Patent Application
20220348886
The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Jan. 21, 2019, corrected Sep. 24, 2020, is named RMDOCS-#6135266-v1-TXT_Copy_of_SEQ_Listing_ -_Corrected_Sept_2020.TXT and is 524,473 bytes in size.
Prevention, diagnostics and treatment of human, animal, and plant bacterial infections.
Bacteria are unicellular, biological entities that are mostly not harmful to humans—less than one percent of the different types make people sick. Many bacterial species are beneficial to humans, such as those that help to digest food, destroy disease-causing cells, and provide needed vitamins.
Infectious bacteria (the harmful one percent) cause illness in humans and animals. They reproduce quickly in the body and produce toxic proteins that cause tissue damage and illness.
Bacteriophages (also referred to as phages) were discovered by Ernest Hankin in 1896, and utilized as antibacterials against cholera. These bacteria-specific viruses can infect and destroy bacterial cells.
Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome. Bacteriophages replicate within bacterium by injecting their viral genetic material (DNA or RNA) into the host cell effectively taking over the cells functions for the production of progeny bacteriophage leading to the rupture of the cell wall and subsequent bacterial cell death.
Bacteriophages continued to be used as antibacterials until the 1930's. However, it was found that bacteria naturally build up resistance to bacteriophages. With the introduction of chemical antibiotics, use of bacteriophages was abandoned.
While antibiotics are the usual treatment, bacterial mutations conferring antibiotic resistance are becoming increasingly common in pathogenic bacteria world-wide. Methicillin-resistant Staphylococcus aureus (MRSA) bacteria, for example, is an increasingly common form of infection, often acquired through transmission in hospitals. MRSA infections are extremely difficult to treat using conventional antibiotics.
Bacteriophages can be very specific to the type of disease-causing bacterial species. Most bacteriophages have structures that enable it to bind to specific molecules on the surface of their target bacteria.
A key advantage of bacteriophages is that they enable the elimination of antibiotic-resistant bacteria without the need for increasingly toxic antibiotics or harmful or irritating chemical-exposure to humans, animals and the environment (see, e.g. U.S. Pat. No. 6,699,701 to Intralytix).
In natural settings, bacteriophages can be isolated from the environment in which the particular bacterium grows following a paired relationship, for example from sewage or feces. Repositories of different types of natural bacteriophages have been created to provide access to bacteriophages to treat difficult infections by specific bacterial species.
One problem with using bacteriophages has been that the patient's own body will often have an immune response against the bacteriophages and eliminate the bacteriophages from blood. U.S. Pat. Nos. 5,660,812, 5,688,501, 5,811,093 and 5,766,892 all show methods of selecting or generating (using mutations) bacteriophages to improve the bacteriophage half-life within the blood of a patient to be treated.
Another problem associated with prior uses of phages to disinfect or treat bacterial contaminants or diseases, are that bacteria can become resistant to bacteriophages. The presence of, for example, a prophage within a bacterium may block the expression of genes from an infectious bacteriophage, thus preventing replication of the infectious bacteriophage and preventing lysis and killing of the bacterium. A prophage may also cause the destruction of incoming phage DNA.
This has previously meant that either the bacteriophage needs to be matched to the bacterium, often requiring complicated genetic analysis of the bacterium, or a number of different phages need to be used in combination. The production of panels of different bacteriophages, such as panels of vir mutants derived from temperate bacteriophage, is disclosed in WO 03/080823.
Currently, only natural bacteriophages exist, and natural bacteriophages that have been mutated and selected for specificity against certain bacteria (see, e.g. U.S. Pat. No. 8,685,697 to Intralytix).
The invention is a template or platform technology for creating customized genetically modified bacteriophages that target and destroy specific bacterial organisms found in humans, animals and agricultural crops, as well as on surfaces in healthcare or food processing facilities.
Specific products can be developed using this template technology such as a disinfectant spray for MRSA, food additive to prevent antibiotic use in animal feed, and treatment of bacterial infections in humans. The invention thus encompasses genetically modified bacteriophages as well as including gene products derived from bacteriophages, used to treat and or remove bacterial infections utilizing bacteriophages.
According to one aspect, there is disclosed a method to manipulate the viral genome to cause functional changes in the life cycle of the virus.
In one embodiment, the invention provides a method of engineering bacteriophages comprising:
In another embodiment, the invention provides a method of engineering bacteriophages comprising:
In another embodiment, the invention provides a method of engineering bacteriophages comprising:
In another embodiment, the invention provides a method of engineering bacteriophages comprising:
In another embodiment, the invention provides a method of growing bacteriophages comprising:
The bacteriophage may comprise a non-native attachment gene, wherein said non-native attachment gene is specific for attaching to a selected bacteria. The bacteriophage may have no native attachment genes. The bacteriophage may be lytic. The non-native attachment gene is specific for pathogenic/non-pathogenic bacteria. The bacteriophage may be used for cleaning, treating, or preventing a bacterial contaminant.
The invention also teaches bacteriophage for diagnosis of the presence or absence of a specific bacteria.
The invention also teaches a method of producing a mutant bacteriophage, the method comprising inactivating an attachment gene from a selected bacteriophage, the selected bacteriophage being isolated from bacteriophages from the environment; inserting, into the selected bacteriophage, a first heterologous nucleic acid sequence comprising a first open reading frame encoding a first specific attachment gene, the first specific attachment gene being different than the inactivated attachment gene and being specific for a selected bacteria, to produce the mutant bacteriophage. A second heterologous nucleic acid sequence may be inserted in a second open reading frame encoding a gene useful for overcoming bacterial defenses. The gene for overcoming bacterial defenses may be a biofilm degrading gene, a glycocalyx degrading gene, a gene encoding an antibacterial protein, and a gene for an enzyme that disrupts the bacterial wall, to produce the mutant bacteriophage. The step of inactivating may inactivate all attachment genes from the selected bacteriophage.
The invention also teaches a bacteriophage which is a lytic bacteriophage, a bateriohage with a small genome size, or a bacteriophage with structural and functional genes to lyse gram negative and gram-positive bacteria, or any combination thereof.
The invention also teaches an anti-microbial composition for sanitizing or decontaminating a surface.
The invention also teaches a method of eliminating a microbial contaminant, the method comprising: obtaining one or more lytic enzymes produced by the mutant bacteriophage; applying the one or more lytic enzymes to a bacterial contaminant, without prior infection of the bacterial contaminant with a bacteriophage, to eliminate the bacterial contaminant.
The methods and techniques of the present disclosure are generally performed according to conventional methods well known in the art and as described in various general and more specific references that are cited and discussed throughout the present specification unless otherwise indicated.
The terms “polypeptide”, “peptide”, and “protein” are typically used interchangeably herein to refer to a polymer of amino acid residues. Amino acids may be referred to herein by either their commonly known three letter symbols or by the one-letter symbols recommended by the IUPAC-IUB Biochemical Nomenclature Commission. Each protein or polypeptide will have a unique function. The invention includes polypeptides and functional fragments thereof, as well as mutants and variants having the same biological function or activity.
In some embodiments, polymeric molecules (e.g., a polypeptide sequence or nucleic acid sequence) are considered to be “homologous” to one another if their sequences are at least 25%, at least 30%, at least 35%, at least 40%, at least 45%, at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, or at least 99% identical.
In some embodiments a fragment of a nucleic acid sequence is a fragment of an open reading frame sequence. In some embodiments, such a fragment encodes a polypeptide fragment (as defined herein) of the protein encoded by the open reading frame nucleotide sequence.
The term “nucleic acid fragment” as used herein refers to a nucleic acid sequence that has a deletion. In some embodiments a fragment of a nucleic acid sequence is a fragment of an open reading frame sequence. In some embodiments, such a fragment encodes a polypeptide fragment (as defined herein) of the protein encoded by the open reading frame nucleotide sequence.
The term “construct” refers to a nucleic acid sequence encoding a protein, operably linked to a promoter and/or other regulatory sequences.
The term “genomic sequence” refers to a sequence having non-contiguous open reading frames, where introns interrupt the protein coding regions.
As used herein, the terms “encoding”, “coding”, or “encoded” when used in the context of a specified nucleic acid mean that the nucleic acid comprises the requisite information to guide translation of the nucleotide sequence into a specified protein. The information by which a protein is encoded is specified by the use of codons. A nucleic acid encoding a protein may comprise non-translated sequences (e.g., introns) within translated regions of the nucleic acid or may lack such intervening non-translated sequences (e.g., as in cDNA).
The term “percent sequence identity” or “identical” in the context of nucleic acid sequences refers to the residues in the two sequences which are the same when aligned for maximum correspondence. For instance, polynucleotide sequences can be compared using the computer program, BLAST (Altschul et al., J. Mol. Biol. 215:403-410 (1990); Gish and States, Nature Genet. 3:266-272 (1993).
The term “substantial homology” or “substantial similarity,” when referring to a nucleic acid or fragment thereof, indicates that, when optimally aligned with appropriate nucleotide insertions or deletions with another nucleic acid (or its complementary strand), there is nucleotide sequence identity in at least about 70%, 80%, 85%, or at least about 90%, or at least about 95%, 96%, 97%, 98% or 99% of the nucleotide bases, as measured by any well-known algorithm of sequence identity, such as BLAST, as discussed above.
As used herein, “heterologous nucleic acid sequence” is any sequence placed at a location in the genome where it does not normally occur. In some embodiments, the heterologous nucleic acid sequence is a natural phage sequence, albeit from a different phage.
A particular nucleic acid sequence also encompasses conservatively modified variants thereof (such as degenerate codon substitutions) and complementary sequences, as well as the sequence explicitly indicated. Thus, a nucleic acid sequence encoding a protein sequence disclosed herein also encompasses modified variants thereof as described herein. Substantially similar nucleic acid fragments of the instant invention may also be characterized by the percent identity of the amino acid sequences that they encode to the amino acid sequences disclosed herein, as determined by algorithms commonly employed by those skilled in this art.
An “orgin bacteriophage” is a phage isolated from a natural or human made environment that has not been modified by genetic engineering. A “mutant bacteriophage” is a bacteriophage that comprises a genome that has been genetically modified by insertion of a heterologous nucleic acid sequence into the genome, or the genome of the phage. In some embodiments the genome of a origin bacteriophage is modified by recombinant DNA technology to introduce a heterologous nucleic acid sequence into the genome at a defined site.
“Operatively linked” or “operably linked” expression control sequences refers to a linkage in which the expression control sequence is contiguous with coding sequences of interest to control expression of the coding sequences of interest, as well as expression control sequences that act in trans or at a distance to control expression of the coding sequence.
A “coding sequence” or “open reading frame” is a sequence of nucleotides that encodes a polypeptide or protein. The termini of the coding sequence are a start codon and a stop codon. The disclosure also includes native, isolated, or recombinant nucleic acid sequences encoding a protein, as well as vectors and/or (host) cells containing the coding sequences for the protein.
Fragments and variants of the disclosed nucleotide sequences and proteins encoded thereby are also encompassed by the present invention. By “fragment” a portion of the nucleotide sequence or a portion of the amino acid sequence and hence protein encoded thereby is intended. Fragments of a nucleotide sequence may encode protein fragments that retain the biological activity of the native protein. Accordingly, the present disclosure relates to any nucleic acid fragment comprising a nucleotide sequence that encodes all or a substantial portion of the amino acid sequences encoded thereby.
The present technology uses synthetic biology to generate bacteriophages that can bind to specific bacterial strains. Since bacteriophages must attach to host bacterial cells to initiate infection of the bacteria, genetic selections or manipulations in the viral DNA or RNA can define binding characteristics, thus expanding the range of host cells beyond the natural paired relationship. According to one embodiment there some characteristics of the disclosed bacteriophages, including the following.
The phages are safe, non-corrosive, and non-toxic. The phages can be engineered so that they do not affect helpful bacteria, animal or human cells. Thus, there is no interference with the food chain, as with antibiotics.
The phages are designed, not discovered in nature. Thus, the technology is adaptable to any bacterial infection. Undesirable genetic components are eliminated. In contrast, the present methods of isolating natural phages for specific bacteria is like finding a “needle in a haystack” for target bacteria.
The phages are engineered to avoid mutation/adaptation of target bacteria resulting in superior kill rates and no resistance. Accordingly, the phages have superior efficacy over known phages. The phages also prevent biofilm formation.
According to one embodiment, the platform is versatile. The disclosed bacteriophages can be used to solve any bacterial problem. The disclosed bacteriophages have application in human health (personalized medicine, disinfectants, and diagnostics) such as for example, in MRSA and VRE, animal health (livestock medicine, diagnostics) such as for example, ear drop for treating dog ear infections of Staphylococcus intermedius, and food safety (produce cleansing, detection of bacterial contamination) such as for example, E. Coli, C. Jejuni, Salmonella, and Listeria.
According to one embodiment, the bacteriophages can not only be used for the treatment of antibiotic-resistant bacterial infections but also for prevention of bacterial-contamination in the environment and in food which may negatively affect human and animal health.
For example, the phages are useful for human health. Methicillin-resistant Staphylococcus aureus (MRSA) bacteria are an increasingly common hospital-acquired infection, often acquired through contact with contaminated surfaces. For facilities with a confirmed MRSA problem, this product can be used to thoroughly clean surfaces and reduce the development of new infections. According to an embodiment, there is provided a multi-strain MRSA-specific disinfectant cleanser that can be used on porous and non-porous surfaces in hospitals including beds, curtains, tables, chairs, diagnostic and monitoring equipment, and medical instruments.
According to an embodiment, the disclosed bacteriophages can be used to reduce or eliminate any bacteria and/or resistant bacteria that are pathogenic to humans and/or animals. In aspects, the advantages of using this disinfectant over the commonly-used disinfectants, such as bleach, are multiple. First, bacteriophage are more effective in destroying bacteria than conventional means. Second, phages can be left on surfaces to destroy new bacterial contamination events, surviving for roughly 24 hours. Third, unlike bleach, bacteriophages do not leave a corrosive residue, and thus do not harm instruments, fabrics, and skin. Fourth, bacteriophages, customized for harmful bacteria, are non-toxic, unlike cleaning solutions.
The phages are also useful in animal health treatments. For example, bacteriophage are tailored to address bacterial infections in chickens, replacing the antibiotic(s) commonly used, resulting antibiotic-free chickens—a commercial benefit in today's marketplace. This treatment also contributes to reducing the growing number of antibiotic-resistant infections that occur as bacteria mutate and evolve to be unaffected by antibiotics.
The phages are also useful in food safety. For example, bacteriophage-cleansing spray can be applied on agricultural crops for the prevention of food-borne illnesses from bacterial contamination during plant cultivation or during harvesting, such as Escherichia coli-contamination of strawberries.
The template technology is utilized to generate bacteriophages with various specific binding domains (thus selecting host range). The technology provides bacteriophages in high concentrations.
In some embodiments, bacteriophage-derived gene products may be useful for “lysis-from-without” whereby bacteria can be eliminated without having to become infected.
According to an embodiment there is provided a method of eliminating a bacterial contaminant without prior infection of the bacterial contaminant with a bacteriophage, the method comprising obtaining one or more lytic enzymes produced by the disclosed bacteriophage; applying the one or more lytic enzymes to a bacterial contaminant to eliminate the bacterial contaminant.
A bacteriophage or phage is defined as a virus that infects bacteria. Bacteriophages have a high specificity to their corresponding host bacteria. To infect bacteria, the bacteriophage attaches to specific receptors on the surface of the bacteria. This attachment determines the host range of each bacteriophage, and normally is restricted to some genera, species, or even subspecies of bacteria. This bacteriophage specificity could provide clinicians, laboratory technicians, technicians in the field, as well as consumers, with the ability to identify (detect or diagnose) specific types of bacteria by exploiting this bacteriophage characteristic.
Bacteriophages experience two types of natural life cycles, or methods of viral reproduction, known as the lytic cycle and the lysogenic cycle. In the lytic cycle, host cells will be broken and suffer death after replication of the virion. In contrast, the lysogenic cycle does not result in immediate lysing of the host cell and consequential host cell death; rather, the bacteriophage genome integrates with the host DNA, or establishes itself as a plasmid, and replicates along with the organism's genome. The endogenous bacteriophage remains dormant until the host is exposed to specific conditions (e.g., stress) at which point the bacteriophage may be activated, initiating the reproductive cycle resulting in the lysis of the host cell.
Endolysins are produced during the last stage of the phage lytic cycle from within their host and most are released into the periplasmic space (Borysowski et al., 2006). From there on, endolysins cleave covalent bonds in the peptidoglycan to release viral progeny (Fischetti, 2008). Within the endolysin subgroup, there are five classes: amidases, endopeptidases, muramidases, glucosaminidases and transglycosylases (Gasset, 2010).
According to an embodiment, there is provided the use of lytic enzymes or enzybiotics from bacterial viruses to combat antimicrobial resistance. An enzybiotic is defined to be a protein that degrades the bacterial cell wall, meaning that it is not subjected to bacteriophage proteins (Borysowski and Gorski, 2010). The term enzybiotics was first conceived in the paper ‘Prevention and elimination of upper respiratory colonization of mice by group A streptococci by using bacteriophage lytic enzyme’ (Nelson et al., 2001). The bacteriophage lytic enzymes are specific. Phage derived lytic enzyme and their destructive activity against certain components of the cell wall found in pathogenic bacterial strains but not the natural microbiota of animals (Gasset. 2010). Two examples include group C streptococcal lysin, effective in lysing group A streptococci but has no effect on normal oral streptococci (Fischetti, 2006). A more relevant example is attained from the use of the outer membrane protein FyuA, commonly expressed in pathogenic Gram-negative Escherichia coli. The fusion of FyuA binding domain to T4 lysozyme results in translocation of the fusion from the outer membrane to the periplasmic space where the lysozyme can destabilize the bacterial cell wall (Lukacik et al., 2013).
According to one embodiment, there is disclosed a method for providing an endolysin protein or plurality of endolysin proteins, which overcome the issues with whole bacteriophages. The one or more endolysins specifically targets and degrades the bacterial cell wall (peptidoglycan) from both within the cell or from outside of the cell resulting in lysis. In aspects, there is provided a method to generate various clones of endolysin genes from numerous bacteriophages and using high-throughput screening, and to evaluate the success of the endolysin clones against one or bacteria, such as for example, Escherichia coli strains, Salmonella typhimurium and Campylobacter jejuni.
Thus, the technology extends the number of bacterial strains that may be treated with bacteriophage or bacteriophage gene products with and without infection.
Bacteriophages multiply themselves by infecting and killing bacteria. During this process, bacterial cell wall components are released along with the bacteriophages. These components may be toxic to humans, animal and bacteria. Thus, large scale preparations of bacteriophages using bacteria require post-manufacturing treatments using harsh organic chemicals to reduce the toxicity to acceptable levels for clinical treatment.
Therefore, according to one embodiment, there is provided a method to grow the disclosed bacteriophages in large-scale use of bacteria by using yeast strains, such as for example, Kluyveromyces lactis and Pichia pastoris. The disclosed methods circumvent the liberation of toxic end products.
Environmental samples were isolated and fully characterized to determine candidates which meet certain criteria. Preferably, a suitable origin bacteriophage is selected from candidates which includes one or more of the following features:
According to an embodiment, there is provided a method to genetically modify one or more suitable origin bacteriophages.
In one embodiment, the origin bacteriophage includes one attachment gene. In another embodiment, the origin bacteriophage includes more than one attachment gene.
In one embodiment, the method generates bacteriophage platforms configured to allow for further interchanging of one or more desired proteins, such as for example, attachment proteins.
According to one embodiment, the bacteriophage genomes are manipulated to change the virus' life cycle, creating gain of function, loss of function or for virus identification (reporter genes). A summary is shown in
In one aspect, the origin bacteriophage is a lytic phage. In one aspect, the origin bacteriophage is a lytic phage that carries one or more attachment gene. In another aspect, the origin bacteriophage is a lytic phage that carries only one attachment gene. In one aspect, the origin bacteriophage carries only one attachment gene.
According to one embodiment, there is provided a method to produce a mutant bacteriophage. In one aspect, the method comprises modifying the phage binding sites of an origin bacteriophage so that the mutant bacteriophage can attach to different serotypes. In one embodiment, the mutant phage is then rescued and the new binding domain is determined.
According to one embodiment, the engineered bacteriophage comprises only lytic genes, wherein any and all lysogenic genes have been removed to ensure integration cannot occur.
According to one embodiment, there is provided a method of ‘cell free cloning’ to provide a template (or platform) technology that allows for the modification/insertion/deletion of viral genes. The platform was generated by constructing a mutant bacteriophage (defined as a phage which was generated from known and unknown genetic codes) using isolated environmental samples.
Genetic comparison of unknown phage types from environmental samples were tested against known phage types allowing us to isolate known gene types.
In one embodiment, there is provided a mutant bacteriophage where genes of interest were added and where unwanted genes were deleted. Together with noncoding regions, the mutant bacteriophage is a genetic platform that carries at least two unique open reading frames (ORF).
These unique ORFs can be used to add genes of interest. With reference to
In aspects, the mutant bacteriophage is a genetic platform that carries four unique open reading frames (ORF).
In one embodiment, the first ORF can be used to insert an attachment gene for a bacteria. In one aspect, the attachment gene can be selected from, but not limited to, the following proteins:
In one embodiment, the second ORF is used to insert a gene encoding a protein useful for overcoming bacterial host defenses.
For example, the second ORF can be for introducing is to add enzymatic functions to combat bacterial defenses. In one aspect, the second ORF can be used to add endolysin genes, and/or biofilm degrading genes.
In an embodiment, the endolysin genes are selected from:
In one embodiment, the biofilm degrading genes and glycocalyx degraders are selected from:
For example, the second ORF can be for introducing antibacterial proteins used in template to address bacterial lysis. In one aspect, an example protein is a bacterial cell wall degrader used to degrade Staphylococcus aureus (>ENA|JQ066320|JQ066320.1 Staphylococcus aureus strain JP1 Psm betal (psm beta1) and Psm beta2 (psm beta2) genes, complete cds). SEQ ID No: 144
In other aspects, the second ORF can be for introducing enzymes which target the key linking chemistries (amide, ester and glycolytic bonds) found in bacterial cell walls. Examples include:
According to an embodiment, there is provided a method of producing a mutant bacteriophage, the method comprising inactivating at least one attachment gene from a selected bacteriophage, the selected bacteriophage can be isolated from bacteriophages from the environment. The method further comprises inserting, into the selected bacteriophage, one or more a heterologous nucleic acid sequences comprising one or more attachment genes. The one or more inserted attachment genes being different than the inactivated native attachment gene and is/are choosen because of its specificity for a selected bacteria, to produce the mutant bacteriophage. In some embodiments, the provision of the selected attachment gene(s) expands the range of possible host cells (i.e. bacteria) beyond the natural paired relationship.
According to an embodiment, there is provided a method of producing a mutant bacteriophage, the method comprising inactivating at least one attachment gene from a selected bacteriophage, the selected bacteriophage can be isolated from bacteriophages from the environment. The method further comprises inserting, into the selected bacteriophage, a first heterologous nucleic acid sequence comprising a first open reading frame encoding a first specific attachment gene. The first specific attachment gene is different than the inactivated attachment gene and is choosen because of its specificity for a selected bacteria, to produce the mutant bacteriophage.
In another embodiment, the method further comprises inserting a second heterologous nucleic acid sequence in a second open reading frame encoding a gene useful for overcoming bacterial defenses. In aspects, the gene for overcoming bacterial defenses may be a biofilm degrading gene, a glycocalyx degrading gene, a gene encoding an antibacterial protein, and a gene for an enzyme that disrupts the bacterial wall, to produce the mutant bacteriophage. In one aspect, the first open reading frame further encodes a second specific attachment gene that is different than the first specific attachment gene.
In some embodiments, the method inactivates all the attachment genes from the selected bacteriophage. In aspects, the step of inactivating comprises making an inactivating mutation in at least one native attachment gene. In some aspects, the inactivating mutation is a point mutation.
According to an embodiment, there is provided an anti-microbial composition for sanitizing or decontaminating a surface. In aspects, the anti-microbial composition comprises the disclosed mutant bacteriophage.
According to an embodiment, there is provided a method of decontaminating a surface suspected of containing a bacteria. In aspects, the bacteria is an infectious or a non-infectious bacteria. The method comprising applying the disclosed anti-microbial composition comprising the disclosed mutant bacteriophage to the surface. In aspects, the amount is effective to decontaminate the surface of at least substantially or all of the contaminating bacteria.
In aspects, the surface is a biological surface (animal or plant).
According to an embodiment, there is provided a method to generate specific mutant bacteriophage gene products. In aspects, there is provided a method of eliminating or substantially eliminating a microbial contaminant (an infectious or non-infectious bacteria), the method comprising: obtaining one or more lytic enzymes produced by the disclosed mutant bacteriophage and applying the one or more lytic enzymes to a bacterial contaminant. In some aspects, the elimination is accomplished without prior bacteriophage infection of the microbial contaminant and therefore leads to result of lysis from without.
All publications and patents mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference.
The foregoing description and certain representative embodiments and details of the invention have been presented for purposes of illustration and description of the invention. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. It will be apparent to practitioners skilled in this art that modifications and variations may be made therein without departing from the scope of the invention.
Samples from sewer and waste, environmental soils, and animal feces were collected and purified to be used for the isolation of bacteriophages. Purified samples were then screened for the presence of bacteriophages against specific bacteria. Protocols and methods for isolating bacteriophages from water samples were adapted from Bonilla et al. (2016) and Bourdin et al. (2014); solid and soil sample methods adapted from Sillankorva (2018), Pausz et al. (2009), and Van Twest & Kropinski (2009).
Solid samples were rehydrated using sterile water for a minimum of 1 hour to allow the bacteriophages to disseminate. Samples are then centrifuged to remove solid materials and large particulates and the supernatant is collected. The centrifuged environmental samples and water samples were then further processed and purified using filters (0.2 μM) to remove bacteria and smaller unwanted particulates. Filtered samples can be further concentrated using filter tubes or stored at 4° C. for future use.
Filtered samples were then tested against bacterial strains of interest using an agar overlay plaque assay technique (Kropinski et al. 2009). Liquid agar overlay was inoculated with filtered environmental sample and the bacterial strain of choice and mixed. It was then poured onto an agar culture plate (bacterial strain dependent) and allowed to harden. Plates were then incubated overnight (conditions are bacterial strain dependent) and observed the next day for plaques against the chosen strains. Plaques containing bacteriophages were then picked and further processed by 3-rounds of subsequent plaque assay overlays to purify the selected phage(s).
Using the method outlined above, numerous (hundreds) EV samples were collected and tested for suitability to develop the template. The function and structural genes were characterized for each EV sample, tested for integration (as detailed below). Candidate phages with a low copy number of lysogenic genes, and the structural and functional genes to allow for gram negative and gram-positive lysis was identified. A selected bacteriophage named PP8 was sequenced and gene structure and function were examined as detailed below. PP8 was selected as it had the desired genes. Although it also had lysogenic genes, these were removed using ORF replacement.
Using environmental sample EV31/PP8, after bacteriophage isolation we purified genomic material with PureLink viral DNA/RNA extraction kit. The full-length genome was amplified (EV31/Full/F/pYESIL and EV31/Full/R/pYESIL see sequence EV31) to have 30bp homology with the pYESIL Sapphire vector. PCR amplification was performed using Phusion high-fidelity DNA polymerase (modification use of touchdown technique for primer annealing starting at 69C and dropping by 0.5C each cycle). PCR products were separated on agarose gels and bands were excised, extracted, and assembled. The resulting construct EV31pYES (unmodified) allowed for the genetic modification of EV31 and the determination of function of mutations in a phage rescue based system.
In brief, the following provides for a method for the genetic manipulation of yeast (Kluyveromyces lactis and Pichia pastoris) cells to include T7 DNA (deoxyribonucleic acid)-dependent RNA (ribonucleic acid) polymerase transcription from Escherichia phage T7 followed by expression of bacteriophage in yeast. There is also provided a method for the genetic manipulation of yeast (Kluyveromyces lactis and Pichia pastoris) cells to include transcriptional components from bacteria (Escherichia coli) and RNA (ribonucleic acid) polymerase (P) inside of yeast followed by expression of the bacteriophage in yeast.
With reference to
Homologous recombination of EV31pYes (unmodified) with pYESIL vector was achieved using 100 ng of each PCR product and transformed into chemically-competent yeast cells. pYESIL vector (100 ng) and EV31 (100 ng) were combined. Competent yeast cells were added and mixed gently followed by the addition of 600 μl of polyethylene glycol (PEG) and lithium acetate (LiAc) solution then mixed gently. The mixture was incubated at 30C for 30 minutes, inverting in 10 minutes intervals. Immediately after incubation, 35.5 μl of dimethyl sulfoxide (DMSO) was added, mixed by inversion and subjected to heat-shock for 20 min at 42C (with occasional inversion). Tubes were then centrifuged at 200-400 xg for 5 minutes, supernatant was discarded and the cell pellet was resuspended in 1 ml sterile 0.9% sodium chloride (NaCl). Visualization of transformation was achieved by spread-plating 100 μl onto selective agar plates (media without tryptophan) and a 3-day incubation period at 30C. Colony-PCR screening can determine the presence of positive transformants. Homologous recombination was achieved by standard cloning techniques to make S. cerevisae strain 5150, chemically-competent. Briefly, using the Gietz and Schiestl 2007 protocol, a spread plate of a single yeast colony from stock was created and incubated overnight at 30C. The next day, 50 μl equivalent of cells was scraped and washed in a tube with 1 ml of sterile nuclease-free water followed by a 13,000xg spin for 0.5 minutes. The following was added to the cell pellet in order: 240 μl of PEG-3350 (50% w/v), 36 μl LiAc (1M), 50 μl single—stranded carrier DNA (2 mg/m1 of pig sperm) and 34 μl plasmid-nuclease free water mixture (<lug plasmid). It was gently vortexed to mix, incubated at 42C for 20-180 minutes (timing is dependent on strain). For EV31, 45 minutes was used. After transformation, it was spun for 13,000xg for 0.5 minutes, then the supernatant was removed and the pellet was resuspended in 1 ml sterile nuclease-free water. The mixture was spread onto selective media plates, yeast synthetic drop out media without uracil and incubated at 30C for 3-4 days. Verification of clone was carried out using Colony-PCR screening.
A graphical representation which depicts the location of the genes of the EV31/PP8 is shown in
Screening for positive-transformants (plate growth colonies) was carried out as follows. Individual yeast colonies were placed in into 15 μl of lysis buffer for inoculation. In a separate tube, 5 μl of each mixture was transferred and stored at 4C, until ready for large scale grow up of positive colonies. The remaining 10 μl of cell suspension was boiled for 5 minutes at 95C, then immediately placed on ice, adding 40 μl of nuclease-free water and mix. 0.5 μl of lysate was added to each PCR reaction in a total volume of 50 μl and visualized by agarose gel electrophoresis. The resulting gel of the PP8 DNA digestion is shown in
Using the PP8 template, a mutant bacteriophage was generated. Native attachment proteins were removed by generating point mutations using homologous recombination.
The mutant bacteriophage can comprises four ORFs: ORF 1 is located at position 46090; ORF 2 is located at position 73195; ORF 3 is located at position 19991; ORF 4 is located at position 60431.
Using modification primers EV31/ORF1/F and EV31/ORF1/R for ORF1 (between nucleotide positions 46,090 and 46,091) and EV31/ORF2/F and ORF2/R for ORF 2 (between nucleotide positions 73,195 and 73,196) and cell free cloning we generated three EV31 mutant constructs. EV31 (ORF1), EV31 (ORF2), and EV31 (ORF1/2). In the construction of ORF2 we first removed the natural binding domain from EV31 and added a multiple restriction enzyme cassette. This cassette is then used to add new bacterial binding domains.
Both homologues recombination and insertion using restriction digests. For restriction digest, the enzyme TspRI allows insertion of a multiple cloning site (MCS). In one example, ORF3 is located at 19991 in ev31/pp8 sequence. In this example, the insertion of the MCS would be done by using TspRI. Once the MCS is inserted, the insertion an attachment gene of choice can done achieved by using restriction enzymes sites found in the MCS. Example of MCS for ORF3: GCCGGCAGTGGATCCCCGGGGAAGATATTC SEQ ID NO: 153. This MCS carries enzymes sites for Nael, TspRI, Xmnl, SmaI. The primers used for adding the MCS to site 19991 are: EV31 ORF3 primer f GCTACACTGCTGAGA SEQ ID NO: 154; EV31 ORF3 primer r TCTCAGCAGTGTAGC SEQ ID NO: 155.
The fourth ORF is located at 60431 in ev31/pp. In this example, the insertion of the MCS would be done by using TspRI. Once the MCS is inserted, the insertion an attachment gene of choice can done achieved by using restriction enzymes sites found in the MCS. The primers used for adding the MCS to site 60431 are: EV31 ORF4 primer f CATCAGATGCTGG SEQ ID NO: 156; EV31 ORF4 primer r CCAGCATCTGATG SEQ ID NO: 157.
An analysis of the genome of the EV31/PP8 revealed a possible lysogenic gene located at 60351-62336. Mutation of the gene by generating an ORF at the site of 60431 (ORF4). Once the lysogenic gene were inactivated, we carried out integration studies to ensure integration did not occur. The results are shown in
Under conditions that promote integration we confirmed that PP8 lacks the ability to integrate. The gel electrophoresis photograph identifies integration events demonstrated by a bacteriophage (bacteriophage induction control), determined by polymerase chain reaction (PCR) on whole bacterial cells. A respective primer set for each bacteriophage would give a positive PCR signal (right panel; lane 5) if the bacteriophage genetic material was integrated inside of the purified (bacteriophage particle-free) bacterial colonies. Contrarily, PP8 cannot integrate into the bacterial host cells, as indicated by the absence of a positive signal for the PP8 sequence in the photograph (left panel; lanes 5-7).
Fresh overnight cultures of the bacterial host (Escherichia coli C) from glycerol stocks were prepared in Luria-Bertani (LB) broth. Once saturated, the cultures were diluted (1:100) in fresh LB broth, supplemented with 2 mM CaCl2 and incubated until an OD600 of 0.6. Mixtures of host (100 μL of E. coli C) and bacteriophage (100 μL at multiplicity of infection of 5) in 3 mL of molten, soft agar were overlaid onto previously, dried LB-agar plates. Following an overnight incubation, three colonies from each plate were picked, re-streaked onto fresh LB-agar plates and incubated overnight for three rounds. The purified colonies (free of contaminating bacteriophage particles) were inoculated into LB-2mM CaCl2 broth and incubated overnight.
Polymerase chain reaction (PCR) master mixes of GoTaq® DNA polymerase (Promega) were set up following the manufacture's recommendations along with the respective primers for each bacteriophage to be evaluated. Five μL from each overnight culture were spiked into their respective PCR reaction. Cycling conditions were altered to include whole-bacterial cell boiling in the initial denaturation period (95° C. for 10 minutes) and an annealing temperature of 59° C. Five μL of completed PCR reactions were subjected 1% agarose gel electrophoresis, stained and visualized under ultraviolet (UV) light. The results are shown in
Using PP8 we developed of a MRSA specific PP8 binding phage by utilizing the PP8 template we removed native attachment genes and added attachment protein SP5 at the ORF 1 location (between 46,090 and 46,091) using homologous recombination. The primer sets used for this homologous recombination are:
TAATACTCTACAGACACCACTAACTGATGCTGCTG
CTCGTTTCAACATCTTTTATTTTGTACAT
ACAAGGGATTAAGCAGTTCTT
ACCC
ATGTACAAAATAAAAGATGTTGAAACGAG
CACCCCTTAATTAAATAAAGTGTATTAGGGTC
CACTTTATTTAATTAAGGGGTGA
TGACTGATTGTTAAGATGGTGTTAATA
TTC
GTGGTAAGGTAAGGTATGGAAGGATGGCAGTAG
The sequence of the insertion (MRSA attachment protein SR5) is shown in SEQ ID NO: 168.
We tested our new PP8(SP5) phage against MRSA infected patient samples 1 through 6. These are MRSA positive patient samples from clinical isolation. An overview of the method is shown in
After sequence analysis of patient sample 3, through sequence analysis and blast searching for attachment sites, a new binding site was revealed.
We also generated a PP8 SR6 mutant and tested this against Staphylococcus aureus. The result is shown in
We then generated a new PP8 strain to attach to and lyse patient sample 3. We further generated a generate PP8 (SRS, SR6) mutant using homologous recombination by adding attachment protein SP6 to ORF 1 of the original PP8 template to generate PP8 (SRS, SR6). The primer sets used for this homologous recombination are:
TAATACTCTACAGACACCACTAACTGATGCTGCTG
CTCGTTTCAACATCTTTTATTTTGTACAT
ACAAGGGATTAAGCAGTTCTT
ACCC
ATGTACAAAATAAAAGATGTTGAAACGAG
TCACCCCTTAATTAAGTAAAGTGTATTAGGGTC
AGACCCTAATACACTTTACTTAATTAAGGGGTGA
TGACTGATTGTTAAGA
TGGTG
GTGGTAAGGTAAGGTATGGAAGGATGGCAGTAG
The sequence of the insertion (MRSA attachment protein SP6) is shown in SEQ ID NO: 169.
The resultant new strain of bacteriophage was called PP8(SP5, SP6). We used this new bacteriophage in conjunction with PP8(SP5) to determine if we could lyse patient samples 1 through 6 using these two new modified bacteriophages. As see in
AAGACTCGGAAGAAGGTAGTCACTAAGGAAAGTG
CCGTAAATCTTAGACCGTTGTCACTGAATCGCAT
GTCAAGTTTTACATAGA
AATCC
ATGCGATTCAGTGACAACGGTCTAAGATTTACGGCAGC
TTATGCTGCGTTACGCCCGATTTTCTCGGCAACGTCC
TTGCCGAGAAAATCGGGCGTAACGCAGCATAA
AAGGTGATGTGGGTCTTGA
TAGG
GCAACACTGTATCGGCTACTTCAAAGTCTTCTCTG
The insertion of the endolysis gene was carried out using normal molecular biology techniques. The sequence of the insertion is shown in SEQ ID NO: 176.
TAATACTCTACAGACACCACTAACTGATGCTGCTG
CATATCCTGCGCCAGTCGCGACAT
ACAAGGGATTAAGCAGTTCTTACCCA
AGC
ATGTCGCGACTGGCGCAGGATATGAAAAAACTGG
TCAATCAGTATACCCGTATACCTGCTC
TTGAGCAGGTATACGGGTATACTGATTGA
TGACTGATTGTTAAGATGGTG
GTGGTAAGGTAAGGTATGGAAGGATGGCAGTAG
AAGACTCGGAAGAAGGTAGTCACTAAGGAAAGTG
CATATCCTGCGCCAGTCGCGACAT
GTCAAGTTTTACATAGAAATCCTGTC
A
ATGTCGCGACTGGCGCAGGATATGAAAAAACTGG
TCAATCAGTATACCCGTATACCTGCTC
TTGAGCAGGTATACGGGTATACTGATTGAA
AGGTGATGTGGGTCTTGATA
GG
GCAACACTGTATCGGCTACTTCAAAGTCTTCTCTG
A sequence analysis of all pathogenic Escherichia coli, Salmonella enterica and Clostridium perfringens species currently causing mortality in Canadian poultry farms allowed evaluation and generation of a universal binding domain, which was used to genetically design phages to destroy these pathogenic bacteria. The process to achieve this was as follows:
1) Sequence analysis:
Samples of feces and other excrement were collected from Manitoba poultry farms for the identification of E. coli. and Salmonella enteric. Clostridium perfringens samples were supplied by an industry partner. All of these samples were used to isolate pathogenic bacteria as well as bacteriophage (to be used to build upon our bacteriophage library) present in the Canadian poultry population. Once pure cultures of pathogenic bacteria were attained, sequence analysis of the bacterium was carried out using an Illumine Miseq 2000. After analysis of these sequences, a ubiquitous attachment region for each bacterium was obtained. Using a Clone Manager genetic program, conserved attachment regions on the surface of various bacterial species were determined, and the generation of a genetic clone which can attach to the conserved bacterial binding domain was reverse engineered.
2) Insertion of conserved attachment region into template and propagation in yeast strain (CP109):
This ubiquitous attachment construct was sub-cloned into the disclosed bacteriophage template. Infectious bacteriophages were generated by transforming and propagating in yeast strain CP 109, which has the capability of holding multiple copies of the bacteriophage template. This was achieved using two methodologies:
a) in vivo by transformation and eventual induction of the bacteriophage template in yeast cells, or
b) in vitro by using cellular extracts of the yeast cells.
Regardless of the method used, the advantage of propagating using these methods lies in the avoidance of classical bacteriophage propagation in which potentially dangerous levels of bacterial endotoxins contaminate the preparations. These methods of phage production remove this hurdle, as yeast cells are used to grow the bacteriophage.
3) Determination of phage ability to target and infect multiple E.coli, Salmonella enterica and Clostridium perfringens pathogenic bacterial species:
Growth characteristics were carried out on the bacteriophage to ensure that the ubiquitous attachment protein was properly inserted. E.coli spp., Salmonella enterica and Clostridium perfringens were infected and phage growth analyzed. Lytic testing was carried out to ensure no integration took place. Cellular toxicity testing was carried out to validate the non-toxic extraction methods in yeast. The phages have been analyzed for binding ability and are ready for evaluation of phage treatment in broiler chickens.
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This application is the National Stage entry under 35 U.S.C. § 371 of International Application Number PCT/CA2019/050074 filed on Jan. 21, 2019, published on Jul. 25, 2019 under publication number WO 2019/140534 A1, which claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 62/619,461 filed Jan. 19, 2018.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CA2019/050074 | 1/21/2019 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 62619461 | Jan 2018 | US |
