Specificity Of Immunochromatographic Assay Research Articles

SARS-CoV-2 Omicron detection by antigen tests using saliva

The Omicron emerged in November 2021 and became the predominant SARS-CoV-2 variant globally. It spreads more rapidly than ancestral lineages and its rapid detection is critical for the prevention of disease outbreaks. Antigen tests such as immunochromatographic assay (ICA) and chemiluminescent enzyme immunoassay (CLEIA) yield results more quickly than standard polymerase chain reaction (PCR). However, their utility for the detection of the Omicron variant remains unclear. We herein evaluated the performance of ICA and CLEIA in saliva from 51 patients with Omicron and 60 PCR negative individuals. The sensitivity and specificity of CLEIA were 98.0% (95%CI: 89.6–100.0%) and 100.0% (95%CI: 94.0–100.0%), respectively, with fine correlation with cycle threshold (Ct) values. The sensitivity and specificity of ICA were 58.8% (95%CI: 44.2-72.4%) and 100.0% (95%CI: 94.0–100.0%), respectively. The sensitivity of ICA was 100.0% (95%CI: 80.5–100.0%) when PCR Ct was less than 25. The Omicron can be efficiently detected in saliva by CLEIA. ICA also detects high viral load Omicron using saliva.

Sensitivity and Specificity of Various Serological Tests for Detection of <i>Brucella spp</i>. Infection in Male Goats and Sheep

Brucellosis is a zoonosis found throughout the world with major implications both in the field of public health and farming economy. It is most often caused by Brucella abortus and Brucella melitensis. This study aimed for evaluation of the sensitivity and specificity of immunochromatographic assay (ICA) and comparing the results with those obtained from Rose Bengal Plate Test (RBPT) and in direct Enzyme Linked Immunsorbent Assay (ELISA) for serodiagnosis of sheep and goat brucellosis. Out of 41 sera samples (21 ram and 20 male goats) which were examined, antibodies against Brucella were detected in ram 8 (38.09%), 6 (28.57%) and 16 (76.19%) in ram samples, whereas they were detected in 3 (15%), 1 (5%) and 12 (60%) serum sample of goats males by RBPT, (ICA) and iELISA respectively. The kappa value between iELISA and ICA was -0.08 and that between RBPT and ELISA was -0.01 in ram and the kappa value between iELISA and ICA was -0.06 and that between RBPT and ELISA was -0.14 in male goats. The sensitivity for RBPT and ICA were 37.5% and 25% while specificity was 60% and 60% in ram; whereas, in male goats, sensitivity for RBPT was 8.33% and ICA was 8.33% while specificity was 75% and 100% respectively. It can be concluded that the developed ICA is immunodiagnostic assay, and it is rapid, non-expensive, economical and suitable for large-scale screening in developing countries and rural areas.

Comparative assessment of postmortem inspection and immunochromatographic techniques for the detection of bovine tuberculosis in slaughter cattle in Nigeria

Animals with tuberculosis pose some risks to humans, especially in developing countries of the world. In this study, postmortem inspection (PMI) and immunochromatographic assay (ICA) techniques were compared for the detection of bovine tuberculosis (BTB) in slaughter cattle in Enugu State, Nigeria using culture as the gold standard. A cross-sectional study was conducted from January-June, 2011 on animals presented at four purposively selected slaughterhouses in the study area, involving a total of 500 randomly selected animals. Blood samples were collected from the jugular veins of selected animals and serum samples harvested for ICA. Thorough PMI was carried out and tissue samples from the lung, liver, intestine, and lymph nodes were collected, with or without lesions for culture; from the animals examined, culture detected 11 positive cases giving a prevalence rate of 2.2%, whereas PMI detected 22 positive cases including 7 (out of the 11) positive cases detected by culture, giving a prevalence rate of 4.4%. Fifteen of the cases detected as positive by PMI were negative by culture. Therefore, the sensitivity and specificity of PMI were 64 and 97%, respectively. ICA detected 59 positive cases including 10 of the 11 positive cases detected by culture, hence, a prevalence rate of 11.8%. Forty-nine of the cases detected as positive by ICA were negative by culture. Hence, the sensitivity and specificity of ICA were 91 and 90%, respectively. In conclusion, the performance of ICA was found sufficiently high to support its use in BTB surveillance and control in cattle in Enugu State, Nigeria.