Cell culture for in vitro growth of Pneumocystis suis

Recent studies underline the host obligate nature of the fungus Pneumocystis and provide information about possible requirements for the growth of the fungus in cell culture, the success of which has so far been limited. The use of respiratory tissue from the appropriate host is likely to be decisive. This study will answer the following questions: Does Pneumocystis f. sp. suis (P. suis), the Pneumocystis species occurring in the lungs of pigs, show a strict host specificity and a strong nutritional dependency on the porcine lung tissue and is the fungus responsible for only minor tissue lesion? In preliminary trials, we have attempted various approaches to cultivate pig respiratory tissue. In a first step, we will improve these cell culture systems. P. suis can be detected in the lungs of approximately every second pig and is known to grow when the immune system of the host is impaired. Hence, we will immunosuppress pigs and collect lung lavage fluid and lung tissue. The P. suis organisms will be separated from these specimen through their binding to antibodies labeled with a fluorescent signal. This fluorescent signal allows the fungal organisms to be collected by a cell sorting machine. The cell culture systems will be infected with the fungal organisms and we will try to cultivate P. suis on the cells. Developmental stages of the fungus and lung tissue lesions caused by the fungus will be imaged by electron microscopy, a method that allows a strong magnification of all structures. Finally, the conversion of the genetic information of P. suis into proteins, named gene expression, will be studied. P. suis is one of the less described Pneumocystis species. Cell culture has had only limited success and every contribution to this topic is essential for the entire Pneumocystis community. The establishment of antibody-based cell sorting systems will create the basis for future projects. Imaging will contribute to a better understanding of the development of P. suis related pneumonias. The gene expression analysis will unlock basic biological functions and will contribute to understanding the complexity of the interactions between host and fungus.