FIG 9.

Cfp4 does not confer a competitive advantage to Histoplasma during murine infection. Competitive index determination of Cfp4-producing and Cfp4-deficient yeasts in vitro and in vivo. Equivalent proportions of Cfp4-producing yeasts marked with GFP (strain OSU77) and Cfp4-lacking yeasts marked with RFP (strain OSU85) were combined and used to inoculate liquid medium (broth culture) and for intranasal infection of mice (inoculum of 10⁴ total yeast cells). After 4 days of growth in broth culture and 9 days of lung infection, dilutions of the yeast suspensions or the lung homogenates were plated and compared to platings of the inoculum mixture. The proportions of Cfp4-producing and Cfp4-deficient yeasts were determined as green and red fluorescent colonies, respectively. The competitive index was calculated as the GFP/RFP ratio at the endpoint divided by the GFP/RFP ratio of the inoculum. Horizontal lines and error bars represent the mean competitive index ± standard deviation (n = 4 replicates [in vitro] or infected mice [in vivo]). The competitive index did not differ significantly from 1.0 for in vitro (P = 0.51) or in vivo (P = 0.58) growth, as determined by Student's t test. Additionally, no significant difference (P = 0.88) was found between in vivo and in vitro growth.