Novel Atomic Force Microscopy Based Biopanning for Isolation of Morphology Specific Reagents against TDP-43 Variants in Amyotrophic Lateral Sclerosis

The overall goal of this procedure is to isolate morphology specific reagents against tar DNA binding protein. 43 variants present in a LS utilizing a two-phase A FM based radio panning technology. This is accomplished by first subjecting a diverse phage library to multiple rounds of negative panning against off-target antigens using immuno tubes.

Negative panning is performed sequentially against bovine serum albumin, aggregated alpha synuclein and healthy human brain tissue. The second step is to complete a FM verification after each set of negative panning to ensure successful removal of all unwanted phages. In this negative panning example, using aggregated alpha synuclein phages are visible after one round, but are absent after the 10th round.

Next, the remaining negative panning rounds are performed on MICA due to limited sample availability. Phages reactive to immuno precipitated TDP 43 from healthy and from frontotemporal dementia or FTD tissue are removed sequentially. The final step is to isolate the phages that bind to the a LS immuno precipitated.

TDP 43 using mica bound phages are alluded using trypsin, triethyl, amine and TG one cells. Ultimately the specificity of these potential a LS clones is verified using indirect fa eliza's and dot blots homogenized A-L-S-F-T-D and healthy human brain tissues are immobilized in both assays. Greater reactivity to a LS tissue is usually detected compared to the other tested groups.

The main advantage of this technique over conventional phage bio panning is the use of exhaustive negative panning protocols as verified by a FM to ensure the isolation of reagents that selectively recognize disease specific protein variants directly from complex biological samples, even when present at low concentrations. Though a FM can provide insight into investigating biomolecular features and the interactions, it can also be applied into other systems such as monitoring the progress of bio penning and confirming the specificity of single CLOs. Begin this procedure with phage production as detailed in the text protocol to perform negative panning against BSA first, add four milliliters of one milligram per milliliter.

BSA solution in phosphate buffered saline or PBS to 12 immuno tubes and incubate overnight at four degrees Celsius. Next, combine phage particles from each of the three libraries, setting aside a small quantity of this phage mixture for future verification of the negative panning process. Then discard the BSA solution from the first tube and wash the tube two to three times with PBS to remove any unbound BSA, add the combined phage libraries to this first tube, incubate for 30 minutes at room temperature on the rotator before collecting the unbound phages.

Keep in mind that it is important to save a small quantity of phage after finishing the numerous rounds of negative panning against each target to verify success of the panning process and in case of contamination, repeat the negative panning process with the remaining tubes of BSA solution each time. Use the unbound phage collected after the incubation of the previous tube. Then verify removal of all BSA phage binders using the A FM procedure detailed in the next section of the video.

To visualize phage binding using a FM, add 10 to 20 microliters of the target antigen to cleaved, mica and incubate for five to 10 minutes. Wash the MICA five times with water, then add 10 to 20 microliters of the phages to the MICA and incubate for five to 10 minutes. Wash the mica another five times with water and allow to air dry.

Execute the a FM imaging process using a FM tapping mode with a nano scope three, a controller in air at room temperature. The silicon a FM probes have a resonant frequency of 300 kilohertz and a spring constant of 40 newton's per meter. Insert the a FM tip into the tip loader.

Attach the tip loader to the A FM microscope. Place the sample under the A FM microscope. Use the knobs to align the laser onto the A FM tip.

Set the scan rate to 3.05 hertz and the scan resolution to 512 samples per line. Auto-Tune the machine to optimize the silica vibration. Frequency of the tip, initiate sample scanning.

The tip will scan the surface of the MICA measuring the height of the bound phage. The phages are the long white lines following acquisition process the images by basic flattening of the background to ensure that all particle sizes are comparable within each image. Phage width may vary from image to image due to other particle sizes and the scanning area, but it will never compromise the accuracy of whether or not phage binds to the antigen.

The image is flattened into A 2D image and poorly imaged regions caused by PEG contamination are highlighted for removal from future data analysis. Immuno precipitate healthy TDP 43 protein from healthy human brain tissue as described in the text protocol due to lower quantity of immuno precipitated protein. Carry out these rounds of negative panning using MICA first Cleave eight MICA surfaces to the first MICA at approximately 100 microliters of the immuno precipitated protein and incubate for five to 10 minutes at room temperature following incubation.

Wash the MICA five times with 0.1%phosphate buffered saline with tween 20 abbreviated PBST. Then add approximately 100 microliters of phage after the negative panning against healthy human brain tissue and incubate for five to 10 minutes at room temperature. At midway incubation, add the immuno precipitated protein to the second mica.

Collect the phage from the first MICA before washing the MICA five times with 0.1%PBST. After washing the second mica, add the previously collected phage. Repeat the entire process until the phage is negatively panned against all eight mica with the immuno precipitated protein.

Verify success of the panning process using the phage after the first and eight rounds of negative panning with a FM to begin immuno precipitate TDP 43 protein from the brains of individuals with a LS as described in the text protocol, cleave three MICA surfaces. Then add 50 microliters of A LS TDP 43 to the first MICA following a five minute incubation at room temperature. Wash the MICA five times with 0.1%PBST.

Next, add 50 microliters of the phage collected after negative panning against healthy TDP 43 to the MICA and incubate for five minutes. Collect the unbound phages. It is important to keep all collected phages in these panning steps separate.

Next, collect the bound phages using three elucian methods. First, add 50 microliters of trypsin to each MICA and incubate for no more than 10 minutes. Collect the solution and save.

Next, add 50 microliters of 100 millimolar triethylamine to each MICA and incubate for no more than 10 minutes. Collect the solution at an equal volume of one molar tris HCL buffer pH 7.4 and save third, add 50 microliters of TG one cells directly to the MICA and incubate for 30 minutes at 37 degrees Celsius. Also, add the phages collected from the first two elucian methods to 100 microliters of TG one cells at the same concentration and incubate for 30 minutes at 37 degrees Celsius.

Next, repeat this process with a second mica. Take the collected unbound phage using the first MICA with A LST DP 43 and add it to the second MICA with A-A-L-S-T-D-P 43 incubate for five minutes. Combine the TG one cells infected with the phages, alluded with trypsin from each A LST DP 43 MICA and plate on all luria burani auger plate with ampicillin or LBA plate.

Repeat the same process for the triethyl amine and TG one alluded phages from the two sets of A LS TDP 43 MICA for a total of three plates. Repeat all the steps with a third A LS mica, however, in this case, use phage collected after two rounds of negative panning against frontotemporal dementia. T DP 43 plate the infected TG one cells on three LBA plates and incubate overnight at 37 degrees Celsius.

The next day. Count the number of colonies on the six LBA plates with a potential a LS clones. There should be fewer colonies on the three LBA plates from the third A LS MICA compared to the three LBA plates after the two rounds of positive panning utilizing the phage after negative panning against healthy TDP 43 produce phage and soluble single chain variable domain antibody fragments or s cvs from these clones and analyze using different immunoassays to verify specificity to a LS tissue.

A FM imaging is used to monitor the negative panning steps against the various targets to ensure all reactive phages are removed. A FM results showed phage binding after one round of negative panning against the aggregated alpha synuclein and no binding after eight rounds. Negative panning against healthy human brain tissue was performed to remove phage binding the many antigens present in healthy human brain homogenate.

Shown here is phage binding to healthy tissue after one round of negative panning and no phage left binding after 10 rounds of negative panning. After preparing both phage and soluble SCFE from potential clones, they were tested in indirect Eliza for specificity to a LS tissue. Almost all of the phages showed a preference for a LS tissue over healthy tissue.

Similar results are obtained when comparing phage binding to a LS to frontotemporal dementia or FTD tissue. Comparison of SCFV binding to a LS tissue in both healthy and FTD tissue again showed selective binding to a LS tissue in almost all clones. The dot blot immunoassay was used to further verify binding to a LS tissue and also to ascertain which clones are reactive in other immunological applications.

Here, clone two a binding to a LS tissue is shown. After watching this video, you should have a good understanding of how to apply a FM based biop panning to isolate reagents against disease, specific target of interests, reagents, which may serve as potential diagnostic and or therapeutic tools.