[Molecular biological monitoring of the polioviruses circulation in Belarus]. / Molekuliarno-biologicheskii monitoring tsirkuliatsii poliovirusov v Belarusi.

A total of 135 polioviruses (PV), including 25 wild and 110 vaccine-related, isolated in Belarus in 1957-1999 were studied by the analysis of the polymorphism of the restriction fragments lengths of two distal regions of the genome: the region (480 oligonucleotide pairs) coding the N-terminal fragment of capsid protein VP1 (RLFP-1) and the region (291 oligonucleotide pairs) coding the N-terminal fragment of nonstructural protein of 3D-polymerase (RLFP-3D1). The genetic analysis of the viruses made it possible to determine 3 epidemiologically different periods of PV circulation: (1) the prevaccination period (1957-1959) when wild PV of all 3 serotypes circulated on the territory of Belarus; (2) the early period of the use of Oral Poliomielytis Vaccine (1960-1966), characterized by simultaneous circulation of wild and vaccine PV, as well as vaccine/wild recombinant PV; (3) the period of the elimination of wild PV of indigenous origin and the circulation of vaccine-related viruses (1967-1999). The characteristic feature of wild PV was their pronounced genetic variability. 8 genetic variants of PV1, including 4 genetic groups, 2 genetic variants of PV2 and 1 genetic variant of PV3 were detected; 2 vaccine/wild recombinant PV were detected in 1960 and 1966. More than 40% of the vaccine-related PV under study had altered genetic characteristics (mutations and/or recombinations. Reverse variability, linked with the loss of a number of signs of attenuation, was shown to be characteristic of vaccine PV1. Recombinants occurred most frequently among PV3 (44.9%) and PV2 (40.0%), their recombinations being formed mainly with PV1. Recombinants PV2/PV1 and PV3/PV1 were found to have high frequency of reversion in the "PV1" fragment of the genome; this frequency exceeded that in PV1 with the homotypical genome (66.7 and 44.4% in contrast to 12.5%).

The immunogenicity and reactogenicity of the trivalent vaccine, Trimovax, indicated for prevention of measles, mumps, and rubella, in 12-month-old children in Belarus.

In the Republic of Belarus, immunization of children against measles and mumps had been carried out using monovalent preparations according to the national schedule of measles vaccination at 12 months of age and mumps vaccination at 24 months of age. A rise of rubella incidence in the last few years (i.e., for the official registration period 1980 to 1998, there was an increase from 72.2 to 607.5 cases per 100,000 population) made it necessary to implement immunization against this infection, as well. Therefore, in 1996, combined vaccination against measles, mumps, and rubella of 12-month-old children was carried out for the first time in a clinical trial that used the vaccine Trimovax [Aventis Pasteur (formerly, Pasteur Mérieux Connaught), Lyon, France]. The reactogenicity of the vaccine was investigated in 372 children. Post-vaccination reactions were noted in 5.6% of children; in 1.3% of children the reactions were classified as severe [i.e. associated with body (axillary) temperature > or = 38.6 degrees C]. For the evaluation of immunogenicity, sera from 324 children were obtained 2 to 2.5 months after inoculation, and serum antibody levels were measured by enzyme immunoassays. Among the vaccines, protective antibody titers (expressed in inverse of dilution units) were observed to measles (> or = 1:50) in 97.8%, to mumps (> or = 1:50) in 93.8%, and to rubella (> or = 1:100) in 96.0% of children. Antibodies to all three components of the vaccine were mainly present in intermediate (1:200-1:800) or high (> or = 1:1600) titers: to measles in 96.3%; to mumps in 75.8%; and to rubella in 73.5% of vaccines. The results of these trials are evidence of the good safety and immunogenicity of this MMR vaccine, which provides an alternative to the currently used measles and mumps monovaccines, with the additional benefit of providing immunity against rubella, as well.

[Active aluminum oxide--a new adsorbent for concentrating intestinal viruses from water]. / Aktivnyi oksid aliuminiia--novyi adsorbent dlia kontsentrirovaniia kishechnykh virusov iz vody.

Concentrating properties of a new adsorbent, active aluminum oxide, towards poliomyelitis virus type III and simian rotavirus are studied using virus contamination of sewage and drinking water. Optimal concentrations of the adsorbent for effective adsorption of both rota- and polioviruses are established (1.5 and 1 g/liter, respectively) at pH typical of sewage and drinking water (7.0-8.5), as well as the optimal time of virus contact with the adsorbent (30 min). Elution conditions are determined: 3% elution agent beef extract and pH 8.5-9.5 are optimal for both viruses. Active aluminum oxide is recommended as an adsorbent for elimination of enteroviruses from water objects.

[The immunological efficacy of the combined vaccine Trimovax intended for the prevention of measles, mumps and rubella]. / Immunologicheskaia éffektivnost' assotsiirovannoi vaktsiny Trimovaks, prednaznachennoi dlia profilaktiki kori, parotita i krasnukhi.

In 1996 the immunization of children against measles, mumps and rubella with combined vaccine Trimovax ("Pasteur Mérieux Connaught", France) was carried out in the Republic of Belarus. The reactogenicity of the vaccine was studied in 372 children. To evaluate immunological effectiveness, the sera of 324 children were used. Postvaccinal reactions of different intensity were registered in 5.6% of the children; of these, 1.3% exhibited severe reactions. Among the vaccinees, protective titers of antibodies to measles were found in 97.6% to mumps, in 93.8% and to rubella, in 96.0% of the children. Antibodies to all three components of the vaccine were present mainly in high and moderate titers. The results thus obtained indicate that, Trimovax was well tolerated and proved to be immunologically active.

[Effectiveness of the selective revaccination of schoolchildren against measles]. / Effektivnost' selektivnoi revaktsinatsii shkol'nikov protiv kori.

The revaccination of 70% of schoolchildren, previously immunized with measles vaccines of 26 different batches with insufficient immunogenic potency, has led to the pronounced and stable increase of immunity in the corresponding groups of children and has decreased measles morbidity among them 20 times.

The results of study of pertussis component of DPT vaccine produced in USSR and some other countries.

The paper presents the results of testing of 16 vaccines under the letter code from 8 countries received from WHO. These vaccines differed both in toxicity and potency. Six lots contained from 1.12 to 6.29 IPU/ml, i. e. they did not meet WHO requirements for pertussis vaccine. To determine toxic properties of the vaccines in mouse body weight gain test it is more reasonable to use one, but not half an individual immunizing dose. According to all data the absence of correlation between protective and toxic properties of the vaccines was quite definitely revealed. Vaccines from USSR (N, O, P) showed the optimal results for all tests. The limited observations on reactogenicity of vaccines N and O (both produced minor reactions) have brought out the tendency of correlation between the data of laboratory tests and reactogenicity rates of vaccines. The necessity for further investigations to confirm these findings is emphasized.