Feline leukemia and sarcoma viruses: susceptibility of human cells to infection

Human embryonic cells are highly susceptible to infection with feline leukemia and sarcoma viruses. These viruses were propagated in human cultures without antigenic modification or loss of infectivity for cat or human cells. Virus stocks contained at least 10(6) infectious units of virus per milliliter for human cells. Virus present in 10(-6) dilution of virus stock replicated to detectable amounts as early as 7 days after virus infection. The feline sarcoma virus induced morphological transformation of human cells.

ST-feline fibrosarcoma virus: induction of tumors in marmoset monkeys

Two newborn marmosets, inoculated with a cell-free extract of feline fibrosarcomas, developed multiple sarcomas and died within 46 days of inoculation, whereas two of these animals inoculated with a crude homogenate developed no tumors. This susceptibility to a mammalian RNA sarcoma virus suggests that marmosets may be particularly suitable for attempts to isolate infectious agents from man.

Characteristics of a virus isolated from a feline fibrosarcoma

A virus was isolated from a radioresistant feline fibrosarcoma. It induced multi-nucleated giant-cell formation and lysis in a cell line derived from a canine fibro-sarcoma, which was used to characterize the virus. End-point titrations in these cells required 28 days. The virus was sensitive to ether and heat and was destroyed at pH 3. Replication was not inhibited by 5-bromodeoxyuridine. Electron microscopy revealed assembly by a budding process from the plasma membrane of infected cells. The average diameter of the virion was 106 nm. Intracisternal particles with an average diameter of 45 nm were present within infected cells. In two instances secondary monolayers of feline renal cells underwent morphological transformation after inoculation of the virus. The two strains of transformed cells are now in continuous culture and do not yield infectious virus.