At the moment, rapid point-of-care diagnostics is a prevalent trend in infectious disease diagnostics. The faster the pathogen is identified, the faster the patient can get the appropriate treatment. In the case of severe infections, this may be crucial for the patient’s survival.
Researchers at the University of Helsinki have developed and patented a technique, which enables rapid antibody detection, potentially revolutionising the diagnostics of both infectious and autoimmune diseases.
Now the researchers have utilised this technique known as RFS (Rapid FRET Serodiagnostics) to develop a test applicable to serodiagnosis of epidemic nephropathy from the patient’s urine sample. Previously, the testing required a blood sample. Puumala virus, the causative agent of epidemic nephropathy, belongs to hantaviruses, the representatives of which cause severe haemorrhagic disease. It is likely thatthe test is applicable to the diagnosis of other hantavirus infections.
The researchers collected urine and blood samples from 40 patients hospitalised for epidemic nephropathy at Tampere University Hospital. In addition, samples were collected from a healthy control group. The samples were analysed in a test based on the new RFS technique.
“The test results gained from the patients’ urine samples corresponded very closely to those gained from the blood samples. All patients with acute Puumala virus infection tested positive with urine as the sample material,” says Docent Jussi Hepojoki from the University of Helsinki.
Antibodies measurable also in urine
The RFS technique, developed by researchers at the University of Helsinki, is based on a new way of measuring antibodies produced by the body – molecules that identify viruses, bacteria or allergens, or autoantibodies developed in autoimmune diseases.
The ability to measure antibodies from urine is based on a new observation:
“Antibodies are composed of two chains, heavy and light. Antibodies bind with their target, such as a virus, through what are known as antigen-binding sites, which are formed together by the heavy and light chains. We found that the light chain alone has the ability to bind the antigen at high enough affinity to enable the measurement. That was an interesting finding, as the cells responsible for antibody production make light chains in excess, which is excreted via urine,” Hepojoki explains.
“The test we have developed can detect antibody response from urine sample. If it proves to be sufficiently sensitive and reliable, it can make the diagnostics easier and reduce the need for blood sampling. At the moment, RFS tests with urine are not yet able to differentiate acute infections from those suffered earlier. The test could well be suited, for example, to demonstrating the protection provided by vaccines, or diagnosing autoimmune diseases and allergies.”
Reference: Satu Hepojoki, Lauri Kareinen, Tomas Strandin, Antti Vaheri, Harry Holthöfer, Jukka Mustonen, Satu Mäkelä, Klaus Hedman, Olli Vapalahti and Jussi Hepojoki. Urine and Free Immunoglobulin Light Chains as Analytes for Serodiagnosis of Hantavirus Infection. Viruses 2019, 11(9), 809; https://doi.org/10.3390/v11090809