Araújo et al. (2008) evaluated RT-PCR and heminested RT-PCR
in brain samples from different animal species, which were thawed
and left at room temperature for 72 h to allow decomposition. They
found a positivity rate of 33.3%, which is much lower than that
observed in the present study, even for those samples that were
stored for >10 years (59.7%). Such a discrepancy may be explained
by the use of different protocols and/or different primers (Soares et
al., 2002), besides that storage temperature in the previous study
was only −20 ◦C.
Biswal et al., 2007 have searched for the rabies virus genome in
sixhumanbrain samples with an undefined diagnosis, and obtained
100% positivity by RT-PCR. In addition to the samples being stored
for 5–6 years at −20 ◦C, they were stored in salt glycerol solution
(1:1), which provides better preservation of neural tissue. In the
present study, the samples were frozen under natural conditions,
without any preservation substance such as glycerol.