During his most active beekeeping period, Mendel kept around 50 bee colonies. It was in this apiary that he tried different ways of overwintering bee colonies, taking meticulous notes all the while. He also worked constantly on finding ways to simplify beehives and improving their handling; indeed, he was always trying to find new methods to move the field forward. Mendel devoted himself to beekeeping until 1878, when he was appointed abbot, after which he gradually found less and less time for his hobby. In that same year, he became an honorary member of the Beekeeping Association. His beekeeping experiences are known to us thanks to a number of short articles in the magazine ‘Včela Brněnská’, where, among other things, you can read about his experience with bee brood rot, a dangerous disease that attacks bees and forced him to destroy all of his bee colonies.
Immunochemical diagnosis of bee brood rot (also known as European Foulbrood)
Bee brood rot, which is caused by the bacterium Melissococcus plutonius, can lead to significant weakening, or even death, of a bee colony. The honey bee is the world’s most important pollinating insect, and thus is irreplaceable, not just for the economy but also for nature as a whole. Despite this, the global bee population has been declining rapidly in recent years. This is due in part to environmental issues, such as pollution and damage to ecosystems; however, other factors threatening bee colonies include a range of diseases, including bee brood rot, which is highly contagiousness and is transmitted rapidly to other bee colonies. As such, there is an urgent need for sensitive methods capable of detecting the disease at an early stage, and thereby help prevent further spread.
Immunochemical methods, the speciality of the Institute of Biochemistry’s Immunoassay and Nanosensor Research Group (Faculty of Science, Masaryk University), represent one possible method for enabling early diagnosis of bee brood rot. This broad group of methods, which are based the specificic properties of antibodies, can be used not only to detect bee pathogens but also many other bacteria, viruses and clinically important substances, such as salmonella, the SARS-CoV-2 coronavirus and cancer biomarkers. The most widespread immunochemical method presently in use is ‘ELISA enzyme determination’ (pictured below), which is based on enzyme markers that, after the addition of a suitable substrate, provide a colour signal directly proportional to the concentration of the substance being determined.
Enhancing sensitivity using nanoparticles
In laboratory diagnostics, it is a huge advantage if the method used is sensitive enough to reliably detect bacteria in lower amounts than are associated with clinical symptoms. For this reason, the Immunoassay and Nanosensor Group is also working on improving the parameters of immunochemical assays using different types of luminescent nanoparticles, e.g. by using photon-upconversion nanoparticles (UCNPs, see below), which are nanocrystals with specialised optical properties.
When using fluorescence (the best-known type of luminescence), ultraviolet radiation with higher energy (i.e. a shorter wavelength) is converted into visible radiation with lower energy (with a longer wavelength). However, UCNPs can reverse this process and create visible radiation from infrared radiation, which has an even lower energy (which uses up several photons due to the law of conservation of energy). Among other things, this phenomenon has a tremendous advantage in that it removes the optical background, thereby increasing detection sensitivity. When using UCNPs as markers in immunoassays, their surface is modified so that they can bind specifically to the bacteria being determined. To this end, a method for modifying UCNPs with streptavidin protein was developed at the Institute of Biochemistry. This protein binds very tightly (with high affinity) to the biotin molecule (vitamin B7); thus, if a biotin-labelled antibody is used, UCNPs can act as a marker for detecting the causative agent of bee brood rot. This UCNP-based method has already proven itself by analysing actual samples of bees, larvae and moths, which has shown the method to be universal, improving the sensitivity of immunochemical methods not only for the diagnosis of bee diseases but also the detection of other pathogens and biomarkers.
Translation: Kevin F. Roche
Editor: Zuzana Jayasundera