Comparative study of Lacazia loboi inoculation in BALB/c and B10: a mice according to histopathological aspects of produced lesions, number of fungi, and viability index

T HESIS

Comparative study of Lacazia loboi inoculation in BALB/c and B10. A mice according to histopathological aspects of produced lesions, number of fungi, and viability index

S. Madeira

^{Correspondence}

THESIS: S. Madeira submitted this dissertation for her Masters in Tropical Diseases at Botucatu School of Medicine, São Paulo State University (UNESP), Botucatu, São Paulo, Brazil, 2001.

Advisor: Professor Diltor Vladimir Araújo Opromolla.

ABSTRACT

This study evaluated inbred mice strains BALB/c and B10.A susceptibility to infection by Lacazia loboi (L. loboi) fungus, by studying the histopathological aspects of produced lesions, number of fungi, and viability index at each sacrifice time. It also observed if response pattern of isogenic strains is homogeneous to allow result correlation. Both hind footpads of 44 BALB/c and 44 B10.A mice were intradermically inoculated with 0.03 ml of a fungal suspension. The fungal suspension was obtained from a single lesion fragment of a Jorge Lobo's disease patient. The biopsy was macerated in 0.85% saline and the suspension was immediately submitted to viability determination with ethidium bromide-fluorescein diacetate vital staining. The fungal concentration was estimated in Neubauer chamber and the results expressed in absolute numbers. The suspension contained 9x10⁵ fungi/ml (2.7 x 10⁴ fungi/0.03mL) and 45% of viable fungi. The animals were sacrificed at 24 and 72 hours; 7 and 15 days; and 1, 4, 7, 10, 13, 16, and 18 months after inoculation. Both footpads were excised, one was submitted to histopathological examination and the other macerated for fungal counting and viability index determination. The BALB/c strain presented an extensive granulomatous infiltrate, very similar to that of human lesions, which evolved progressively at the different sacrifice periods. The number of recovered fungi also increased progressively throughout the experiment and after the 7^th month, macroscopic changes were observed on the footpad of two animals. At the end of the experimental period, 34% of the animals presented macroscopic changes. Viability indexes varied from 0 to 43%. The B10.A strain also showed an extensive granulomatous infiltrate, but no macroscopic changes were observed in the animals. There was a slight increase in the number of recovered fungi; this remained close to that of the inoculated fungi. Viability indexes were lower, varying from 0 to 26%. Considering the histopathological findings, the macroscopic changes, and the great amount of recovered fungi, we conclude that the BALB/c strain is more susceptible to L. loboi infection than the B10.A.

Key words: BALB/c, B10.A, Lacazia loboi, histopathological aspects, number of fungi, viability index, Jorge Lobo' s disease.

Publication Dates

• Publication in this collection
  24 Sept 2004
• Date of issue
  2004