In the past, we have co-cultured HIV-1 producing T cell lines (expressing full length HIV-Env), human teratocarcinoma or melanoma cell lines expressing Env of the human endogenous retrovirus HERV-K as well as human cells producing the porcine endogenous retrovirus PERV (also expressing full length PERV-Env) with PBMCs from normal human donors and did not observe IL-10 release (unpublished data). Here, IL10 is linked to teratocarcinoma.