Abstract:
A method for the augmentation of immune function is described. The invention comprises a combination of β-1,3(4)-endoglucanohydrolase, β-1,3(4)glucan, diatomaceous earth, mineral clay and glucomannan, which is fed to or consumed by mammalian or avian species in amounts sufficient to augment immune function. The invention described may be admixed with feeds or foods, incorporated into pelleted feeds or foods or administered orally to mammalian and avian species.

Description:
REFERENCE TO RELATED APPLICATION 
     This application is a divisional of application Ser. No. 10/829,633 filed Apr. 5, 2004 now abandoned and also claims priority from application Ser. No. 10/388,525 filed Mar. 17, 2003 which claims priority from 60/414,838, filed Sep. 27, 2002, each of which is incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     This disclosure relates to methods and compositions for the augmentation of immune function in mammalian and avian species. 
     BACKGROUND OF THE INVENTION 
     The immune system consists of two general features. These are: 1) the innate immune system and 2) the adaptive (antibody-mediated) immune system. The innate system represents the first line of defense against an invading pathogen (whether bacterial or fungal) and provides the adaptive immune system with enough time (3-5 days) for it to build up antibodies which are used to “fight” pathogens. While the innate and adaptive systems are often described separately, they function in tandem; striving to sequester and neutralize a pathogen challenge. 
     The innate immune system. The innate immune system consists of several interesting components: Aspects include: 
     1. Physical and chemical barriers to pathogens provided by epithelium, gastric acid and digestive enzymes. 
     2. Cells which engulf and digest invading pathogens (e.g., neutrophils). 
     3. Receptors on the surface of these cells which recognize and bind to pathogens. 
     4. Signaling molecules (e.g., chemokines, cytokines) which communicate sites of infection and regulate expression of immune genes. 
     Neutrophils. Neutrophils are among the most important cells of the innate immune system. They are the first cell to arrive at a site of infection. In mammals, there are billions of neutrophils of which about one-half are freely circulating in the blood (Burton and Erskine, 2003). The remainder are held in reserve in bone marrow where they are formed. Neutrophils express an extracellular binding protein on their membranes termed “L-selectin” (also termed CD62L). The role of L-selectin is to interact weakly with the endothelial cell wall thereby allowing the neutrophil to “roll” along the wall of a blood vessel and to “monitor” the cell wall for the presence of signals which indicate a local infection ( FIG. 1 ). The presence of pathogens in peripheral tissues causes release of local chemicals which then signal a rolling neutrophil of an infection. In response to these signals, L-selectin is shed from the surface of the neutrophil (see  FIG. 1 ) and other more adhesive molecules are expressed on its surface. These molecules essentially “glue” the neutrophil within the blood vessel adjacent to the site of infection. The activated neutrophil then migrates through the endothelial cell wall toward the invading pathogen. Interleukin-1β is produced by the neutrophil as a pro-inflammatory cytokine. This aids in mediating inflammation and in facilitating containment of invading pathogens. During neutrophil migration, chemical signals originating from the site of infection (such as TNF-β and interferon γ) activate the neutrophil to become a mature “killer cell”. The mature neutrophil migrates toward the site of infection where it interacts with pathogen-associated microbial patterns (PAMPs) on the surface of pathogens via several types of receptors. These receptors are expressed on the surface of the neutrophil and include the following well-identified types ( FIG. 2 ): 
     a—CD18 and CD14 
     b—Toll-like receptors (TLRs) 
     c—C3b and C3bi (complement factors) 
     d—Fc 
     Binding of neutrophils to pathogens via receptors. Both CD14 and CD18 receptors bind with lipopolysaccharide (LPS), a common polysaccharide structure associated with membranes of gram-negative bacteria. In addition, neutrophils express toll-like receptors (TLRs) which recognize and bind to additional structures associated with pathogens. So far, ten different toll-like receptors have been identified in mammals ( FIG. 2  and Table 1). TLRs play a critical role in early innate immunity to invading pathogens by sensing microorganisms. These evolutionarily conserved receptors recognize highly conserved structural motifs only expressed by microbial pathogens, called pathogen-associated microbial patterns (PAMPs: Invivogen, 2004). Stimulation of TLRs by PAMPs initiates a signaling cascade that involves a number of proteins, such as MyD88 and IRAK ( FIG. 2 ). This signaling cascade leads to the activation of the transcription factor NF-kB which induces the secretion of cytokines that direct the adaptive (i.e., antibody-mediated) immune response. TLRs are predominantly expressed in tissues involved in immune function, such as spleen and peripheral blood leukocytes, as well as those exposed to the external environment such as lung and the gastrointestinal tract. Ten human and nine mouse TLRs have been characterized, seven of which have had their ligands identified. For examples, TLR2 is essential for the recognition of a variety of PAMPs, including bacterial lipoproteins, peptidoglycan, and lipotechoic acids. TLR3 is implicated in virus-derived double-stranded RNA. TLR4 is predominantly activated by lipopolysaccharide. TLR5 detects bacterial flagellin and TLR9 is required for response to unmethylated CpG DNA (Table 1). Recently, TLR7 and TLR8 were shown to recognize synthetic antiviral molecules. These receptors are essential elements in host defense against pathogens by activating the innate immunity (Invivogen, 2004). 
     Bovine TLRS. Relatively few studies on PAMPs have been completed with bovine cells. So far, bovine immune cells have been reported to contain TLR2 and TLR4 (Werling et al., 2004). Polymorphisms have been reported in bovine TLR4 which may determine susceptibility to bovine respiratory disease and Johne&#39;s disease (White et al., 2003). 
     C3b and C3bi are components of the complement cascade whereas the Fc receptor binds to the “constant region” of antibodies. Hence, pathogens which are coated with complement factors or antibody (i.e., pathogens which are opsonized) are also recognized by activated neutrophils and are subsequently phagocytosed. In other words, activated neutrophils possess several means by which they recognize pathogens (Table 1). 
     Phagocytosis and killing. The binding of neutrophils, (and other phagocytic cells) to cell-surface markers of pathogens via these receptors, then permits the phagocytic cell to engulf the invading pathogen and “kill” it ( FIG. 3 ). Presently, two mechanisms for “killing” are known. These include: 1) an oxidative burst, where the phagocyte expresses reactive oxygen species which destroy the phagocytosed pathogen, and 2) fusion of the engulfed pathogen with a lysosome-like structure to form a “phagosome”. The phagosome is rich in digestive enzymes which mediate complete digestion of pathogens. 
     Common infections. Mammalian and avian species are continually challenged by pathogens in the gastrointestinal track and in the lung. These are important sites for resident neutrophils where minimize pathogen invasion. In addition, the mammary gland of mammals represents a site for pathogen challenge. In all infections, the innate immune system plays a key initial role in fighting-off the initial immune challenge. The innate system is essential to allow the adaptive (antibody-mediated) system to develop and mount a more-specific and directed immune response. 
     Cooperation between the innate and acquired immune system in ruminants. Antibodies which are specific to an invading pathogen leak into a site of infection to optimize clearance of a pathogen. Individuals with a high titer against a specific antigen are able to deliver these antibodies into the site of infection via a leaky endothelium (arising from an inflammatory response). Arrival of reactive antibodies (i.e., IgG.sub.2) in the alveolus coats (opsonizes) the pathogen and, as noted previously, allows neutrophil recognition of pathogens via Fc receptors (Table 1) and phagocytosis. 
     Stress and immune function. Stress reduces individuals&#39; abilities to fight disease. The negative effects of stress on the immune system are mediate by the steroidal stress hormones (cortisol, hydrocortisone and corticosterone). Burton and co-workers at Michigan State University (Weber et al., 2001) have identified the mechanism by which stress brings about a reduction in immune function. Specifically, they have documented that glucocorticoids (i.e., cortisol) “spike” near parturition ( FIG. 4 ) and reduce L-selectin expression in neutrophils ( FIG. 5 ). This compromises one important aspect of an individual&#39;s first line-of-defense against pathogen challenge. Specifically, a stressed, immunosuppressed individual has reduced ability to monitor endothelial cell lining for sites of infection and to attack and to sequester pathogens. This may result in an infection ( FIG. 6 ). 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a novel and previously unknown method for augmentation of the immune system in mammalian and avian species. The invention may be applied to, but not limited to, mammalian and avian species and will reduce susceptibility of an individual to both fungal and bacterial diseases. 
     A further object of this invention is to provide a method for augmentation of immune function and to thereby minimize or obviate morbidities and mortalities caused by, but not limited to, pathogenic fungi and bacteria with a preparation comprising a combination of β-1,3(4)-endoglucanohydrolase, β-glucan, diatomaceous earth, glucomannan, and mineral clay, such as aluminum silicate, montmorillonite clay, bentonite or zeolite. 
     Another object of the invention is to provide a composition comprising a combination of β-1,3(4)-endoglucanohydrolase, β-glucan, diatomaceous earth, mineral clay, and glucomannan, which additively augments immune function and thereby, reduces potential of pathogenic fungi and bacteria to cause morbidities and mortalities in mammalian and avian species. 
     Additional objects, advantages and novel features of the invention will be set forth, in part, in the description that follows and will, in part, become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. To achieve the foregoing and other objects, and in accordance with the purposes of the present invention as described herein, a novel method is described for the augmentation of immune function of mammalian and avian species. In particular, this invention increases expression of neutrophil L-selectin and interleukin-1β and thereby minimizes or eliminates the colonization of the epithelial surfaces and underlying parenchymal tissues by pathogenic fungi and bacteria, reduces the populations of pathogenic organisms in blood and thereby minimizes or eliminates pathologies directly caused by and indirectly caused by this colonization. The invention comprises a mixture of β-1,3(4)-endoglucanohydrolase, β-glucan, diatomaceous earth, mineral clay, and glucomannan. The diatomaceous earth is standard commercial grade available from a variety of sources. The β-1,3(4)-endoglucanohydrolase is produced from submerged fermentation of a strain of Trichoderma longibrachiatum. The β-1,3(4)glucan and glucomannan are derived from a commercial product and are an extraction from any of a number of yeast organisms. The mineral clay product is a standard commercial grade (examples include, but are not limited to, montmorillonite clay, bentonite and zeolite). Extractions and productions of diatomaceous earth, yeast cell wall extract and mineral clay are well known in the art and commercially-available. 
     The compositions which are provided by the invention can be fed to any mammalian or avian species including, but not limited to, bovine, equine, ovine, caprine and avian species. When admixed with the feed or food or fed as a supplement, the invention augments immune function thereby reducing colonization by pathogens. The invention also minimizes or eliminates invasion of the blood compartment by pathogenic fungi and bacteria. The invention thereby minimizes or eliminates the manifestations of the pathologies typically associated with epithelial and systemic fungal and bacterial infections. Administration of the product may be used as a prophylactic (i.e., to prevent colonization and growth of pathogenic fungal and bacterial species in mammalian or avian species), as an additive to feeds or foods infected with pathogenic fungi or bacteria or as a preferred method to treat and thereby minimize or eliminate an existing, diagnosed or non-diagnosed, fungal or bacterial infection. Application of the invention as described herein and via the specific and novel mechanisms described herein will minimize and possibly eliminate manifestations of fungal and bacterial infections. Application of the invention as described herein will also minimize or possibly eliminate manifestations associated with the presence of pathogenic fungal and bacterial organisms, as identified above, in food or feed of mammalian and avian species. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings and photographs which are incorporated into the following “Detailed Description of the Invention” form part of the specification and illustrate several aspects of the present invention and, together with the Detailed Description, serve to explain the details of the invention. In the following section five figures are presented. 
         FIG. 1  is a schematic drawing illustrating the movement of neutrophils through a blood vessel, L-selectin (CD 62 L) is shown as circles on the surface of the neutrophils A-E. These allow docking of the neutrophils with endothelium. There is shedding of L-selecting and migration of neutrophil into peripheral tissue toward a site of infection F. (Source: Burton and Erskine, 2003.) 
         FIG. 2  is a schematic diagram illustrating toll-like receptors (TLRs) on the surface of an immune cell, and signal transduction following binding of TLRs with microbial PAMPs (pathogen-associated molecular patterns). (Source: M. Adib-Conquy, C. Fitting,  2002 .) 
         FIG. 3  illustrates a macrophage cell engulfing a bacterium in a process called phagocytosis. Toll-like and other receptor direct phagocytes to recognize microbes. Pseudopodial projections surround the bacterium. (Source: Travis,  2002 .) 
         FIG. 4  is a bar graph of cortisol levels in dairy cattle relative to day of parturition. Cortisol peaks at day of parturition. (Source: Weber et al.,  2001 .) 
         FIG. 5  is a bar graph of neutrophil surface CD 62 L (L-selectin) expression in cattle relative to day of parturition. (Source: Weber et al,  2001 .) 
         FIG. 6  is a schematic diagram illustrating neutrophils lacking L-selectin expression in a stressed dairy cow. (Source: Burton and Erskine,  2003 .) 
         FIG. 7 . Effect of five experimental treatments on concentrations of neutrophil L-selectin. An experiment was conducted with 60 sheep. Twelve sheep were allocated to each treatment. The treatments consisted of: 
       1. Control 
       2. Immunosuppressed (daily injections of Azium [Dexamėthasone], 0.1 mg/kg twice/day). 
       3. Immunosuppressed plus experimental product fed at 0.5% of daily dry matter intake. 
       4. Immunosuppressed plus moldy feed (addition of  Aspergillus fumigatus -infected wheat mill run; 1.5 lbs/head/day). 
       5. Immunosuppressed plus moldy feed (as in Treatment 4) plus the experimental feed product as outlined in Treatment 3. 
       The duration of the trial was 28-days. On Day 28, blood was taken from six sheep per treatment and neutrophils were recovered by Percoll gradient centrifugation. The concentrations of L-selectin were determined by Western blot analysis using an antibody specific to L-selectin. Relative concentrations of L-selectin among the five treatment groups are shown in  FIG. 8 . 
         FIG. 8 . Scanning densitometry of data shown in  FIG. 7 . 
         FIG. 9 . Analysis of neutrophil interleukin-1β in the same sheep neutrophil samples presented in  FIG. 7 . 
         FIG. 10 . Scanning densitometry of data shown in  FIG. 9 . 
         FIG. 11 . Concentrations of  Aspergillus fumigatus  in blood samples taken from sheep on Day 28 of the above study.  A. fumigatus  DNA levels were assessed using a quantitative Sybr-Green PCR-based assay specific for  A. fumigatus.    
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is based on the novel discovery that a combination of β-1,3(4)-endoglucanohydrolase, β-1,3(4)glucan, diatomaceous earth, mineral clay, and glucomannan effectively augments immune function and reduces colonization of tissues and blood by a pathogen. 
     The β-1,3(4)-endoglucanohydrolase is from a commercial source and is produced from submerged fermentation of a strain of  Trichoderma longibrachiatum.    
     The diatomaceous earth is prepared by methods commonly known in the art. It is available as a commercially-available acid-washed, product with 95% silica (SiO 2 ) and with its remaining components not assayed but consisting primarily of ash (minerals) as defined by the Association of Analytical Chemists (AOAC, 2002). 
     The yeast cell wall extract is prepared by a method commonly known in the art. It is a commercial source of β-1,3(4)glucan and glucomannan derived from primary inactivated yeast (Saccharomyces cerevisiae) with the following chemical composition: 
     
       
         
               
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Moisture 
                 2-3% 
                   
               
               
                   
                 Dry matter 
                 97-98% 
               
               
                   
                 Proteins 
                 14-17% 
               
               
                   
                 Fats 
                 20-22% 
               
               
                   
                 Phosphorous 
                 1-2% 
               
               
                   
                 Mannans 
                 22-24% 
               
               
                   
                 β-1,3-(4)glucan 
                 24-26% 
               
               
                   
                 Ash 
                 3-5% 
               
               
                   
                   
               
             
          
         
       
     
     The mineral clays (aluminosilicates) used in this invention may be fulfilled by any of a variety of commercially-available clays including, but not limited to, montmorillonite clay, bentonite and zeolite. 
     In a preferred embodiment of the invention, β-1,3(4)-endoglucanohydrolase, diatomaceous earth, yeast cell wall extract and mineral clay are combined at 0.05-3%, 1-40%, 1-20% and 40-92%, respectively. In a preferred composition, β-1,3(4)-endoglucanohydrolase, diatomaceous earth, yeast cell wall extract and mineral clay are combined at 0.1-3%, 5-40%, 2-10% and 40-80%, respectively. In an especially preferred embodiment of the invention, β-1,3(4)-endoglucanohydrolase, diatomaceous earth, yeast cell wall extract and mineral clay are combined at 0.2-3%, 30-40%, 4-6% and 50-65%, respectively. The preferred physical form of the invention is a dry, free-flowing powder which is suitable for direct inclusion into a feed, food product or as a supplement to a total mixed ration or diet. 
     The compositions provided by the present invention may be incorporated directly into commercially-available feeds or food products or fed as supplements to commercially-available feeds or food products. The composition contained in the present invention may be fed to any mammalian or avian species. The methods of the invention comprise augmenting immune function in mammalian and avian species. When incorporated directly into feeds, the present invention may be added to feeds in amounts ranging from 0.1 to 5 kg per ton of feed. In an especially preferred composition, the invention may be added to feeds in amounts ranging from 1-2 kg per ton of feed. 
     The composition contained in the present invention may be added to animal feedstuffs or to foods in amounts ranging from 0.0125% to 2% by weight of feed. In a preferred embodiment, the composition is added to animal feedstuffs or to food in amounts from 0.0625% to 1% by weight of feed. In an especially preferred embodiment, the invention is added in amounts from 0.125% to 0.5% by weight of feed. 
     Alternatively, the composition contained in the present invention may be fed directly to mammalian or avian species as a supplement in amounts 0.016 grams/kg to 0.37 grams/kg of live body weight per day. In an especially preferred embodiment, the invention may be provided to mammalian and avian species in amounts of 0.10 grams/kg to 0.20 grams/kg of body weight per day. One of skill in the art can appreciate that the amount of the invention fed can vary depending upon the animal species, size of the animal and type of the feedstuff to which the invention is added. 
     The novel methods of this invention comprise the ability of a combination of β1,3(4)-endoglucanohydrolase, diatomaceous earth, yeast cell wall extract and clay to augment immune function. The benefits resulting from the application of the invention to mammalian species include, but are not limited to, reduced death losses, reduced incidence of mycotic abortion, reduced incidence of jejunal hemorrhage syndrome (dead gut syndrome), reduced incidence of scouring (diarrhea), improved growth rate, improved efficiency of growth, improved milk production, improved efficiency of milk production and reduced somatic cell counts in milk products (dairy animals). The benefits from the application of the invention to avian species include, but are not limited to, reduced death losses, improved growth and egg production, improved fertility, and reduced incidence of enteric diseases. 
     The following are intended to be illustrative of the invention, and are not to be considered restrictive of the scope of the invention as otherwise described herein. 
     EXAMPLE 1 
     An experiment was conducted using 60 growing male and female sheep. Sheep were allocated to one of the five treatments (seven females and five males per treatment): 
     1. Control. 
     2. Immunosuppressed (daily injections of Azium [Dexamethasone], 0.1 mg/kg twice/day). 
     3. Immunosuppressed plus the invention fed at 0.5% of daily dry matter intake. 
     4. Immunosuppressed plus moldy feed (addition of  Aspergillus fumigatus -infected wheat mill run; 1.5 lbs/head/day). 
     5. Immunosuppressed plus moldy feed (as in Treatment 4) plus the invention as outlined in Treatment 3. 
     Animals were fed a dairy-type diet for a period of 28 days. Immunosuppression was mediated in Treatments 2, 3, 4 and 5 by daily injection of Azium using a high dose (a model of extreme stress: Weber et al., 2001). Sheep on Treatments 4 and 5 were challenged with a pathogenic mold by feeding wheat mill run which had been contaminated with a pathogenic mold ( Aspergillus fumigatus ). Sheep on Treatments 3 and 5 were supplemented with the invention at a rate of 0.5% of their daily dry matter intake. Following 28 days, blood samples were taken via jugular puncture and the neutrophil fractions were isolated using Percoll density gradient centrifugation. Following this, samples of neutrophil protein were processed using sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blotting using antibodies which are specific for L-selectin and interleukin-1-β. Relative concentrations of L-selectin and interleukin-1-β. were assessed using scanning densitometry. 
       FIGS. 7 and 8  demonstrate effects of the five experimental treatments on neutrophil L-selectin. Injection with Azium caused a marked reduction (P&lt;0.05) in L-Selectin and provides evidence that Azium injection was, in fact, immunosuppressive. Addition of mold to the diets had no effect (P&gt;0.05) on L-selectin concentrations. Of interest, addition of the invention to feed (Treatments 3 and 5) caused restoration (augmentation: P&lt;0.05) of L-selectin. 
     Interpretation: The novel invention successfully restored (augmented) normal levels neutrophil L-selectin. 
     Restoration of L-selectin on neutrophil surfaces will re-establish their ability to monitor the endothelial lining for pathogens. 
       FIGS. 9 and 10  demonstrate effects of the five experimental treatments on neutrophil interleukin-1-β concentrations. Azium treatment caused a marked reduction (P&lt;0.05) in neutrophil inerleukin-1-β concentration. This demonstrates that Azium was immunosuppressive. The novel invention had no effect (P&gt;0.05) on neutrophil interleukin-1-β in the absence of a pathogen challenge (i.e., Treatment 3 versus Treatment 2); however the invention caused a marked increase (P&lt;0.05) in neutrophil interleukin-1-β in the presence of a pathogen challenge (i.e., Treatment 5 versus Treatment 4). 
     Interpretation. Interleukin-1β is an important pro-inflammatory cytokine which enables the neutrophil to fulfill its role as a phagocyte. Ability of the feed product to restore interleukin-1β. in the presence of a pathogen ( A. fumigatus ) demonstrates that pathogens potential effects of the invention on immune function. 
       FIG. 11  shows the effects of the five experimental treatments on blood concentrations of  A. fumigatus. A. fumigatus  concentrations were determined using a Sybr-Green real-time quantitative polymerase chain reaction (PCR) assay developed in our laboratory. The results demonstrate that the invention reduced (P&lt;0.05)  A. fumigatus  concentrations in blood. 
     Interpretation. The restoration of neutrophil function shown in  FIGS. 7-10  manifests itself by reducing pathogen load detected within the blood compartment. The invention reduces pathogen load. 
     These results show that the composition of the invention (i.e., mineral clay, yeast cell wall extract, diatomaceous earth and β-1,3(4)-endoglucanohydrolase) is capable of a previously-undescribed effect of augmenting immune function. The invention specifically restores levels of L-selectin and interleukin-1-β in neutrophils thereby restoring the ability of neutrophils to monitor for the presence of invading pathogens. 
     The combination of products augments immunity in mammalian and domestic species and thereby prevents the invasion and colonization of the blood compartment. It represents a mixture which is flowable and easily incorporated into feed products and food products. The present invention was effective in achieving its immunostimulatory effects under growth conditions which might be found in mammalian and avian digestive systems where nutrients, moisture, oxygen and elevated temperatures are provided by the host. 
     The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above illustrations. The embodiment was chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Summary of mechanisms by which neutrophils can recognize/bind 
               
               
                 to pathogen prior to phagocytosis. 
               
             
          
           
               
                 Neutrophil 
                   
                   
               
               
                 receptor 
                 PAMP 1  or Ligand 
                 Comment 
               
               
                   
               
               
                 CD14 
                 lipopolysaccharide 
                 direct binding to pathogen 
               
               
                 CD18 
                 lipopolysaccharide 
                 direct binding to pathogen 
               
               
                 TLR2 
                 lipoprotein, peptidoglycan, 
                 direct binding to pathogen 
               
               
                   
                 lipotechoic acid 
               
               
                 TLR3 
                 virus-derived double- 
                 direct binding to pathogen 
               
               
                   
                 stranded RNA 
               
               
                 TLR4 
                 lipopolysaccharide 
                 direct binding to pathogen 
               
               
                 TLR5 
                 Flagellin 
                 direct binding to pathogen 
               
               
                 TLR7/8 
                 Small synthetic anti-viral 
                 direct binding to pathogen 
               
               
                   
                 molecules 
               
               
                 TLR 9 
                 unmethylated CpG DNA 
                 direct binding to pathogen 
               
               
                 C3b/C3bi 
                 Complement factors 
                 binds opsonized pathogen 
               
               
                 Fc 
                 “constant region” of 
                 binds opsonized pathogen 
               
               
                   
                 antibodies 
               
               
                   
               
               
                   1 PAMP: Pattern-associated molecular pattern