Comparative pathogenicity analysis of Cryptococcus neoformans RAPD types

Cryptococcus neoformans and Cryptococcus gattii are the major causes of Cryptococcosis, an invasive fungal infection of human and animals. Few data have been reported on the pathophysiology of Pattern I (PI) and Pattern IV (PIV) of C. neoformans with context of their clinical outcome. In this study an extensive comparison of PI and PIV was conducted to provide a more complete and reliable assessment of their biological and clinical behaviour. Representative strains of PI and PIV of C. neoformans were collected from Outreach Programme on Zoonotic Diseases (OPZD) at Department of Veterinary Public Health of West Bengal University of Animal and Fishery Sciences and infective inoculum was prepared by adjusting the number of Cryptococci at 3.25X 10⁵/ml in phosphate buffer saline (pH 7.4). Mice were challenged with 0.2 ml of inoculum at lateral tail vein and infected mice were examined for histopathological study and survivability study for 21 days. This present study showed that PIV produced more cystic structure in brain (χ² =4.22, P< 0.05) and granuloma in liver (χ²=4.05, P<0.05) with lower mean survival time (P= 0.044) but lack a statistical significance in micro-abscess formation in kidney (χ²=0.017, P> 0.05). PIV was associated with an approximate 4-fold increase in risk of death as compared with PI (P< 0.05, OR= 4.38, 95% CL= 1.32 to 14.50). Our study suggested that Pattern IV produced more severe Cryptococcosis in murine model due to its difference in genotype.