Mass spectrometry is essentially a scale for weighing molecules. A laser turns a sample into ionised particles, which are then accelerated in a vacuum toward a detector. The time lapsed prior to registering on the detector helps researchers determine the mass of the particles. By targeting characteristic particles, or peptides, belonging to the viral coat protein, the virus can be positively identified by matching the results to entries in genetic databases.
In the study, the researchers analysed a stool sample treated with virus-like particles, which closely resemble norovirus but are noninfectious. Using mass spectrometry, the researchers were able to detect the norovirus capsid protein down to levels typically found in clinical specimens from sick individuals.
"This is the first report of the use of mass spectrometry for the detection of norovirus," said David R. Colquhoun, lead author of the study and research fellow with the Johns Hopkins Center for a Livable Future. "This is a significant step towards using mass spectrometry as an environmental surveillance tool for the detection of pathogenic human viruses in complex environmental samples."
Typically, bacteria and viruses are identified by cultivation on selective media and cell lines. However, this process does not work for human norovirus, which cannot be cultured outside the human body.
Rolf Halden, PhD, assistant professor in the Department of Environmental Health Sciences and senior author of the study, pointed out that proteomic mass spectrometry is appealing because it has the potential to identify different types and strains of viruses regardless of whether their presence is suspected or not. "Unlike other processes, we do not need to know what we are looking for in advance. Any pathogen whose genetic information is contained in online genetic databases represents a suitable potential target.”
MEDICA.de; Source: Johns Hopkins University Bloomberg School of Public Health