Drug – bio-affecting and body treating compositions – Immunoglobulin – antiserum – antibody – or antibody fragment,... – Structurally-modified antibody – immunoglobulin – or fragment...
Reexamination Certificate
1993-12-28
2002-06-04
Huff, Sheela (Department: 1642)
Drug, bio-affecting and body treating compositions
Immunoglobulin, antiserum, antibody, or antibody fragment,...
Structurally-modified antibody, immunoglobulin, or fragment...
C424S139100, C424S141100, C424S151100, C530S387300, C530S388600
Reexamination Certificate
active
06399062
ABSTRACT:
SPECIFICATION
DEPOSIT INFORMATION
The Hybridoma, NVS3 (Navy Vivax Sporozite 3) is deposited in the American Type Culture Collection (ATCC), 10801 University Blvd., Manassas, Va. 20110-2209, USA, by a deposit received Nov. 30, 1990, under the terms and conditions of the Budapest treaty for a period of thirty (30) years. The ATCC designation number is HB 10615, Under the terms of the deposit access to the culture will be available during pendency of the patent application to one determined by the Commissioner of Patents and Trademarks to those found to be entitled thereto under 37 CFR 1.14 and 35 U.S.C. 122, and all restrictions on the availability to the public of the culture will be irrevocably removed upon grant of the Patent.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a passive protective agent against
P. vivax
. More particularly this invention relates to an antibody that, when a concentration of the antibody is injected intravenously, protects a subject to the limits of that concentration of antibody from developing malaria when the subject is subsequently challenged with live, infectious
P. vivax
sporozoites.
2. Description of the Prior Art
There have been major efforts toward development of malaria vaccines undertaken during the past 20 years. Although a commercially viable vaccine has not been achieved to the time this application is filed, there have been successes in providing vaccine protection. The continued vast investment in vaccine research by both governments world wide and industry shows an expectation of achieving a commercially viable vaccine. A commercially viable vaccine is one that provides protection with minimum side effects, is capable of being produced in quantity, and is stable in storage for a reasonable time under reasonable conditions. These conditions and requirements are well known in the medical and pharmaceutical arts. Even the near misses of total successes (e.g. successes with only a small population) are useful in understanding the mechanisms of malaria and further defining the parameters that will lead to a commercially successful vaccine or treatment. The current status of malaria vaccine development has been summarized in a recent Institution of Medicine Report
1
. The introduction to the section on vaccines is included verbatim to provide part of the background for this application.
WHERE WE ARE TODAY
Prospects for a Vaccine
Vaccination is an exceptionally attractive strategy for preventing and controlling malaria. Clinical and experimental data support the feasibility of developing effective malaria vaccines. For example, experimental vaccination with irradiated sporozoites can protect humans against malaria, suggesting that immunization with appropriate sporozoite and liver-stage antigens can prevent infection in individuals bitten by malaria-infected mosquitoes. In addition, repeated natural infections with the malaria parasite induce immune responses that can prevent disease and death in infected individuals, and the administration of serum antibodies obtained from repeatedly infected adults can control malaria infections in children who have not yet acquired protective immunity. These data suggest that immunization with appropriate blood-stage antigens can drastically reduce the consequences of malaria infection. Finally, experimental evidence shows that immunization with sexual-stage antigens can generate an immune response that prevents parasite development in the vector or, offering a strategy for interrupting malaria transmission.
Prospects for the development of malaria vaccines are enhanced by the availability of suitable methods for evaluating candidate antigens. These include protocols that allow humans volunteers to be safely infected with malaria, and the identification of many areas in the world where more than 75 percent of individuals can be expected to become infected with malaria during a three-month period. In contrast to vaccine for disease of low incidence, for which tens of thousands of immunized and non-immunized controls must be studied over several years, malaria vaccines could be evaluated in selected areas in fewer than 200 volunteers in less than a year.
Developments in molecular and cellular biology, peptide chemistry, and immunology provide the technological base for engineering subunit vaccines composed of different parts of the malaria parasite, an approach that was not possible 10 years ago. During the past 5 years, more than 15 experimental malaria vaccines have undergone preliminary testing in human volunteers. Although none of these vaccines has proven suitable for clinical implementation, progress has been made in defining the parameters of a successful vaccine and the stage has been set for further advancement.
Despite the inherent attractiveness and promise of this approach, there remain a number of obstacles to vaccine development. With the exception of the erthrocytic (blood) stages of
P. falciparum
, human malaria parasites cannot be readily cultured in vitro, limiting the ability of researchers to study other stages of this parasite and all stages of the other three human malaria parasite species.
In vitro assays, potentially useful for screening candidate vaccines for effectiveness, do not consistently predict the level of protective immunity seen in vivo. The only laboratory animals that can be infected with human malaria parasites are certain species of nonhuman primates, which are not naturally susceptible to these organisms. This makes it difficult to compare the results of many studies done in animals with what happens in human malaria infection.
The promises of modern vaccinology, while potentially revolutionary, have so far proved elusive. Few commercially available vaccines have been produced by this technology, for both scientific and economics reasons. Scientists have not yet been able to assemble defined synthetic peptides and recombinant proteins and combine them with new adjuvants and delivery systems into a practical human malaria vaccine. However, as discussed above and in the remainder of this chapter, there are good reasons to believe that this approach will ultimately succeed.
Approaches to Vaccine Development
The complex life cycle of the malaria parasite provides a number of potential targets for vaccination. Under investigation are vaccines that would be effective against the extracellular sporozoite, during the short period it spends in the bloodstream; the exoerythrocytic (or liver-stage) parasite, during the roughly seven days it develops within liver cells; the extracellular merozoite, released from liver cells or infected erthrocytes and free in the circulation prior to invading other erthrocytes; the asexual parasite that develops within red blood cells; exogenous parasite material released from infected erthrocytes; and the sexual-stage parasite, which occurs both inside erythrocytes and in mosquitoes. The optimal vaccine would include antigens from the sporozoite, asexual, and sexual stages of the parasite, thus providing multiple levels of control, but vaccines effective against individual stages could also prove highly useful. In addition, a vaccine against the Anopheles mosquito itself, which reduced the insect's life span and prevented complete development of the parasite, could be valuable.
Regardless of the stage of parasite targeted for vaccine development, a similar strategy is envisioned. Based on knowledge of the mechanisms of protected immunity, specific parasite antigens (immunogens) are identified that induce a protective immune response, and synthetic or recombinant vaccines that accurately mimic the structure of that antigen are prepared.
In the subunit approach to vaccine development, this is done by combining the immunogen with carrier proteins, adjuvants, and live vectors or other delivery systems. This approach is being pursued throughout the world in laboratories studying infectious diseases. Clinical utility has yet to be demonstrated for the majority of these efforts, and barriers to obtaining sa
Beaudoin Richard L.
Charoenvit Yupin
Hoffman Stephen L.
Harris Charles H.
Huff Sheela
Spevack A. David
The United States of America as represented by the Secretary of
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