Phenotypic Variability Correlates with Clinical Outcome in Isolates Obtained from Botswanan HIV/AIDS Patients.


Pathogenic species of cause hundreds of thousands of deaths annually. Considerable phenotypic variation is exhibited during infection, including increased capsule size, capsule shedding, giant cells (≥15 μm), and micro cells (≤1 μm). We examined 70 clinical isolates of and from HIV/AIDS patients in Botswana to determine whether the capacity to produce morphological variants was associated with clinical parameters. Isolates were cultured under conditions designed to simulate stresses. Substantial variation was seen across morphological and clinical data. Giant cells were more common in while micro cells and shed capsule occurred in only. Phenotypic variables fell into two groups associated with differing symptoms. The production of "large" phenotypes (greater cell and capsule size and giant cells) was associated with higher CD4 count and was negatively correlated with intracranial pressure indicators, suggesting that these are induced in early stage infection. "Small" phenotypes (micro cells and shed capsule) were associated with lower CD4 counts, negatively correlated with meningeal inflammation indicators, and positively correlated with intracranial pressure indicators, suggesting that they are produced later during infection and may contribute to immune suppression and promote proliferation and dissemination. These trends persisted at the species level, indicating that they were not driven by association with particular species. Isolates possessing giant cells, micro cells, and shed capsule were rare, but strikingly, they were associated with patient death ( = 0.0165). Our data indicate that pleomorphism is an important driver in infection. Cryptococcosis results in hundreds of thousands of deaths annually, predominantly in sub-Saharan Africa. is an encapsulated yeast, and during infection, cells have the capacity for substantial morphological changes, including capsule enlargement and shedding and variations in cell shape and size. In this study, we examined 70 isolates causing meningitis in HIV/AIDS patients in Botswana in order to look for associations between phenotypic variation and clinical symptoms. Four variant phenotypes were seen across strains: giant cells of ≥15 µm, micro cells of ≤1 µm, shed extracellular capsule, and irregularly shaped cells. We found that "large" and "small" phenotypes were associated with differing disease symptoms, indicating that their production may be important during the disease process. Overall, our study indicates that strains that can switch on cell types under different situations may be more able to sustain infection and resist the host response.

Year of Publication
Date Published
2018 10 23
PubMed ID
PubMed Central ID
Grant list
R01 AI073896 / AI / NIAID NIH HHS / United States
R01 AI093257 / AI / NIAID NIH HHS / United States
U19 AI110818 / AI / NIAID NIH HHS / United States