[Reactivation of Epstein-Barr virus (Herpesviridae: Lymphocryptovirus, HHV-4) infection during COVID-19: epidemiological features].

INTRODUCTION: Immunodeficiency underlying the development of severe forms of new coronavirus infection may be the result of mixed infection with SARS-CoV-2 and other pathogens, including Epstein-Barr virus (EBV).The aim is to study the prevalence and epidemiological features of co-infection with SARS-CoV-2 and EBV. MATERIAL AND METHODS: A cross-sectional randomized study was conducted in Moscow region from March to May 2020. Two groups were examined for EBV-markers: hospital patients (n = 95) treated for SARS-CoV-2 infection and blood donors (n = 92). RESULTS: With equal EBV prevalence the detection of active infection markers in donors (10.9%) was noticeably lower than in SARS-CoV-2 patients (80%). Significant differences in this indicator were also found when patients from subgroups with interstitial pneumonia with the presence (96.6%) and absence (97.2%) of SARS-CoV-2 in the nasopharyngeal smear were compared with the subgroup of patients with mild COVID-19 (43.3%). The average IgG VCA and IgG EBNA positivity coefficients in donor group were higher than in patient group (p < 0.05). Patients with active EBV infection markers were significantly more likely to have pneumonia, exceeding the reference values of ALT and the relative number of monocytes (odds ratio - 23.6; 3.5; 9.7, respectively). DISCUSSION: The present study examined the incidence and analyzed epidemiological features of active EBV infection in patients with COVID-19. CONCLUSION: A significantly higher rate of detection of active EBV infection markers in hospital patients indicates a combined participation SARS-CoV-2 and EBV in the development of interstitial pneumonia. Low levels of specific IgG EBV serve as predictors of EBV reactivation. Exceeding the reference values of ALT and the relative number of monocytes in patients should serve as a reason for examination for active EBV infection markers.

[Comparative evaluation of effectiveness of traditional serologic and modified methods of herpes zoster laboratory diagnostics].

AIM: Comparative evaluation of effectiveness of traditional serologic and modified diagnostic methods of disease arising due to varicella and herpes zoster virus (VZV) reactivation. MATERIALS AND METHODS: 2 groups of patients were examined. The main group consisted of 39 patients with manifest form of herpes zoster (HZ), control--20 healthy donors. Sex composition of the groups did not differ. Traditional method of serologic diagnostics included determination of anti-gE VZV IgG and anti-VZV IgG and anti-IgM in patient and donor blood sera by using EIA. Modified methods consisted of isolation in density gradient and cultivation for 48 hours of peripheral blood mononuclears (PBMC) in RPMI-1640 complete culture medium containing 10% of fetal bovine serum, 4 mM L-glutamin and gentamycin. Concentrations ofanti-VZV IgG and IgM were then determined in culture medium by using EIA. RESULTS: In all the examined HZ patients and healthy donors anti-VZV IgG were detected in blood. Only in 26 (67%) of 39 HZ patients anti-gE VZV IgG and anti-VZV IgM were determined in blood sera. Among donors false positive results for these markers were detected in 10% and 5% of cases, respectively. During simultaneous determination of anti-gE VZV IgG and anti-VZV IgM the specificity of the method increased to 100%, sensitivity of the diagnostic method based on simultaneous determination of anti-gE VZV IgG and anti-VZV IgM was 59%. During analysis of spontaneous production of anti-VZV antibodies by PBMC in 38 (97.4%) of 39 patients anti-VZV IgG were determined in PBMC culture, anti-VZV IgM production was observed only in 4 patients. In control group false positive results of anti-VZV IgG and IgM production by PBMC was not detected by the modified method (100% specificity). At equal specificity level sensitivity of the modified method based on determination of spontaneous anti-VZV IgG production by PBMC culture was significantly higher than effectiveness of the traditional serologic diagnostics (97.4% and 59%, p < 0.0001). CONCLUSION: The data obtained allow to recommend during diagnostics of manifest and atypical VZV infection forms arising due to endogenous virus reactivation the new modified method of laboratory diagnostics of the disease as having higher sensitivity compared with traditional serologic method.

[Enzyme immunoassay system for the detection of low-avid lgG antibodies to human cytomegalovirus ("CMV-diagnost")].

The new Russian enzyme immunoassay system "CMV-Diagnost" based on the detection of low-avid IgG antibodies has been developed for the rapid diagnosis of cytomegalovirus infection. The system was found not only to determine the strained immunity in response to cytomegalovirus, but also to judge the current infection from the avidity index of detectable IgG antibodies with a high degree of validity. The antibody avidity index of less than 30% suggests an acute stage of primary cytomegalovirus infection. The minimum antibody threshold bodies (deltaOD has been established for the correct interpretation of data on low-avid antibodies. deltaOD of > or =0.6 optic units was for the developed test system "CMV-Diagnost. A correlation was found between the serum levels of low-avid antibodies and IgM antibodies to cytomegalovirus at the acute stage of the disease.

[Detection of low avidity IgG as a promising approach to diagnosis of primary herpetic infection]. / Vyiavleniie nizkoavidnykh IgG-antitel--perspektivnyi podkhod v diagnostike pervichnoi gerpeticheskoi infektsii.

A Russian immune-enzyme test-system ("HERPES-DIAGNOST") was designed on the basis of detection of low-avidity IgG antibodies in order to promote the laboratory value of serological examinations of patients with different clinical manifestations of the herpetic infection. The key test parameters were tuned; the immunosorbent production based on antigens (herpes simplex virus--HSV), types 1 and 2, was optimized; and the concentration was chosen for the main reagent that removes the low-avidity antibodies (8 M urea solution) and, finally, the temporal and temperature regimes were selected for testing. A system was elaborated for registering and interpreting the results. The avidity index of antibodies lower than 35% was found to be a reliable criterion confirming the presence of acute primary infection triggered both by HSV-1 and by HSV-2. If there is a relapse of herpetic infection, the avidity index of antibodies can range from 30 to 45%.

[The specific activity and immunological safety of the intranasal method of revaccination with a live measles vaccine made from the Leningrad-16 strain]. / Spetsificheskaia aktivnost' i immunologicheskaia bezopasnost' intranazal'nogo sposoba revaktsinatsii zhivoi korevoi vaktsinoi iz shtamma Leningrad-16.

The search for alternative routes for administration of live measles vaccine is associated both with the threat of infection with human immunodeficiency virus, hepatitis B virus, and with the development of a more physiological, natural and less traumatic mode of vaccine administration. The influence of the intranasal administration on the general condition of the immune system, its immunomodulating effect (the emergence of inducer suppressors, cell response to the inactivated virus), was studied as well as the level and intensity of secretory and general humoral immunity. The studies confirmed the immunological effectiveness and safety of the intranasal administration of a live measles vaccine and suggested its advantages for revaccination against measles.

[The rapid diagnosis of measles by using immunoenzyme analysis based on peroxidase-labelled viral antigens]. / Ekspress-diagnostika kori s pomoshch'iu immunofermentnogo analiza na osnove mechennykh peroksidazoi virusnykh antigenov.

The sensitivity and specificity of the enzyme immunoassay (the capture variant), based on the use of the complex of anti-IgM-IgM to purified measles virus, the peroxidase-labeled lysate and nucleocapsid antigens of measles virus, were evaluated. The advantages of the nucleocapsid conjugate were established. The study of 200 serum samples from measles patients revealed that antimeasles IgM antibodies could be detected in 100% of cases, and the assay of 15 serum samples from healthy donors and 5 serum samples from patients with autoimmune diseases did not yield a single false positive result.

Enzyme immunoassay--a method of serological survey of measles vaccination.

Enzyme immunoassay (EIA) for detection of antibodies to measles virus designed in the Moscow Research Institute of Viral Preparations has proved highly sensitive (98%) and specific (100%) as tested in 492 vaccinated children. Comparison of EIA and haemagglutination inhibition (HI) test allowed to determine the cut-off value of the optical density to be equal to 0.1. The serum dilution 1:10 was found appropriate for the screening.

[Isolation and properties of hybridomas producing monoclonal antibodies to the Leningrad-16 measles virus]. / Poluchenie i svoistva gibridom, produtsiruiushchikh monoklonal'nye antitela k virusu kori Leningrad-16.

A panel of 18 hybridomas producing MCA to measles virus (the L-16 strain) was produced by somatic hybridization method. Thirteen hybridomas produce immunoglobulins of the G class represented by all known subclasses of mouse immunoglobulins; the subclass G 2a is predominant. Five hybridomas produce immunoglobulins of the M class. The resulting preparations of MCA are highly reactive in several serological tests: IFA, NIF, HI, NT. MCA have been divided into 3 groups according to their capacity to combine with three strains of morbilli viruses: L-16, LEC, and carnivora distemper virus (strain EPM).

[Rapid serological screening of human sera for the presence of measles virus antibodies in solid-phase immunoenzyme analysis]. / Bystryi serologicheskii skrining syvorotok liudei na nalichie antitel k virusu kori v tverdofaznom immunofermentnom analize.

A single dilution technique has been used for the determination of antimeasles antibody titer. The method involved the plotting of the calibration curve and the characterization of the serum by arbitrary "evaluation units" in comparison with the specially selected positive serum whose titer was taken to be equal to 100 "evaluation units". By means of this method 57 sera obtained from children immunized against measles and 118 sera from non-vaccinated adults aged 18-22 years were examined. The values of the calculated titers were similar to those determined experimentally. This recommends this method for seroepidemiological investigations aimed at determining the level of herd immunity to measles.

[Correlation of titers of antibodies to the measles virus by an immunoenzyme method and in the hemagglutination inhibition reaction]. / Izuchenie korreliatsii titrov antitel k virusu kori metodom IFA i v RTGA.

The authors analyze the results of comparative studies on 15 paired sera from children with suspected measles, of 32 sera from children and adolescents aged 1.5 to 16 immunized against measles, and of 21 sera from adults aged 19 to 86 with a history of the disease. EIA proved to be more sensitive than HAIT: the detection rate of positive sera was higher, as were the titers of antibodies detected by it, in examinations of the sera from vaccinated children and the adults. Analysis of the distribution of sera with different titers of antibody to measles virus in EIA and HAIT has revealed a correlation between the titers in the sera with high antibody levels. In the cases with low antihemagglutinin titers, no correlation between the titers determined in the two tests has been observed.

[Induced mutagenesis of plasmid as well as chromosomal genes inserted into plasmid DNA. II. The mutagenic action of chemical factors]. / Indutsirovannyi mutagenez plazmidnykh, a takzhe khromosomnykh genov, vkliuchennykh v plazmidnuiu DNK. Soobshchenie II. Mutagennoe deistvie khimicheskikh faktorov.

To proceed the works on induced mutagenesis in plasmids, mutagenic effects of chemicals on the DNA of RSF2124 plasmid mediating colicine E1 biosynthesis and resistance to ampicillin, were studied. After exposure to mutagens, plasmid DNA was used to transform Escherichia coli C600 rk-mk-cells. The lethal effect was estimated from inactivation of the ampicillin marker, the mutagenic effect being measured by the appearance of mutants unable to synthesize colicine (Col-). The reaction of the plasmid DNA with a mutagen was stopped by 10-fold dilutions of aliquots in TEN buffer, followed by dialysis in 10 mH CaCl2 for 24 h. To select the most efficient mutagens for plasmid DNA, the compounds were predominantly tested which are known to be effective in other systems (transforming and transfecting DNA, microbial viruses). An a result, all chemicals tested by their activity were classified into 4 groups: inducing more than 100 fold increase (hydroxylamine, O-methylhydroxylamine); inducing 10 fold increase (UV-irradiation, lambda = 254 nm; W-mutagenesis, gamma-irradiation, nitrous acid, mitomycin C); inducing less than 10fold increase (indirect UV-mutagenesis, nitrous acid, beta-chloroethyldiethylamine hydrochloride, nitrosoguanidine); no mutagenic effect (acridine orange, ethyl methane sulfonate, sodium azide, O-beta-diethylhydroxylamine).

[Induced mutagenesis of plasmid and chromosomal genes inserted into plasmid DNA. I. The mutagenic action of radiation]. / Indutsirovannyi mutagenez plazmidnykh, a takzhe khromosomnykh genov, vkliuchennykh v plazmidnuiu DNK. Soobshchenie I. Mutagennoe deistvie izluchenii.

This paper describes the results of treating plasmid DNA in vitro with mutagens, to obtain mutations both in plasmid genes and chromosomal genes comprised within the plasmid, thus avoiding disorganization characteristic of in vivo mutagenesis. The model system is represented by DNA of RSF2124 responsible for colicine E1 synthesis and resistance to ampicillin. Col- mutants were looked for after exposure to UV- and gamma-irradiation. The lethal effect was estimated as inactivation of the ampicillin resistance marker. After reisolation from mutant transformant of the plasmid DNA, the novel character and resistance to ampicillin proved to retain in the course of subsequent transformations and passages of transformed colonies, suggesting the mutational nature of the changes. Exposure of RSF2124 to short-wave UV-irradiation (lambda = 254 nm) produced a pronounced mutagenic effect: the relative quantity of Col- mutants under optimal conditions of mutagenesis increased about 10 times. In the case of W-reactivation (additional UV-irradiation of C600 wild type cells) of lethal lesions, a 95% reliable increase in mutagenic effect was observed. Significant enhancement of mutagenesis (about 4-fold) was detected when only recipient cells were exposed to low doses of UV (the so-called indirect UV mutagenesis). Thus, with regard to W- and indirect UV mutagenesis, the plasmid DNA behaves like DNA of temperate phages which suggests their evolutionary relationship. Treatment of plasmid DNA with acridine orange prior to UV, only protected from lethal lesions. Gamma-irradiation (60Co) at the dose producing 100-fold inactivation, increased the yield of Col- mutants by one order of magnitude. The presence of RSF2124 plasmid in a cell does not affect its UV sensitivity.