In vitro characterization of different genetic strains of rabies virus isolated from non hematophagous bats

Rabies is one of the oldest diseases recognized by humanity, caused by the rabies virus (RABV). This zoonosis has a worldwide distribution and still causes the death of approximately 60,000 people a year. Despite advances in research, there are still gaps in knowledge about how RABV is maintained in the wild, especially aspects related to its biology and its mechanisms for adapting to its hosts. In recent years, reports of the isolation of RABV in different bat species, with varying feeding and behavioral habits, have increased public health concerns. The possibility of these animals developing synanthropic habits, considering that they are reservoirs for RABV, could lead to a greater risk of human infections. The aim of this study was to elucidate adaptive aspects of RABV maintenance in different species of non hematophagous bats. To this end, 9 RABV samples isolated from different species were initially selected. Initially, these RABV samples were submitted to genetic characterization through RNA extraction, reverse transcription followed by polymerase chain reaction (RT-PCR) targeting the nucleoprotein, genetic sequencing and phylogenetic analysis. After selection and characterization, the samples were subjected to intracerebral inoculation in Swiss albino mice and then adapted to in vitro growth in human embryonic kidney cells (HEK 293 T). Each serial passage in cells was subjected to Direct Immunofluorescence (DFAT). The following RABV genetic lineages were identified: genetic lineage of frugivorous bat Artibeus lituratus (3 samples), genetic lineage of insectivorous bat Eptesicus furinalis (3 samples) and genetic lineage of insectivorous bat Tadarida brasiliensis (3 samples). Ten successive passages of the samples described were performed on HEK 293 T cells, 6 samples could be adapted to the cell culture and only 3 samples did not adapt, 1 from genetic lineage of the insectivorous bat Eptesicus furinalis (IP1282/16) and 2 from genetic lineage of insectivorous bat Tadarida brasiliensis (PG980/17 and PG981/17). For the kinetics tests, viral penetration tests and viral growth curves were performed with the samples adapted in the HEK 293 T cell line. The results of the viral replication kinetics tests showed significant differences between samples in the viral penetration phase. However, there were no significant differences between the samples in the viral growth and propagation phase in the cells. With the knowledge acquired from each genetic lineage of RABV in this study, it is possible to propose improvements in rabies diagnosis as well as in surveillance to control the disease specifically in these species.