Abstract:
Disclosed are methods for monitoring the gastrointestinal tract of the human gastrointestinal system. The method includes: 1) grouping microbes into specific operational taxonomic units (OTU); 2) using oligonucleotide probes and PCR primers to detect and quantify specific microbes (bacteria, fungi/yeast, protozoans and parasitic worms) in human fecal material. The inventions also discloses a kit that includes: a DNA isolation step; 2) accumulation of specific operational taxonomic units (OTU); 3) identification and quantifying of sequences internal to the OTU; 4) reporting changes the indigenous population of the human gastrointestinal system.

Description:
CROSS REFERENCE TO A PROVISIONAL APPLICATION 
       [0001]    This application claims the benefit of Provisional Application Ser. No. 61/041,581, filed on Apr. 1, 2008, and Provisional Application Ser. No. 61/041,584, also filed on Apr. 1, 2008, and the entirety of each is hereby incorporated herein by reference. 
     
    
     SEQUENCE LISTING 
       [0002]    This application includes a Sequence Listing presented herewith. Filed herewith is electronic file “GI Sequences_ST25.txt” created Apr. 1, 2009, with a size of 48 KB, the entirety of which is hereby incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    The present invention relates to the use specific oligonucleotide probes and PCR primers in molecular-based methods to detect and quantify microbes indigenous and pathogenic to the human gastrointestinal tract. 
         [0005]    2. Background of the Invention 
         [0006]    The following literature is of use in the subject matter of the present invention and is incorporated herein by reference:
   1. Mackie R I, Sghir A, Gaskins H R. Developmental microbial ecology of the neonatal gastrointestinal tract.  Am J Clin Nutr . May 1999; 69(5):1035S-1045S.   2. Hawrelak J A, Myers S P. The causes of intestinal dysbiosis: a review.  Altern Med. Rev . June 2004; 9(2):180-197.   3. Galland L, Barrie S. Intestinal dysbiosis and the causes of diseases.  J. Advancement Med.  1993; 6:67-82.   4. Savage D C. Microbial ecology of the gastrointestinal tract.  Annu Rev Microbiol.  1977; 31:107-133.   5. Berg R D. The indigenous gastrointestinal microflora.  Trends Microbiol . November 1996; 4(11):430-435.   6. Finegold S, Sutter V, Mathisen G.  Normal indigenous intestinal flora . New York: Academic Press; 1983.   7. Leff et al., 1995, Appl. Environ. Microbiol., 61:1634-1636.   8. Xiao et al, 1999, Appl Environ. Microbiol., 65:3386-3391.   
 
         [0015]    The population of the microbiota of the human gastrointestinal (“GI”) tract is widely diverse and complex with a high population density. All major groups of organisms are represented. While predominately bacteria, a variety of protozoa are also present. In the colon there are over 10 11  bacterial cells per gram and over 400 different species. These bacterial cells outnumber host cells by at least a factor of 10. This microbial population has important influences on host physiological, nutritional and immunological processes. In particular, they protect against pathogenic bacteria and drive the development of the immune system during neonatal life. Further metabolic activities of the GI microbiota that beneficially affect the host include continued degradation of food components, vitamin production, and production of short chain fatty acids that feed the colonic mucosa. It is clear that factors such as diet, sickness, stress, or medication can result in loss of well-being of the host, and it is assumed that some of these symptoms are due to perturbation of what is termed the normal balance of the gut microbiota. Knowledge of the structure and function of the standard microbiota, and its response to diet, genetic background and lifetime of the host must be taken into account when designing probiotic-based functional foods. Moreover, this biomass should more rightly be considered a rapidly adapting, renewable organ with considerable metabolic activity and significant influence on human health. Consequently there is renewed and growing interest in identifying the types and activities of these gut microbes. 1    
         [0016]    The normal, healthy balance in microbiota provides colonization resistance to pathogens. Since anaerobes comprise over 95% of these organisms, their analysis is of prime importance. Gut microbes might also stimulate immune responses to prevent conditions such as intestinal dysbiosis. Intestinal dysbiosis may be defined as a state of disordered microbial ecology that causes disease. Specifically, the concept of dysbiosis rests on the assumption that patterns of intestinal flora, specifically overgrowth of some microorganisms found commonly in intestinal flora, have an impact on human health. Symptoms and conditions thought to be caused or complicated by dysbiosis include inflammatory bowel diseases, inflammatory or autoimmune disorders, food allergy, atopic eczema, unexplained fatigue, arthritis, mental/emotional disorders in both children and adults, malnutrition and breast and colon cancer. 2,3    
         [0017]    Most studies of microbiota in the GI tract have used fecal samples. These do not necessarily represent the populations along the entire GI tract from stomach to rectum. Conditions and species can alter greatly along this tract and generally run from lower to higher population densities. The stomach and proximal small intestine with highly acid conditions and rapid flow contain 10 3  to 10 5  bacteria per gram or ml of content. These are predominated by acid tolerant lactobacilli and streptococci bacteria. The distal small intestine to the ileocecal valve usually ranges to 10 8  bacteria per gram or ml of content. The large intestine generates the highest growth due to longer residence time and ranges from 10 10  to 10 11  bacteria per gram or ml of content. This region generates a low redox potential and high amount of short chain fatty acids. 
         [0018]    Not only does the microbiota content change throughout the length of the GI tract but there are also different microenvironments where these organisms can grow. At least four microhabitats exist: the intestinal lumen, the unstirred mucus layer that covers the epithelium, the deeper mucus layer in the crypts between villi, and the surface mucosa of the epithelial cells. 4,5  Given this diverse ecological community the question arises as to how to sample the various environments to identify populations of microbes and ultimately understand the host-microbe interactions. This problem is an extremely difficult one since any intervention to obtain a sample potentially disrupts the population. Fecal sampling has been used for years in microbiota assessment. But it should be understood that this sample primarily most appropriately represents organisms growing in the colon. In addition, &gt;98% of fecal bacteria will not grow in oxygen. 4  Therefore, standard culture techniques miss the majority of organisms present. 
         [0019]    Conventional bacteriological methods like microscopy, culture, and identification are used for the analysis and/or quantification of the intestinal microbiota. 6  Limitations of conventional methods are their low sensitivities, 7  their inability to detect noncultivatable bacteria and unknown species, their time-consuming aspects, and their low levels of reproducibility due to the multitude of species to be identified and quantified. In addition, the large differences in growth rates and growth requirements of the different species present in the human gut indicate that quantification by culture is bound to be inaccurate. The application of molecular techniques for detection and identification of microbes has provided a major breakthrough in the analysis of microbial ecosystems and their function. 7    
         [0020]    To overcome the problems of culture, a number of molecular-based methods have been employed to characterize the microbiota of the human gastrointestinal tract. Although identification and characterization of genomic sequence data for individual microbes may provide for the identification of specific microbes, such targeted testing fails to provide a comprehensive, economically feasible system for monitoring the ecosystem of the gastrointestinal tract. The accuracy of a molecular diagnostic test for a microbe may be compromised where the pathogenic agent is endemic, or possesses substantial genetic similarity to non-pathogenic organisms. 7,8    
         [0021]    Detailed information of the microbial community composition in natural systems can be gained from the phylogenetic analysis of 16S rDNA sequences obtained directly from samples by PCR amplification, cloning and sequencing. However, the results showed that the microbial community is complex, and that the bacterial diversity cannot be comprehended by culturing. 8    
         [0022]    Considering the aforementioned, there is an obvious need in the art for process and methods that enable real-time monitoring of the balance of indigenous microorganisms of the human gastrointestinal tract. The monitoring system should also allow for detection of known, as well as unknown, pathogenic microbes that may have a negative impact on human health. 
       SUMMARY OF THE INVENTION 
       [0023]    In one aspect the present invention provides a method for monitoring the microbiota of the human gastrointestinal tract. The method includes the steps of identifying universal PCR primers to group microbial operational taxonomic units, and then applying the universal PCR primers to a sample of the gastrointestinal tract to produce PCR products between 500 bp-1500 bp in size. In another aspect, the universal PCR primers are specific to bacteria operational taxonomic units and include the sequence of any one of SEQ ID NO:1-SEQ ID NO:2 and SEQ ID NO. 54-SEQ ID NO. 55. In another aspect, the universal PCR primers are specific to fungi and yeast operational taxonomic units and include the sequence of any one of SEQ ID NO:82-SEQ ID NO:83 and SEQ ID NO:92-SEQ ID NO:93. In yet another aspect, the universal PCR primers are specific to parasitic protozoans and worms operational taxonomic units and include the sequence of any one of SEQ ID NO:92-SEQ ID NO:93. 
         [0024]    In another aspect, the universal PCR primers obtain qualitative or quantitative data and report for specific microbial DNA sequences by analyzing DNA sequences of specific microbial operational taxonomic units using molecular-based methods. The molecular based methods may include DNA hybridization, DNA arrays, DNA sequencing, PCR Arrays and multiplex PCR. The oligonucleotides probes may include sequences of any one of SEQ ID NO:1-SEQ ID NO:309 for the differentiation of microbes localized to the internal sequences of a specific operational taxonomic unit. 
         [0025]    In yet another aspect, the invention provides a process for monitoring microorganisms that are indigenous and/or pathogenic to an ecosystem. The process including providing a method for simultaneous collection and inactivation of microbial growth in fecal material, providing a method for extracting DNA from fecal material that is amendable to sensitive nucleic acid analysis, and providing a method for concentrating target microbial nucleic acids. The process then provides for the specific identification and quantification of nucleic acid sequences specific to a microorganism at the genus or species level. The ecosystem of interest may include the human gastrointestinal tract. The fecal material may be collected in medium containing 0.1%-50% formalin and the target nucleic acid may be DNA. 
         [0026]    In yet another aspect, the present invention provides a method for detecting a microbial species in a sample. The method includes the steps of lysing cells in said sample to release genomic DNA. Contacting genomic DNA from the previous step with a primer pair comprising sequences of any one of SEQ ID NO:1-SEQ ID NO:309 for the differentiation of microbes localized to the internal sequences of a specific operational taxonomic unit. Amplifying the microbial DNA to produce an amplification product. And detecting said amplification product wherein the presence of said product is indicative of the presence of a microbial species in said sample and the absence of said product is indicative of the absence of a microbial species in said sample. The method may also include quantitating the level of a microbial species in the sample. The method includes the steps of quantitating the level of said amplification product by comparison with at least one reference standard, wherein the level of said amplification product is indicative of the level of said microbial species. 
         [0027]    These and other aspects of the invention will become apparent from the following description of the preferred embodiments taken in conjunction with the tables and figures. As would be obvious to one skilled in the art, many variations and modifications of the invention may be effected without departing from the spirit and scope of the novel concepts of the disclosure. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0028]    Because of the demand for screening test that are rapid for pathogen and antibiotic resistance identification, molecular diagnostics are playing an increasingly important role in diagnosing and preventing infections and improving overall hospital operations. As physicians, pharmacists and even hospitals administrators demand rapid microbiology results, many laboratories are focusing on being part of cross-functional implementation teams that not only assure the new tests are implemented efficiently, but that the results affect real change for patient management, hospital operations and laboratory efficacy. The present invention provides a process for monitoring the microbial populations of the human gastrointestinal tract. To improve our understanding of the intestinal ecosystem the present invention takes a ribosomal RNA-approach targeting the small and large-subunit rRNA&#39;s with various molecular methods, each having its advantages. The present invention may be embodied in a variety of ways. 
         [0029]    According to a first embodiment of the invention, there is provided a consortium of microorganisms indigenous and/or pathogenic to the human gastrointestinal tract. This embodiment comprises a method to prepare a DNA sample from fecal material preserved in formalin, the method comprises grouping the DNA sequences into operational taxonomic units (OTUs) using universal PCR primers. The primers used to detect microbial operational taxonomic units are presented in the Sequence Listing below. 
         [0030]    The combination of the non-specific fragmenting genomic DNA by formalin and the DNA isolation method used the aforementioned universal PCR primers disclosed in this invention are design to amplify target sequences that are between 500-1200 base pairs. Moreover these primers flank regions of high sequence heterogeneity that allows the differentiation of microbial organism at the genus/species level. 
         [0031]    The method may include identifying at least one nucleic acid sequence that is specific to a single OTU isolated nucleic acid having a sequence derived from a single predetermined microbial operational taxonomic unit. The microbial operational taxonomic unit PCR primers are disclosed in this invention for bacteria, fungi/yeast, protozoan&#39;s, and parasitic worms. 
         [0032]    According to the first embodiment of the invention, there is provided a primer pair for PCR amplification of bacteria DNA, said primer pair comprising: (a) a first oligonucleotide of at least 18 nucleotides having a sequence selected from one strand of a bacterial 16S rDNA gene; and (b) a second oligonucleotide of at least 18 nucleotides having a sequence selected from the other strand of said 16S rDNA gene downstream of said first oligonucleotide sequence; wherein at least one of said first and second oligonucleotides is selected from: (i) any one of SEQ ID NO: 1 to SEQ ID NO: 2; or (ii) a DNA sequence having at least 92% identity with any one SEQ ID NO: 1 to SEQ ID NO: 2. 
         [0033]    According to another embodiment of the present invention, there is provided a primer pair for PCR amplification of Bacteria DNA, said primer pair comprising: (a) a first oligonucleotide of at least 18 nucleotides having a sequence selected from one strand of a bacterial 23S rDNA gene; and (b) a second oligonucleotide of at least 18 nucleotides having a sequence selected from the other strand of said 23S rDNA gene downstream of said first oligonucleotide sequence; wherein at least one of said first and second oligonucleotides is selected from: (i) any one of SEQ ID NO: 54 to SEQ ID NO: 55; or (ii) a DNA sequence having at least 92% identity with any one SEQ ID NO: 54 to SEQ ID NO: 55. 
         [0034]    According to another embodiment of the present invention, there is provided a primer pair for PCR amplification of fungi/yeast DNA, said primer pair comprising: (a) a first oligonucleotide of at least 18 nucleotides having a sequence selected from one strand of a fungus or yeast 18S rDNA gene; and (b) a second oligonucleotide of at least 12 nucleotides having a sequence selected from the other strand of said 18S rDNA gene downstream of said first oligonucleotide sequence; wherein at least one of said first and second oligonucleotides is selected from: (i) any one of SEQ ID NO: 82 to SEQ ID NO: 83; or (ii) a DNA sequence having at least 92% identity with any one SEQ ID NO: 82 to SEQ ID NO: 83. 
         [0035]    According to another embodiment of the present invention, there is provided a primer pair for PCR amplification of fungi, protozoan and parasitic worm DNA, said primer pair comprising: (a) a first oligonucleotide of at least 18 nucleotides having a sequence selected from one strand of a protozoan/worm 18S rDNA gene; and (b) a second oligonucleotide of at least 12 nucleotides having a sequence selected from the other strand of said 18S rDNA gene downstream of said first oligonucleotide sequence; wherein at least one of said first and second oligonucleotides is selected from: (i) any one of SEQ ID NO: 92 to SEQ ID NO: 93; or (ii) a DNA sequence having at least 92% identity with any one SEQ ID NO: 92 to SEQ ID NO: 93. 
         [0036]    According to yet another embodiment, the present invention may provide a method for monitoring the microbiota of the human gastrointestinal tract whereby quantitative and qualitative data can be provided by using quantifiable labels to label the universal PCR primers that represent individual or all of the microbial operational taxonomic units disclosed in this invention. Furthermore, these labeled operation taxonomic units in conjunction with a plurality (SEQ ID NO:1 thru SEQ ID NO:309) of available oligonucleotide probes (40 bp-100 bp) that are localize internally to the disclosed universal sequences may be used in DNA hybridization or array based methods to provide information on the abundance of specific organisms of interest, such as key bioindicators, pathogens, or microbial contaminants in a gastrointestinal tract system. 
         [0037]    In yet another embodiment of the present invention, there is provided a kit for monitoring the microbiota of the human gastrointestinal tract comprising: at least one primer according to an embodiment of the invention; or at least one primer pair according to another embodiment of the invention; or at least one probe according to yet another embodiment of the invention. 
       Examples 
       [0038]    The primers used to detect microbial operational taxonomic units are presented in the Sequence Listing. 
       Universal Bacteria PCR 
       [0039]    The melting temperature calculated for entbac1 (SEQ ID NO:1) was 60 degree C. and a fragment size of approximately 1052 nucleotides was calculated in a PCR with primer (SEQ ID NO:2). The entbac2 (SEQ ID NO:2) sequence corresponds to the sequence at positions 440 to 457 of the  E. coli  16S rDNA gene. The PCRs were carried out according to methods detailed in “Molecular Cloning: a Laboratory Manual” Sambrook et al. 2nd ed. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y. (1989) which is incorporated herein by reference, at an annealing temperature of 55 degrees C. The results of electrophoretic analysis of PCRs on an agarose gel are presented in  FIG. 1 . Details of the material analysed in each lane of the gel are given in  FIG. 1 . The results depicted in  FIG. 1  are tabulated below in Table 1. 
         [0000]                                  TABLE 1                   Evaluation of the sensitivity of the universal bacteria primer set       (SEQ ID 1 and SEQ ID 2) using  Helicobacter pylori  (Control DNA).                Lane   Scoring                       Lane 1 (1 ng)   +++           Lane 2 (250 pg)   ++           Lane 3 (10 pg)   +           Lane 4 (100 fg)   +/−                       The scorings for the agarose gel electrophoresis analysis is by quantitating the intensity of the PCR products in the stained gel using the naked eye. A definition of the scoring follows: − = no band; +/− = very faint band; + through ++++ = increasing intensity of the PCR products.            
Amplification of Universal Bacteria DNA from Different Transport Medium
 
         [0040]    The bacterial universal primer pairs were used to amplify DNA extracted from 3 different transport mediums and the results are presented in  FIG. 2 . The PCRs were carried out according to methods detailed in Sambrook et al. (1989) at an annealing temperature of 55 degrees C. The results of electrophoretic analysis of PCRs on an agarose gel are presented in  FIG. 2 . Details of the material analysed in each lane of the gel are given in  FIG. 2 . The results depicted in  FIG. 2  are tabulated below in Table 2. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Amplification of fecal DNA extracted from different 
               
               
                 transport mediums using the universal bacteria 
               
               
                 primer set (SEQ ID 1 and SEQ ID 2). 
               
             
          
           
               
                   
                 Lane 
                 Scoring 
               
               
                   
                   
               
               
                   
                 Lane 1 (CS medium) 
                 +++ 
               
               
                   
                 Lane 2 (Formalin medium) 
                 +++ 
               
               
                   
                 Lane 3 (Metametrix Nucleic Acid 
                 +++ 
               
               
                   
                 Recovery Solution) 
               
               
                   
                   
               
               
                   
                 The scorings for the agarose gel electrophoresis analysis is by quantitating the intensity of the PCR products in the stained gel using the naked eye. A definition of the scoring follows: − = no band; +/− = very faint band; + through ++++ = increasing intensity of the PCR products. 
               
             
          
         
       
     
       Evaluation of the Specificity of the Universal Bacteria DNA 
       [0041]    The bacterial universal primer pairs were used to amplify DNA from bacteria ( Lactobacillus ), protozoan ( cryptosporidium parvum ), and fungal ( Candidia albicans ) to evaluated the specificity of the primer set. The PCR&#39;s were carried out according to methods detailed in Sambrook et al. (1989) at an annealing temperature of 55 degrees C. The results of this assay are presented in  FIG. 3 . The results of electrophoretic analysis of PCRs on an agarose gel are presented in  FIG. 3 . Details of the material analysed in each lane of the gel are given in  FIG. 3 . The results depicted in  FIG. 3  are tabulated below in Table 3. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Amplification of bacterial, fungal, and protozoan DNA using 
               
               
                 the universal bacteria primer set (SEQ ID 1 and SEQ ID 2). 
               
             
          
           
               
                   
                 Lane 
                 Scoring 
               
               
                   
                   
               
               
                   
                 Lane 1 (Bacteria DNA) 
                 +++ 
               
               
                   
                 Lane 2 (Fungi DNA) 
                 − 
               
               
                   
                 Lane 3 (Protozoan DNA) 
                 − 
               
               
                   
                   
               
               
                   
                 The scorings for the agarose gel electrophoresis analysis is by quantitating the intensity of the PCR products in the stained gel using the naked eye. A definition of the scoring follows: − = no band; +/− = very faint band; + through ++++ = increasing intensity of the PCR products. 
               
             
          
         
       
     
       Evaluation of the Specificity of Oligonucleotide Probes in a PCR Assay 
       [0042]    The primer for the specific detection of  Helicobacter pylori  (SEQ ID NO: 283) was used in a diagnostic PCR. The primer was designed originally for the hybridization experiments. The specificity of this primer can be appreciated from the sequence alignment presented in  FIG. 4  which is an alignment of 16S rDNA sequences of bacterial species localized to the human GI tract against (SEQ ID NO: 283). A melting temperature of 60 degrees C. was calculated for the primer (SEQ ID NO: 50) and a fragment size of approximately 356 nucleotides in a PCR with the forward primer (SEQ ID NO:282) used for the specific detection of  H. pylori  as experimentally determined. The PCRs were carried out according to methods detailed in Sambrook et al. (1989) at an annealing temperature of 50 degrees C. The results of electrophoretic analysis of PCRs on an agarose gel are presented in  FIG. 4 . Details of the material analysed in each lane of the gel are given in  FIG. 4 . The results depicted in  FIG. 4  are tabulated below in Table 4. 
         [0000]                                  TABLE 4                   PCR amplification of  Helicobacter pylori         DNA using oligonucleotide probes.                Lane   Scoring                       Lane 1 ( helicobacter  genus probe)   +++           Lane 2 ( H. pylori  specific probe)   +++                       The scorings for the agarose gel electrophoresis analysis is by quantitating the intensity of the PCR products in the stained gel using the naked eye. A definition of the scoring follows: − = no band; +/− = very faint band; + through ++++ = increasing intensity of the PCR products.            
Amplification of Universal Bacteria DNA Extracted from Human Fecal Material.
 
         [0043]    The bacterial universal primer pairs were used to amplify DNA extracted from 21 human fecal samples and the results are shown in  FIG. 5 . The PCRs were carried out according to methods detailed in Sambrook et al. (1989) at an annealing temperature of 55 degrees C. The results depicted in  FIG. 5  are tabulated below in Table 5. 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Amplification of DNA extracted from human fecal material using 
               
               
                 the universal bacteria primer set (SEQ ID 1 and SEQ ID 2). 
               
             
          
           
               
                   
                 Lane # 
                 Scoring 
               
               
                   
                   
               
             
          
           
               
                   
                 1 
                 ++ 
               
               
                   
                 2 
                 ++ 
               
               
                   
                 3 
                 + 
               
               
                   
                 4 
                 ++++ 
               
               
                   
                 5 
                 +++ 
               
               
                   
                 6 
                 +++ 
               
               
                   
                 7 
                 ++ 
               
               
                   
                 8 
                 ++++ 
               
               
                   
                 9 
                 +++ 
               
               
                   
                 10 
                 +/− 
               
               
                   
                 11 
                 +++ 
               
               
                   
                 12 
                 +++ 
               
               
                   
                 13 
                 ++++ 
               
               
                   
                 14 
                 +++ 
               
               
                   
                 15 
                 − 
               
               
                   
                 16 
                 + 
               
               
                   
                 17 
                 ++ 
               
               
                   
                 18 
                 ++ 
               
               
                   
                 19 
                 ++++ 
               
               
                   
                 20 
                 − 
               
               
                   
                 21 
                 ++ 
               
               
                   
                   
               
               
                   
                 The scorings for the agarose gel electrophoresis analysis is by quantitating the intensity of the PCR products in the stained gel using the naked eye. A definition of the scoring follows: − = no band; +/− = very faint band; + through ++++ = increasing intensity of the PCR products. 
               
             
          
         
       
     
         [0044]    All of the compositions, processes and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the compositions, processes and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the compositions, processes and methods and in the steps or in the sequence of steps of the methods described herein without departing from the concept, spirit, and scope of the invention. More specifically, it will be apparent that certain compositions, such as DNA sequences, primers, or probes, which are both chemically and physiologically related may be substituted for the compositions described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope, and concept of the invention.