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In silico selection against progesterone receptor DNA-binding domain

Navien TN, Thevendran R, Citartan M

Anal Biochem, 2025 Apr;699:115752.
PMID: 39719189 DOI: 10.1016/j.ab.2024.115752

Progesterone receptor is one of the markers used in antibody-based immunohistochemistry for the diagnostics of breast cancer. The shortcomings of antibodies raise the need to focus on alternative molecular recognition. Aptamers are chosen due to their many advantages as compared to antibodies. However, the rigor of conventional SELEX intensifies the efforts to select DNA aptamers using in silico-docking approach. In this study, we performed in silico selection and experimental validation of DNA aptamers against the progesterone receptor DNA binding domain (PR DBD) using the ssDNA sequences derived from human progesterone response elements (PREs). Firstly, a library of sixty-four different ssDNA was subjected to secondary and tertiary structural determination prior to docking using PatchDock. PRDBDapt17 appeared to be the best candidate, with the highest docking scores of 11334. Molecular dynamic simulation also substantiates PRDBDapt17 as the most potent aptamer. This aptamer, PRDBDapt17 was validated by using direct ELASA. Direct ELASA demonstrated a limit of detection of 3.91 nM while the equilibrium dissociation constant was estimated at 366.6 nM. As PRDBDapt17 also interacts with estrogen receptor and androgen receptor, it can also be a potential universal binder of steroid hormone receptors. PRDBDapt17 can be used in the diagnostics of breast cancer.
In silico molecular docking in DNA aptamer development

Navien TN, Thevendran R, Hamdani HY, Tang TH, Citartan M

Biochimie, 2020 Oct 18;180:54-67.
PMID: 33086095 DOI: 10.1016/j.biochi.2020.10.005

Aptamers are single-stranded DNA or RNA oligonucleotides generated by SELEX that exhibit binding affinity and specificity against a wide variety of target molecules. Compared to RNA aptamers, DNA aptamers are much more stable and therefore are widely adopted in a number of applications especially in diagnostics. The tediousness and rigor associated with certain steps of the SELEX intensify the efforts to adopt in silico molecular docking approaches together with in vitro SELEX procedures in developing DNA aptamers. Inspired by these endeavors, we carry out an overview of the in silico molecular docking approaches in DNA aptamer generation, by detailing the stepwise procedures as well as shedding some light on the various softwares used. The in silico maturation strategy and the limitations of the in silico approaches are also underscored.
Mathematical approaches in estimating aptamer-target binding affinity

Thevendran R, Navien TN, Meng X, Wen K, Lin Q, Sarah S, et al.

Anal Biochem, 2020 07 01;600:113742.
PMID: 32315616 DOI: 10.1016/j.ab.2020.113742

The performance of aptamers as versatile tools in numerous analytical applications is critically dependent on their high target binding specificity and selectivity. However, only the technical or methodological aspects of measuring aptamer-target binding affinities are focused, ignoring the equally important mathematical components that play pivotal roles in affinity measurements. In this study, we aim to provide a comprehensive review regarding the utilization of different mathematical models and equations, along with a detailed description of the computational steps involved in mathematically deriving the binding affinity of aptamers against their specific target molecules. Mathematical models ranging from one-site binding to multiple aptameric binding site-based models are explained in detail. Models applied in several different approaches of affinity measurements such as thermodynamics and kinetic analysis, including cooperativity and competitive-assay based mathematical models have been elaborately discussed. Mathematical models incorporating factors that could potentially affect affinity measurements are also further scrutinized.
Aptamers isolated against mosquito-borne pathogens

Navien TN, Yeoh TS, Anna A, Tang TH, Citartan M

World J Microbiol Biotechnol, 2021 Jul 09;37(8):131.
PMID: 34240263 DOI: 10.1007/s11274-021-03097-0

Mosquito-borne diseases are a major threat to public health. The shortcomings of diagnostic tools, especially those that are antibody-based, have been blamed in part for the rising annual morbidity and mortality caused by these diseases. Antibodies harbor a number of disadvantages that can be clearly addressed by aptamers as the more promising molecular recognition elements. Aptamers are defined as single-stranded DNA or RNA oligonucleotides generated by SELEX that exhibit high binding affinity and specificity against a wide variety of target molecules based on their unique structural conformations. A number of aptamers were developed against mosquito-borne pathogens such as Dengue virus, Zika virus, Chikungunya virus, Plasmodium parasite, Francisella tularensis, Japanese encephalitis virus, Venezuelan equine encephalitis virus, Rift Valley fever virus and Yellow fever virus. Intrigued by these achievements, we carry out a comprehensive overview of the aptamers developed against these mosquito-borne infectious agents. Characteristics of the aptamers and their roles in diagnostic, therapeutic as well as other applications are emphasized.
Fulltext Diagnostic accuracy of serological tests for the diagnosis of Chikungunya virus infection: A systematic review and meta-analysis

Andrew A, Navien TN, Yeoh TS, Citartan M, Mangantig E, Sum MSH, et al.

PLoS Negl Trop Dis, 2022 Feb;16(2):e0010152.
PMID: 35120141 DOI: 10.1371/journal.pntd.0010152

BACKGROUND: Chikungunya virus (CHIKV) causes febrile illnesses and has always been misdiagnosed as other viral infections, such as dengue and Zika; thus, a laboratory test is needed. Serological tests are commonly used to diagnose CHIKV infection, but their accuracy is questionable due to varying degrees of reported sensitivities and specificities. Herein, we conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of serological tests currently available for CHIKV.
METHODOLOGY AND PRINCIPAL FINDINGS: A literature search was performed in PubMed, CINAHL Complete, and Scopus databases from the 1st December 2020 until 22nd April 2021. Studies reporting sensitivity and specificity of serological tests against CHIKV that used whole blood, serum, or plasma were included. QUADAS-2 tool was used to assess the risk of bias and applicability, while R software was used for statistical analyses. Thirty-five studies were included in this meta-analysis; 72 index test data were extracted and analysed. Rapid and ELISA-based antigen tests had a pooled sensitivity of 85.8% and 82.2%, respectively, and a pooled specificity of 96.1% and 96.0%, respectively. According to our meta-analysis, antigen detection tests serve as a good diagnostic test for acute-phase samples. The IgM detection tests had more than 90% diagnostic accuracy for ELISA-based tests, immunofluorescence assays, in-house developed tests, and samples collected after seven days of symptom onset. Conversely, low sensitivity was found for the IgM rapid test (42.3%), commercial test (78.6%), and for samples collected less than seven of symptom onset (26.2%). Although IgM antibodies start to develop on day 2 of CHIKV infection, our meta-analysis revealed that the IgM detection test is not recommended for acute-phase samples. The diagnostic performance of the IgG detection tests was more than 93% regardless of the test formats and whether the test was commercially available or developed in-house. The use of samples collected after seven days of symptom onset for the IgG detection test suggests that IgG antibodies can be detected in the convalescent-phase samples. Additionally, we evaluated commercial IgM and IgG tests for CHIKV and found that ELISA-based and IFA commercial tests manufactured by Euroimmun (Lübeck, Germany), Abcam (Cambridge, UK), and Inbios (Seattle, WA) had diagnostic accuracy of above 90%, which was similar to the manufacturers' claim.
CONCLUSION: Based on our meta-analysis, antigen or antibody-based serological tests can be used to diagnose CHIKV reliably, depending on the time of sample collection. The antigen detection tests serve as a good diagnostic test for samples collected during the acute phase (≤7 days post symptom onset) of CHIKV infection. Likewise, IgM and IgG detection tests can be used for samples collected in the convalescent phase (>7 days post symptom onset). In correlation to the clinical presentation of the patients, the combination of the IgM and IgG tests can differentiate recent and past infections.