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Published on: December 12, 2011
Evaluation of an in-practice test for feline coronavirus antibodies
Diane D Addie1, Shona A McLachlan, Matthew Golder
1Department of Veterinary Pathology, Institute of Comparative Medicine, Companion Animal Diagnostics, University of Glasgow, Bearsden Road, Glasgow, Scotland G61 1QH, UK. D.D.Addie@vet.gla.ac.uk
Insights
A new feline coronavirus (FCoV) antibody test shows high sensitivity (95%) for screening cats, making negative results reliable for FCoV-free cattery entry.
Area of Science:
- Veterinary Diagnostics
- Immunology
- Feline Infectious Diseases
Background:
- Feline coronavirus (FCoV) is a common pathogen in cats.
- Accurate antibody testing is crucial for diagnosing FCoV infections and managing feline infectious peritonitis (FIP).
- The immunofluorescent antibody (IFA) test is considered the gold standard for FCoV antibody detection.
Purpose of the Study:
- To evaluate the performance of a commercially available in-practice test for feline coronavirus (FCoV) antibodies.
- To compare the in-practice test results with the gold standard FCoV immunofluorescent antibody (IFA) test.
- To assess the clinical utility of the in-practice test for FCoV screening and FIP diagnosis.
Main Methods:
- One hundred and three feline serum or plasma samples were tested using both the in-practice FCoV Immunocomb test and the gold standard FCoV IFA test.
- Sensitivity, specificity, and correlation of antibody titres were calculated.
- False positive and false negative results were analyzed.
Main Results:
- The in-practice test demonstrated a sensitivity of 95% and a specificity of 83%.
- There were 5 false positive and 4 false negative results.
- While IFA titres correlated significantly with the in-practice test, the correlation was not clinically useful for monitoring antibody levels.
- False negative samples had low IFA titres, suggesting low FCoV excretion risk.
Conclusions:
- The in-practice FCoV antibody test is reliable for screening cats entering FCoV-free environments.
- A negative result is likely accurate for screening purposes.
- Strong positive results may aid in FIP diagnosis, but all positive results require IFA confirmation and titration.
- The test is less valuable for monitoring FCoV infection in healthy cats due to unreliable titre comparison.
Abstract:
A commercially available in-practice test for feline coronavirus (FCoV) antibodies (FCoV Immunocomb, Biogal Galed Laboratories) was evaluated by comparison with the gold standard FCoV immunofluorescent antibody (IFA) test. One hundred and three serum or plasma samples were selected and tested: 70 were positive by both tests, 24 were negative by both tests. The in-practice test produced five false positive and four false negative results. The sensitivity of the in-practice test was 95% and the specificity was 83%. When the titres were compared it was found that the in-practice test results were significantly correlated with IFA titres but the degree of correlation was not likely to be clinically useful. The IFA titres of the four false negative samples were found to be low (less than 40) which suggests that even a cat with a false negative result is still unlikely to be excreting FCoV. A negative result with the in-practice assay is likely to be reliable for screening cats prior to entry into an FCoV-free cattery or stud. It would also be useful in the investigation of suspected FIP as most cats with this condition have high IFA titres of antibodies. A strong positive result would be useful in the diagnosis of FIP (in conjunction with other biochemical and cytological testing), but positive results would be of limited value in monitoring FCoV infection in healthy cats as the antibody titre could not be reliably compared with those obtained with IFA. All positive results obtained using the in-practice kit should be confirmed and titrated by IFA. The kit also appeared to work efficiently with ascites samples (n=6) but too few samples were analysed to draw firm conclusions.
