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T HE virus of Rift Valley fever (RVF) has been grown in a variety of tissue culture systems. The culture systems that have been reported to support the growth of this virus include minced chick embryo in Tyrodes solution;8.12 em-bryonic mouse brain;2 rat sarcoma cells, human embryo, rat, mouse, and swinie fibroblasts; 15,17 ovine kidney cells;8.1S1 monkey kidney Oells; and Chang's human liver cells.4 Tho, urpose of this report is to record the ability of five establisfi lines of cells to support the growth of Rift Valley fever vii S (RVFV).AN EHD Virc 8train. The van Wyk strain of RVFV was used. Kaschula 5 dencribed its isolation from the blood of a sheep from the Boshof District of the Orange Free State in the Union of South Africa. The working seed virus (lamb serum) used in these studies had a titer of 1 X 109-5 mouse intraperi-toneal median lethal doses (MIPLD~o) per ml. All material that contained virus was assayed by the intraperitoneal (IP) inoculation of mice (Swiss-Webster strain, 10 to 14 gram