Abstract:
The present invention is concerned with novel compositions and vaccines useful for prophylactic an/or therapeutic treatment of mucosal infections, and in particular it is concerned with oral vaccines and with methods of enhancing mucosal resistance to infection or for treating established infections, of the respiratory tract.

Description:
TECHNICAL FIELD  
         [0001]    The present invention is concermed with novol vaccino compositions that induce mucosal protection and in particular to oral vaccines and to methods of johicg mucosal resistance to infcction or for treating established infections.  
         BACKGROUND ART  
         [0002]    Endobronchitis has been used as a model of mucosal immunology and more specifically to reflect a particular balance of the host-parasite relatioship at the mucosal surface. The normally sterile bronchus mucosa becomes colonised by “avirulent” bacteria which do not generally invade. Most prominent is non-typable  Haemophilus influensae (NTHI). Acute episodes of infection in subjects with chronic lung disease are thus likely to be initiated by events which disturb a finely balanced relationship between colonising bacteria and the bronchus mucosa. The restraining host response involves Th 1 T cells (which produce γ interferon), which operate by recruiting and activation neutrophils within the bronchus mucosa. If excessive and/or appropriate, this process leads to increase cough and purulent sputum, the hallmark of “acute bronchitis” in subjects with established chronic lung disease.  
           [0003]    The original oral vaccine used killed NTHI to activate the common mucosal system to enhance release of lymphocytes (then considered to be antibody producing B lymphocytes) from the Peyer&#39;s patches along the small intestine, which relocated within the bronchus mucosa, producing IgA antibody which would prevent descent of bacteria into the bronchi. The concept has been superseded. this vaccine requires that (i) a single bacterial content (ii) no added adjuvant. The absence of adjuvant was though necessary to avoid the then considered restrictions imposed by the highly downregulated musosal environment, ie additions of adjuvant to a simple single bacterial vaccine would enhance mucosal downregulation, reduce vaccine effectiveness, and even promote or exacerbate infection.  
           [0004]    It is an object of the present invention to overcome or at least arneliorate one or more of the limitations of the prior art or to provide a useful alternative.  
         SUMMARY OF THE INVENTION  
         [0005]    According to a first aspect there is provided a mucosally administrable composition comprising one or more antigens derived from at least one microorganism which is capable of causing infection at a mucasal surface and a probiotic.  
           [0006]    Preferably the antigen is dervied from a bacterium, a fungus or a virus. Even more perference, when the antigen is a whole microorganism, it is a killed microorganism. As a fruther however it will be understood that live or live attenuated microorganisms may also be used effectively. It will also by understood however, that individual antigents or homogenates and sonicates of mircoorganisms can also be used with the expectation of achieving similar results.  
           [0007]    Particularly preferred are respiratory tract bacterial and fungal pathogens or those normally colonising the respiratory tract bacterial and fungul pathogens or those example NTHI,  Pseudomonas aeruginosa, Streptococcus pneumoniae, Staphylococcus albus, Staphylococcus aureus  and the like, singularly or in combination.  
           [0008]    The compositions of the present invention are intended to be administered orally and thus may be combined with the known pharmaceutically acceptable, carriers, solvents and excipients.  
           [0009]    Preferably the probiotic used in the compositions of the present invention is a single species, or a mixture of species, of a probiotic mircoorganism. Even more preferred are microorganisms which are probiotic bacteria. Further preferred are probiotic bacteria which can induce a cellular immune response of the TH1 type. The probiotic bacteria may advantageously be selected from, but no limited to, lactic acid bacteria or Bifidobacterium species. Even more preferred is the use of  Lactobacillus acidophilus  ( L. acidophilus ) or  Lactobacillus fermentum  ( L. fermentum ), or parts thereof which are capable of inducing the Th1 cellular response. Specially preferred is  L. fermentum  ), or parts thereof which are capable of inducing the probiotic bacteria may be used live or as an inactivated preparation, as long as they are capable of inducing the Th1 response. For preference  L. acidophilus and    L. acidophilus  are used, individually or in combination, as live preparations. It is considered that other bacteria would also be suitable as probiotics, for example the well known bacteria such as for example  L. casei, L. plantarum, L. rhamnosus, bifidobacterium breve  and the like.  
           [0010]    Additional known conventional adjuvants may also be included. A range of suitable pharmaceutical adjuvants, excipients and carriers, and methods of preparing suitable formulations, would be well known to those skilled in the field of pharmaceutical formulation, and details of such adjuvants, excipents and carriers can be found in standard texts and manuals, such as for example “Remington: The Science and Practice of Pharmacy (Mack Publishing Co., 1995) which is incorporated in its entirety herein by reference.  
           [0011]    Further, the compositions of the present invention may be in the form of a food product or a food supplement, such as for example a dairy product or supplement. The methods of preparation of such products and supplements would also be clear to those skilled in the art, as they are well known procedures and processes, particularly those concerning the production of for example yoghurts and other milk products.  
           [0012]    According to a second aspect of the present invention there is provided a vaccine comprising the composition according to the first aspect.  
           [0013]    According to a third aspect there is provided a method of therapeutic or prophylactic treatment of a mucosal infection comprising the administration to a subject required such treatment a composition according to the first aspect or a vaccine according to the second aspect.  
           [0014]    It will be understood however that a subject required treatment, whether prophylactic or therapeutic, may be administered initially only a part of the compostion, for example the probiotic bacteria such as  L. acidophilus  and/or  L. ferementum  may be administered first, followed thereafter by the asministration of the anitgen or antigens intended to ultimately provide specific immunity to the potential pathogen. The initial treatment witht he probiotic may take the form of a single bolus dose but may also, and for preference, be administered in repeated doses for a period of time before the antigen is administered. The administration of the probiotic may also cintinue after cessation of antigen administration.  
           [0015]    As it is now clear that the mucosal immune system is common to all mucosal surfaces, the compositions and vaccines of the present invention can be applied to any potential mucosal pathogen and any mucosal surface, including but to limited to buccal cavity, the respiratory tract and the instestinal tract.  
           [0016]    Preferably the composition or vaccines of the present invention are administered orally bey application to any mucosal surface, for example the mucosa of the respiratory tract or mucosa of the intestinal tract, is contemplated.  
           [0017]    The compositions and vaccines of the present invention are advatageously used to induce mucosal protection against infection however they can also be used as prophylactics in the treatment of existing bacterial, fungal and/or viral mucosal infections. Further, the preferred use of the compositions and vaccines of the present invention is when the mucosal surfaces are already colonised by bacteria.  
           [0018]    Thus according to a fourth aspect there is provided a method of therapeutic or prophylactic treatment of a mucosal infection comprising the administation to a subject requiring such treatment the probiotic part of a composition according to the first aspect, followed by the antigen part of a composition according to the first aspect.  
           [0019]    Preferably the treatment with the probiotic part is by administration of a single bolus dose of probiotic however treatment with the probiotic. More preferred however, is that the probiotic and the antigen are co-administered.  
           [0020]    In a further embodiment of the invention, where the probiotic is administered before or together with the antigen, the administration of the probiotic may continue after the administration of the antigen part.  
           [0021]    The compositions and vaccines of the present invention may be administered to any mucosal surface and have the desired effect because of the common mucosal immune system. Preferred mucosal surfaces buccal cavity, the respiratory tract and the intestinal tract, however, as mentioned above, it will be understood by those skilled in this field that administration to any mucosal surface would be effective.  
           [0022]    The compositions and vaccines of the present invention may be administered to any muscosal surface and have the desired effect because of the common mucosal immune system. Preferred mucosal surfaces buccal cavity, the respiratory tract and the intestinal tract, however, as mentioned above, it will be understood by those skilled in this field that administration to any mucosal surface would be effective.  
           [0023]    Preferably the compositions of the vaccines are administered orally.  
           [0024]    Preferably, the vaccine in administered in two courses, followed by a booster course.  
           [0025]    The preferred dosage of the probiotic, when the adjuvant is a whole live probiotic bacterium, is from about 1×10 8  to about 1×10 12  organisms. More preferred is a dosage wherein the ratio of whole killed microoganisms (antigen) to probiotic bacteria is about 5:1 or greater.  
           [0026]    Also preferred is the administration of the compositions or the vaccines, each year before outbreak of seasonal infections. 
       
    
    
     BRIEF DESCRIPITON OF THE FIGURE  
       [0027]    [0027]FIG. 1 IL-4 and IFN-γ production following feeding with  Lactobacullus acidophilus   
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]    It has been suprisingly found that by combining, for example, a specific antigen relevant to mucosal infection (e.g. whole bacteria such as  Haemophilus influenzae ) and non-specific bacteria, ie. those that are not normally associated with mucosal infection, protracted protection against mucosal infection can be achieved. Without wishing to be bound by any particular mechanism of action, the present invention is based on the notion that the non-specific bacteria used induce T cells to produce a particular cytokine response which amplifies the protection otherwise expected from administration of traditional vaccine preparations. More specifically, but again not wishing to be bound by any particular mechanism of action, it is thought that by the administration of non-specific bacteria the mucosal immune system is being biased towards the Th1 (ie IFN-γ) end of the T cell response spectrum. It is considered that the Th1 response best controls mucosal colonisation. The use of such organisms, and other adjuvants capable of stimulating a Th1 response, determines a Th1 response that is detectable and can have effects distant from the site of administration.  
         [0029]    It is demonstated herein that a non-specific bacteria such as lactic acid bacteria, have the capacity to downregulate IL-4 and to enhance IFN-γ production in a highly “Th2-biased” murine model (see Example 1). It is also demonstated herein that a non-specific bacterium such as lactobacillus provides additive protection in a rat model of non-typale  Haemophilus influenzae  (HTHI) clearance from the bronchus (shown in involve CD4 T cells, with no antibody) see Example 2).  
         [0030]    The animal model used by way of example in th epresent studises is a model of conlonisaiton, relevant to both therapy and prevention of infection. Colonisation is an essential deterninant for infection and the model has been used in the context of other therapeutic and prophylactic vaccines to establish efficacy, dosage protocols and the like.  
         [0031]    In a particular embodiment of the present inveniton a therpeutic oral vaccine conbines: 1) specific bacteria which are found within the respiratory tact, singly or in combination (for example, but not limited to, MTHI,  S. pneumoniae, Ps. asruginosa, S. albus, S. aureus ), as killed or live bacteria, and 2) non-specific bacteria (also referred to herein as probiotic bacteria), wjocj jave tje catp switch nucosal immunity in the directionof a Th1 T cell response (may also be used killed or live), for example, but not limited to, Lactobacillus species (eg.  L. acidophilus ) and/or Mycobacterium species, (eg  M. vaccae ).  
         [0032]    This type of oral vaccine operates best when the mucsal surface is already colonised (as thses bacteria re-stimulate newly relocated cells within the mucosa) ie functions as a therapeutic vaccine. it can, however, function as a proghylactic vaccine.  
         [0033]    To avoid inactivation of bacteria by gastric, enteric coated capsues (or similar) may be used to release the bacterial contents along the small intestine. Another option is longer term use of the non-specific bacteria to create a more durable Th1 mucosal envirnment, prior to the administration of the specific antigen(s) or bacteria intended to induce a specific immune response against the potential mucasal pathogen. The ‘non-specific’ bacteria alone do not induce specific protection.  
         [0034]    The non-specific bacteria also enhance repsonse to certain antigens given parenterally, particularly those influencing mucosal protection (by favouring a particular immune outcome).  
         [0035]    A combination of Gran+ve bacteria as probiotic asjuvants has synergistic activity in this system and is also comtemplated herein. Various respiratory mucosal surfaces can be protected as the mucosal immune system is common to all mucosal surfaces (eg bronchus, sinus, and middle ear among others).  
         [0036]    The invention will now be more particularly described with reference to specific, non-limiting, examples.  
       EXAMPLE 1  
     Effect of probiotic bacteria on Th1/Th2 cytokine response  
       [0037]    To determine whether probiotic bacteria down-regulate Th2 and up-regulate Th1 cytokine response, C57/B16 mice were fed intragastrically using a feeding needle, various numbers of  Lactobacillus acidophilus  ( obtained from University of New South Wales, School of Mircobiology and Immunology Culture Collection, Sydney, Australia) on (OVA) and aluminium hydroxide in 0.2 mL phosphate-buffered saline administered by peritoneal injection. The mice were further fed ten times with  L. acidophilus  every two days for two weeks before they were sacrificed. Lymphocytes were isolated by teasing spleens through a sieve, washed with PBS, and resuspended at 10×10 6  . One mL aliquots of the cell suspension were dispensed into wells of a 24-well flat-bottomed microtitre plate and stimulated with OVA (5 μg/mL). After incubation for 4 days the supernatants were collected and assayed for IL-4 and IFN-γ production by standard ELISA techniques using IL-4 or IFN-γ monclonal antibody pairs.  
         [0038]    Briefly, wells of a 24-well microtitre plate were coated with a capture anti-IL-4 antibody. After incubation at room temperature for 1 hr, the wells washed and biotinylated anti-IL-4 antibody was added to each well. Following incubation for a further 1 hr, the wells wene washed and strepavdin-peroxidase conjugate was added to each well. After incubation for 30 , the wells were wathed and then gubstrate was added The colour developmcal was read at 450/620 nm in an ELISA plate reader level of IL-4 in known samples was quantitated by intrapolation using a stardard curve. A similar procedure was used for measureent of IFN-γ.  
         [0039]    The results shown in FIG. 1 A and B demonsrate that feeding  L. acidophilus. resulted in the suppression of IL-4 production in dose-dependent manner(FIG. 1A) whereas the production of IFN-γ was enhanced (FIG  1 B).  
       EXAMPLE 2  
     Enhanced Clearance of NTHi from the Respiratory Tract Induced by a Single Intra-Lumenal dose of live  L. acidophilus  and killed NIHi  
       [0040]    The capacity of  L. acidophilus  to enhance clearance of non-typeable H influenzae (NTHI) from the respiratory tract was investigated in a rat model.  
         [0041]    DA rats (200-250 gm, 8-10 weeks old, Animal Resource Centre, Perth, WA were immunised by a single intra-humenal (IL) injection (into the lumen of the small intestine) of 0.75 mL of PBS containing 5×10 9  killed NTHi alone or in combination with 2.5×10 10    L. acidophilus (as shown in Table  1). The IL dose was by direct injection into the intestinal lumen after exposing the duodenum by laparotomy. This considered equivalent to an enteric-coated dose (as may be prepared for humans) being released into the gut lumen affter oral ingestion. The rats were given an intra-tracheal (IT) boost with 50 μL of PBS alone (group A) or containing 5×10 8  killed NTHI in 50 μL of PBS. After 4 hrs, the rats were sacrificed and the total number of NTHI in bronchial lavage (BAL) and lung homogenate (LH) was determined by plating out serial 10-folk dilutions of the BAL or LH onto chocolate agar plates. Ater overnight incubation at 37° C. the number of colonies were counted. The total number of bacteria in BAL and LH, expressed as colony forming units (CFU), as shown in Table 2.  
                                 TABLE 1                           Rat groups: IL dose and IT boost                Group   IL dose   IT boost                       A   PBS   PBS           B   NTHi   NTHi           C   NTHi/ L. acidophilus     NTHi           D     L. acidophilus     NTHi                      
 
         [0042]    [0042]                                 TABLE 2                           Recovery of live NTHi from the respiratory tract (mean ± SEM)                Group   BAL CFU (10 6 )   LH CFU (10 6 )                       A   3.2 ± 1.1   19.4 ± 5.9           B   1.0 ± 0.3   19.2 ± 10.4           C   0.5 ± 0.3 a,c      3.3 ± 0.7 b,d             D   1.7 ± 0.3   25.9 ± 10.0                                                                                                
       EXAMPLE 3  
     Enhanced Clearance of NTHi from the lungs of Immunised Rats Fed  L. Acidophilus    
       [0043]    DA rat (200-250 gm, 8-10 weeks old, Animal Resource Centre, Perth, WA) were fed by gavage with 5×10 10    L. acidophilus  in 1.0 mL PBS or PBS alone every 2 days for 7 days at which time the rats were immunised with formalin-killed NTHi (5×10 9  per rat) administered intralumenally (IL) in 0.5 mL of PBS. Rats continued to be fed every 2 days for 2 weeks and were then boosted with 50 μL of PBS containing formalin killed NTHi (5×10 8  per rat) administered by the intratracheal (IT) route. After feeding with  L. acidophilus  for a further 7 days, the raats were infected IT with 50 μL of PBS containing 5×10 8  live NTHi. After 4 hrs, levels of colonisation in the lung were determined in BAL and LH as described in Example 2. The immunization and feeding of the various groups is shown in Table 3. The bacterial recovery is shown in Table 4 +L.  
                                     TABLE 3                           Rat groups: dosing regimens                Group                       (5 rats per group)   Feed   IL dose   IT boost                       A   Nil   PBS   PBS           B   Nil   NTHi   NTHi           C     L. acidophilus     PBS   PBS           D     L. acidophilus     NTHi   NTHi                      
 
         [0044]    [0044]                                 TABLE 4                           Recovery of live NTHi from the lungs                Group   BAL CFU (10 6 /mL)   LH CFU (10 6 /mL)                       A   25.9 ± 7.4   90.2 ± 29.0           B    4.6 ± 3.0 a      4.9 ± 1.2 b             C    0.7 ± 0.3 c     12.5 ± 5.7 d             D    0.2 ± 0.1 e,g      3.2 ± 2.0 f,h                                                                                                                          
         [0045]    Rats fed  L. acidophilus  and immunised with killed NTHi were more resistant to infection by NTHi in the lungs than rats immunised with killed NTHi only or fed  L. acidophilus  only. Furthermore, rats fed by gavage with repeated doses of  L. acidophilus  were more resistant to infection than rats given a single bolus of  L. acidophilus (example  2). Not wishing to be bound by any particular mechanism of action, this data suggestss that enhanced clearance may be due to increased colonisation in the gut with  L. acidophilus  following repeated feeding.  
       EXAMPLE 4  
     Intra-Lumenal Dosing with Killed NTHi and live  L. fermentum  Provides Enhanced Protection Against a Subsequent Acute NTHi infection  
       [0046]    The capacity of  L. fermentum  to enhance clearance of NTHi, either alone or in combination with killed NTHi was evaluated in a rat model of acute NTHi respiratoryl infection.  
         [0047]    DA specific pathogen-free rats (177-200 g) were obtained from the Central Animal house, University of Newcastle, Newcastle, NSW). Groups of 5 rats were given a single injection into the gut lumen of the small intestine of 0.75 mL of PBS only or PBS containing either 5×10  9  killed NTHi only, plus 2.5×10 10    L. fermentum , or 2.5×10 10    L. fermentum  only as shown in Table  5 l below. On day  14, rats in group A were sham-boosted IT with 50 μL of PBS and rats in groups B-D were boosted with 50 μL of PBS containing 5×10 8  killed NTHi. On day 21 the rats were infected IT with 5×10 8  live NTHi in 50 μL of PBS. Four hours later rats were killed by an overdose fo pentobarbitone administered intra-peritoneally. The lungs were lavaged with 10 mL of PBS to obtain broncho-alveolar lavage fluid (BAL). The lungs were then homogenised in 10 mL f PBS to obtain lung homogenate (LH). The number of bacteria in BAL and LH was determined by performing serial dilution of BAL and LH and plating known volumes on chocolate agar plates. After overnight incubation at 37° C. the colonies were counted were counted and the total number of colony-forming units (CFU) in BAL and LH determined. The number of bacteria in each rat group is shown in Table 6.  
                             TABLE 5                           Rats (5 per group) were given a single intra-lumenal dose of various       combinations of killed NTHi and live  L. fermentum  as follows:            Rat group   IL immunization   IT boost               A   PBS   PBS       B   NTHi 5 × 10 9     NTHi 5 × 10 1         C   NTHi 5 × 10 9  +  L. fermentum     NTHi 5 × 10 2             2.5 × 10 10         D     L. fermentum  2.5 × 10 10     NTHi 5 × 10 3                    
 
         [0048]    [0048]                                 TABLE 6                           Recovery of live NTHi from the lung.                Rat group   BAL CFU (10 6 )   LH CFU (10 6 )                       A (5)   3.67 ± 1.30   103.5 ± 34.2           B (5)   0.40 ± 0.22 P = 0.038*    17.4 ± 6.8  P = 0.039*           C (5)   0.27 ± 0.11 P = 0.032*    5.7 ± 1.5  P = 0.021*           D (5)   0.49 ± 0.19 P = 0.042*    0.82 ± 0.37 P = 0.017*                                                
         [0049]    This data suggests that  L. fermentum  slone or with killed NTHi has greater efficacy as a prophylactic against subsequent acute respiratory infection than does killed NTHi alone. Thus, this lactobacillus strain is also effective against acute respiratory infection.  
       EXAMPLE 5  
     Dose-Ranging Study of  L. acidophilus  Given with a Fixed NTHi Dose  
       [0050]    DA specific pathogen-free rats (197-230 g) were obtained from the Central Animal house, University of Newcastle, Newcastle, NSW). Groups of 6 rats were given a single IL dose of PBS or a fixed dose of killed NTHi (5×10 9 ) plus one of various doses of live  L. acidophilus  as shown in Table 7 below. On day 14, rats in group A were sham-boosted with 50 μL of PBS and rats in groups B-D were boosted with 50 μL of PBS containing 5×10 8  killed NTHi. Boosting was by intra-tracheal delivery. On day 21 the rats were infected by intra-tracheal instillation of 5×10 8  live NTHi in 50 μL of PBS. Four hours later rats were killed by an overdose of pentobarbitone administered intra-peritoneally. The lungs were lavaged with 10 mL of PBS to obtain broncho-alveolar lavage fluid (BAL). The lungs were then homogenised in 10 mL of PBS to obtain lung homogenate (LH). The number of bacteria in BAL and LH was determining by performing serial dilution of BAL and LH and plating known volumes on chocolate agar plates. After overnight incubation at 37° C. the colonies were counted and the total number of colony-forming units (CFU) in BAL and LH determined The number of bacteria in each group is shown in Table 8.  
                                 TABLE 7                           Rat groups: IL dosing and IT boosting                Rat group   IL immunization   IT boost                       A (6)   PBS   PBS           B (5)   NTHi +  L. acidophilus  2 × 10 8     NTHi           C (6)   NTHi +  L. acidophilus  1 × 10 9     NTHi           D (6)   NTHi +  L. acidophilus  5 × 10 9     NTHi           E (6)   NTHi +  L. acidophilus  2.5 × 10 10     NTHi                      
 
         [0051]    [0051]                                 TABLE 8                           Recovery of live NTHi from the lung:                Rat group   BAL CFU (10 6 )   LH CFU (10 6 )                       A (6)   1.96 ± 0.54   17.9 ± 4.5           B (5)   0.65 ± 0.46    3.3 ± 1.7 P = 0.021*           C (6)   1.22 ± 0.49    4.7 ± 1.4 P = 0.019*           D (6)   0.71 ± 0.22    6.8 ± 2.8           E (6)   3.75 ± 1.74   13.2 ± 5.2                                    
         [0052]    The lower doses of lactobacillus are more effective than the higher doses. Again, without wishing to be bound by any particular mechanism of action, this dtata suggests that the ‘adjuvant effect’ may be operating differently from the lactobacillus-only effect.  
         [0053]    From the above data the equivalent dosage for humans is likely to be of the order of 1×10 8  to 1×10 12  bacteria.  
       Example  6   
     Evaluation of Optical Dose-Size/Dose-Regimen for NTHi Immunization  
       [0054]    The optical dose size and dosing regimen for killed NTHi immunization were determined. The different regimens evaluated are shown in Table 9. A single IL dose, a single IL dose followed by a gavage dose, and a single IL dose followed by two gavage doses were evaluated. Only one dose could be given IL as this involves surgery to expose the duodenum. Animal ethics considerations allow only one surgical intervention. Sebsequent dos s were therefore delivered by garage.  
                                         TABLE 9                           Dosing regimens                Dose 1   Dose 2   Dose 3               Regimen   (IL)   (Gavage)   (Gavage)   IT boost   Infection/kill               1   Day 0   —   —   Day 28   Day 35       2   Day 0   Day 14   —   Day 28   Day 35       3   Day 0   Day 14   Day 21   Day 28   Day 35                  
 
         [0055]    Results:  
         [0056]    (i) Regimen 1  
         [0057]    DA specific pathogen-free rats (187-213 g) were obtained from the Central Animal house, University of Newcastle, Newcastle, NSW). Rats (6 per group) were given a single IL dose of killed NTHi as per regimen 1 in table 9, of various dose sizes as shown in Table 10. The killed NTHi was contained in 0.3 mL of PBS. The IT boost was with PBS (group A) or 2×10 7  killed NTHI (groups B-D). Rats were infected intra-tracheally with 50 μL of PBS containing 5×10 8  live NTHi. The bacteria recovered from BAL and LH is shown in Table 11.  
                                 TABLE 10                           Dose sizes tested in regimen 1                Rat group   IL immunization   IT boost                       A   PBS   PBS           B   NTHi 3 × 10 9     NTHi 2 × 10 7             C   NTHi 3 × 10 8     NTHi 2 × 10 7             D   NTHi 3 × 10 7     NTHi 2 × 10 7                        
 
         [0058]    [0058]                                 TABLE 11                           Recovery of live NTHi from the lung:                Rat group   BAL CFU (10 6 )   LH CFU (10 6 )                       A (5)   1.12 ± 0.20   17.1 ± 1.9           B (6)   0.76 ± 0.14 P = 0.029*    8.0 ± 1.5 P = 0.042*           C (6)   0.70 ± 0.20 P = 0.030*    5.2 ± 1.4 P = 0.006*           D (6)   1.76 ± 0.37   16.1 ± 4.7                                                
         [0059]    It is apparent that for a single immunizing IL-dose both the higher dose levels (3×10 8  and 3×10 8 ) were equally effective in providing protective immunity. The lowest dose (3×10 7 ) was ineffective.  
         [0060]    (ii) Regimen 2  
         [0061]    DA specific pathogen-free rats (187-219 g) were obtained from the Central Animal house, University of Newcastle, Newcastle, NSW). Rats (6 per group) were given a single IL dose of killed NTHi as per regimen 2 in table  9+ , fvarious dose sizes as shown in Table  12. The killed NTHi was contained in 0.3 mL of PBS. The IT boost was with PBS (group A) or 2×10 7  killed NTHI (groups B-D) in 50 μL of PBS. Rats went infected intra-tracheally with 50 μL of PBS containing 5×10 8  live NTHi. The bacteria recovered from BAL and LH is shown in Table 13.  
                                     TABLE 12                           Dose sizes tested in regimen 2            Rat                       group   IL dose   Oral dose   IT boost   Infect/kill               A   PBS   PBS   PBS   NTHi 3 × 10 8         B   NTHi 3 × 10 7     NTHi 3 × 10 7     NTHi 8 × 10 7     NTHi 3 × 10 8         C   NTHi 3 × 10 8     NTHi 3 × 10 8     NTHi 8 × 10 7     NTHi 3 × 10 8         D   NTHi 3 × 10 9     NTHi 3 × 10 9     NTHi 8 × 10 7     NTHi 3 × 10 8         Day   0   14   28   35                  
 
         [0062]    [0062]                                                   TABLE 13                           Recovery of live bacteria from the lung:            Rat group   BAL CFU (10 6)     LH CFU (10 6 )                    A (6)   12.7 ± 4.0         44.7 ± 10.0           B (5)   2.9 ± 1.3       13.5 ± 1.2   P = 0.019*       C (5)   5.1 ± 3.4       17.2 ± 4.7   P = 0.042*       D (6)   2.9 ± 4.0   P = 0.042*   15.4 ± 9.8   P = 0.045*                            
         [0063]    It is apparent that when two doses are given, all three dose sizes give the same degree of protection in LH. The level of protection is also comparable for the 3 doses in BAL but is only statistically significant for the highest dose in this experiement.  
         [0064]    (ii) Regimen 3  
         [0065]    DA specific pathogen-free rats (176-213 g) were obtained from the Central Animal house, University of Newcastle, Newcastle, NSW). Rats (6 per group) were given a single IL dose of killed NTHi as per regimen 3 in table  9 , of various dose sizes as shown in Table 14. The killed NTHi was contained in 0.3 mL of PBS. The IT boost was with 50 μL of PBS (group A) or 2×10 7  killed NTHI in 50 μL of PBS (groups B-D). Rats were infected inta-tracheally with 50 μL of PBS containing 5×10 8  live NTHi. The bacteria recovered from BAL and LH is shown in Table 15.  
                                     TABLE 14                           Dose sizes tested in regimen 3            Rat                       group   IL dose   Oral doses   IT boost   Infect/kill               A   PBS   PBS   PBS   NTHi 3 × 10 8         B   NTHi 3 × 10 7     NTHi 3 × 10 7     NTHi 8 × 10 7     NTHi 3 × 10 8         C   NTHi 3 × 10 8     NTHi 3 × 10 8     NTHi 8 × 10 7     NTHi 3 × 10 8         D   NTHi 3 × 10 9     NTHi 3 × 10 9     NTHi 8 × 10 7     NTHi 3 × 10 8         Day   0   14 and 21   28   35                  
 
         [0066]    [0066]                                                       TABLE 15                           Recovery of live bacteria from the lung:                Rat group   BAL CFU (10 6)     LH CFU (10 6 )                            A (6)   2.2 ± 0.7       16.8 ± 8.0            B (6)   0.48 ± 0.23   P = 0.045*   3.3 ± 1.4           C (6)   0.79 ± 0.21       5.6 ± 1.8           D (6)   0.45 ± 0.23   P = 0.042*   3.7 ± 1.5                                    
         [0067]    For 3 intestinal doses (one IL plus two by gavage) similar protection is provided by all three dose levels. There is no apparent advantage of three doses over two doses (regimen 2).  
         [0068]    From the above data the equivalent dosage for humans is likely to be of the order of 1×10 12  bacteria.  
       Example 7  
     Long-Term Immunization with NTHi and  L. acidophilus by a single IL Dose.    
       [0069]    An experiment was performed to determine the duration of the enhanced protection provided by addition of  L. acidophilus . DA specific pathogen-free rats (201-293 g) were obtained from the Central Animal house, University of Newcastle, Newcastle, NSW). Groups of 6 rats were given an IL dose of 0.75 mL of PBS of PBS containing 5×10 8  killed NTHI or a mixture of 5×10 9  killed NTHi and 2.5×10 10  live  L. acidophilus  as shown in Table 16. Rats were IT boosted 14 days later with 50 μK if PBS or PBS containing 5×10 8  killed NTHi as shown in Table 16. Three months after the IL dose rats were infected intr-tracheally (IT) with 5×10 8  live NTHi in 50 μL of PBS. Four hours after infection rats-were sacrificed and BAL and LH prepared for determination of total bacteria, measured as described in above examples and expressed as colony forming units (CFU).  
                                 TABLE 16                           Rat groups: IL dose and IT boost                Rat group   IL-immunization   IT-boost                       A   PBS   PBS           B   NTHi   NTHi           C     L. acidophilus     PBS           D   NTHi +  L. acidophilus     NTHi                      
 
         [0070]    [0070]                                                   TABLE 17                           Live bacteria recovered from the lung:            Rat group   BAL CFU (10 6 )   LH CFU (10 6 )                    A (6)   6.2 ± 1.3       10.4 ± 1.7           B (6)   1.7 ± 0.4   P = 0.007*    7.3 ± 1.4   P = 0.02 a         C (6)   3.0 ± 0.8       18.8 ± 3.9       D (5)   2.6 ± 2.0       16.6 ± 8.4                                                    
         [0071]    Over this 3 month experiment the immunization with NTHi alone was most effective. There is no apparent effect of additional  L. acidophilus  dosing over this time period.  
         [0072]    Although the present invention was described with reference to specific examples and preferred embodiments, it will be understool that variations in keeping with the broad concepts and the spirit of the invention herein described are also contemplated.