Isolation of a new strain М-2020 of the camelpox virus (<i>Poxviridae: Orthopoxvirus: Camelpox virus</i>) in Republic of Kazakhstan and study of its reproduction in various biological systems

Abstract

Introduction. This article presents the results of isolation of camel smallpox virus (Poxviridae: Orthopoxvirus: Camelpox virus, CMLPV) and study of its reproductive properties on sensitive biological systems.Material and methods. The epizootic strain M-96 of the virus as well as its attenuated variants KM-40 and KM-70 obtained by sequential passivation were used in the study. Isolation of the pathogen from suspension of biopsy specimens was performed on cell culture and in embryonated chicken eggs (ECEs). All experiments were performed with the number of replications ensuring obtaining reliable results.Results. The CMLPV was isolated from the crusts and pox papules of the skin taken from sick camels (Camelus bactrianus) during an outbreak in various districts of the Mangistau region at the end of 2019. The signs of pathogen reproduction on chorio-allantoic membrane (CAM) were observed from 3 passages. The obtained virus caused formation of pathological changes on the CAM in the form of elevated dot or solid white formations separated from the surrounding tissue, with hemorrhagic foci in the center. The reproductive properties of the isolate on sensitive biological systems were determined in comparison with the epizootic CMLPV strain M-96, isolated earlier in the territory of Kazakhstan during the outbreak 23–24 years ago, as well as its attenuated variants. The isolated virus was given the conventional name M-2020.Discussion. When studied in two sensitive cultivation systems (cell culture and ECEs), strain M-96 and its attenuated variants KM-40, KM-70, which were used in the experiments as a control, demonstrated high infectious activity with titer 4.75-6.75 lg TCID50/cm3, while for the examined isolate M-2020 of CMLPV had the significantly lower values (3.00-4.75 lg TCID50/cm3, p 0,05).