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Bijon Kumar Sil,1 Mohd Raeed Jamiruddin,2 Md Ahsanul Haq,1 Mohib Ullah Khondoker,3 Nowshin Jahan,1 Shahad Saif Khandker,1 Tamanna Ali,1 Mumtarin Jannat Oishee,1 Taku Kaitsuka,4 Masayasu Mie,5 Kazuhito Tomizawa,6 Eiry Kobatake,5 Mainul Haque,7 Nihad Adnan8 1Gonoshasthaya-RNA Molecular Diagnostic and Research Center, Dhaka, 1205, Bangladesh; 2Department of Pharmacy, BRAC University, Dhaka, 1212, Bangladesh; 3Gonoshasthaya Samaj Vittik Medical College, Savar, Dhaka, 1344, Bangladesh; 4School of Pharmacy, International University of Health and Welfare, Okawa, Fukuoka, 831-8501, Japan; 5School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8502, Japan; 6Department of Molecular Physiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, 860-0811, Japan; 7The Unit of Pharmacology, Faculty of Medicine and Defence Health Universiti Pertahanan, Nasional Malaysia (National Defence University of Malaysia), Kuala Lumpur, 57000, Malaysia; 8Department of Microbiology, Jahangirnagar University, Savar, Dhaka, 1342, BangladeshCorrespondence: Nihad AdnanDepartment of Microbiology, Jahangirnagar University, Savar, Dhaka, 1342, BangladeshTel +8801705709910Email nihad@juniv.eduMainul HaqueThe Unit of Pharmacology, Faculty of Medicine and Defence Health, Universiti Pertahanan, Nasional Malaysia (National Defence University of Malaysia), Kem Perdana Sungai Besi, Kuala Lumpur, 57000, MalaysiaTel +60109265543Email runurono@gmail.comBackground: Serological tests detecting severe acute respiratory syndrome coronavirus− 2 (SARS-CoV-2) are widely used in seroprevalence studies and evaluating the efficacy of the vaccination program. Some of the widely used serological testing techniques are enzyme-linked immune-sorbent assay (ELISA), chemiluminescence immunoassay (CLIA), and lateral flow immunoassay (LFIA). However, these tests are plagued with low sensitivity or specificity, time-consuming, labor-intensive, and expensive. We developed a serological test implementing flow-through dot-blot assay (FT-DBA) for SARS-CoV-2 specific IgG detection, which provides enhanced sensitivity and specificity while being quick to perform and easy to use.Methods: SARS-CoV-2 antigens were immobilized on nitrocellulose membrane to capture human IgG, which was then detected with anti-human IgG conjugated gold nanoparticle (hIgG-AuNP). A total of 181 samples were analyzed in-house. Within which 35 were further evaluated in US FDA-approved CLIA Elecsys SARS-CoV-2 assay. The positive panel consisted of RT-qPCR positive samples from patients with both < 14 days and > 14 days from the onset of clinical symptoms. The negative panel contained samples collected from the pre-pandemic era dengue patients and healthy donors during the pandemic. Moreover, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of FT-DBA were evaluated against RT-qPCR positive sera. However, the overall efficacies were assessed with sera that seroconverted against either nucleocapsid (NCP) or receptor-binding domain (RBD).Results: In-house ELISA selected a total of 81 true seropositive and 100 seronegative samples. The sensitivity of samples with < 14 days using FT-DBA was 94.7%, increasing to 100% for samples > 14 days. The overall detection sensitivity and specificity were 98.8% and 98%, respectively, whereas the overall PPV and NPV were 99.6% and 99%. Moreover, comparative analysis between in-house ELISA assays and FT-DBA revealed clinical agreement of Cohen’s Kappa value of 0.944. The FT-DBA showed sensitivity and specificity of 100% when compared with commercial CLIA kits.Conclusion: The assay can confirm past SARS-CoV-2 infection with high accuracy within 2 minutes compared to commercial CLIA or in-house ELISA. It can help track SARS-CoV-2 disease progression, population screening, and vaccination response. The ease of use of the assay without requiring any instruments while being semi-quantitative provides the avenue of its implementation in remote areas around the globe, where conventional serodiagnosis is not feasible.Keywords: COVID-19, SARS-CoV-2, dot-blot immunoassay, AuNP, gold nanoparticle, serosurveillance, nucleocapsid, receptor binding domain

Mohd Raeed Jamiruddin,1 Md Ahsanul Haq,2 Kazuhito Tomizawa,3 Eiry Kobatake,4 Masayasu Mie,4 Sohel Ahmed,5 Shahad Saif Khandker,2 Tamanna Ali,2 Nowshin Jahan,2 Mumtarin Jannat Oishee,2 Mohib Ullah Khondoker,2 Bijon Kumar Sil,2 Mainul Haque,6 Nihad Adnan7 1Department of Pharmacy, BRAC University, Dhaka, 1212, Bangladesh; 2Gonoshasthaya-RNA Molecular Diagnostic & Research Center, Dhaka, 1205, Bangladesh; 3Department of Molecular Physiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, 860-0811, Japan; 4School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8502, Japan; 5Department of Biochemistry and Molecular Biology, Jahangirnagar University, Savar, Dhaka, 1342, Bangladesh; 6The Unit of Pharmacology, Faculty of Medicine and Defence Health, Universiti Pertahanan Nasional Malaysia (National Defence University of Malaysia), Kuala Lumpur, 57000, Malaysia; 7Department of Microbiology, Jahangirnagar University, Savar, Dhaka, 1342, BangladeshCorrespondence: Nihad AdnanDepartment of Microbiology, Jahangirnagar University, Savar, Dhaka, 1342, BangladeshTel +8801705709910Email nihad@juniv.eduMainul HaqueThe Unit of Pharmacology, Faculty of Medicine and Defence Health, Universiti Pertahanan Nasional Malaysia (National Defence University of Malaysia), Kem Perdana Sungai Besi, Kuala Lumpur, 57000, MalaysiaTel +60109265543Email runurono@gmail.comBackground: Dynamics and persistence of neutralizing and non-neutralizing antibodies can give us the knowledge required for serodiagnosis, disease management, and successful vaccine design and development. The disappearance of antibodies, absence of humoral immunity activation, and sporadic reinfection cases emphasize the importance of longitudinal antibody dynamics against variable structural antigens.Methods: In this study, twenty-five healthy subjects working in a SARS-COV-2 serodiagnostic assay development project were enrolled, and their sign and symptoms were followed up to six months. Three subjects showed COVID-19-like symptoms, and three subjects’ antibody dynamics were followed over 120 days by analyzing 516 samples. We have developed 12 different types of in-house ELISAs to observe the kinetics of IgG, IgM, and IgA against four SARS-CoV-2 proteins, namely nucleocapsid, RBD, S1, and whole spike (S1+S2). For the development of these assays, 30– 104 pre-pandemic samples were taken as negative controls and 83 RT-qPCR positive samples as positive ones.Results: All three subjects presented COVID-19-like symptoms twice, with mild symptoms in the first episode were severe in the second, and RT-qPCR confirmed the latter. The initial episode did not culminate with any significant antibody development, while a multifold increase in IgG antibodies characterized the second episode. Interestingly, IgG antibody development concurrent with IgM and IgA and persisted, whereas the latter two weans off rather quickly if appeared.Conclusion: Antibody kinetics observed in this study can provide a pathway to the successful development of sero-diagnostics and epidemiologists to predict the fate of vaccination currently in place.Keywords: antibody dynamics, COVID-19, SARS-CoV-2, reinfection, vaccination

Study of deep defects in unannealed and annealed Fe-doped semi-insulating InP using photoluminescence (PL) and thermally-simulated current (TSC) techniques reveals the presence of a deep phosphorous vacancy complex. The spectra obtained from TSC methods exhibits four TSC peaks at ionization energies of 0.23, 0.16 and 0.42 electron volts. PL emissions at 917 and 888 nanometers reveal 0.16 and 0.32 electron volt traps. These features indicate the absence of a phosphorous vacancy complex.

Homogenous ice nucleation temperatures (TH) of aqueous solutions of methanol, ethylene glycol, glycerol, xylitol, poly(ethylene glycol)s, glucose, and fructose are measured as a function of solute concentration. Through experimental data, it is shown that the magnitude of TH depends strongly on the nature of the solute.

Examines the evaluation of Ga[subAs] and Ge[subAs] antisite defects in neutron-transmutation-doped semi-insulating gallium arsenide by the photoluminescence (PL) measurements. Experiment; Temperature dependence of PL spectra for samples annealed after neutron irradiation.