Antibodies have been the workhorse for diagnostic immunohistochemistry to specifically interrogate the expression of certain protein to aid in histopathological diagnosis. This review introduces another dimension of histochemistry that employs aptamers as the core tool, the so-called aptahistochemistry. Aptamers are an emerging class of molecular recognition elements that could recapitulate the roles of antibodies. The many advantageous properties of aptamers suited for this diagnostic platform are scrutinized. An in-depth discussion on the technical aspects of aptahistochemistry is provided with close step-by-step comparison to the more familiarized immunohistochemical procedures, namely functionalization of the aptamer as a probe, antigen retrieval, optimization with emphasis on incubation parameters and visualization methods. This review offers rationales to overcome the anticipated challenges in transition from immunohistochemistry to aptahistochemistry, which is deemed feasible for an average diagnostic pathology laboratory.
Leptospirosis is a potentially life-threatening zoonosis caused by pathogenic Leptospira. The major hurdle of the diagnosis of Leptospirosis lies in the issues associated with current methods of detection, which are time-consuming, tedious and the need for sophisticated, special equipments. Restrategizing the diagnostics of Leptospirosis may involve considerations of the direct detection of the outer membrane protein, which can be faster, cost-saving and require fewer equipments. One such promising marker is LipL32, which is an antigen with high amino acid sequence conservation among all the pathogenic strains. In this study, we endeavored to isolate an aptamer against LipL32 protein via a modified SELEX strategy known as tripartite-hybrid SELEX, based on 3 different partitioning strategies. In this study, we also demonstrated the deconvolution of the candidate aptamers by using in-house Python-aided unbiased data sorting in examining multiple parameters to isolate potent aptamers. We have successfully generated an RNA aptamer against LipL32 of Leptospira, LepRapt-11, which is applicable in a simple direct ELASA for the detection of LipL32. LepRapt-11 can be a promising molecular recognition element for the diagnosis of leptospirosis by targeting LipL32.