable CpG-ODN nanoparticle adjuvant suitable for manufacture and use in vaccines.

A CpG-Ficoll Nanoparticle Adjuvant for Anthrax Protective Antigen Enhances Immunogenicity and Provides Single-Immunization Protection against Inhaled Anthrax in Monkeys

Nanoparticulate delivery systems for vaccine adjuvants, designed to enhance targeting of secondary lymphoid organs and activation of APCs, have shown substantial promise for enhanced immunopotentiation. We investigated the adjuvant activity of synthetic oligonucleotides containing CpG-rich motifs linked to the sucrose polymer Ficoll, forming soluble 50-nm particles (DV230-Ficoll), each containing >100 molecules of the TLR9 ligand, DV230. DV230-Ficoll was evaluated as an adjuvant for a candidate vaccine for anthrax using recombinant protective Ag (rPA) from Bacillus anthracis. A single immunization with rPA plus DV230-Ficoll induced 10-fold higher titers of toxin-neutralizing Abs in cynomolgus monkeys at 2 wk compared with animals immunized with equivalent amounts of monomeric DV230. Monkeys immunized either once or twice with rPA plus DV230-Ficoll were completely protected from challenge with 200 LD50 aerosolized anthrax spores. In mice, DV230-Ficoll was more potent than DV230 for the induction of innate immune responses at the injection site and draining lymph nodes. DV230-Ficoll was preferentially colocalized with rPA in key APC populations and induced greater maturation marker expression (CD69 and CD86) on these cells and stronger germinal center B and T cell responses, relative to DV230. DV230-Ficoll was also preferentially retained at the injection site and draining lymph nodes and produced fewer systemic inflammatory responses. These findings support the development of DV230-Ficoll as an adjuvant platform, particularly for vaccines such as for anthrax, for which rapid induction of protective immunity and memory with a single injection is very important.

Clinical experience with therapeutic AIDS vaccines

Recently, there has been a renewed interest in therapeutic vaccination as an adjunct or alternative to current treatment options for HIV. The first immunotherapeutic trial relevant to this topic was published in 1983. Since then, several dozen therapeutic vaccine trials have been carried out. The results have consistently shown that although in vitro-measured HIV-specific immune responses were evident as a result of vaccination, clinical improvement has been seldom observed. The instances of apparent clinical benefit however, were invariably associated with the usage of vaccines that acted in accord with the principles of allo- or autoimmunization. The majority of these vaccines were derived from the blood of HIV carriers or a cell culture and therefore inherently contained host-cell antigens unrelated to HIV. These observations raise the issue of whether this clinically successful approach has been unduly neglected. Most commercial vaccines on the market today are made the old-fashioned way, but very little support or attention has been given to the development of such vaccines for AIDS therapy. The current strategy, biased toward vaccines which have shown little evidence of clinical efficacy, is shortsighted and needs to be revised.

Prolonged survival of end-stage AIDS patients immunized with therapeutic HIV vaccine V-1 Immunitor

Death, rather than surrogate markers, is a single and most straightforward clinical endpoint, defining unequivocally the merit of a therapeutic intervention. As there is still neither a cure for AIDS nor a vaccine to prevent HIV infection, an AIDS diagnosis remains associated with a death sentence. V-1 Immunitor (V1) is an experimental, oral, therapeutic AIDS vaccine licensed as a dietary supplement. As part of a charity program V1 has been offered at Wat Phra Baht Nam Phu--a Buddhist hospice for end-stage AIDS patients. Out of 117 approached individuals, 53 decided to take V1 and 64 declined the treatment. Patients in both groups did not differ in age, gender, or severity of disease. All patients were in WHO terminal stage 4 at study entry and had received similar palliative care. None of the patients had received conventional antiviral drugs. At 9 weeks the last two patients in the non-V1 group died. In contrast, 56.6% (30/53) in the V1 group remained alive. Kaplan-Meier survival analysis showed that median short-term survival time for non-treated and treated patients was 4 and 10 weeks, respectively. The difference was statistically significant by Wilcoxon signed rank test (P=0.000089). Patients who remained alive were followed until the last patient died at 142 weeks. Based on the main outcome, i.e. time to death, patients on V1 had a 15.8 times longer life expectancy than the control group (P<0.000001). Observed results are encouraging and V1 needs to be tested in controlled clinical trials as a life-saving immunotherapy.

Vaccines for viral diseases with dermatologic manifestations

Vaccines against infectious diseases have been available since the 1800s, when an immunization strategy against smallpox developed by Jenner gained wide acceptance. Until recently, the only vaccination strategies available involved the use of protein-based, whole killed, and attenuated live virus vaccines. These strategies have led to the development of effective vaccines against a variety of diseases with primary or prominent cutaneous manifestations. Effective and safe vaccines now used worldwide include those directed against measles and rubella (now commonly used together with a mumps vaccine as the trivalent MMR), chickenpox, and hepatitis B. The eradication of naturally occurring smallpox remains one of the greatest successes in the history of modern medicine, but stockpiles of live smallpox exist in the United States and Russia. Renewed interest in the smallpox vaccine reflects concerns about a possible bioterrorist threat using this virus. Yellow fever is a hemorrhagic virus endemic to tropical areas of South America and Africa. An effective vaccine for this virus has existed since 1937, and it is used widely in endemic areas of South America, and to a lesser extent in Africa. This vaccine is recommended once every 10 years for people who are traveling to endemic areas. Advances in immunology have led to a greater understanding of immune system function in viral diseases. Progress in genetics and molecular biology has allowed researchers to design vaccines with novel mechanisms of action (eg, DNA, vector, and VLP vaccines). Vaccines have also been designed to specifically target particular viral components, allowing for stimulation of various arms of the immune system as desired. Ongoing research shows promise in prophylactic and therapeutic vaccination for viral infections with cutaneous manifestations. Further studies are necessary before vaccines for HSV, HPV, and HIV become commercially available.

Safety and efficacy of an oral HIV vaccine (V-1 Immunitor) in AIDS patients at various stages of the disease

PURPOSE

To evaluate the safety and efficacy of an orally available, therapeutic HIV vaccine (V-1 Immunitor) in patients who were not treated with antiviral drugs.

METHOD

All entrants who had been tested at least once at entry and at postimmunization were considered for analysis. Main endpoints were vaccine safety and differential effects on CD4 and CD8 cell counts, plasma HIV RNA levels, and body weight change. Forty patients, 21 females (52%) and 19 males (48%), aged 22-65 years (mean/median age, 35/32 years) with a mean 225/mm3 CD4 cells at baseline were retrospectively analyzed. Patients self-administered two 850-mg pills containing inactivated HIV-1 antigens b.i.d. for 27 weeks (median, 24 weeks).

RESULTS

The treatment was well tolerated without significant adverse effects. The mean body weight gain was 2.2 kg (p =.0004). The mean increase in absolute CD4 and CD8 cells was 51 (18%; p =.0088) and 172 (16%; p =.0199) cells/mm3. Viral load was measured by polymerase chain reaction (PCR) in 8 individuals; although overall decrease did not reach standard cut-off statistical significance (Friedman p =.0588), the trend in reduction of viremia attributable to vaccine administration was highly significant (Spearman correlation test: r = 0.96, p =.0005).

CONCLUSION

Mucosal delivery of HIV antigens provides compelling results and deserves further evaluation in placebo-controlled clinical trials.