RT Journal Article SR Electronic(1) A1 Buscaglia, Celina A1 Calnek, Bruce W.YR 1988 T1 Maintenance of Marek’s Disease Herpesvirus Latency in vitro by a Factor Found in Conditioned Medium JF Journal of General Virology, VO 69 IS 11 SP 2809 OP 2818 DO https://doi.org/10.1099/0022-1317-69-11-2809 PB Microbiology Society, SN 1465-2099, AB Summary Chicken spleen cells latently infected with Marek’s disease virus were cultured with and without conditioned medium (CM) obtained from concanavalin A-stimulated chicken spleen cell cultures. The expression of viral internal antigen(s) (VIA), which is usually associated with cultivation, was prevented or markedly reduced by the CM. This effect required the continued presence of CM, since its removal after 48 h resulted in the subsequent appearance of VIA. Although CM contains both gamma interferon (IFN-γ) and interleukin 2, our studies suggest that the ‘latency-maintaining activity’ (LMF) may not be associated with either of these products of stimulated lymphocytes. However, IFN-γ may also have had some suppressive effect. LMF appears to have an M r greater than 10000 and to be inactivated by heating to 90 °C for 5 min., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-69-11-2809