Murine Monoclonal Antibodies for Antigenic Discrimination of HIV-1 Envelope Proteins.

In the influenza virus field, antibody reagents from research animals have been instrumental in the characterization of antigenically distinct hemagglutinin and neuraminidase membrane molecules. These small animal reagents continue to support the selection of components for inclusion in human influenza virus vaccines. Other cocktail vaccines against variant pathogens (e.g., polio virus, pneumococcus) are similarly designed to represent variant antigens, as defined by antibody reactivity patterns. However, a vaccine cocktail comprising diverse viral membrane antigens defined in this way has not yet been advanced to a clinical efficacy study in the HIV-1 field. In this study, we describe the preparation of mouse antibodies specific for HIV-1 gp140 or gp120 envelope molecules. Our experiments generated renewable reagents able to discriminate HIV-1 envelopes from one another. Monoclonals yielded more precise discriminatory capacity against their respective immunogens than did a small panel of polyclonal human sera derived from recently HIV-1-infected patients. Perhaps these and other antibody reagents will ultimately support high-throughput cartography studies with which antigenically-distinct envelope immunogens may be formulated into a successful HIV-1 envelope cocktail vaccine.

Safety and immunogenicity of an intranasal Sendai virus-based human parainfluenza virus type 1 vaccine in 3- to 6-year-old children.

Human parainfluenza virus type 1 (hPIV-1) is the most common cause of laryngotracheobronchitis (croup), resulting in tens of thousands of hospitalizations each year in the United States alone. No licensed vaccine is yet available. We have developed murine PIV-1 (Sendai virus [SeV]) as a live Jennerian vaccine for hPIV-1. Here, we describe vaccine testing in healthy 3- to 6-year-old hPIV-1-seropositive children in a dose escalation study. One dose of the vaccine (5 × 10(5), 5 × 10(6), or 5 × 10(7) 50% egg infectious doses) was delivered by the intranasal route to each study participant. The vaccine was well tolerated by all the study participants. There was no sign of vaccine virus replication in the airway in any participant. Most children exhibited an increase in antibody binding and neutralizing responses toward hPIV-1 within 4 weeks from the time of vaccination. In several children, antibody responses remained above incoming levels for at least 6 months after vaccination. Data suggest that SeV may provide a benefit to 3- to 6-year-old children, even when vaccine recipients have preexisting cross-reactive antibodies due to previous exposures to hPIV-1. Results encourage the testing of SeV administration in young seronegative children to protect against the serious respiratory tract diseases caused by hPIV-1 infections.

Heterologous Prime-Boost HIV-1 Vaccination Regimens in Pre-Clinical and Clinical Trials.

Currently, there are more than 30 million people infected with HIV-1 and thousands more are infected each day. Vaccination is the single most effective mechanism for prevention of viral disease, and after more than 25 years of research, one vaccine has shown somewhat encouraging results in an advanced clinical efficacy trial. A modified intent-to-treat analysis of trial results showed that infection was approximately 30% lower in the vaccine group compared to the placebo group. The vaccine was administered using a heterologous prime-boost regimen in which both target antigens and delivery vehicles were changed during the course of inoculations. Here we examine the complexity of heterologous prime-boost immunizations. We show that the use of different delivery vehicles in prime and boost inoculations can help to avert the inhibitory effects caused by vector-specific immune responses. We also show that the introduction of new antigens into boost inoculations can be advantageous, demonstrating that the effect of `original antigenic sin' is not absolute. Pre-clinical and clinical studies are reviewed, including our own work with a three-vector vaccination regimen using recombinant DNA, virus (Sendai virus or vaccinia virus) and protein. Promising preliminary results suggest that the heterologous prime-boost strategy may possibly provide a foundation for the future prevention of HIV-1 infections in humans.

Preclinical and clinical development of a multi-envelope, DNA-virus-protein (D-V-P) HIV-1 vaccine.

The human immune system has evolved to recognize antigenic diversity, a strength that has been harnessed by vaccine developers to combat numerous pathogens (e.g., pneumococcus, influenza virus, rotavirus). In each case, vaccine cocktails were formulated to include antigenic variants of the target. To combat HIV-1 diversity, we assembled a cocktail vaccine comprising dozens of envelopes, delivered as recombinant DNA, vaccinia virus, and protein for testing in a clinical trial. One vaccinee has now completed vaccinations with no serious adverse events. Preliminary analyses demonstrate early proof-of-principle that a multi-envelope vaccine can elicit neutralizing antibody responses toward heterologous HIV-1 in humans.

First phase I clinical trial of an HIV-1 subtype D gp140 envelope protein vaccine: immune activity induced in all study participants.

To combat HIV-1 diversity, we are developing a multienvelope vaccine (comprising DNA, vaccinia virus and protein vectors). Toward this goal, we conducted a phase I clinical trial of EnvPro, a gp140 protein formulated in alum. The vaccine was well tolerated and elicited an immune response in every trial participant.