Histological and serological evidence of experimental paracoccidioidomycosis in Calomys callosus (Rodentia: Cricetidae)

Abstract

The responses of animal experimental models related to the infectivity, virulence and pathogenicity of Paracoccidioides brasiliensis is constantly used to develop new perspectives of investigation. The rodent Calomys callosus, Rengger 1830 (Rodentia: Cricetidae) is an indigenous inhabitant of the savannah environment found in the central regions of Brazil. The aim of the present work was to evaluate the histopathological and serological features of C. callosus after inoculation with the Pb18 strain of P. brasiliensis. Furthermore, A/Sn and B10.A mice strains were also tested to compare the results obtained in C. callosus to these well-established experimental models of resistance and susceptibility respectively. In every instance, survival analysis was performed, and histopathological study of the lungs, liver and spleen was employed to investigate tissue involvement, degree of inflammation and fungal presence. Levels of antibodies to P. brasiliensis were measured by using an enzyme-linked immunosorbent assay after 4 weeks and at the advanced stage of infection. The mortality rate was proportional to inoculation dose in all groups, but overall it was much superior in C. callosus than in the B10.A-susceptible mice. Macroscopical and microscopical pathological alterations were also more extensive and remarkable for C. callosus, once again proportional to inoculation dose, but more noticeable differences among the studied groups were found with 0.6x10(5) inoculum. In addition, the serological profile of C. callosus was similar to that found for B10.A-susceptible mice. Infection of C. callosus with 0.6x10(8) Pb18 inoculum resulted in more serious illness, and it decreased in severity in proportion to the inoculum dose. This difference was more pronounced in C. callosus, and the clinical, serological and pathological findings in this animal were more intense and precocious compared with the B10.A-susceptible mice. The present results suggest that C. callosus is a potentially alternative experimental animal model for paracoccidioidomycosis infection.

Road-killed wild animals: a preservation problem useful for eco-epidemiological studies of pathogens

“…These findings corroborate those already described in the literature and show the importance of this animal group as reservoirs of several pathogens (46). Some rodent species are considered reservoirs of Coccidioides immitis and Penicillium marneffei; similarly, the rodents Calomys callosus have been recently described as susceptible to experimental infection with P. brasiliensis (47)(48)(49)(50).…”

Paracoccidioides brasiliensis pancreatic destruction in Calomys callosusexperimentally infected

“…The lack of such information can be alternatively ascribed either to a complete resistance of C. callosus to the fungus or to an efficient immune resistance developed by the host. The later hypothesis is however the most probable in face of the demonstration in this present report and by others [ 14 ], that this rodent can be experimentally infected with P. brasiliensis .…”

“…Previously, it was shown that using a virulent P. brasiliensis 18 strain, C. callosus presented a destructive granuloma formation and disease progression [14]. However, that work failed to show the lesion and granuloma formation in several other important organs.…”

“…Because of the unique response of C. callosus to different pathogens they may be useful as an animal model for the development of experimental infections by P. brasiliensis . A recent work showed that C. callosus succumbs to the P. brasiliensis strain 18 infection, presenting evidence of inflammatory reaction in several organs and specific humoral response to P. brasiliensis antigens [ 14 ]. Natural infection of C. callosus with P. brasiliensis has not yet been reported even though they reside in endemic areas of Paracoccidioidomycosis (PCM).…”

Caracterização da inter-relação entre as vias de sinalização Notch e TLR na paracoccidioidomicose experimental

“…Após atingir os pulmões, o fungo pode disseminar-se via linfo-hematogênica, atingindo, com maior frequência, os linfonodos, mucosas, pele, glândula supra renais, e ainda, com menor frequência, a medula óssea, baço, fígado e o sistema nervoso central e outros órgãos (BERBERT et al, 2007;BORGES-WALMSLEY et al, 2002;MONTENEGRO & FRANCO, 2004). Em qualquer fase, histopatologicamente, a doença segue um padrão que é comum às micoses profundas, tendo início por um fluxo de leucócitos polimorfonucleares (neutrófilos) em reposta à presença do microrganismo.…”