Influence of long-term storage of blood serum samples in a biobank for population-based seroepidemiologic studies

Abstract

Aim. To assess the safety of IgG antibodies during long-term storage of blood serum samples using measles- and rubella-specific antibodies as an example.Material and methods. The study used serum samples from the collection of the Department of Epidemiology of the Gamaleya National Research Center for Epidemiology and Microbiologya, which were tested for measles- or rubella-specific IgG antibodies immediately upon admission to the laboratory, were frozen and stored at -70оC (n=180). The samples were reexamined after 20 months (n=90) and 6 years (n=90).Results. Reexamination after 20-month storage showed a decrease in the mean level of measles- and rubella-specific antibodies by 13,1% (from 0,36 (0,08-1,21) to 0,31 (0,02-1,2) IU/ml) and by 11,8% (from 151,4 (45-235) to 133,5 (72-198) IU/ml), respectively (p<0,05 for all). At the same time, the number of seronegative samples did not change. After a 6-year storage period, the mean level of measles-specific antibodies decreased by 33,8% (p<0,05) from 0,72 (0,4-1,79) to 0,34 (0,18-1,14) IU/ml and only two samples became seronegative. It was shown that the higher the IgG level in native samples, the more pronounced its decrease was during the second examination.Conclusion. Storage of serum samples in a biobank for 20 months at -70оC ensures the safety of measles- and rubella-specific IgG antibodies, and is the basis for the reliability of future studies.