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The conducted virologic, serological and molecular-and-biological investigations showed that virus Coxsakie B4, isolated from cerebrospinal fluid and rhinopharyngeal lavages of patients, was the main etiological agent, which caused mainly an outbreak of enterovirus infection in the city of Vitebsk in 2001. Coxsakie B4 viruses were found in 30% of samples by using the cultural method and in 76.9% of samples--by polymerase chain reaction (PCR) while carrying out the sanitary-and-virologic investigations in drinking water, including in infection foci. Besides, we found infectious non-cytolitic enteroviruses (EV) with changed biological properties (which could not be detected by the classic cultural method) in drinking water by using the method of PCR integrated with cell culture in the "-" strand of EV RNA. Peculiar clinical-and-epidemiological characteristics of the disease outbreak, i.e. "explosive" onset, multiple clinical forms, mixed EV infections and disease decay after drinking-water chlorination, as well as the isolation of one and the same EV serotype from patients and from water testify to a possible water origin of the outbreak.

Data on the usage of chemical inhibitors nifan and belvtazid, which possess a selective and antienteroviral effect, in the primary identification of enteroviruses and their differentiation into polio- and non-poliomyelytic ones isolated from human clinical materials or the environment by using the cell culture are presented in the article. The method is recommended for the practical use by the virology service in the diagnostics of enteroviral infections and in the identification of cytopathic agents isolated from the enviroment.

In the recent years Echovirus-30 associated outbreaks have taken place in different European countries. Aseptic meningitis caused by Echovirus-30 was the main diagnosis of a large outbreak in Belarus in Summer-Autumn, 1997, involving 460 patients. Echovirus-30 was detected in cerebrospinal fluid of the patients with aseptic meningitis. This serotype played the dominant role in the outbreak. Minor serotypes and mixtures of enteroviruses were detected in faeces and nasopharyngeal lavages. Investigation of environmental samples gave evidence of expressed viral contamination of drinking water and water sources (river and ground sources). River water sources were considerably contaminated with viruses. The incidence of virus isolation was 50%. After cleaning procedures, the incidence became two times lower, proving imperfect water purification and disinfection procedures. Sequence analysis of isolates from Belarus (isolates from water and patient's cerebrospinal fluid) showed the difference of 0.2%. The outbreak peculiarities such as high attack rate and wide-spread of the disease incidences, clinical form variability, isolation of outbreak strain from water and a good agreement between minor serotypes isolated from faeces and water samples as well as correlation in the dynamics of acute intestine infections, aseptic meningitis morbidity and bacterial water contamination can be considered as evidence of its water-borne. Echovirus-30 isolates from Belarus were very closely related to each other and to several European isolates. Sequence difference between isolates of 1994-1998 from European countries was found to be 4.3%. The data can point to the common primary source of enterovirus infection, connected to water and to the possibility of epidemic strain transmission from neighbouring states to the Republic of Belarus.

In recent years outbreak of enterovirus infections caused by Echovirus-30 were rather frequently registered in different European countries. A major outbreak caused by this virus took place during the summer-autumn period of 1997 in the city of Gomel, Belarus. Sanitary epidemiological and molecular epidemiological studies made it possible to determine that the outbreak was water-borne. The sequence analysis of Echovirus-30 strains isolated from water and the cerebrospinal fluid of patients revealed a minor divergence between them (0.2%) indicative of their practical identity. The comparison of the Belorussian isolates with the strains isolated in Europe in 1994-1998 also showed a small percentage of differences in their genomes, which showed that the outbreak of Echovirus-30 infection was probably brought to Belarus from the territories of European countries.

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.

Indirect immunofluorescence (IIF) and RT-PCR were used for rapid diagnosis of enterovirus infection during an outbreak of aseptic meningitis in Gomel. IgM to enterovirus were detected in 93.6% sera by IIF and in 71.4% cerebrospinal fluid specimens by RT-PCR. IIF takes only 1.5-2 h and RT-PCR 6-7 h. The methods are recommended for rapid diagnosis of enterovirus infection.

The state of general and specific responsiveness of thymocytes and splenocytes in non-inbred white mice has been studied in the reaction of lymphocyte blast transformation under the influence of phytohemagglutinin (PHA) and herpes simplex virus. Experimental herpetic encephalitis has been shown to give rise to the development of pronounced immunosuppression, which is confirmed by a considerable decrease (P less than 0.05) in the levels of the PHA- and virus-induced transformation of thymocytes and splenocytes in infected mice in comparison with the similar transformation characteristics of intact lymphocytes. The inhibition of the general and specific responsiveness of T-lymphocytes has been found to be one of the possible mechanisms of immunosuppression in acute herpes infection.