Research by a team of scientists from the Institute of Physics of the Czech Academy of Sciences has been published by the prestigious Journal of Travel Medicine

Scientists from the Institute of Physics of the Czech Academy of Sciences have published the results of extensive research in the field of public health. Their aim was to map the occurrence of SARS-CoV-2 virus in Prague public transport during the COVID-19 pandemic. The team from the Laboratory of Functional Biointerfaces, led by Hana Lísalová, developed special biosensors for testing. Their use has provided new insights into the fight against infectious diseases.  The research, which has recently been published inJournal of Travel Medicine, was implemented in collaboration with the Biology Centre of the Czech Academy of Sciences, University of South Bohemia in České Budějovice, Taiwanese Academia Sinica, ELI ERIC and Prague Public Transit Company.

The study confirmed the potential of biosensors as a tool for virus detection in public environments. Specifically, it focused on virus detection in hundreds of diverse complex samples prepared from swabs of surfaces in public transport. The research builds on the team's previous work published in ACS Applied Materials and Interfaces, which provided a novel biosensor design and demonstrated its effectiveness in detecting SARS-CoV-2 virus in clinical samples from patients with COVID-19. Now the team has extended their method to significantly more diverse swab samples from surfaces of exposed sites in public spaces.

Hana Lísalová, head of the research team, said: "We are excited about the results of our research and believe that our findings can have a significant impact on public health. Biosensors are proving to be a promising tool for monitoring the presence of viruses and infectious risks in public spaces, allowing for the rapid and effective setting of adequate measures to reduce the possibility of disease spread."

"I greatly appreciate the courage of Hana Lísalová and her team to break into the public health field and embark on research into the ways SARS-CoV-2 virus can be spread even in such a turbulent and uncertain time as the COVID-19 pandemic. All the logistics of sample collection were made possible by the collaboration of the entire interdisciplinary team of the Division of Optics, including the involvement of our students," said Alexandr Dejneka, head of the Division of Optics of the Institute of Physics.

The biosensor system is highly adaptable and can be used to detect a wide range of viruses. The result could not have been achieved without collaboration with the Biology Centre of the Czech Academy of Sciences and the University of South Bohemia in České Budějovice.

 "While testing the samples collected in public transport, several were positive for the detection of SARS-CoV-2 virus. Subsequently, we were interested in whether this was an infectious virus or already inactivated viral particles. We verified the infectivity of the virus by culture experiments in our BSL3 laboratory. A laboratory with this classification has to meet very strict biosafety criteria, so that even these high-risk pathogens can be studied there," said Václav Hönig from the Biology Centre of the Czech Academy of Sciences.

 "Our research team is interested in the development of universal biosensors that are able to detect a wide range of pathogens, so we were pleased to be involved in the collaboration with Dr. Lísalová and her research team using this uniquely designed biosensor. The COVID-19 pandemic enabled the collection of a large number of samples that were used not only to test the sensitivity and specificity of the biosensors, but also to analyse the importance of the much-discussed transmission of infection through surfaces in everyday life. Dr. Lísalová's biosensor confirmed its versatility, and we believe that it has the potential to be used for the detection of other pathogens and thus contribute to the protection of human health worldwide," summarises Ján Štěrba from the Faculty of Science of the University of South Bohemia in České Budějovice.

 The study also focused on the comparison of the results of SARS-CoV-2 detection using the biosensor and the standard PCR method. The results showed that the combination of two sensitive and reliable methods based on different detection principles can monitor the risk of the virus spread in public spaces much more accurately than using only one method. The results of the study have the potential to revolutionise the way we monitor and detect viruses in public spaces and demonstrate the potential of biosensors as a complementary screening tool in epidemic monitoring and forecasting. They could pave the way for further breakthroughs in public health.

The research by the team from the Institute of Physics of the Czech Academy of Sciences not only provides revolutionary findings in the field of biosensors, but also underlines the importance of collaboration between research institutions and universities. The published work is proof that this collaboration allows to cross the boundaries of individual disciplines.

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The significance of this finding lies in the long-term effects that the gut microbiome has on its hosts. From reducing the likelihood of immune disease to parasite infections, the presence of an adequate gut microbial community early in life has a positive impact on host health.

But how can tiny great and blue tit hatchlings harbor complex bacterial communities in the first place? Senior author Katerina Sam, Czech Academy of Sciences and University of South Bohemia, said: "Previous studies have shown that birds hatch with nearly sterile guts, and in the case of tits, once they are in the nest, they are quickly colonized by bacteria until a well-established microbial community is present after 8-10 days. We wanted to explore how this colonization works, and the best way we could think of was by altering it."

The team, consisting of researchers from the Czech Academy of Sciences and the University of Copenhagen, then began planning an experiment that would take place during the breeding season - usually between April and June in Central Europe - when Tit clutches hatch and the colonization process begins. There are two ways to alter a bacterial community: with antibiotics or with probiotics, and they decided to try both. In each experimental nest, the researchers administered antibiotics to two chicks and probiotics to two others for nearly two weeks, while the last two experimental chicks in each nest served as controls.

Disruptions in the process of colonizing the gut could affect nutrient absorption and thus limit growth. Each time the researchers applied a treatment, they weighed the chicks and took a microbiome sample by gently swabbing the chick's cloaca.

They found that the gut colonization was resilient enough to overcome such perturbations, and that the source of this bacterial input was primarily the bacterial community in the nest, followed by vertical transmission from females. The results have been recently published in the journal Molecular Ecology.

The researchers expected a general effect of antibiotics and probiotics on chicks from different nests, since antibiotics generally inhibit the growth of certain bacteria, while probiotics are expected to promote beneficial bacteria. However, this was not the case: "We were surprised in some ways that the treatments had no measurable effect on the growth and bacterial community of the chicks, since poultry have been treated with antibiotics for decades to improve growth and avoid certain pathogenic bacteria. So, we kept digging to find out how the gut microbiome might be resilient to such disruptions" said co-lead author Kasun H. Bodawatta, University of Copenhagen".

The microbial nest environment was found to be the main contributor to the chick gut microbiome, and researchers hypothesized a continuous colonization from the nest that impeded the treatments to be effective. In fact, the gut microbiome of siblings resembles each other to a greater degree than that of unrelated neighbors. "The similarity of gut and nest microbiome is important in that the microbial communities in the nest depend on the nest material selected by females, that is an indirect maternal influence on the gut microbiome of chicks," said co-lead author David Diez-Méndez, Czech Academy of Sciences.

However, there are some aspects that differ between great tits and blue tits. The research team found that neighboring great tits had more different gut microbiomes the farther away their nests were, whereas neighboring blue tits did not exhibit this distance relationship. Differences in habitat or prey quality may explain this pattern, since Great tits are usually dominant over Blue tit because of their size difference. 

The current study tries to give explanations to differences between species, as well as the reasons for the more similar gut microbiomes between chicks and mothers as opposed to fathers, which appear to harbor a different microbial community. Sam stresses that more research is needed to truly understand the process of gut colonization in these hole-nesting species. "We know that the chick gut microbiome comes from the nest, from the mother, and to a lesser extent from the father, but those three sources explain at most half of it; we need to figure out the whole colonization process and the exact contribution of each source”.

Reference: Diez‐Méndez, D., Bodawatta, K. H., Freiberga, I., Klečková, I., Jønsson, K. A., Poulsen, M., & Sam, K. (2023). Indirect maternal effects via nest microbiome composition drive gut colonization in altricial chicks. Molecular Ecology. https://doi.org/10.1111/mec.16959