IMPROVEMENT OF THE QUALITY CONTROL OF ELISA TESTING FOR THE LABORATORY CONFIRMATION OF MEASLES AND RUBELLA INFECTIONS AT THE STAGE OF THE MEASLES/ RUBELLA ELIMINATION PROGRAM
Authors: Mamaeva T. A. , Zheleznova N. V. , Nаumova M. A. , Chekhlyaeva T. S. , Vorobeychikovc E. V. , Ben Mamou M. , Aleshkin V. A. 
Published: March 2017

To estimate ELISA serological studies results of IgM and IgG specific Measles and Rubella Viruses (MRV) antibodies detection the “in-house” laboratory controls (ILC) including the specific markers of MRV infections were for the first time commercially prepared by the Vector Best PLC (Russia): “Measles-IgM, ser.1”, “Measles-IgM, ser.2”, “Rubella-IgM”, Measles-IgG” and “Rubella-IgG”. This task was realized under the special Executive Order of the Government of Russia N 523-r, 2014, April, 4. According to passport characteristics ILC samples are the lyophilized human sera, inactivated by heating (1 hour at 56°C) and stabilized by the mixture of sucrose (5%) and ProClin-3000 as the conservation agent. Samples are free of HBs Ag, anti-HVC, T.Pallidum, HIV-1/2, HIV-1Ag р24.The aim of the study was to evaluate the possibility of using the ILC for detection of the MRV IgM and IgG antibodies by ELISA with commercial ELISA kits used in Russia and CIS countries. In the process of detecting the specific activity of “Measles-IgM, ser.1”, “Measles-IgM, ser.2” and “Rubella-IgM” by ELISA kits of different formats (Vector Best, EcoLab and Siemens Companies) the statistically different results were received (p 0.05). The optical density (OD) values of IgM in the “Measles-IgM, ser.1” and “Measles-IgM, ser.2” ILC, obtained by ELISA “VectoMeasles IgM” (Vector Best) were significantly higher than those obtained by ELISA IgEnzygnost®Anti-MeaslesVirus/IgМ. These values consisted for the ser. 1–1.33±0.02 о.u. vs. 0.18±0.01 о.u. (р 0.05) and for the ser. 2–2.83±0.03 о.u. vs. 0.7±0.02 о.е. (р 0.05) in the Vector Best and Siemens ELISA kits correspondently. In the “Rubella-IgM” ILC the OD values of the specific IgM by the “ELISA-Rubella IgM” EcoLab were also higher than those obtained by IgEnzygnost®Anti-RubellaVirus/IgМ ELISA kit. These values consisted 2.92±0.04 о.u. vs. 0.88±0.03 о.u. (р  0.05) in EcoLab and Siemens ELISA test-systems correspondently. In the studies when the ILC working solution parameters for ELISA of “capture” and “indirect” formats were evaluated the statistic reliability and high information capability of the mathematic models of the OD value changes vs. the degree of dilution of the initial ILC were determined. For the “capture” and “indirect” formats the determination coefficient (R2) consisted 97.34 and 99.29 correspondently, the Fisher criteria (F) — 219.62 and 556.55 correspondently, the significance level (p) — 0.05 for both formats. The evaluated optimal working dilution degrees of the IgM-containing ILC make possible to exclude the influence of the IgG antibodies as the non-target marker in the ILC. On the other hand, taking into account the format of the used ELISA kit the optimal working dilution degrees give the possibility to obtain the desirable 2–3 “cut-off” values of the specific marker. Moreover, the issue of the target marker quantitative content in ILC is discussed in the study. In order to improve the quality of the commercial MRV IgM and IgG ELISA test-systems the joint studies with those who develop and produce these systems are desirable to be organized.