Comparison of PCR, Nested PCR, and RT-LAMP for Rapid Detection of Feline Calicivirus Infection in Clinical Samples.

Simple Summary: Feline calicivirus (FCV) is a major cause of upper respiratory tract (URT) disease in cats that can lead to acute or subacute illness. It is highly contagious and widespread in the feline population, with many cats being asymptomatic carriers. However, FCV infection can also cause various clinical problems, resulting in high morbidity rates. Unfortunately, existing diagnostic techniques are not always sufficiently quick or specific enough to detect the virus, making it difficult to diagnose and treat. The current study compared the diagnostic abilities of different methods—polymerase chain reaction (PCR), nested PCR, and reverse transcription loop-mediated isothermal amplification (RT-LAMP)—to detect FCV in clinical samples from cats. The development of rapid and sensitive diagnostic methods is crucial for timely healing, reducing the risk of severe symptoms, and preventing the spread of viruses. Feline calicivirus (FCV) is a highly contagious virus that causes upper respiratory tract disease, commonly known as cat flu. It is widely distributed worldwide and poses a major threat to feline health. Therefore, it is essential to find an efficient and rapid method for detecting FCV. In this study, the colorimetric reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay, using neutral red as an indicator, was developed and validated to target the ORF2 gene of FCV for the first time. Additionally, the study compared the diagnostic abilities of polymerase chain reaction (PCR), nested PCR, and RT-LAMP assays for detecting FCV in clinical samples. The optimized RT-LAMP amplification was carried out at 56.3 °C. The technique visually detected FCV within 70 min, with a limit of detection of 14.3 × 10¹ copies/µL, and showed no cross-reactivity with other feline pathogens. Out of 54 oropharyngeal swab samples, 17 tested positive for FCV using both nested PCR and RT-LAMP, while only one tested positive using conventional PCR. The positivity rate was higher with nested PCR and RT-LAMP (31.48%) compared to conventional PCR (1.85%). Consequently, these results demonstrated the effectiveness of the colorimetric RT-LAMP assay developed in this study as an alternative for diagnosing FCV in cats. [ABSTRACT FROM AUTHOR]