Results and Discussion
The Samples Fox1_C_thous_PB_Brazil_2010 and
Fox2_C_thous_PB_Brazil_2013 were similar to a cluster containing
strains isolated from wild and domestic Brazilian canids, and to the
subcluster C. thous (Figure 1B). Therefore, we confirmed the
existence of a RABV lineage circulating in the C. thous , that is
distinct from previous reports describing RABV in the same host species
(Carnieli et al, 2013).
Crab-eating foxes are RABV reservoirs due to factors of high
susceptibility of this species to this virus, the virus incubation
period, the morbidity period, the clinical syndrome observed and the
long period necessary for viral dissemination through the
parasympathetic nervous system of the foxes (Hanlon, 2013). Importantly,
in the State of Paraiba the RABV is endemic, and infects domestic and
wild animals during the whole year, with peaks every four years
(Bernardi et al, 2005).
Next, we used the results of the deep-sequencing analysis to search for
variants in the viral population. We observed the existence of a
C>T mutant in the L gene (nucleotide 10,733), which caused
the non-synonymous mutation Ala1775Val. This mutation reached the
frequency of 30% of the reads in the region (Figure 1C). Although this
variant did not reach the threshold of dominance (50%), it hints the
existence of a heterogeneous virus population, and the existence of
possible escape mutants
Reports of wild rabies increased recently, and in the present study we
report a new lineage of RABV in C. thous in Northeastern Brazil.
The contact between foxes and dogs has the potential to generate new
RABV variants. Therefore, continued rabies vaccination programs for
dogs, and surveillance of rabies in wild animals are essential to
prevent cases in humans, and to prevent the emergence of new virus
lineages.