Patients who are weakened or have immune systems that do not function properly, that is, who are immunocompromised, often catch fungal infections. Every year over 300,000 people around the world are diagnosed with invasive aspergillosis. Fatality rate may be up to 50-96 percent in certain patient groups, even if they receive proper treatment. A single fungal species is responsible for 90% of the cases. Researchers at UD were willing to find out why, out of the over 300 aspergillus species, it is Aspergillus fumigatus that causes the most health problems.
- One of the basic features of beings is that they are able to adapt to their constantly changing environment. Through the examination of the stress responses of fungi, we try to explore how they are able to adapt to negative environmental changes, to the environment they live in, be it a fermentor, a food storage facility, or the human body. When our body is attacked by fungi, our traditional response is trying to kill the microbe that caused the infection. However, another method would be to prevent the adaptation of fungi to the special environment of the human body – explained Tamás Emri, associate professor at the Faculty of Science and Technology, Department of Biotechnology and Microbiology.
The research programme was launched two years ago, when three databases vital for the analysis were completed with the contribution of associates of the department. Researchers based their examinations on the synthesis of these databases. The first, already existing database contains the genome sequence data of 18 Aspergillus fungal species. The second one identifies potential fungal stress genes, that is, genes that play a part in shaping the stress responses of fungi. The third database organises the stress tolerance data of genome-sequenced Aspergillus species, and shows the extent to which fungi are able to cope with particular stress stimuli.
- We were looking for an answer to the question that had been a riddle for a long time: How stress genes of a fungal species define its stress tolerance, that is, can we conclude, based on the composition of stress genes, on how well the species can cope with specific stress stimuli?– explained Tamás Emri.
The examinations produced a surprising result: It turned out that based on the stress genes we can conclude on the family relations of a fungal species, as any change in the composition of stress genes may result in the appearance of new species. However, on the basis of stress genes we cannot conclude on the stress tolerance of the given species.
- It is a stunning finding, the exact opposite of what we expected. It is safe to say that in the fungi studied the key factor is not their stress gene composition, but rather how they control the operation of these genes. It also means that Aspergillus fumigatus does not need specialized genes to adapt to the human body. It is able to survive with a basic Aspergillus stress gene composition. This is bad news, because if it had specialised genes, we could hinder the species' adaptation by switching off these genes. Instead, we have to focus on the processes governing the control of the operation of the genes, and hinder the adaptation of the species by blocking these processes. The understanding of how signal transferring networks work may be of key importance in terms of curing patients with fungal infections as well – pointed out Tamás Emri.
The research programme was described in a leading journal on mycology, Studies In Mycology, under the title "Duplications and losses of genes encoding known elements of the stress defence system of the Aspergilli contribute to the evolution of these filamentous fungi but do not directly influence their environmental stress tolerance."
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How does the stress genes composition of a fungal species determine its stress tolerance? A research group at UD has studied the behaviour of pathogens of aspergillosis, a fungal infection. Findings have been published in a leading journal on mycology.
