Patent Publication Number: US-2012039905-A1

Title: The Role of p110 delta Signaling in Morbidity and Lung Pathology Induced by Influenza Virus Infection

Description:
BACKGROUND OF THE INVENTION 
     Seasonal influenza virus infections affect 5-15% of the human population and 250,000-500,000 deaths occur each year due to severe pneumonia, multiple organ failure and acute respiratory distress-like syndrome. Although the exact mechanism of influenza virus pathogenicity is unknown, the induction of an overreacting immune response is the primary suspect. The emerging danger of a pandemic infection with H5N1 avian influenza virus strain and the possibility of influenza virus as a bioterrorism agent further underscore the necessity of understanding the mechanisms that lead to severe disease. Infection with pandemic strains is characterized by an intense inflammatory response and the unusual pathogenicity of avian flu and the 1918 pandemic strains have been attributed to increased production of inflammatory cytokines and this has been confirmed in non-human primates. In patients infected with H5N1, an intense immune activation is accompanied by a cytokine storm and may be the reason for the increased mortality associated with this infection. What induces the cytokine storm in severe influenza disease is currently unknown. 
     The spreading of influenza type A virus resistance to existing drugs, and the emergence of pandemic strains such as the novel H1N1 strain, has made the discovery of novel therapeutic targets for influenza virus urgent. A number of host signaling pathways have been shown in vitro to be hijacked by influenza virus for its propagation. 
     PI3K represent a family of enzymes that phosphorylate D-myo-phosphatidylinositol (PtdIns) or its derivatives on the 3-hydroxyl of the inositol group (Vanhaesebroeck et al., 2001  Annu Rev Biochem  70: 535-602). PI3Ks are classified as class I, II, or III, depending on their subunit structure, regulation, and substrate selectivity (Vanhaesebroeck et al., 2001  Annu Rev Biochem  70: 535-602; Fruman at al., 2002  Semin Immunol  14: 7-18), PI3K belonging to class I are heterodimers composed of a catalytic subunit of approximately 110 kDa, and a tightly associated regulatory subunit that modulates the activity and cellular location of the enzyme. Four isoforms (p110α, p110β, p110γ, and p110δ) of the catalytic subunits of class I PI3K exist (Vanhaesebroeck et al., 2001  Annu Rev Biochem  70: 535-602; Fruman et al., 2002  Semin Immunol  14: 7-18). PI3K p110δ is expressed preferentially by hematopoietic cells (Vanhaesebroeck et al., 1997  Proc. Natl Acad Sci USA  94: 4330-4335; Chantry et al., 1997  J Biol Chem  272: 19236-19241) and plays an important role in B and T cell development and function (Okkenhaug et al., 2003  Nat Rev Immunol  3: 317-330; Okkenhaug et al., 2002  Science  297: 1031-1034; Clayton et al., 2002  J Exp Med  196: 753-763; Okkenhaug et al., 2006  J Immunol  177:5122-5128). 
     Current drugs that block influenza virus replication (Tamiflu, Relenza) do not eliminate the morbidity symptoms associated with virus infection: fever, malaise, weight loss. There is therefore a need in the art for drugs that can eliminate morbidity symptoms associated with virus infection. The present invention satisfies this need. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides compositions and methods for modulating p110 delta in a cell. Preferably, the cell is a lung epithelial cell. Preferably, the cell is infected with a virus. 
     The invention includes a composition for inhibiting influenza virus infection. In one embodiment, the composition comprises an inhibitor of phosphoinositide 3 kinase (PI3K) isoform p110 delta. Preferably, the inhibitor interferes with PI3K p110 delta activation and replication of influenza virus. 
     In one embodiment, the inhibitor interferes with influenza virus pathogenesis. 
     In one embodiment, the inhibitor is selected from the group consisting of a small interfering RNA (siRNA), a microRNA, an antisense nucleic acid, a ribozyme, an expression vector encoding a transdominant negative mutant, an intracellular antibody, a peptide and a small molecule. 
     In another embodiment, the composition further comprises a physiologically acceptable carrier. 
     The invention also provides a method of inhibiting influenza virus replication. The method comprises inhibiting phosphoinositide 3 kinase (PI3K) isoform p110 delta in a cell comprising contacting a cell with a composition comprising an inhibitor of PI3K p110 delta. 
     The invention also provides a method of inhibiting influenza virus pathogenesis. The method comprises inhibiting phosphoinositide 3 kinase (PI3K) isoform p110 delta in a cell comprising contacting said cell with a composition comprising an inhibitor of PI3K p110 delta. 
     The invention also includes a method of treating or preventing influenza virus infection in a mammal, preferably a human. The method comprises administering an effective amount of a composition comprising an inhibitor of phosphoinositide 3 kinase (PI3K) isoform p110 delta to a mammal in need thereof. Preferably, the inhibitor interferes with PI3K p110 delta activation and replication of influenza virus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For the purpose of illustrating the invention, there are depicted in the drawings certain embodiments of the invention. However, the invention is not limited to the precise arrangements and instrumentalities of the embodiments depicted in the drawings. 
         FIG. 1 , comprising  FIGS. 1A through 1C , is a series of images depicting that p110δ is expressed by lung epithelial cells and is required for influenza virus replication.  FIG. 1A  depicts a Western blot analysis showing the expression of p110δ PI3K in the human lung epithelial cell line A549. Western blot was performed on cell lysates from A549 human lung epithelial cells, C57Bl/6 mouse splenocytes (positive control) and p110δ−/− mouse splenocytes (negative control). Asterisk indicates non-specific band.  FIG. 1B  is an image demonstrating that blocking p110δ PI3K activity with the specific inhibitor IC87114 (100 μM) inhibits influenza virus replication in A549 human lung epithelial cells infected with influenza virus strain PR8 (MOI=0.01).  FIG. 1C  is an image depicting that lung influenza virus viral load was determined in the lungs of p110δ−−/− and C57Bl/6 mice infected with influenza virus strain PR8 by RT-PCR and standardized according to a viral stock of known concentration (each symbol represents one animal and horizontal lines represent median values). Viral replication was quantitated by specific RT-PCR. 
         FIG. 2 , comprising  FIGS. 2A through 2E , is a series of images demonstrating reduced morbidity and inflammation in p110δ−/− mice infected with influenza virus. p110δ−/− (white circles) and C57Bl/6 control mice (black circles) were infected with a sublethal dose of influenza virus A strain PR8.  FIG. 2A  is a chart depicting weight loss as measured throughout the infection until mice started to recover (means of n=11-14 animals per group shown, vertical lines represent SE; *p=0.001, **p=0.01).  FIG. 2B  is a chart depicting percentage of inflamed lung. Briefly, lung lobes were collected at days 6 and 10 after infection and processed for H&amp;E staining and evaluated for tissue infiltration with immune cell (each symbol represents one mouse, horizontal lines represent means).  FIG. 2C  is a chart depicting the number of cells infiltrating the lungs of infected mice at 6 days post-infection as determined by using flow cytometry (each symbol represents one mouse, horizontal lines represent mean values).  FIG. 2D  is a chart depicting total number of NP (366-374) -specific CD8+ T cells in the lungs of infected C57Bl/6 and p110δ−/− mice at the peak of the response (day 10) as determined by using flow cytometry and tetramers (each symbol represents one mouse, horizontal lines represent means values).  FIG. 2E  is a chart depicting TNFα, MCP-1, IFNγ, and MIP-2 mRNA present in the lung tissue of p110δ−/− and C57Bl/6 mice at day 6 post-infection as determined by using RT-PCR. The fold induction was calculated relative to uninfected control mice (each symbol represents one mouse, horizontal lines represent mean values). 
         FIG. 3 , comprising  FIGS. 3A and 3B , is a series of images demonstrating that inhibition of p110δ protects from lethal influenza virus infection.  FIG. 3A  is a chart demonstrating that p110δ−/− mice are protected from lethal challenge with a virulent influenza virus strain. p110δ−/− (solid line) and C57Bl/6 (control, dotted line) were infected with 10×LD 50  of virulent in mice H7N7 A/Equine/London/1416/73 influenza virus strain.  FIG. 3B  is a chart demonstrating that pharmacological inhibition of p110δ protects mice lethally challenged with virulent influenza virus. Wild type mice were infected with 10×LD 50  of virulent in mice H7N7 A/Equine/London/1416/73 influenza virus strain and were either treated with p110δ specific inhibitor IC87114 (solid line) or left treated with vehicle only (dotted line). Statistical significance is indicated in the figures. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention provides compositions and methods for regulating p110 delta kinase thereby providing a means for treating symptoms associated with viral infection, including, for example, influenza virus infection. In one embodiment, the invention provides specific inhibitors of the p110 delta kinase. Preferably, the inhibitors are used to inhibit influenza virus infection. The inhibitors may also be used to inhibit the unwanted effects of morbidity and lung pathology that accompany seasonal and pandemic influenza virus infections. 
     The invention is partly based on the discovery that mice that have an inactivating mutation in the leukocyte-specific phosphoinositide 3 kinase (PI3K) isoform p110 delta (p110 delta−/−) manifest significantly reduced morbidity after influenza virus infection, compared to wild-type C57BL/6 mice. 
     In some instances, the invention includes interfering with p110 delta and downstream signaling associated with p110 delta to inhibit influenza virus infections. Using the methods disclosed elsewhere herein, the skilled artisan can readily inhibit influenza virus infection by blocking at least p110 delta signaling. The methods of the invention are contemplated for use in a mammal, preferably, a human. 
     Based on the disclosure presented herein, a skilled artisan would appreciate that interfering with p110 delta and downstream p110 delta signaling is useful as an anti-influenza therapy. 
     In one embodiment, inhibiting p110 delta can reduce lung viral loads in infected mammals compared to the level of viral loads in an otherwise identical infected mammal where p110 delta has not been inhibited. 
     In another embodiment, inhibiting p110 delta can reduce cellular infiltration into the lung of infected mammals compared to the level of cellular infiltration into the lung an otherwise identical infected mammal where p110 delta has not been inhibited. 
     In yet another embodiment, inhibiting p110 delta can reduce the number of inflammatory cells infiltrating into the lung of infected mammals compared to the number of inflammatory cells infiltrating into the lung in an otherwise identical infected mammal where p110 delta has not been inhibited. 
     In yet another embodiment, inhibiting p110 delta can reduce the production of inflammatory cytokines believed to contribute to influenza virus morbidity in infected mammals compared to the amount of inflammatory cytokine production in an otherwise identical infected mammal where p110 delta has not been inhibited. 
     DEFINITIONS 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although any methods and materials similar or equivalent to those described herein can be used in the practice for testing of the present invention, the preferred materials and methods are described herein. In describing and claiming the present invention, the following terminology will be used. 
     It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. 
     The articles “a” and “an” are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element. 
     An “amino acid” as used herein is meant to include both natural and synthetic amino acids, and both D and L amino acids. “Standard amino acid” means any of the twenty L-amino acids commonly found in naturally occurring peptides. “Nonstandard amino acid residues” means any amino acid, other than the standard amino acids, regardless of whether it is prepared synthetically or derived from a natural source. As used herein, “synthetic amino acid” also encompasses chemically modified amino acids, including but not limited to salts, amino acid derivatives (such as amides), and substitutions. Amino acids contained within the peptides, and particularly at the carboxy- or amino-terminus, can be modified by methylation, amidation, acetylation or substitution with other chemical groups which can change a peptide&#39;s circulating half life without adversely affecting activity of the peptide. Additionally, a disulfide linkage may be present or absent in the peptides. 
     “About” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass variations of ±20% or ±10%, more preferably +5%, even more preferably ±1%, and still more preferably +0.1% from the specified value, as such variations are appropriate to perform the disclosed methods. 
     “Antisense” refers particularly to the nucleic acid sequence of the non-coding strand of a double stranded DNA molecule encoding a polypeptide, or to a sequence which is substantially homologous to the non-coding strand. As defined herein, an antisense sequence is complementary to the sequence of a double stranded DNA molecule encoding a polypeptide. It is not necessary that the antisense sequence be complementary solely to the coding portion of the coding strand of the DNA molecule. The antisense sequence may be complementary to regulatory sequences specified on the coding strand of a DNA molecule encoding a polypeptide, which regulatory sequences control expression of the coding sequences. 
     The term “antibody,” as used herein, refers to an immunoglobulin molecule which specifically binds with an antigen. Antibodies can be intact immunoglobulins derived from natural sources or from recombinant sources and can be immunoreactive portions of intact immunoglobulins. Antibodies are typically tetramers of immunoglobulin molecules. The antibodies in the present invention may exist in a variety of forms including, for example, polyclonal antibodies, monoclonal antibodies, Fv, Fab and F(ab) 2 , as well as single chain antibodies and humanized antibodies (Harlow et al., 1999, In: Using Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, NY; Harlow et al., 1989, In: Antibodies: A Laboratory Manual, Cold Spring Harbor, N.Y.; Houston et al., 1988, Proc. Natl. Acad. Sci. USA 85:5879-5883; Bird et al., 1988, Science 242:423-426). 
     A “coding region” of a gene consists of the nucleotide residues of the coding strand of the gene and the nucleotides of the non-coding strand of the gene which are homologous with or complementary to, respectively, the coding region of an mRNA molecule which is produced by transcription of the gene. 
     A “coding region” of an mRNA molecule also consists of the nucleotide residues of the mRNA molecule which are matched with an anti-codon region of a transfer RNA molecule during translation of the mRNA molecule or which encode a stop codon. The coding region may thus include nucleotide residues corresponding to amino acid residues which are not present in the mature protein encoded by the mRNA molecule (e.g., amino acid residues in a protein export signal sequence). 
     “Encoding” refers to the inherent property of specific sequences of nucleotides in a polynucleotide, such as a gene, a cDNA, or an mRNA, to serve as templates for synthesis of other polymers and macromolecules in biological processes having either a defined sequence of nucleotides (i.e., rRNA, RNA and mRNA) or a defined sequence of amino acids and the biological properties resulting therefrom. Thus, a gene encodes a protein if transcription and translation of mRNA corresponding to that gene produces the protein in a cell or other biological system. Both the coding strand, the nucleotide sequence of which is identical to the mRNA sequence and is usually provided in sequence listings, and the non-coding strand, used as the template for transcription of a gene or cDNA, can be referred to as encoding the protein or other product of that gene or cDNA. 
     Unless otherwise specified, a “nucleotide sequence encoding an amino acid sequence” includes all nucleotide sequences that are degenerate versions of each other and that encode the same amino acid sequence. Nucleotide sequences that encode proteins and RNA may include introns. 
     “Effective amount” or “therapeutically effective amount” are used interchangeably herein, and refer to an amount of a compound, formulation, material, or composition, as described herein effective to achieve a particular biological result. Such results may include, but are not limited to, the inhibition of virus infection as determined by any means suitable in the art. 
     As used herein “endogenous” refers to any material from or produced inside an organism, cell, tissue or system. 
     The term “epitope” as used herein is defined as a small chemical molecule on an antigen that can elicit an immune response, inducing B and/or T cell responses. An antigen can have one or more epitopes. Most antigens have many epitopes; i.e., they are multivalent. In general, an epitope is roughly five amino acids and/or sugars in size. One skilled in the art understands that generally the overall three-dimensional structure, rather than the specific linear sequence of the molecule, is the main criterion of antigenic specificity and therefore distinguishes one epitope from another. 
     As used herein, the term “exogenous” refers to any material introduced from or produced outside an organism, cell, tissue or system. 
     The term “expression” as used herein is defined as the transcription and/or translation of a particular nucleotide sequence driven by its promoter. 
     “Expression vector” refers to a vector comprising a recombinant polynucleotide comprising expression control sequences operatively linked to a nucleotide sequence to be expressed. An expression vector comprises sufficient cis-acting elements for expression; other elements for expression can be supplied by the host cell or in an in vitro expression system. Expression vectors include all those known in the art, such as cosmids, plasmids (e.g., naked or contained in liposomes) and viruses (e.g., lentiviruses, retroviruses, adenoviruses, and adeno-associated viruses) that incorporate the recombinant polynucleotide. 
     As used herein, the term “fragment,” as applied to a nucleic acid, refers to a subsequence of a larger nucleic acid. A “fragment” of a nucleic acid can be at least about 15 nucleotides in length; for example, at least about 50 nucleotides to about 100 nucleotides; at feast about 100 to about 500 nucleotides, at least about 500 to about 1000 nucleotides, at least about 1000 nucleotides to about 1500 nucleotides; or about 1500 nucleotides to about 2500 nucleotides; or about 2500 nucleotides (and any integer value in between). 
     As used herein, the term “fragment,” as applied to a protein or peptide, refers to a subsequence of a larger protein or peptide. A “fragment” of a protein or peptide can be at least about 20 amino acids in length; for example at least about 50 amino acids in length; at least about 100 amino acids in length, at least about 200 amino acids in length, at least about 300 amino acids in length, and at least about 400 amino acids in length (and any integer value in between). 
     “Homologous” as used herein, refers to the subunit sequence identity between two polymeric molecules, e.g., between two nucleic acid molecules, such as, two DNA molecules or two RNA molecules, or between two polypeptide molecules. When a subunit position in both of the two molecules is occupied by the same monomeric subunit; e.g., if a position in each of two DNA molecules is occupied by adenine, then they are homologous at that position. The homology between two sequences is a direct function of the number of matching or homologous positions; e.g., if half (e.g., five positions in a polymer ten subunits in length) of the positions in two sequences are homologous, the two sequences are 50% homologous; if 90% of the positions (e.g., 9 of 10), are matched or homologous, the two sequences are 90% homologous. By way of example, the DNA sequences 5′-ATTGCC-3′ and 5′-TATGGC-3′ share 50% homology. 
     The term “immunoglobulin” or “Ig”, as used herein is defined as a class of proteins, which function as antibodies. The five members included in this class of proteins are IgA, IgG, IgM, IgD, and IgE. IgA is the primary antibody that is present in body secretions, such as saliva, tears, breast milk, gastrointestinal secretions and mucus secretions of the respiratory and genitourinary tracts. IgG is the most common circulating antibody. IgM is the main immunoglobulin produced in the primary immune response in most mammals. It is the most efficient immunoglobulin in agglutination, complement fixation, and other antibody responses, and is important in defense against bacteria and viruses, IgD is the immunoglobulin that has no known antibody function, but may serve as an antigen receptor. IgE is the immunoglobulin that mediates immediate hypersensitivity by causing release of mediators from mast cells and basophils upon exposure to allergen. 
     As used herein, the term “influenza virus” refers to members of the orthomyxoviridae family of enveloped viruses with a segmented antisense RNA genome (Knipe and Rowley (eds.) Fields Virology, 4th edition, Lippincott Williams and Wilkins, Philadelphia, Pa., 2001). The term influenza virus may include any strain of influenza virus, such as influenza A, B, or C, which is capable of causing disease in an animal or human subject. 
     As used herein, an “instructional material” includes a publication, a recording, a diagram, or any other medium of expression which can be used to communicate the usefulness of the compositions and methods of the invention. The instructional material of the kit of the invention may, for example, be affixed to a container which contains the nucleic acid, peptide, and/or composition of the invention or be shipped together with a container which contains the nucleic acid, peptide, and/or composition. Alternatively, the instructional material may be shipped separately from the container with the intention that the instructional material and the compound be used cooperatively by the recipient. 
     As used herein, the term “modulate” is meant to refer to any change in biological state, i.e. increasing, decreasing, and the like. For example, the term “modulate” refers to the ability to regulate positively or negatively the expression, stability or activity of p110 delta, including but not limited to transcription of p110 delta mRNA, stability of p110 delta mRNA, translation of p110 delta mRNA, stability of p110 delta polypeptide, p110 delta post-translational modifications, p110 delta activity, or any combination thereof. Further, the term modulate can be used to refer to an increase, decrease, masking, altering, overriding or restoring of activity, including but not limited to, p110 delta activity. 
     As used herein, the term “inhibit” is meant to refer to a decrease change in biological state. For example, the term “inhibit” refers to the ability to regulate negatively the expression, stability or activity of p110 delta, including but not limited to transcription or p110 delta snRNA, stability of p110 delta mRNA, translation of p110 delta mRNA, stability of p110 delta polypeptide, p110 delta post-translational modifications, p110 delta activity, p110 delta signaling pathway or any combination thereof. 
     By the term “an inhibitor of p110 delta,” as used herein, is meant any compound or molecule that detectably inhibits p110 delta. 
     A “p110 delta antagonist” is a composition of matter which, when administered to a mammal such as a human, detectably inhibits a biological activity attributable to the level or presence of p110 delta. 
     “Isolated” means altered or removed from the natural state. For example, a nucleic acid or a peptide naturally present in a living animal is not “isolated,” but the same nucleic acid or peptide partially or completely separated from the coexisting materials of its natural state is “isolated.” An isolated nucleic acid or protein can exist in substantially purified form, or can exist in a non-native environment such as, for example, a host cell. 
     An “isolated nucleic acid” refers to a nucleic acid segment or fragment which has been separated from sequences which flank it in a naturally occurring state, i.e., a DNA fragment which has been removed from the sequences which are normally adjacent to the fragment, i.e., the sequences adjacent to the fragment in a genome in which it naturally occurs. The term also applies to nucleic adds which have been substantially purified from other components which naturally accompany the nucleic acid, i.e., RNA or DNA or proteins, which naturally accompany it in the cell. The term therefore includes, for example, a recombinant DNA which is incorporated into a vector, into an autonomously replicating plasmid or virus, or into the genomic DNA of a prokaryote or eukaryote, or which exists as a separate molecule (i.e., as a cDNA or a genomic or cDNA fragment produced by PCR or restriction enzyme digestion) independent of other sequences. It also includes a recombinant DNA which is part of a hybrid gene encoding additional polypeptide sequence. 
     In the context of the present invention, the following abbreviations for the commonly occurring nucleic acid bases are used. “A” refers to adenosine, “C” refers to cytosine, “G” refers to guanosine, “T” refers to thymidine, and “U” refers to uridine. 
     Unless otherwise specified, a “nucleotide sequence encoding an amino acid sequence” includes all nucleotide sequences that are degenerate versions of each other and that encode the same amino acid sequence. The phrase nucleotide sequence that encodes a protein or an RNA may also include introns to the extent that the nucleotide sequence encoding the protein may in some version contain an intron(s). 
     The term “operably linked” refers to functional linkage between a regulatory sequence and a heterologous nucleic acid sequence resulting in expression of the latter. For example, a first nucleic acid sequence is operably linked with a second nucleic acid sequence when the first nucleic acid sequence is placed in a functional relationship with the second nucleic acid sequence. For instance, a promoter is operably linked to a coding sequence if the promoter affects the transcription or expression of the coding sequence. Generally, operably linked DNA sequences are contiguous and, where necessary to join two protein coding regions, in the same reading frame. 
     “Parenteral” administration of an immunogenic composition includes, e.g., subcutaneous (s.c.), intravenous (i.v.), intramuscular (i.m.), or intrasternal injection, or infusion techniques. 
     The term “polynucleotide” as used herein is defined as a chain of nucleotides. Furthermore, nucleic acids are polymers of nucleotides. Thus, nucleic acids and polynucleotides as used herein are interchangeable. One skilled in the art has the general knowledge that nucleic acids are polynucleotides, which can be hydrolyzed into the monomeric “nucleotides.” The monomeric nucleotides can be hydrolyzed into nucleosides. As used herein polynucleotides include, but are not limited to, all nucleic acid sequences which are obtained by any means available in the art, including, without limitation, recombinant means, i.e., the cloning of nucleic acid sequences from a recombinant library or a cell genome, using ordinary cloning technology and PCR™, and the like, and by synthetic means. 
     As used herein, the terms “peptide,” “polypeptide,” and “protein” are used interchangeably, and refer to a compound comprised of amino acid residues covalently linked by peptide bonds. A protein or peptide must contain at least two amino acids, and no limitation is placed on the maximum number of amino acids that can comprise a protein&#39;s or peptide&#39;s sequence. Polypeptides include any peptide or protein comprising two or more amino acids joined to each other by peptide bonds. As used herein, the term refers to both short chains, which also commonly are referred to in the art as peptides, oligopeptides and oligomers, for example, and to longer chains, which generally are referred to in the art as proteins, of which there are many types. “Polypeptides” include, for example, biologically active fragments, substantially homologous polypeptides, oligopeptides, homodimers, heterodimers, variants of polypeptides, modified polypeptides, derivatives, analogs, fusion proteins, among others. The polypeptides include natural peptides, recombinant peptides, synthetic peptides, or a combination thereof. 
     “Pharmaceutically acceptable” refers to those properties and/or substances which are acceptable to the patient from a pharmacological/toxicological point of view and to the manufacturing pharmaceutical chemist from a physical/chemical point of view regarding composition, formulation, stability, patient acceptance and bioavailability. “Pharmaceutically acceptable carrier” refers to a medium that does not interfere with the effectiveness of the biological activity of the active ingredient(s) and is not toxic to the host to which it is administered. 
     “Primer” refers to a polynucleotide that is capable of specifically hybridizing to a designated polynucleotide template and providing a point of initiation for synthesis of a complementary polynucleotide. Such synthesis occurs when the polynucleotide primer is placed under conditions in which synthesis is induced, i.e., in the presence of nucleotides, a complementary polynucleotide template, and an agent for polymerization such as DNA polymerase. A primer is typically single-stranded, but may be double-stranded. Primers are typically deoxyribonucleic acids, but a wide variety of synthetic and naturally occurring primers are useful for many applications. A primer is complementary to the template to which it is designed to hybridize to serve as a site for the initiation of synthesis, but need not reflect the exact sequence of the template. In such a case, specific hybridization of the primer to the template depends on the stringency of the hybridization conditions. Primers can be labeled with, e.g., chromogenic, radioactive, or fluorescent moieties and used as detectable moieties. 
     “Probe” refers to a polynucleotide that is capable of specifically hybridizing to a designated sequence of another polynucleotide. A probe specifically hybridizes to a target complementary polynucleotide, but need not reflect the exact complementary sequence of the template. In such a case, specific hybridization of the probe to the target depends on the stringency of the hybridization conditions. Probes can be labeled with, e.g., chromogenic, radioactive, or fluorescent moieties and used as detectable moieties. 
     The term “promoter” as used herein is defined as a DNA sequence recognized by the synthetic machinery of the cell, or introduced synthetic machinery, required to initiate the specific transcription of a polynucleotide sequence. 
     As used herein, the term “promoter/regulatory sequence” means a nucleic acid sequence which is required for expression of a gene product operably linked to the promoter/regulatory sequence. In some instances, this sequence may be the core promoter sequence and in other instances, this sequence may also include an enhancer sequence and other regulatory elements which are required for expression of the gene product. The promoter/regulatory sequence may, for example, be one which expresses the gene product in a tissue specific manner. 
     A “constitutive” promoter is a nucleotide sequence which, when operably linked with a polynucleotide which encodes or specifies a gene product, causes the gene product to be produced in a cell under most or all physiological conditions of the cell. 
     An “inducible” promoter is a nucleotide sequence which, when operably linked with a polynucleotide which encodes or specifies a gene product, causes the gene product to be produced in a cell substantially only when an inducer which corresponds to the promoter is present in the cell. 
     A “tissue-specific” promoter is a nucleotide sequence which, when operably linked with a polynucleotide encodes or specified by a gene, causes the gene product to be produced in a cell substantially only if the cell is a cell of the tissue type corresponding to the promoter. 
     The term “RNA” as used herein is defined as ribonucleic acid, 
     The term “recombinant DNA” as used herein is defined as DNA produced by joining pieces of DNA from different sources. 
     The term “recombinant polypeptide” as used herein is defined as a polypeptide produced by using recombinant DNA methods. 
     The term “therapeutic” as used herein means a treatment and/or prophylaxis. A therapeutic effect is obtained by suppression, remission, or eradication of a disease state. 
     The term “treatment” as used within the context of the present invention is meant to include therapeutic treatment as well as prophylactic, or suppressive measures for the disease or disorder. Thus, for example, the term treatment includes the administration of an agent prior to or following the onset of a disease or disorder thereby preventing or removing all signs of the disease or disorder. As another example, administration of the agent after clinical manifestation of the disease to combat the symptoms of the disease comprises “treatment” of the disease. This includes for instance, prevention of influenza infection. 
     The term “transfected” or “transformed” or “transduced” as used herein refers to a process by which exogenous nucleic acid is transferred or introduced into the host cell. A “transfected” or “transformed” or “transduced” cell is one which has been transfected, transformed or transduced with exogenous nucleic acid. The cell includes the primary subject cell and its progeny. 
     The phrase “under transcriptional control” or “operatively linked” as used herein means that the promoter is in the correct location and orientation in relation to a polynucleotide to control the initiation of transcription by RNA polymerase and expression of the polynucleotide. 
     “Variant” as the term is used herein, is a nucleic acid sequence or a peptide sequence that differs in sequence from a reference nucleic acid sequence or peptide sequence respectively, but retains essential properties of the reference molecule. Changes in the sequence of a nucleic acid variant may not alter the amino acid sequence of a peptide encoded by the reference nucleic acid, or may result in amino acid substitutions, additions, deletions, fusions and truncations. Changes in the sequence of peptide variants are typically limited or conservative, so that the sequences of the reference peptide and the variant are closely similar overall and, in many regions, identical. A variant and reference peptide can differ in amino acid sequence by one or more substitutions, additions, deletions in any combination. A variant of a nucleic acid or peptide can be a naturally occurring such as an allelic variant, or can be a variant that is not known to occur naturally. Non-naturally occurring variants of nucleic acids and peptides may be made by mutagenesis techniques or by direct synthesis. 
     The term “vaccine” as used herein is defined as a material used to provoke an immune response after administration of the material to a mammal. 
     As used herein, “vaccination” is intended for prophylactic or therapeutic vaccination. 
     A “vector” is a composition of matter which comprises an isolated nucleic acid and which can be used to deliver the isolated nucleic acid to the interior of a cell. Numerous vectors are known in the art including, but not limited to, linear polynucleotides, polynucleotides associated with ionic or amphiphilic compounds, plasmids, and viruses. Thus, the term “vector” includes an autonomously replicating plasmid or a virus. The term should also be construed to include non-plasmid and non-viral compounds which facilitate transfer of nucleic acid into cells, such as, for example, polylysine compounds, liposomes, and the like. Examples of viral vectors include, but are not limited to, adenoviral vectors, adeno-associated virus vectors, retroviral vectors, and the like. 
     The term “virus” as used herein is defined as a particle consisting of nucleic acid (RNA or DNA) enclosed in a protein coat, with or without an outer lipid envelope, which is capable of replicating within a whole cell. 
     DESCRIPTION 
     The invention provides compositions and methods for regulating phosphoinositide 3 kinase (PI3K) isoform p110 delta signaling system. A variety of components of p110 delta and downstream signaling system can serve as targets for inhibition in order to inhibit influenza virus infection. In one embodiment, the invention encompasses inhibiting p110 delta as a therapeutic target for influenza virus infection. 
     The invention is based on the discovery that inhibiting p110 delta serves to reduce influenza virus infection. In one instance, presence of an inactivating mutation in p110 delta (p110 delta−/−) manifested significantly reduced morbidity after influenza virus infection. In another instance, pharmaceutical inhibition of p110 delta reduced influenza virus infection. Thus, the present invention provides an anti-influenza virus therapy comprising inhibiting at least p110 delta signaling. 
     Composition 
     As described elsewhere herein, the invention is based on the discovery that inhibition of p110 delta can provide a therapeutic benefit by inhibiting influenza virus infection. Thus, the invention comprises compositions and methods for modulating p110 delta in a cell thereby inhibiting the p110 delta response in the cell. 
     Based on the disclosure herein, the present invention includes a generic concept for inhibiting p110 delta or p110 delta signaling pathway in a cell of a mammal suffering from, or at risk of, influenza infection. 
     In one embodiment, the invention comprises a composition for inhibiting p110 delta. The composition comprises an inhibitor done or more of the following: p110 delta or p110 delta down stream signaling pathway in a cell. Thus, as referred to herein, inhibiting p110 delta can also encompass inhibiting any component of the p110 delta signaling pathway. 
     The composition comprising the inhibitor of a component of the p110 delta signaling pathway can be any type of inhibitor. For example and without limitation, the inhibitor can be selected from the group consisting of a small interfering RNA (siRNA), a microRNA, an antisense nucleic acid, a ribozyme, an expression vector encoding a transdominant negative mutant, an intracellular antibody, a peptide and a small molecule. 
     As disclosed herein, the inhibition of a component of the p110 delta signaling pathway in a eel) inhibits influenza infection in the cell. These effects are mediated through inhibition of p110 delta signaling pathway. One skilled in the art will appreciate, based on the disclosure provided herein, that one way to decrease the mRNA and/or protein levels of a component of the p110 delta signaling pathway in a cell is by reducing or inhibiting expression of the nucleic acid encoding a desired component of the p110 delta signaling pathway. Thus, the protein level of the component of the p110 delta signaling pathway in a cell can also be decreased using a molecule or compound that inhibits or reduces gene expression such as, for example, an antisense molecule or a ribozyme. 
     By way of a non-limited example, inhibition of a component of p110 delta signaling pathway is described below in the context of decreasing the mRNA and/or protein levels of a component of the p110 delta signaling pathway in a cell by reducing or inhibiting expression of the nucleic acid encoding a desired component of the p110 delta signaling pathway. 
     In a preferred embodiment, the modulating sequence is an antisense nucleic acid sequence which is expressed by a plasmid vector. The antisense expressing vector is used to transfect a mammalian cell or the mammal itself, thereby causing reduced endogenous expression of a desired component of the p110 delta signaling pathway in the cell. However, the invention should not be construed to be limited to inhibiting expression of a component of the p110 delta signaling pathway by transfection of cells with antisense molecules. Rather, the invention encompasses other methods known in the art for inhibiting expression or activity of a protein in the cell including, but not limited to, the use of a ribozyme, the expression of a non-functional component of the p110 delta signaling pathway (i.e. transdominant negative mutant) and use of an intracellular antibody. 
     Antisense molecules and their use for inhibiting gene expression are well known in the art (see, e.g., Cohen, 1989, In: Oligodeoxyribonucleotides, Antisense Inhibitors of Gene Expression, CRC Press). Antisense nucleic acids are DNA or RNA molecules that are complementary, as that term is defined elsewhere herein, to at least a portion of a specific mRNA molecule (Weintraub, 1990, Scientific American 262:40). In the cell, antisense nucleic acids hybridize to the corresponding mRNA, forming a double-stranded molecule thereby inhibiting the translation of genes. 
     The use of antisense methods to inhibit the translation of genes is known in the art, and is described, for example, in Marcus-Sakura (1988, Anal. Biochem. 172:289). Such antisense molecules may be provided to the cell via genetic expression using DNA encoding the antisense molecule as taught by Inoue, 1993, U.S. Pat. No. 5,190,931. 
     Alternatively, antisense molecules of the invention may be made synthetically and then provided to the cell. Antisense oligomers of between about 10 to about 30, and more preferably about 15 nucleotides, are preferred, since they are easily synthesized and introduced into a target cell. Synthetic antisense molecules contemplated by the invention include oligonucleotide derivatives known in the art which have improved biological activity compared to unmodified oligonucleotides (see U.S. Pat. No. 5,023,243). 
     The ability to specifically inhibit gene function in a variety of organisms utilizing antisense RNA or dsRNA-mediated interference (RNAi or dsRNA) is well known in the fields of molecular biology. dsRNA (RNAi) typically comprises a polynucleotide sequence identical or homologous to a target gene (or fragment thereof) linked directly, or indirectly, to a polynucleotide sequence complementary to the sequence of the target gene (or fragment thereof). The dsRNA may comprise a polynucleotide linker sequence of sufficient length to allow for the two polynucleotide sequences to fold over and hybridize to each other; however, a linker sequence is not necessary. The linker sequence is designed to separate the antisense and sense strands of RNAi significantly enough to limit the effects of steric hindrances and allow for the formation of dsRNA molecules and should not hybridize with sequences within the hybridizing portions of the dsRNA molecule. The specificity of this gene silencing mechanism appears to be extremely high, blocking expression only of targeted genes, while leaving other genes unaffected. Accordingly, one method for treating influenza virus infection according to the invention comprises the use of materials and methods utilizing double-stranded interfering RNA (dsRNAi), or RNA-mediated interference (RNAi) comprising polynucleotide sequences identical or homologous to a desired component of TGF-β signaling pathway. The terms “dsRNAi”, “RNAi”, “iRNA”, and “siRNA” are used interchangeably herein unless otherwise noted. 
     RNA containing a nucleotide sequence identical to a fragment of the target gene is preferred for inhibition; however, RNA sequences with insertions, deletions, and point mutations relative to the target sequence can also be used for inhibition. Sequence identity may optimized by sequence comparison and alignment algorithms known in the art (see Gribskov and Devereux, Sequence Analysis Primer, Stockton Press, 1991, and references cited therein) and calculating the percent difference between the nucleotide sequences by, for example, the Smith-Waterman algorithm as implemented in the BESTFIT software program using default parameters (e.g., University of Wisconsin Genetic Computing Group). Alternatively, the duplex region of the RNA may be defined functionally as a nucleotide sequence that is capable of hybridizing with a fragment of the target gene transcript. 
     RNA may be synthesized either in vivo or in vitro. Endogenous RNA polymerase of the cell may mediate transcription in vivo, or cloned RNA polymerase can be used for transcription in vivo or in vitro. For transcription from a transgene in vivo or an expression construct, a regulatory region (e.g., promoter, enhancer, silencer, splice donor and acceptor, polyadenylation) may be used to transcribe the RNA strand (or strands); the promoters may be known inducible promoters such as baculovirus. Inhibition may be targeted by specific transcription in an organ, tissue, or cell type. The RNA strands may or may not be polyadenylated; the RNA strands may or may not be capable of being translated into a polypeptide by a cell&#39;s translational apparatus. RNA may be chemically or enzymatically synthesized by manual or automated reactions. The RNA may be synthesized by a cellular RNA polymerase or a bacteriophage RNA polymerase (e.g., T3, T7, SP6). The use and production of an expression construct are known in the art (see, for example, WO 97/32016; U.S. Pat. Nos. 5,593,874; 5,698,425; 5,712,135; 5,789,214; and 5,804,693; and the references cited therein). If synthesized chemically or by in vitro enzymatic synthesis, the RNA may be purified prior to introduction into the cell. For example, RNA can be purified from a mixture by extraction with a solvent or resin, precipitation, electrophoresis, chromatography, or a combination thereof. Alternatively, the RNA may be used with no, or a minimum of, purification to avoid losses due to sample processing. The RNA may be dried for storage or dissolved in an aqueous solution. The solution may contain buffers or salts to promote annealing, and/or stabilization of the duplex strands. 
     Fragments of genes can also be utilized for targeted suppression of gene expression. These fragments are typically in the approximate size range of about 20 consecutive nucleotides of a target sequence. Thus, targeted fragments are preferably at least about 15 consecutive nucleotides. In certain embodiments, the gene fragment targeted by the RNAi molecule is about 20-25 consecutive nucleotides in length. In a more preferred embodiment, the gene fragments are at least about 25 consecutive nucleotides in length. In an even more preferred embodiment, the gene fragments are at least 50 consecutive nucleotides in length. Various embodiments also allow for the joining of one or more gene fragments of at least about 15 nucleotides via linkers. Thus, RNAi molecules useful in the practice of the instant invention can contain any number of gene fragments joined by linker sequences. 
     In yet other embodiments, the invention includes full length or fragments of p110 delta. The gene fragments can range from one nucleotide less than the full-length gene. Nucleotide sequences for p110 delta and components of p110 delta signaling pathway are known in the art and can be obtained from patent publications, public databases containing nucleic acid sequences, or commercial vendors. A skilled artisan would understand that the disclosure presented herein provides sufficient written support for any fragment length ranging from about 15 consecutive polynucleotides to one nucleotide less than the full length polynucleotide sequence of p110 delta and components of p110 delta signaling pathway can have a whole number value ranging from about 15 consecutive nucleotides to one nucleotide less than the full length polynucleotide. 
     Accordingly, methods utilizing RNAi molecules in the practice of the subject invention are not limited to those that are targeted to the full-length polynucleotide or gene. Gene product can be inhibited with an RNAi molecule that is targeted to a portion or fragment of the exemplified polynucleotides; high homology (90-95%) or greater identity is also preferred, but not essential, for such applications. 
     In another aspect of the invention, the dsRNA molecules of the invention may be introduced into cells with single stranded (ss) RNA molecules which are sense or anti-sense RNA derived from the nucleotide sequences disclosed herein. Methods of introducing ssRNA and dsRNA molecules into cells are well-known to the skilled artisan and includes transcription of plasmids, vectors, or genetic constructs encoding the ssRNA or dsRNA molecules according to this aspect of the invention; electroporation, biolistics, or other well-known methods of introducing nucleic acids into cells may also be used to introduce the ssRNA and dsRNA molecules of this invention into cells. 
     Other types of gene inhibition technology can be used to inhibit p110 delta and/or components of p110 delta signaling pathway in a cell. Ribozymes and their use for inhibiting gene expression are also well known in the art (see, e.g., Cech et al., 1992, J. Biol. Chem. 267:17479-17482; Hampel et al., 1989, Biochemistry 28:4929-4933; Eckstein et al., International Publication No. WO 92/07065; Altman et al., U.S. Pat. No. 5,168,053). Ribozymes are RNA molecules possessing the ability to specifically cleave other single-stranded RNA in a manner analogous to DNA restriction endonucleases. Through the modification of nucleotide sequences encoding these RNAs, molecules can be engineered to recognize specific nucleotide sequences in an RNA molecule and cleave it (Cech, 1988, J. Amer. Med. Assn. 260:3030). A major advantage of this approach is the fact that ribozymes are sequence-specific. 
     There are two basic types of ribozymes, namely, tetrahymena-type (Hasselhoff, 1988, Nature 334:585) and hammerhead-type. Tetrahymena-type ribozymes recognize sequences which are four bases in length, while hammerhead-type ribozymes recognize base sequences 11-18 bases in length. The longer the sequence, the greater the likelihood that the sequence will occur exclusively in the target mRNA species. Consequently, hammerhead-type ribozymes are preferable to tetrahymena-type ribozymes for inactivating specific mRNA species, and 18-base recognition sequences are preferable to shorter recognition sequences which may occur randomly within various unrelated mRNA molecules. 
     Ribozymes useful for inhibiting the expression of a component of p110 delta signaling pathway may be designed by incorporating target sequences into the basic ribozyme structure which are complementary to the mRNA sequence of the desired component of p110 delta signaling pathway of the present invention. Ribozymes targeting the desired component of p110 delta signaling pathway may be synthesized using commercially available reagents (Applied Biosystems, Inc., Foster City, Calif.) or they may be genetically expressed from DNA encoding them. 
     In another aspect of the invention, the component of the p110 delta signaling pathway can be inhibited by way of inactivating and/or sequestering the desired component of the p110 delta signaling pathway. As such, inhibiting the effects of a component of the p110 delta signaling pathway can be accomplished by using a transdominant negative mutant. Alternatively an intracellular antibody specific for the desired component of the p110 delta signaling pathway, otherwise known as an antagonist to the component of the p110 delta signaling pathway may be used. In one embodiment, the antagonist is a protein and/or compound having the desirable property of interacting with a binding partner of the component of the p110 delta signaling pathway and thereby competing with the corresponding wild-type component of the p110 delta signaling pathway. In another embodiment, the antagonist is a protein and/or compound having the desirable property of interacting with the component of the p110 delta signaling pathway and thereby sequestering the component of the p110 delta signaling pathway. 
     By way of a non-limited example, an antibody is described below as an example of inactivating and/or sequestering the desired component of the p110 delta signaling pathway. 
     Antibodies 
     As will be understood by one skilled in the art, any antibody that can recognize and specifically bind to p110 delta or a component involved in p110 delta signaling pathway is useful in the present invention. The invention should not be construed to be limited to any one type of antibody, either known or heretofore unknown, provided that the antibody can specifically bind to a component involved in p110 delta signaling pathway. Methods of making and using such antibodies are well known in the art. For example, the generation of polyclonal antibodies can be accomplished by inoculating the desired animal with the antigen and isolating antibodies which specifically bind the antigen therefrom. Monoclonal antibodies directed against full length or peptide fragments of a protein or peptide may be prepared using any well known monoclonal antibody preparation procedures, such as those described, for example, in Harlow et al. (1989, Antibodies, A Laboratory Manual, Cold Spring Harbor, N.Y.) and in Tuszynski et al. (1988, Blood 72:109-115). Quantities of the desired peptide may also be synthesized using chemical synthesis technology. Alternatively, DNA encoding the desired peptide may be cloned and expressed from an appropriate promoter sequence in cells suitable for the generation of large quantities of peptide. Monoclonal antibodies directed against the peptide are generated from mice immunized with the peptide using standard procedures as referenced herein. However, the invention should not be construed as being limited solely to methods and compositions including these antibodies, but should be construed to include other antibodies, as that term is defined elsewhere herein. 
     In some instances, it is desirable to prepare monoclonal antibodies from various mammalian hosts, such as rodents (e.g., mice), primates (e.g., humans), etc. Descriptions of techniques for preparing such monoclonal antibodies are well known and are described, for example, in Harlow et al., ANTIBODIES: A L ABORATORY  M ANUAL , C OLD  S PRING  H ARBOR  L ABORATORY , Cold Spring Harbor, N.Y. (1988); Harlow et al., U SING  A NTIBODIES : A L ABORATORY  M ANUAL , (Cold Spring Harbor Press, New York, 1998); Breitling et al., R ECOMBINANT  A NTIBODIES  (Wiley-Spektrum, 1999); and Kohler et al., 1997  Nature  256: 495-497; U.S. Pat. No. 5,693,762; U.S. Pat. No. 5,693,761; U.S. Pat. No. 5,585,089; U.S. Pat. No. 6,180,370. 
     Nucleic acid encoding an antibody obtained using the procedures described herein may be cloned and sequenced using technology which is available in the art, and is described, for example, in Wright et al. (1992, Critical Rev in Immunol 12:125-168) and the references cited therein. Further, the antibody of the invention may be “humanized” using the technology described in Wright et al. (supra) and in the references cited therein, and in Gu et al. (1997, Thrombosis and Hematocyst 77:755-759). 
     Alternatively, antibodies can be generated using phage display technology. To generate a phage antibody library, a cDNA library is first obtained from mRNA which is isolated from cells, e.g., the hybridoma, which express the desired protein to be expressed on the phage surface, e.g., the desired antibody. cDNA copies of the mRNA are produced using reverse transcriptase. cDNA which specifies immunoglobulin fragments are obtained by PCR and the resulting DNA is cloned into a suitable bacteriophage vector to generate a bacteriophage DNA library comprising DNA specifying immunoglobulin genes. The procedures for making a bacteriophage library comprising heterologous DNA are well known in the art and are described, for example, in Sambrook et al. (1989, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor, N.Y.). 
     Bacteriophage which encode the desired antibody, may be engineered such that the protein is displayed on the surface thereof in such a manner that it is available for binding to its corresponding binding protein, e.g., the antigen against which the antibody is directed. Thus, when bacteriophage which express a specific antibody are incubated in the presence of a cell which expresses the corresponding antigen, the bacteriophage will bind to the cell. Bacteriophage which do not express the antibody will not bind to the cell. Such panning techniques are well known in the art and are described for example, in Wright et al. (supra). 
     Processes such as those described above, have been developed for the production of human antibodies using MI3 bacteriophage display (Burton et al., 1994, Adv. Immunol. 57:191-280). Essentially, a cDNA library is generated from mRNA obtained from a population of antibody-producing cells. The mRNA encodes rearranged immunoglobulin genes and thus, the cDNA encodes the same. Amplified cDNA is cloned into MI3 expression vectors creating a library of phage which express human Fab fragments on their surface. Phage which display the antibody of interest are selected by antigen binding and are propagated in bacteria to produce soluble human Fab immunoglobulin. Thus, in contrast to conventional monoclonal antibody synthesis, this procedure immortalizes DNA encoding human immunoglobulin rather than cells which express human immunoglobulin. 
     The procedures just presented describe the generation of phage which encode the Fab portion of an antibody molecule. However, the invention should not be construed to be limited solely to the generation of phage encoding Fab antibodies. Rather, phage which encode single chain antibodies (scFv/phage antibody libraries) are also included in the invention. Fab molecules comprise the entire Ig light chain, that is, they comprise both the variable and constant region of the light chain, but include only the variable region and first constant region domain (CH1) of the heavy chain. Single chain antibody molecules comprise a single chain of protein comprising the Ig Fv fragment. An Ig Fv fragment includes only the variable regions of the heavy and light chains of the antibody, having no constant region contained therein. Phage libraries comprising scFv DNA may be generated following the procedures described in Marks et al. (1991, J Mol Biol 222:581-597). Panning of phage so generated for the isolation of a desired antibody is conducted in a manner similar to that described for phage libraries comprising Fab DNA. 
     The invention should also be construed to include synthetic phage display libraries in which the heavy and light chain variable regions may be synthesized such that they include nearly all possible specificities (Barbas, 1995, Nature Medicine 1:837-839; de Kruif et al., 1995, J Mol Biol 248:97-105). 
     The invention encompasses polyclonal, monoclonal, synthetic antibodies, and the like. One skilled in the art would understand, based upon the disclosure provided herein, that the crucial feature of the antibody of the invention is that the antibody specifically bind with a component involved in p110 delta signaling pathway. 
     Vectors 
     In other related aspects, the invention includes an isolated nucleic acid encoding an inhibitor of the invention, operably linked to a nucleic acid comprising a promoter/regulatory sequence such that the nucleic acid is preferably capable of directing expression of the inhibitor encoded by the nucleic acid. Thus, the invention encompasses expression vectors and methods for the introduction of exogenous DNA into cells with concomitant expression of the exogenous DNA in the cells such as those described, for example, in Sambrook et al. (2001, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York), and in Ausubel et al. (1997, Current Protocols in Molecular Biology, John Wiley &amp; Sons, New York). 
     In another aspect, the invention includes a vector comprising an siRNA polynucleotide. Preferably, the siRNA polynucleotide is capable of inhibiting the expression of a target polypeptide, wherein the target polypeptide is p110 delta. The incorporation of a desired polynucleotide into a vector and the choice of vectors is well-known in the art as described in, for example, Sambrook et al., supra, and Ausubel et al., supra. 
     In specific embodiments, the expression vector is selected from the group consisting of a viral vector, a bacterial vector and a mammalian cell vector. Numerous expression vector systems exist that comprise at least a part or all of the compositions discussed above. Prokaryote- and/or eukaryote-vector based systems can be employed for use with the present invention to produce polynucleotides, or their cognate polypeptides. Many such systems are commercially and widely available. 
     Further, the expression vector may be provided to a cell in the form of a viral vector. Viral vector technology is well known in the art and is described, for example, in Sambrook et al. (2001), and in Ausubel et al. (1997), and in other virology and molecular biology manuals. Viruses, which are useful as vectors include, but are not limited to, retroviruses, adenoviruses, adeno-associated viruses, herpes viruses, and lentiviruses. In general, a suitable vector contains an origin of replication functional in at least one organism, a promoter sequence, convenient restriction endonuclease sites, and one or more selectable markers. (See, e.g., WO 01/96584; WO 01/29058; and U.S. Pat. No. 6,326,193. 
     For expression of the desired inhibitor of p110 delta, at least one module in each promoter functions to position the start site for RNA synthesis. The best known example of this is the TATA box, but in some promoters lacking a TATA box, such as the promoter for the mammalian terminal deoxynucleotidyl transferase gene and the promoter for the SV40 genes, a discrete element overlying the start site itself helps to fix the place of initiation. 
     Additional promoter elements, i.e., enhancers, regulate the frequency of transcriptional initiation. Typically, these are located in the region 30-110 bp upstream of the start site, although a number of promoters have recently been shown to contain functional elements downstream of the start site as well. The spacing between promoter elements frequently is flexible, so that promoter function is preserved when elements are inverted or moved relative to one another. In the thymidine kinase (tk) promoter, the spacing between promoter elements can be increased to 50 bp apart before activity begins to decline. Depending on the promoter, it appears that individual elements can function either co-operatively or independently to activate transcription. 
     A promoter may be one naturally associated with a gene or polynucleotide sequence, as may be obtained by isolating the 5′ non-coding sequences located upstream of the coding segment and/or exon. Such a promoter can be referred to as “endogenous.” Similarly, an enhancer may be one naturally associated with a polynucleotide sequence, located either downstream or upstream of that sequence. Alternatively, certain advantages will be gained by positioning the coding polynucleotide segment under the control of a recombinant or heterologous promoter, which refers to a promoter that is not normally associated with a polynucleotide sequence in its natural environment. A recombinant or heterologous enhancer refers also to an enhancer not normally associated with a polynucleotide sequence in its natural environment. Such promoters or enhancers may include promoters or enhancers of other genes, and promoters or enhancers isolated from any other prokaryotic, viral, or eukaryotic cell, and promoters or enhancers not “naturally occurring,” i.e., containing different elements of different transcriptional regulatory regions, and/or mutations that alter expression. In addition to producing nucleic acid sequences of promoters and enhancers synthetically, sequences may be produced using recombinant cloning and/or nucleic acid amplification technology, including PCR™, in connection with the compositions disclosed herein (U.S. Pat. No. 4,683,202, U.S. Pat. No. 5,928,906). Furthermore, it is contemplated the control sequences that direct transcription and/or expression of sequences within non-nuclear organelles such as mitochondria, chloroplasts, and the like, can be employed as well. 
     Naturally, it will be important to employ a promoter and/or enhancer that effectively directs the expression of the DNA segment in the cell type, organelle, and organism chosen for expression. Those of skill in the art of molecular biology generally know how to use promoters, enhancers, and cell type combinations for protein expression, for example, see Sambrook et al. (2001). The promoters employed may be constitutive, tissue-specific, inducible, and/or useful under the appropriate conditions to direct high level expression of the introduced DNA segment, such as is advantageous in the large-scale production of recombinant proteins and/or peptides. The promoter may be heterologous or endogenous. 
     A promoter sequence exemplified in the experimental examples presented herein is the immediate early cytomegalovirus (CMV) promoter sequence. This promoter sequence is a strong constitutive promoter sequence capable of driving high levels of expression of any polynucleotide sequence operatively linked thereto. However, other constitutive promoter sequences may also be used, including, but not limited to the simian virus 40 (SV40) early promoter, mouse mammary tumor virus (MMTV), human immunodeficiency virus (HIV) long terminal repeat (LTR) promoter, Moloney virus promoter, the avian leukemia virus promoter, Epstein-Barr virus immediate early promoter, Rous sarcoma virus promoter, as well as human gene promoters such as, but not limited to, the actin promoter, the myosin promoter, the hemoglobin promoter, and the muscle creatine promoter. Further, the invention should not be limited to the use of constitutive promoters. Inducible promoters are also contemplated as part of the invention. The use of an inducible promoter in the invention provides a molecular switch capable of turning on expression of the polynucleotide sequence which it is operatively linked when such expression is desired, or turning off the expression when expression is not desired. Examples of inducible promoters include, but are not limited to a metallothionine promoter, a glucocorticoid promoter, a progesterone promoter, and a tetracycline promoter. Further, the invention includes the use of a tissue specific promoter, which promoter is active only in a desired tissue. Tissue specific promoters are well known in the art and include, but are not limited to, the HER-2 promoter and the PSA associated promoter sequences. 
     In order to assess the expression of the desired inhibitor of p110 delta, the expression vector to be introduced into a cell can also contain either a selectable marker gene or a reporter gene or both to facilitate identification and selection of expressing cells from the population of cells sought to be transfected or infected through viral vectors. In other embodiments, the selectable marker may be carried on a separate piece of DNA and used in a co-transfection procedure. Roth selectable markers and reporter genes may be flanked with appropriate regulatory sequences to enable expression in the host cells. Useful selectable markers are known in the art and include, for example, antibiotic-resistance genes, such as neo and the like. 
     Reporter genes are used for identifying potentially transfected cells and for evaluating the functionality of regulatory sequences. Reporter genes that encode for easily assayable proteins are well known in the art. In general, a reporter gene is a gene that is not present in or expressed by the recipient organism or tissue and that encodes a protein whose expression is manifested by some easily detectable property, e.g., enzymatic activity. Expression of the reporter gene is assayed at a suitable time after the DNA has been introduced into the recipient cells. 
     Suitable reporter genes may include genes encoding luciferase, beta-galactosidase, chloramphenicol acetyl transferase, secreted alkaline phosphatase, or the green fluorescent protein gene (see, e.g., Ui-Tei et al., 2000 FEES Lett, 479:79-82). Suitable expression systems are well known and may be prepared using well known techniques or obtained commercially. Internal deletion constructs may be generated using unique internal restriction sites or by partial digestion of non-unique restriction sites. Constructs may then be transfected into cells that display high levels of siRNA polynucleotide and/or polypeptide expression. In general, the construct with the minimal 5′ flanking region showing the highest level of expression of reporter gene is identified as the promoter. Such promoter regions may be linked to a reporter gene and used to evaluate agents for the ability to modulate promoter-driven transcription. 
     In the context of an expression vector, the vector can be readily introduced into a host cell, e.g., mammalian, bacterial, yeast or insect cell by any method in the art. For example, the expression vector can be transferred into a host cell by physical, chemical or biological means. 
     Physical methods for introducing a polynucleotide into a host cell include calcium phosphate precipitation, lipofection, particle bombardment, microinjection, electroporation, and the like. Methods for producing cells comprising vectors and/or exogenous nucleic acids are well-known in the art. See, for example, Sambrook et al. (2001, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York), and in Ausubel et al. (1997, Current Protocols in Molecular Biology, John Wiley &amp; Sons, New York). 
     Biological methods for introducing a polynucleotide of interest into a host cell include the use of DNA and RNA vectors. Viral vectors, and especially retroviral vectors, have become the most widely used method for inserting genes into mammalian, e.g., human cells. Other viral vectors can be derived from lentivirus, poxviruses, herpes simplex virus I, adenoviruses and adeno-associated viruses, and the like. See, for example, U.S. Pat. Nos. 5,350,674 and 5,585,362. 
     Chemical means for introducing a polynucleotide into a host cell include colloidal dispersion systems, such as macromolecule complexes, nanocapsules, microspheres, beads, and lipid-based systems including oil-in-water emulsions, micelles, mixed micelles, and liposomes. A preferred colloidal system for use as a delivery vehicle in vitro and in vivo is a liposome (i.e., an artificial membrane vesicle). The preparation and use of such systems is well known in the art. 
     Regardless of the method used to introduce exogenous nucleic acids into a host cell or otherwise expose a cell to the inhibitor of the present invention, in order to confirm the presence of the recombinant DNA sequence in the host cell, a variety of assays may be performed. Such assays include, for example, “molecular biological” assays well known to those of skill in the art, such as Southern and Northern blotting, RT-PCR and PCR; “biochemical” assays, such as detecting the presence or absence of a particular peptide, e.g., by immunological means (ELISAs and Western blots) or by assays described herein to identify agents falling within the scope of the invention. 
     To generate a genetically modified cell, any DNA vector or delivery vehicle can be utilized to transfer the desired p110 delta inhibitor polynucleotide to a cell in vitro or in vivo. In the case where a non-viral delivery system is utilized, a preferred delivery vehicle is a liposome. The above-mentioned delivery systems and protocols therefore can be found in Gene Targeting Protocols, 2ed., pp 1-35 (2002) and Gene Transfer and Expression Protocols, Vol. 7, Murray ed., pp 81-89 (1991). 
     “Liposome” is a generic term encompassing a variety of single and multilamellar lipid vehicles formed by the generation of enclosed lipid bilayers or aggregates. Liposomes may be characterized as having vesicular structures with a phospholipid bilayer membrane and an inner aqueous medium. Multilamellar liposomes have multiple lipid layers separated by aqueous medium. They form spontaneously when phospholipids are suspended in an excess of aqueous solution. The lipid components undergo self-rearrangement before the formation of closed structures and entrap water and dissolved solutes between the lipid bilayers (Ghosh and Bachhawat, 1991). However, the present invention also encompasses compositions that have different structures in solution than the normal vesicular structure. For example, the lipids may assume a micellar structure or merely exist as nonuniform aggregates of lipid molecules. Also contemplated are lipofectamine-nucleic acid complexes. 
     p110 Delta Inhibitor 
     In addition to a genetic approach, the invention includes the use of small molecule compounds to inhibit p110 delta, a component of the p110 delta signaling pathway, or any combination thereof. By way of a non-limiting example, IC87114, a selective inhibitor of p110 delta is useful in inhibiting p110 delta signaling pathway in a cell. The disclosure presented herein demonstrates that p110 delta inhibitors are able to inhibit p110 delta, a component of the p110 delta signaling pathway, or a combination thereof, to provide a therapeutic benefit in infected mammals. For example, the p110 delta inhibitor in the form of a small molecule compound can significantly reduced lung viral loads of infected mammals. In addition, the p110 delta inhibitor is able to reduce the number of cellular infiltration in the lung compared to a mammal not treated with the inhibitor. Also, the treatment with the inhibitor reduces the number of inflammatory cells infiltrating the lungs of infected mammals. Thus, the inhibitor of the invention provides a means to regulate influenza viral replication and pathogenesis. That is, any inhibitor of the invention that can therapeutically target p110 delta provides a therapy against influenza virus infection. Thus, both genetic and pharmacologic means of p110 delta signaling inhibition is included in the invention as a useful strategy against influenza virus infection. 
     Therapeutic Application 
     The present invention includes an inhibitor of p110 delta, a component of p110 delta signaling pathway, or any combinations thereof. The invention also includes a cell having heighted anti-influenza virus activity compared to an otherwise identical cell not treated according to the present invention. 
     The present invention envisions treating a disorder or symptoms associated with influenza virus infection in a mammal by the administration to the mammal in need thereof a composition of the invention, e.g. an inhibitor of p110 delta, a component of p110 delta signaling pathway, or any combinations thereof. The mammal is preferably a human. 
     In one embodiment, the present invention provides a method of treating a disease, disorder, or condition associated with a viral infection. Preferably, the viral infection influenza. The method comprises administering a mammal in need thereof a therapeutically effective amount of a pharmaceutical composition comprising an inhibitor of p110 delta, an inhibitor of a component of p110 delta, or any combination thereof. 
     Thus, the invention includes pharmaceutical compositions. Administration of the composition in accordance with the present invention may be continuous or intermittent, depending, for example, upon the recipient&#39;s physiological condition, whether the purpose of the administration is therapeutic or prophylactic, and other factors known to skilled practitioners. The administration of the compositions of the invention may be essentially continuous over a preselected period of time or may be in a series of spaced doses. Both local and systemic administration is contemplated. The amount administered will vary depending on various factors including, but not limited to, the composition chosen, the particular disease, the weight, the physical condition, and the age of the mammal, and whether prevention or treatment is to be achieved. Such factors can be readily determined by the clinician employing animal models or other test systems which are well known to the art. 
     One or more suitable unit dosage forms having the compositions of the invention, which, as discussed elsewhere herein, may optionally be formulated for sustained release (for example using microencapsulation, see WO 94/07529, and U.S. Pat. No. 4,962,091 the disclosures of which are incorporated by reference herein), can be administered by a variety of routes including parenteral, including by intravenous and intramuscular routes, as well as by direct injection into the diseased tissue. The formulations may, where appropriate, be conveniently presented in discrete unit dosage forms and may be prepared by any of the methods well known to pharmacy. Such methods may include the step of bringing into association the therapeutic agent with liquid carriers, solid matrices, semi-solid carriers, finely divided solid carriers or combinations thereof, and then, if necessary, introducing or shaping the product into the desired delivery system. 
     When the compositions of the invention are prepared for administration, they are preferably combined with a pharmaceutically acceptable carrier, diluent or excipient to form a pharmaceutical formulation, or unit dosage form. The total active ingredients in such formulations include from 0.1 to 99.9% by weight of the formulation. A “pharmaceutically acceptable” is a carrier, diluent, excipient, and/or salt that is compatible with the other ingredients of the formulation, and not deleterious to the recipient thereof. The active ingredient for administration may be present as a powder or as granules; as a solution, a suspension or an emulsion. 
     Pharmaceutical formulations containing the therapeutic agents of the invention can be prepared by procedures known in the art using well known and readily available ingredients. The therapeutic agents of the invention can also be formulated as solutions appropriate for parenteral administration, for instance by intramuscular, subcutaneous or intravenous routes. 
     The pharmaceutical formulations of the therapeutic agents of the invention can also take the form of an aqueous or anhydrous solution or dispersion, or alternatively the form of an emulsion or suspension. 
     Thus, the therapeutic agent may be formulated for parenteral administration (e.g., by injection, for example, bolus injection or continuous infusion) and may be presented in unit dose form in ampules, pre-filled syringes, small volume infusion containers or in multi-dose containers with an added preservative. The active ingredients may take such forms as suspensions, solutions, or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilizing and/or dispersing agents. Alternatively, the active ingredients may be in powder form, obtained by aseptic isolation of sterile solid or by lyophilization from solution, for constitution with a suitable vehicle, e.g., sterile, pyrogen-free water, before use. 
     The pharmaceutical formulations of the present invention may include, as optional ingredients, pharmaceutically acceptable carriers, diluents, solubilizing or emulsifying agents, and salts of the type that are well-known in the art. Specific non-limiting examples of the carriers and/or diluents that are useful in the pharmaceutical formulations of the present invention include water and physiologically acceptable buffered saline solutions, such as phosphate buffered saline solutions pH 7.0-8.0. 
     The expression vectors, transduced cells, polynucleotides and polypeptides (active ingredients) of this invention can be formulated and administered to treat a variety of disease states by any means that produces contact of the active ingredient with the agent&#39;s site of action in the body of the organism. They can be administered by any conventional means available for use in conjunction with pharmaceuticals, either as individual therapeutic active ingredients or in a combination of therapeutic active ingredients. They can be administered alone, but are generally administered with a pharmaceutical carrier selected on the basis of the chosen route of administration and standard pharmaceutical practice. 
     In general, water, suitable oil, saline, aqueous dextrose (glucose), and related sugar solutions and glycols such as propylene glycol or polyethylene glycols are suitable carriers for parenteral solutions. Solutions for parenteral administration contain the active ingredient, suitable stabilizing agents and, if necessary, buffer substances. Antioxidizing agents such as sodium bisulfate, sodium sulfite or ascorbic acid, either alone or combined, are suitable stabilizing agents. Also used are citric acid and its salts and sodium Ethylenediaminetetraacetic acid (EDTA). In addition, parenteral solutions can contain preservatives such as benzalkonium chloride, methyl- or propyl-paraben and chlorobutanol. Suitable pharmaceutical carriers are described in Remington&#39;s Pharmaceutical Sciences, a standard reference text in this field. 
     Additionally, standard pharmaceutical methods can be employed to control the duration of action. These are well known in the art and include control release preparations and can include appropriate macromolecules, for example polymers, polyesters, polyamino acids, polyvinyl, pyrolidone, ethylenevinylacetate, methyl cellulose, carboxymethyl cellulose or protamine sulfate. The concentration of macromolecules as well as the methods of incorporation can be adjusted in order to control release. Additionally, the agent can be incorporated into particles of polymeric materials such as polyesters, polyamino acids, hydrogels, poly (lactic acid) or ethylenevinylacetate copolymers. In addition to being incorporated, these agents can also be used to trap the compound in microcapsules. 
     Accordingly, the pharmaceutical composition of the present invention may be delivered via various routes and to various sites in a mammal body to achieve a particular effect (see, e.g., Rosenfeld et al., 1991; Rosenfeld et al., 1991a; Jaffe et al., supra; Berkner, supra). One skilled in the art will recognize that although more than one route can be used for administration, a particular route can provide a more immediate and more effective reaction than another route. Local or systemic delivery can be accomplished by administration comprising application or instillation of the formulation into body cavities, inhalation or insufflation of an aerosol, or by parenteral introduction, comprising intramuscular, intravenous, peritoneal, subcutaneous, intradermal, oral, as well as topical administration. 
     The active ingredients of the present invention can be provided in unit dosage form wherein each dosage unit, e.g., a teaspoonful, tablet, solution, or suppository, contains a predetermined amount of the composition, alone or in appropriate combination with other active agents. The term “unit dosage form” as used herein refers to physically discrete units suitable as unitary dosages for human and mammal subjects, each unit containing a predetermined quantity of the compositions of the present invention, alone or in combination with other active agents, calculated in an amount sufficient to produce the desired effect, in association with a pharmaceutically acceptable diluent, carrier, or vehicle, where appropriate. The specifications for the unit dosage forms of the present invention depend on the particular effect to be achieved and the particular pharmacodynamics associated with the pharmaceutical composition in the particular host. 
     Combinational Therapy 
     The compositions of the invention relating to inhibiting p110 delta, a component of p110 delta signaling pathway, or any combinations thereof, can be combined with one or more immunomodulators are provided. A preferred composition has an effective amount of a p110 delta inhibitor to inhibit or reduce influenza virus infection in combination with an effective amount of one or more, anti-inflammatory agents, preferably non-steroidal anti-inflammatory agents to reduce inflammatory responses in the subject. 
     Immunomodulators include immune suppressors or enhancers and anti-inflammatory agents. Preferred immunomodulators are anti-inflammatory agents. The anti-inflammatory agent can be non-steroidal, steroidal, or a combination thereof. 
     Preferred anti-inflammatory agents are non-steroidal anti-inflammatory (NSAID) agents. Representative examples of non-steroidal anti-inflammatory agents include, without limitation, oxicams, such as piroxicam, isoxicam, tenoxicam, sudoxicam; salicylates, such as aspirin, disalcid, benorylate, trilisate, safapryn, solprin, diflunisal, and fendosal; acetic acid derivatives, such as diclofenac, fenclofenac, indomethacin, sulindac, tolmetin, isoxepac, furofenac, tiopinac, zidometacin, acematacin, fentiazac, zomepirac, clindanac, oxepinac, felbinac, and ketorolac; fenamates, such as mefenamic, meclofenamic, flufenamic, niflumic, and tolfenamic acids; propionic acid derivatives, such as ibuprofen, naproxen, benoxaprofen, flurbiprofen, ketoprofen, fenoprofen, fenbufen, indopropfen, pirprofen, carprofen, oxaprozin, pranoprofen, miroprofen, tioxaprofen, suprofen, alminoprofen, and tiaprofenic; pyrazoles, such as phenylbutazone, oxyphenbutazone, feprazone, azapropazone, and trimethazone. Mixtures of these non-steroidal anti-inflammatory agents may also be employed. 
     In one embodiment, immunomodulators are COX-2 inhibitors such as celecoxib and aminosalicylate drugs such as mesalazine and sulfasalazine. In a preferred embodiment, the disclosed composition contains an effective amount of an inhibitor of p110 delta to inhibit or reduce influenza virus infection in a subject in combination with an effective amount of celecoxib and mesalazine to reduce inflammatory responses in the subject. 
     Representative examples of steroidal anti-inflammatory drugs include, without limitation, corticosteroids such as hydrocortisone, hydroxyl-triamcinolone, alpha-methyl dexamethasone, dexamethasone-phosphate, beclomethasone dipropionates, clobetasol valerate, desonide, desoxymethasone, desoxycorticosterone acetate, dexamethasone, dichlorisone, diflorasone diacetate, diflucortolone valerate, fluadrenolone, fluclorolone acetonide, fludrocortisone, flumethasone pivalate, fluosinolone acetonide, fluocinonide, flucortine butylesters, fluocortolone, fluprednidene (fluprednylidene) acetate, flurandrenolone, halcinonide, hydrocortisone acetate, hydrocortisone butyrate, methylprednisolone, triamcinolone acetonide, cortisone, cortodoxone, flucetonide, fludrocortisone, difluorosone diacetate, fluradrenolone, fludrocortisone, diflurosone diacetate, fluradrenolone acetonide, medrysone, amcinafel, amcinafide, betamethasone and the balance of its esters, chloroprednisone, chlorprednisone acetate, clocortelone, clescinolone, dichlorisone, diflurprednate, flucloronide, flunisolide, fluoromethalone, fluperolone, fluprednisolone, hydrocortisone valerate, hydrocortisone cyclopentylpropionate, hydrocortamate, meprednisone, paramethasone, prednisolone, predisone, beclomethasone dipropionate, triamcinolone, and mixtures thereof. 
     These methods described herein are by no means all-inclusive, and further methods to suit the specific application will be apparent to the ordinary skilled artisan. Moreover, the effective amount of the compositions can be further approximated through analogy to compounds known to exert the desired effect. 
     EXAMPLES 
     The invention is now described with reference to the following Examples. These Examples are provided for the purpose of illustration only and the invention should in no way be construed as being limited to these Examples, but rather should be construed to encompass any and all variations which become evident as a result of the teaching provided herein. 
     Extensive preliminary studies revealed that in wild type C57BL/6 mice, the adaptive immune response to influenza virus is primarily mediated by CD8+ cytotoxic T cells and during the first ten days of infection mice lose progressively about 25-30% of their initial body weight. Histopathologic evaluation of the infected lungs, indicate that during the course of the viral infection there is a massive infiltration of lung air space with lymphocytes, polymorphonuclear leucocytes and monocytes. Experimental infection of immunocompetent mice with sub-lethal doses of influenza virus resolves in 10-15 days and is followed by a long lasting immunological memory. 
     In contrast to wild-type C57BL/6 mice, the results presented herein demonstrate that mice having a genetic deletion of the leukocyte-specific phosphoinositide 3 kinase (PI3K) isoform p110 delta (p110δ, same genetic background as wild-type mice) manifested significantly reduced morbidity after influenza virus infection. At day 6 post infection the numbers of lung CD8+ T cells, NK cells, granulocytes and macrophages were reduced in p110δ deficient mice compared to C57Bl/6 control mice. The number of activated T cells and NK cells were reduced by 3-fold in p110δ deficient mice compared to C57Bl/6 control mice. At the peak of the anti-viral immune response (day 10), the total numbers of lymphocytes, virus-specific CD8+ T cells, B cells, CD4+ T cells, macrophages and granulocytes infiltrating the lungs of p110δ deficient mice were reduced compared to wild-type mice. In addition, the lung viral loads were reduced at days 6 and 10 after infection p110δ deficient mice compared to wild type animals. Without wishing to be bound by any particular theory, it is believed that p110δ deficient mice constitute a valuable mouse model to study the contribution of the immune response induced by influenza virus infection to morbidity symptoms and lung pathology. Therefore, experiments were designed and conducted to determine whether deficient signaling through p110δ induces changes of the immune response to influenza virus that results in decreased morbidity and lung pathology and whether deficient signaling through p110δ inhibits influenza virus infection. 
     Example 1 
     P110δ Signaling is Required for Influenza Virus Infection/Replication 
     The results demonstrate that that the p110δ catalytic isoform of the PI3K signaling pathway plays an important role in influenza virus replication. Identifying the PI3K isoforms involved in influenza virus replication is critical as PI3K isoforms regulate many essential homeostatic functions in cells and therefore, non-specific inhibition of these pathways may have considerable toxicity (Crabbe et al., 2007  Trends Biochem Sci  32: 450-456). Deletion of p110α and p110β is embryonic lethal in mice, while deletion of p110γ affects glucose metabolism (Vanhaesebroeck et al., 2005  Trends Biochem Sci  30: 194-204) and cardiac function (Ban et al., 2008  Circ Res  103: 643-653). p110  deficient mice are healthy indicating that toxicity associated with blocking of this isoform would be minimal. The results presented herein demonstrate that p110δ plays a critical role in influenza virus infection. 
     Although p110δ was first described in cells of hematopoietic origin (Vanhaesebroeck et al., 1997  Proc Natl Acad Sci USA  94: 4330-4335; Chantry et al., 1997 J Biol Chem 272: 19236-19241), there is evidence that some non-haematopoietic cells also express p110δ (Sawyer et al., 2003 Cancer Res 63: 1667-1675; Eickholt et al., 2007 PLoS ONE 2:e869). The results presented herein demonstrate that lung epithelial cells express p110δ protein by Western blotting ( FIG. 1A ). Furthermore, it was observed that p110δ is directly involved in influenza virus replication in lung epithelial cells. When the A549 epithelial cell line was infected with influenza virus and treated with IC87114, a selective inhibitor of the p110δ PI3K (Sadhu et al., 2003  J Immunol  170: 2647-2654), it was observed that viral mRNA production was reduced ˜25-fold in cells compared to untreated cells ( FIG. 1B ). IC87114 did not affect the survival of A549 cell (data not shown). Without wishing to be bound by any particular theory, it is believed that the reduced virus produced by a human epithelial cell line when p110δ is pharmacologically inhibited suggest that p110δ signaling is directly involved in influenza virus replication and may serve as a target for in vivo infection. 
     Example 2 
     Examine Viral Loads, Morbidity, Lung Pathology Lung Inflammation and the Level of Pro-Inflammatory Cytokines in the Lungs of p110δ Deficient Mice Compared to C57BL/6 Mice During Influenza Virus Infection 
     Mice deficient in p110δ and wild-type C57Bl/6 controls were infected with influenza virus strain PR8 (3 TCID 50 ). Lungs from the animals were harvested at days 3, 5 and 7 after infection. Flow-cytometry was used to examine the immune cell populations that infiltrated the lungs of p110δ deficient mice and wild-type controls at days 3, 5 and 7 after infection with influenza virus in order to determine whether the lower morbidity of p110δ deficient mice correlated with a reduced cellular infiltration of the lungs. Flow-cytometry can also be used to determine how early after infection can the differences between p110δ deficient mice and wild-type controls be detected. 
     Experiments were designed to examine whether the morbidity observed in C57BL/6 mice after influenza virus infection correlates with the production of one or more pro-inflammatory cytokines. The mice deficient in p110δ and the wild-type C57Bl/6 controls that were infected with influenza virus discussed elsewhere herein can be used in this study in the following way: a piece of the lung harvested at days 3, 5 and 7 after infection can be used to measure the amount of different pro-inflammatory cytokines (IL-1, IL-6, IL-8, TNFα) by RT-PCR, using commercially available primer pairs. 
     The role of p110δ PI3K in influenza virus replication was further verified by testing p110δ PI3K deficient mice (p110δ−/− mice). The results presented herein demonstrate that p110δ PI3K was critical to disease pathogenesis and contributed to both morbidity and mortality. It was observed that influenza virus infected p110δ−/− mice had significantly reduced lung viral loads ( FIG. 1C ). 
     During influenza virus infection, the air space of the lung is invaded by immune cells that kill the virus-infected epithelial cells and can also secrete inflammatory cytokines. Intense production of proinflammatory cytokines and reduced gas exchange contribute to the morbidity symptoms displayed by influenza virus infected mice (weight loss, labored breathing, lack of appetite, reduced activity). Therefore, lung tissue destruction during viral infection in p110δ deficient mice and in C57Bl/6 control mice, at days 3, 5, 7 and 10 after infection can be evaluated. A piece of the lung collected at the desired time points can be rinsed in PBS, inflated and stored in 4% paraformaldehyde solution before paraffin embedding and processing for histopathologic evaluation. 
     P110δ−/− mice demonstrated reduced weight loss ( FIG. 2A ) and lung pathology, with p110δ−/− mice presented fewer areas of cellular infiltration in the lung compared to control mice ( FIG. 2B ). The numbers of inflammatory cells infiltrating the lungs of p110δ−/− mice were also decreased compared to wild type animals ( FIG. 2C ). At day 6 post infection, granulocytes, macrophages, dendritic cells, activated CD8+ T cells and B cells were reduced in lungs of influenza virus infected p110δ−/− mice ( FIG. 2C ). At day 10, the peak of the CD8+ T cell response against influenza virus, the immunodominant NP 366-374 -specific CD8+ T cell response was reduced in p110δ−/− mice ( FIG. 2D ). In addition, the production of inflammatory cytokines believed to contribute to influenza virus morbidity (Hayden et al., 1998  J Clin Invest  101: 643-649; Skoner et al., 1999  J Infect Dis  180: 10-14; Cheung et al., 2002  Lancet  360: 1831-1837; de Jong et al., 2006  Nat Med  12: 1203-1207; Kobasa et al., 2007  Nature  445: 319-323), was also significantly reduced in p110δ−/− mice ( FIG. 2E ). These findings demonstrate that p110δ PI3K plays an important role in influenza viral replication and pathogenesis. 
     Example 3 
     Determine Whether Morbidity Associated with Influenza Virus Infection is Reduced by treating mice with a specific inhibitor of p110δ 
     A specific inhibitor of p110δ, belonging to the quinazolin family, has been reported (Sadhu et al., 2003 Journal of Immunology 170: 2647-54), C57Bl/6 mice lose up to 30% of their initial body weight during influenza virus infection. The optimal route of administration of this drug can be determined by treating C57Bl/6 mice, either intranasally or intraperitoneally, at day 0 of infection. Also, the optimal dose of inhibitor for each route of administration can be determined. Once these optimal parameters are established, infected C57Bl/6 mice can be treated with the p110δ inhibitor at different time points after infection in order to determine whether it can stop morbidity after viral replication in the lung had started. 
     To determine whether inhibition of p110δ signaling could protect against lethal influenza virus infection, lethal challenges (10×LD 50 ) in mice with the virulent for mice influenza virus H7N7 London strain (A/Equine/London/1416/73) was performed (Kawaoka et al., 1991  J Viral  65: 3891-3894). Both p110δ−/− mice and wild type mice treated with IC87114 inhibitor were tested ( FIGS. 3A and 3B ). It was observed that with both p110δ deficiency and pharmacological inhibition of p110δ led to increased survival after lethal challenge ( FIGS. 3A and 3B ). The results presented herein demonstrate that P110δ PI3K is an important therapeutic target for influenza virus infection. These findings also provide proof of concept that pharmacological inhibition of p110δ is a useful strategy against severe influenza virus infection. 
     PI3K isoforms regulate many essential homeostatic functions in cells and therefore inhibiting these pathways may have considerable toxicity (Crabbe et al., 2007  Trends Biochem Sci  32: 450-456), Targeting p110δ to ameliorate pathology and viral replication during influenza virus infection is an attractive strategy as it may not interfere with normal homeostasis of the host. Targeting p110δ in combination with other PI3K isoforms such as p110δγ may synergize and provide additional protective effect. 
     In summary the results presented herein show that p110δ PI3K plays an important role in the morbidity and mortality of influenza virus infection by controlling viral replication. Therapeutic targeting of such host related molecules may have the advantage of being less prone to the virus developing resistance as mutated virus that does not require p110 PI3K would be expected to sustain a cost in replicative fitness and would result in reduced viral replication and morbidity. Pharmacological inhibition of p110δ therefore may present a novel therapeutic strategy for pandemic and seasonal influenza virus infection. 
     The experiments presented herein also expand the understanding of the contribution of the immune response to lung pathology and morbidity occurring during influenza virus infection. The results presented herein are novel because in the p110δ deficient mice the virus is cleared as efficiently as in wild-type mice, yet these mice did not lose significant weight and their immune response was moderately reduced compared with wild-type controls. 
     The disclosures of each and every patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety. 
     While the invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and variations of this invention may be devised by others skilled in the art without departing from the true spirit and scope of the invention. The appended claims are intended to be construed to include all such embodiments and equivalent variations.