PRACTICAL ASPECTS ON IDENTIFICATION, CULTIVATION AND CHARACTERISTICS OF VARICELLA ZOSTER VIRUS ISOLATES.

Introduction. Until now, it is considered that the infectivity of the Varicella Zoster Virus (VZV - Varicella Zoster Virus) remains closely related to the cell, and the newly formed virus is not released into the culture medium. It is also known that VZV is difficult to grow in cell cultures, because it replicates slowly, has a limited range of sensitive cell cultures. In addition, VZV isolation depends on the type of cell culture used, the nature of the clinical material, the presence of a viable virus and the time of transportation. Objectives. To study the production of infectious extracellular VZV using different cell cultures. Materials and methods. The 8 different cell cultures were used in the work, including diploid lung cells of a human embryo and skin and muscle tissue of a human embryo (KM-27), as well as human and monkey. As clinical isolates, crusts from vesicular rash were used, which were placed in cryo-vials with a transport medium and transported in liquid nitrogen. Infectivity of VZV was assessed on infected cell cultures by hemo-adsorption with a suspension of erythrocytes isolated from the blood of guinea pigs or people with a zero blood group, and was confirmed in the reaction by indirect immunofluorescence with polyclonal sera from people who had had varicella or herpes zoster. Results. The study examined 27 clinical samples in the form of crusts from vesicular rash from patients with chickenpox, as well as one sample from a patient aged 63 years in the phase of exacerbation of recurrent herpes zoster. Primary infection with clinical isolates was performed on strains of diploid lung cells of a human embryo (HLEC – human lung embryo cells) at low temperatures. It was found that the crusts from the vesicular rash, taken from patients 1 to 18 days inclusive from the onset of the rash, caused a cytopathic effect on the monolayer of HLEC cells in the form of cytolysis of cells around the crust. The specificity of the cytopathic effect was confirmed using real-time polymerase chain reaction (rt-PCR). To assess the immune sera, viral antigens were prepared on 7 cell lines infected with the laboratory strain Ellen VZV (USA). A high specific antigenic activity of mouse sera in ELISA was detected when all the lysates of infected cell lines were used as the solid-phase sorbent. In experiments on the reproduction of VZV, it was found that the extracellular virus is released into the culture medium from the 1st day after the infection of sensitive cells, and the infectivity of the virus-containing fluid increases during further cultivation.