Detection and molecular characterization of Frog virus 3 in bullfrogs from frog farms in Brazil

Abstract The objective of this study was to perform the molecular diagnosis of ranavirus Frog virus 3 (FV3) in bullfrogs (Lithobates catesbeianus) obtained from frog farms in the central-southern region of Brazil. From each frog farm, we collected adult animals with a mean weight of 120 g ± 8.0 and tadpoles with a mean weight of 7 g ± 1.2, totaling 235 animals. For the diagnosis, liver, kidney and spleen samples were collected from the animals and subjected to DNA extraction and conventional PCR. Positive samples were detected on one farm in the state of Sao Paulo. To confirm the results, we performed nucleotide sequencing of the MCP gene and phylogenetic analysis. The results revealed that FV3 strains are present in Brazil with their own phylogenetic profile, and that these strains differ from those affecting amphibians and reptiles described so far in other countries. Further studies are necessary to better understand the circulation of this pathogen in aquatic systems and the dynamics of the dissemination of this disease in Brazil.