Análises de diversidade genética e padronização de diagnóstico molecular para detecção e quantificação de retrovírus felinos

Abstract

Feline immunodeficiency virus (FIV) and Feline leukemia virus (FeLV) belong to the Retroviridae family and are the etiological agents of two highly prevalent infectious diseases that affect domestic and wild cats worldwide. FIV infection results in feline acquired immunodeficiency syndrome, which leads to opportunistic infections, neurological diseases and tumors. FeLV infection also leads to a suppression of the activity of the immune system, and the development of lymphomas, secondary infections and a drastic reduction in the life expectancy of cats. Both viruses show high genetic diversity due to recombination events (between different viruses and with endogenous feline sequences) and mutation. The diagnosis of infections in the clinical routine is performed using rapid (immunochromatographic) and molecular tests (mainly PCR, polymerase chain reaction). PCR is the main technique used to detect and quantify these viruses. The present study aimed to analyze the genetic diversity of FIV and FeLV with samples from Genbank and to standardize PCR methods for the detection and quantification of FIV and FeLV in samples from Caxias do Sul/RS. The analysis of the genetic diversity of FIV and FeLV was carried out from sequences deposited in genetic databases. The standardization of PCR assays for the detection and quantification of FIV and FeLV was carried out with the establishment of methods in the laboratory and analysis of blood samples from jugular puncture of domestic cats, previously evaluated with rapid tests (immunochromatographic). The results obtained showed a positive correlation between the tests. The PCR assay for FIV detection showed a sensitivity of 83%, specificity of 96% and a Kappa value of 0.7. In the case of FeLV, the PCR test showed a sensitivity of 69%, a specificity of 80% and a Kappa value of 0.4. In addition, the assays enabled the determination of low and high viral loads, with Cts ranging from 25.3-37.4 for FIV and between 13.4-37.8 for FeLV. The results were consistent for FIV, with the demonstration of recombination events in the evolution of this virus and the existence of six different lineages, disseminated worldwide. On the other hand, it was not possible to analyze FeLV diversity, due to the excessive amount of recombination events in the deposited sequences. These results reinforce the importance of carrying out phylogenetic studies to determine the diversity of these viruses and the need for standardization and validation of Molecular Biology methods for the diagnosis of feline retroviruses. [resumo fornecido pelo autor]