The drug resistance in tuberculosis (TB) is a rising concern for the diagnosis and treatment of the disease. Being able to detect the presence of drug resistance accurately and rapidly in the patient strain is essential for improving individual treatment outcomes and reducing further transmission of resistant strains, which are more costly and difficult to treat than drug-susceptible strains. However, the current methods come in short in point-of-care (POC) settings, due to problems such as long processing time, high complexity, and necessity for specialized personnel/equipment. Oligonucleotide ligation assay (OLA) provides a high sensitivity and specificity against TB drug resistance, and here, I have developed a novel lateral flow test (LFT) device that incorporates OLA into it, which have shown comparable specificity and sensitivity against traditional protocol of OLA in lab setting followed by LFT. Moreover, the simplicity of the design enables further incorporation of other techniques such as isothermal DNA amplification, for a compact, one-step TB drug resistance diagnostic device for low-resource environment. 

Bacteriophage MS2 phage-like particles (PLPs) are artificially constructed viral-like particles. The similarity of the particle to a virus allows the particles to be used as a control system for molecular detection and drug delivery systems. The capsid is made up of single chain coat protein dimers (SCCPD) and a singular maturase, and is able to package mRNA within the protein coat due to the dimerization of coat proteins spontaneously forming the capsid structure in the presence of a packaging signal. In addition, the PLPs also have the ability to display what is being packaged on the surface. Currently, it has been shown that PLPs are able to be purified via His-tag affinity, due to fusion of the His-tag onto the SCCPDs. However, if a peptide is displayed at the SCCPD site, the His-tag must be attached elsewhere on the PLP to ensure the PLP can be purified. To address this, I designed a new PLP by plasmid engineering via site-directed mutagenesis to display a peptide on AB-loops within the SCCPD, whilst packaging the corresponding mRNA within the capsid. I purified the PLP via a His-tag attached to the maturase protein. To verify correct particle formation, I ran SDS-PAGE to observe the density of bands corresponding to SCCPD and maturase. I designed a reverse transcriptase polymerase chain reaction and carried out a nuclease protection assay to verify mRNA packaging. Preliminary data of SDS-PAGE has shown the particle has successfully purified, and is correctly forming due to the observed maturase to SCCPD band density ratio on the gel meeting the expected ratio.