Reproduction of Lassa virus in different cell cultures.

Sierra Leone strain of Lassa virus was growing to high titres of 10(5)-10(6) plaque forming units (PFU) per ml in Vero, L and swine kidney cell lines as well as in diploid human cells and primary human embryo kidney cells. As many as 80% of the cells became infected as demonstrated by the immunofluorescence (IF) technique. In BHK-21, CV-1, HeLa, FL, HEp-2 and dog kidney cell lines, the virus reproduced to lower titres (10(4)-10(5) PFU per ml), whereas in primary chick embryo fibroblasts it did not multiply at all. The virus formed plaques under agar overlay only in CV-1 and Vero cells.