Abstract

The global health crisis caused by COVID-19 has overwhelmed both healthcare settings and economies globally. While mass population testing has improved drastically, recent reviews of existing methods have highlighted various shortcomings with these methods. 
The aim of this project was to investigate whether the LAA could be modified and utilised as a rapid detection test which either matched or exceeded the existing sensitivity and specificity values.   
The latex agglutination assay (LAA) investigated whether the COVID-19 spike protein could be detected in samples. COVID-19-specific  IgM and IgG were used in conjunction with a series of non-specific antigens. Control or AG-containing samples were mixed with AB-microsphere complexes on glass microscope slides. 
Manual visualisation identified various levels of agglutination. Light microscopy and spectrophotometry at 405 nm determined that the LAA could detect at least 2.3 ng of spike protein.  
The particle-counting tool of ImageJ was utilised to obtain a data set which was subjected to statistical analysis which indicated that there was a significant difference between control samples and live tests, P = 0.000102 for the spike protein assay and P = 0.254 for the non-specific assay respectively. 
The results obtained fell in line with a similar study conducted by Buffin et al. in 2018. 

The analytical methods used in this project twinned with data obtained in previous studies supports the significant difference between control values and live test values. The LAA is easier, quicker to use (results in ≤ 30 minutes) and cheaper, with potentially better sensitivity to existing methods. This could benefit high- and low-income countries alike upon further research and optimisation. 

Keywords

SARS – Severe acute respiratory syndrome, ARDS – acute respiratory distress syndrome, LAMP – Loop mediated isothermal amplification, AB – Antibody, AG – Antigen, LAA – Latex agglutination assay, ELISA – Enzyme linked immunosorbent assay

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