Susceptibility of human cultured cells to Mason-Pfizer monkey virus

Mason-Pfizer monkey virus (M-PMV), originally isolated from mammary carcinoma of a rhesus monkey, is infectious to various human cells in tissue culture. Human epithelioid cells (HeLa and HEp-2), fibroblastic cells (embryonic cells as well as virus-transformed embryonic RSb cells), and glial cells (KC) have all been infected with M-PMV. Electron microscope studies have shown that all infected cells produce progeny virus. The titer of infectious M-PMV in cultures of HeLa and HEp-2 cells assayed by KC syncytium formation was 10(1) syncytium-forming unit (SFU) per 0.2 ml. The titers for whole human embryonic cells (HEC), human embryonic lung cells (HEL), and embryonic skin Detroit-551 cells were 10(4) SFU/0.2 ml for each, and 10(3) SFU/0.2 ml for RSb and KC cells.