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To assess sensitivity and specificity of phosphorescent immunochips developed by the authors on the basis of microplate phosphorescent assay (PHOSPHAN) for detection of IgM and IgG antibodies to tick-borne encephalitis virus (TBEV) in sera of patients and to compare results of PHOSPHAN assay with results obtained by lanthanide immunofluorescence assay (LIFA) and solid-phase enzyme immunoassay (SPEIA).Two hundred sixty one serum samples were tested, including 155 samples from 74 patients with clinical diagnosis of TBE confirmed by serologic identification of IgM antibodies to TBEV. Sera were collected in 2003 in Perm region from persons, which fell ill during seasonal increased activity of ticks-vectors of TBEV, as well as from healthy blood donors. Phosphorescent immunochip corresponds 96-well plate with 4 active microzones formed on the bottom of each well, which are able to detect specific IgM and IgG antibodies to TBEV. Immune reaction was visualized by conjugate of streptavidin with Pt-coproporphyrin. Intensity of fluorescence was measured by scanning the bottom of previously dried microwell with scanner IFI-02.Comparable sensitivity and specificity of POSHPHAN assay, LIFA and SPEIA was demonstrated for detection of IgM and IgG antibodies to TBEV in samples. Immunoluminescence-based PHOSPHAN assay and LIFA were more sensitive for analysis of sera with low titer of specific IgM antibodies.PHOSPHAN assay could be used for early serologic diagnostics of TBE as well as for assessment of antibody level for control of efficacy of treatment in patients with prolonged illness or level of protective immunity in vaccinees.

Possibility to use blood dried on filter paper for serological testing on antibodies to tick-borne encephalitis (TBE). Sensitivity and specificity of specific IgM detection in dry stains of blood by lanthanide fluorescence immunoassay was 94.9% (86.9-100%) and 97.5% (94-100%) respectively, compared with results obtained in tests of sera. Agreement in positive and negative results of tests for IgM against TBE in 562 serum samples and dry blood stains was 95.3%. During analysis of both types of biomaterial high degree of correlation was observed between intensity of fluorescence when testing for both IgM (r=0.86700; p=0.05; n=562), and IgG (r=0.83883; p=0.05; n=337) toTBE virus. Use of this mildly invasive technique of blood draw is reasonable during conduction of large-scale population studies for seroepidemiologic monitoring, investigation of disease outbreaks, control of effectiveness of vaccination against TBE, assessing of level of specific immunity in population of endemic regions, control of treatment, and serologic diagnostics of acute TBE in hospitalized patients, in which blood draw is difficult to perform.

Lanthanide immunofluorescence assay (LIFA) was used to detect IgM of antibodies to tick-borne encephalitis (TBE) virus in 791 patients who had been fallen ill with acute febrile diseases in the period of seasonal activity of carrier ticks in the endemic region of Russia (the Perm Region) (1786 sera being tested). This assay was equally effective as the commercial enzyme immunoassay test system (EITS) in the early serological diagnosis of TBE, verifying the clinical diagnosis in about 70% of patients just within the first week of disease. At the same time, the sensitivity of LIFA was much (nearly 5 times) higher than that of EITS in revealing antibody IgM in patients with chronic TBE, as well as in those with the acute course of disease, accompanied by the low level and untypical trend of accumulation of antibodies ofthis class.

The lanthanide fluorescence immunoassay was elaborated for quantitative determination of the total thyroxin T4 in bloodstain dried in filter paper; the fields of its clinical application were defined. The method is based on the hardphase concurrent immunoassay with specific monoclonal antibodies to T4 marked by chelates of europium ions and with conjugate of the T3 heterologous hapten sorbed in plate holes with bovine serum albumin. Measurements of the fluorescence intensity were made by a fluorometer in the time resolution mode. The method ensures the T4 determination in a dry bloodstain with a diameter of 3.4 mm within the concentration range of 0 to 400 nmol/l and with the variation coefficient of below or equal to 15%; the results correlated with the findings of the T4 analysis by the DELFIA Neo T4 set, "Wallac Oy", Finland. The method efficiency was demonstrated for screening and verifying the congenital thyroid deficiency in newborns; it was also confirmed that the method can be used for monitoring the functional thyroid condition in adult patients.