Experiments on intramuscular inoculation and feeding domestic cats (Felis catus) with brains of mice previously infected by rabies viruses

Abstract

Nineteen kittens divided into four groups were fed with brains of mice infected with rabies viruses. Each four kittens (group I) received four brains infected with the PV fixed strain; nine kittens (group II) ingested 4-5 brains infected with the field isolate T-9/95, isolated from the Desmodus rotundus vampire bat; two kittens (group III) fed ten T-9/95-infected brains, and four cats consumed 32-37 PV strain-infected brains. One adult male, inoculated into masseter muscle with a 20% T-9/95-infected brain suspension, presented rabies after an incubation period of six days, followed with 8 days of clinical evolution, and died thereafter and this cat was considered as the rabies "positive standard". After observing for 20-230 days, all the cats feeding the rabid brains were submitted to euthanasia, by using Acepran®, Zoletil®, and T-61®. At necropsy, samples of brain, heart, lung, kidney, submaxillary salivary gland, and cervical medulla were collected from all the cats and further submitted to the direct fluorescence antibody test (dFA), mouse inoculation test (MIT) and to the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. Brain, cervical medulla, and the submaxillary salivary gland of the positive standard cat were dFA-positive, and brain and cervical medulla were positive for MIT. All specimens of this cat tested by the RT-PCR were found positive. No animals ingesting PV or T-9/95 virus-infected brains developed clinical signs and all materials tested were negative by dFA and MIT. Several specimens, however, showed positive reactions by the RT-PCR technique, but cats were resistant to rabies through the viruses administered orally.