SELECTION OF SYSTEMS FOR CULTIVATION OF DUCK VIRUS HEPATITIS AGENT
Duck virus hepatitis causes considerable economic damage to duck farms, especially to commercial ones, because it results in the mass mortality of ducklings younger than 30 days old and the decreased performance of ducks. The damage caused by duck virus hepatitis is aggravated by costs for restrictive measures upsetting the economy of the farm, especially when the disease becomes permanent. In spite of the achievements in attenuated virus strain cultivation and use, the countries with a well-developed duck farming industry still continue the search for new biological systems (including heterogeneous ones) to prepare the virus-containing material with the maximum level of its activity. The results of testing different cell cultures, as well as duck, guinea fowl and chicken embryos, for their susceptibility to VGNKI-K vaccine strain, duck virus hepatitis agent, are presented. The optimal cultivation systems which allow the preparation of virus-containing materials with activity of at least 6.5 lg ELD<sub>50</sub> intended for the development of diagnostic and vaccine products have been identified.