Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Carbohydrate doai
Reexamination Certificate
2001-04-06
2004-11-23
Guzo, David (Department: 1636)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Carbohydrate doai
C435S320100, C435S455000, C435S465000
Reexamination Certificate
active
06821955
ABSTRACT:
FIELD OF INVENTION
This invention relates to the use of aggregated protein-polycationic polymer conjugates in genetic vaccines. More particularly it relates to the use of macroaggregated albumin conjugates for oral delivery of vaccines.
BACKGROUND OF THE INVENTION
The mucosal immune system is extremely important in human resistance to microbial pathogens, but complicating the picture is the role of the mucosal immune system in suppressing undesirable antigenic responses to inhaled and ingested antigens in order to avoid massive allergic sensitivity (Mowat, 1987). In addition, systemic immunization usually does not elicit significant mucosal immune responses (Mestecky et al., 1994). In the context of HIV, the genital surface is the most important target tissue for immunity, and it is particularly difficult to immunize directly, especially in the male. Hence, an HIV vaccine aimed at inducing mucosal immunity will almost certainly have to be administered elsewhere (e.g., the gut), but it must still result in the accumulation of immune effector cells and molecules in the genital mucosa. Airway immunization (e.g., intranasal and intratracheal) and gut immunization have both been shown to produce responses with effector cells spilling over to other mucosal surfaces, especially the genital tract. Recent work has revealed that antigens (and particles) are delivered across the mucosal surface relatively unchanged to antigen presenting cells underneath the surface via specialized cells (membranous cells or M cells) that are derived from the normal epithelium. It is generally believed that antigens taken up by the M cells, which cover the mucosal inductive sites, are channeled to parenchymal macrophages, dendritic cells, B lymphocytes and even mast cells. Under some conditions, such as viral infection, or perhaps genetic immunization, the antigen can be processed and perhaps presented directly by the epithelial cells to the underlying B and T cells. Hence, regardless of how the antigen is administered, antigen (or antigen expressed via plasmid DNA) that can be delivered to these antigen presenting cells should result in mucosal immune responses.
In genetic immunization, a simple mammalian expression plasmid containing the gene for an antigen is administered to the animal rather than the antigen itself. Expression of the antigen gene in this manner produces the antigen intracellularly, making it a substrate for major histocompatibility (MHC) class I presentation (Schirmbeck et al., 1995) thereby enabling strong cellular immune responses to be produced. The mechanisms of antigen presentation include transfection and expression of the antigen within professional antigen presenting cells (e.g., macrophages or dendritic cells), or transfer of peptides from a different expressing cell (e.g., cytoplasm transfer from muscle cells) to a professional antigen presenting cell (Doe et al., 1996, Huang et al., 1994). Anti-HIV envelope cytotoxic T-lymphocytes (CTL) have been induced in mice and nonhuman primates by genetic immunization (Wang et al., 1994). Furthermore, intramuscular genetic vaccination with influenza nucleoprotein expressing plasmids has produced long-lived CD8
+
CTL mediating cross-strain protection against flu (Ulmer et al., 1994). Humoral responses, e.g., to HIV-1 envelope protein (Wang et al., 1993, Lu et al., 1995), are also produced by such immunizations, either by the target cells themselves acting as antigen presenting cells, or by shedding of the protein products from the cell surface and subsequent processing of the peptides by professional antigen presenting cells through the MHC class II pathway. In fact, repeated intramuscular injections of plasmids have resulted in a conversion of the dominant CTL response into a humoral response, with waning of the cellular cytotoxicity response in some reports (Fuller et al., 1994). Hence, the appropriate dose, timing, and route(s) for administration are critical to producing an optimal genetic immunization response.
Inefficient DNA delivery remains one of the main impediments to successful gene therapy and DNA immunizations (Thierry et al., 1997). Transfection in vivo has been accomplished using cationic lipid/DNA complexes administered by injection intravenously (Zhu et al., 1993) and intramuscularly (Mitchell et al., 1995), and by application to mucosal surfaces (Schmid et al., 1994). Naked DNA has also been used intravenously, but it has a very brief half-life (Lew et al., 1995 and Kawabata, et al. 1995) and thus is extremely inefficient. However, intramuscular and intradermal injection of naked DNA has been effective in a variety of animal models. Viral vectors can be very efficient transiently, but the induction of antiviral immune responses prevents repeated administrations and may result in lowered transgene expression (Weichselbaum et al., 1997). In addition, toxicity may result from either cationic lipids or viral vectors in some cases. Microencapsulated plasmids containing reporter genes given orally penetrate the gastrointestinal tract surfaces and cause expression of the foreign genes in the cells of the gut and associated lymphoid tissue (Mathiowitz et al., 1997). Microspheres can also penetrate lymphoid tissue given by other routes as well, as has been observed in studies of protein antigen delivery (Marx et al., 1993 and Jenkins et al., 1995). Delivery of DNA to cutaneous tissues using a gene gun (Williams et al., 1991) has produced humoral systemic immunization (Tang et al., 1992) and cellular responses that were protective in the lung against
Mycoplasma pulmonis
infection (Barry et al., 1995). Despite all of these different, methods, none has proved to be broadly efficient in gene transfection application in vivo.
Mucosal immunity has been induced by nasal administration of plasmid DNA expression vectors, e.g., protective immunity to flu virus challenge with a vector encoding the influenza hemagglutinin protein (Fynan et al., 1993). Packaging with viral vectors (e.g., adeno-associated viruses), or incorporating antigenic genes into vaccinia virus has been frequently used, but has the disadvantage of inducing an immune reaction to the associated viral proteins as well, limiting the potential for boosting, or for administration of other antigens by the same route.
Expression library immunization (ELI) is a novel vaccine approach that weds the power of recombinant DNA technology to genetic immunization (Barry et al., 1995). In ELI, a pathogen's genome is broken into small fragments and cloned into mammalian expression plasmids to create a vaccine representing all or most of the antigens of the pathogen. The expression plasmids contain a strong promoter (e.g., CMV) and expression of the protein products can be controlled by fusion to targeting sequences, i.e., the carboxy terminus of ubiquitin, which directs the protein to the proteasome for MHC class I presentation, a signal sequence for secretion, which directs the product to be secreted for antibody induction for MHC class II presentation, or without an additional sequence, which the protein is processed based on the native properties of the protein sequence. ELI was first demonstrated effective against the bacterial pathogen
Mycoplasma pulmonis
by Michael Barry and colleagues (Barry et al., 1995). Expression libraries were generated by fusing fragments of
M. pulmonis
genomic DNA to the carboxy-termini of human growth hormone (containing a signal sequence for secretion) or ubiquitin. Ubiquitin fusions were recently reported to produce CTL, but reduce antibody induction (Gillanders et al., 1997); however, gene gun vaccination with these ELI vaccines for
M. pulmonis
produced both CTL and antibody protection against mycoplasma infection at least an order of magnitude better than the best traditional mycoplasma vaccine available. ELI appears useful for generating multiple immune responses simultaneously, in a manner analogous to that of a live/attenuated pathogen vaccine. Given the pattern of responses seen in the resistant sexually exposed individuals i
Bhogal Balbir S.
Kinsey Berma M.
Orson Frank M.
Baylor College of Medicine
Guzo David
Nguyen Quang
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