Induction of endogenous viral gene expression by halogenated hydrocarbons

Endogenous avian RNA tumor virus gene expression was induced in chick embryo cells by the 1,1,1-trichloro-2-, 2-bis(p-chlorophenyl ethane) metabolites bis(chlorophenyl)acetic acid and dichlorodiphenyl dichloroethylene and the antibacterial agent hexachlorophene. Line 100 x 7, C/ABE, chick cell cultures were incubated with each of these chemicals or the known endogenous virus inducer bromodeoxyuridine. At subtoxic levels, all four chemicals induced the production of virus particles as determined by assay for the viral-specific reverse transcriptase and infectivity. Since the endogenous virus produced is of subgroup E and consequently unable to infect surrounding cells of the type C/ABE, amplification of the induced virions was accomplished by infecting the subgroup E susceptible cell line 15B C/C with supernatants from the chemically treated cultures. Fluorescent antibody treatment of line 100 x 7 C/ABE cultures showed approximately 35% to 40% of the cells stained in the chemically treated cell cultures, suggesting that only a portion of the cells were responding to the chemical induction.