Evaluation of an Immunochromatographic Rapid Test for the Detection of Anti-Coronavirus Antibodies in Blood and Effusions
E. Sagols; S. Audhuy; J. Morlet; E. Claret
Introduction
Feline coronavirus (FCoV) is a ubiquitous worldwide infection of cats, leading in 5 to 10% of infections to a lethal immune-mediated vasculitis known as feline infectious peritonitis (FIP). There are two different clinical presentations of FIP: the wet form, with effusion, and the dry form, which results in a general loss of condition. Detection of anti-FCoV antibodies can be helpful for the veterinarian to evaluate a previous contact with the coronavirus and, in case of symptoms, to narrow the diagnosis of FIP in combination with other examinations. The aim of this study was to assess the performance of a rapid immunochromatographic test for the detection of anti-coronavirus antibodies (Speed F-coronaTM; BVT Groupe Virbac, La-Seyne-sur-Mer, France), in comparison with an immunofluorescent antibody test (IFAT).
Materials and Methods
One-hundred and one samples were tested. The samples were divided into a group of FCoV seronegative cats (n = 49; 41 blood samples and 8 effusion samples) and a group of FCoV seropositive cats (n = 52; 29 blood samples and 23 effusion samples). Samples of plasma, serum, anticoagulated whole blood or effusion were tested with the rapid immunochromatographic test, in accordance with the manufacturer's instructions. Reading of the test was performed after 15 minutes of migration. The status of each sample was determined with IFAT to calculate the sensitivity and specificity values of the rapid test.
Results
All 49 samples with negative IFAT results were negative with the rapid test, so the rapid test proved to be 100% specific. Regarding the global analysis of the results, the rapid test detected 48 out of 52 positive samples, indicating a sensitivity of 92.3%. The analysis of blood samples on the one hand, and effusion samples on the other hand, shows respectively a sensitivity of 96.5% (detection of 28 out of 29 positive blood samples) and 87% (detection of 20 out of 23 positive effusion samples).
Conclusions
The rapid immunochromatographic test Speed F-CoronaTM is 100% specific and 96.5% sensitive on blood samples. Additionally, this study shows that effusion analysis has also a high specificity of 100% and a good sensitivity of 87%. Such results in effusion can be explained by the frequent presence of immune complexes in effusions, which reduces the availability of antibodies for the test.