Isolation of Blastomyces dermatitidis yeast from lung tissue during murine infection for in vivo transcriptional profiling.

Fungal Genet Biol

Blastomyces dermatitidis belongs to a group of thermally dimorphic fungi that grow as sporulating mold in the soil and convert to pathogenic yeast in the lung following inhalation of spores. Knowledge about the molecular events important for fungal adaptation and survival in the host remains limited. The development of high-throughput analytic tools such as RNA sequencing (RNA-Seq) has potential to provide novel insight on fungal pathogenesis especially if applied in vivo during infection. However, in vivo transcriptional profiling is hindered by the low abundance of fungal cells relative to mammalian tissue and difficulty in isolating fungal cells from the tissues they infect. For the purpose of obtaining B. dermatitidis RNA for in vivo transcriptional analysis by RNA-Seq, we developed a simple technique for isolating yeast from murine lung tissue. Using a two-step approach of filtration and centrifugation following lysis of murine lung cells, 91% of yeast cells causing infection were isolated from lung tissue. B. dermatitidis recovered from the lung yielded high-quality RNA with minimal murine contamination and was suitable for RNA-Seq. Approximately 87% of the sequencing reads obtained from the recovered yeast aligned with the B. dermatitidis genome. This was similar to 93% alignment for yeast grown in vitro. The use of near-freezing temperature along with short ex vivo time minimized transcriptional changes that would have otherwise occurred with higher temperature or longer processing time. In conclusion, we have developed a technique that recovers the majority of yeast causing pulmonary infection and yields high-quality fungal RNA with minimal contamination by mammalian RNA.

Year of Publication
Fungal Genet Biol
Date Published
2013 Jul
PubMed ID
PubMed Central ID
Grant list
R37 AI035681 / AI / NIAID NIH HHS / United States
HHSN272200900018C / AI / NIAID NIH HHS / United States
5K08AI071004 / AI / NIAID NIH HHS / United States
K08 AI071004 / AI / NIAID NIH HHS / United States
R37AI035681 / AI / NIAID NIH HHS / United States
R01 AI093553 / AI / NIAID NIH HHS / United States
HHSN272200900018C / PHS HHS / United States