Title : Serological aspects of the specific immune response in patients with measles of different ages in a territory with a high incidence
Abstract:
Relevance. Not only children are involved in the epidemic process, but also adults, whose encounter with the measles virus is accompanied by the synthesis of antibodies according to the primary or secondary type of immune response. The diagnosis of measles infection in previously vaccinated individuals is a difficult task, since the results depend not only on the format of the diagnostic kits, but also on the qualitative and quantitative indicators of the immune response.
Target. Assessment of the significance of humoral immune response indicators in measles patients of different ages in a territory with a high incidence.
Materials and methods. To confirm the primary and secondary immune response in 1832 measles patients of different ages in a territory with a high incidence rate (6.3 per 100 thousands of population), qualitative and quantitative indicators of IgM and IgG were determined using specific kits of different formats: VectoMeasles-IgM, (Vector-Best, Russia, capture format), Anti-Measles Virus NP ELISA IgM (Euroimmun, Germany, indirect format).
Detection of IgG and determination of the degree of avidity of class G antibodies were performed using commercial test systems Anti-Measles Viruses ELISA (IgG) and Avidity Anti-Measles Viruses ELISA IgG, (Euroimmun, Germany). The basis for laboratory confirmation of the diagnosis of measles with a primary immune response in the patient was a positive result for IgM, the presence of class G antibodies with a low degree of avidity; with a secondary immune response - positive for IgM, high concentration (more than 5 IU / ml) of highly avidity IgG in sera obtained on days 4-7 of the onset of the rash.
Results. As a result of testing 1832 blood serum samples for the content of specific IgM, it was found that measles was laboratory confirmed in 100% of cases using the VectoMeasles-IgM capture variant test systems and 88.33% using the Anti-Measles Virus NP ELISA IgM indirect format. In the sera of 75.05% of patients with a primary immune response, low-avid IgG was detected at a concentration of 0.83±0.9 IU/ml;
in sera with a secondary immune response - highly avidity antibodies of class G at a concentration of 24.2 ± 5.4 IU / ml, which was 29.2 times higher than in the group with a primary immune response (0.83 ± 0.9 IU / ml ) (p<0.05). Age-specific analysis showed that in the group with a primary immune response, the number of children under 14 years old and adults 18-70 years old was almost the same: 49.6% and 47.56%, respectively, and children and adult patients with a secondary immune response - 1.31 % and 97.16%, respectively (p<0.05). There were 46 adolescents (15-17 years old), 39 of whom responded with a primary immune response.
Conclusion:
a) a significant difference was found in the detection of IgM using test systems of different formats: 100% in the VectoMeasles-IgM "capture" kit and 88.33% in Anti-Measles Virus NP ELISA IgM indirect format (Euroimmun) (p<0.05);
b) qualitative and quantitative indicators of specific IgG antibodies were determined in the primary immune response - low avidity (18.8±14.8%) at a concentration of 0.83±0.9 IU/ml and in the secondary - high avidity (95.5±6, 5%) at a concentration of 24.2±5.4 IU/ml;
c) data have been obtained to assess both the composition of the “participants in the epidemic process” and the “gaps” in the organization of the measles immunization program.
