Desenvolvimento e validação de ensaios sorológicos para o diagnóstico de infecção pelo vírus da leucemia felina (FeLV).

Abstract

The Feline Leukemia Virus (FeLV), which causes Feline Viral Leukemia, has a high prevalence, morbidity and mortality, and can present asymptomatically or symptomatically. The infection can result in 4 distinct forms, depending on virulence and infective dose of the virus, age and immunity factors of the host, namely: progressive, regressive, abortive and focal/atypical. Early diagnosis is crucial to initiate the effective treatment, prevent viral spread, relevant in blood banks, testing prior to vaccination and acquisition/adoption and identification of the type of infection, especially in asymptomatic animals. Testing methodologies such as enzyme-linked immunosorbent assay (ELISA), lateral flow immunochromatography (Rapid Test), Polymerase Chain Reaction, Reverse Transcriptase Polymerase Chain Reaction, contribute to achieve the early diagnosis. This study aimed to develop and validate two diagnostic platforms for FeLV, ELISA and rapid test (RT), for the detection of FeLV antigens (p27) in serum, plasma and whole blood samples from domestic felines. ELISA and RT were standardized and the parameters of clinical sensitivity and specificity for the detection of p27 antigen, accuracy, precision, among others, were determined using a panel of 1,118 serum and plasma samples characterized by molecular biology in the detection of proviral DNA and/or viral RNA and p27 antigen. The Kappa (k) index was used to assess the level of agreement between methods. When comparing the global panel, ELISA presented sensitivity of 92.38%, specificity of 98.66% and accuracy of 97.41%, while RT obtained 97.31%, 99.11% and 98.75%, respectively. The ELISA (k=0.918) and RT (k=0.961) showed almost perfect agreement with the reference method. Another analysis was performed with the stratified panel, samples characterized by detection of the p27 antigen, showed almost perfect agreement for the ELISA (k=0.929) and RT (k=0.983), and values of 93.67% sensitivity, 98.77% specificity and 97.63% accuracy for the ELISA and 99.55%, 99.44% and 99.46% for the RT, respectively. The agreement between the ELISA and RT developed was almost perfect (k=0.935) and both tests can be used as complementary diagnostic assays for FeLV diagnosis, thus contributing to the well-being of felines and the control of viral spread.