Supernatants of virus-infected macrophages prime uninfected macrophages for lipopolysaccharide-induced apoptosis by both an interferon-dependent and an independent mechanism.

Virus-infected macrophages (M phi) release factors priming uninfected M phi for LPS-induced apoptosis. This was shown for bovine M phi infected with cytopathogenic bovine virus diarrhea (BVD) virus or with bovine herpes virus-1 (BHV-1) but not for M phi infected with noncytopathogenic BVD virus. The former two viruses also induced interferon type I in M phi, which also primes macrophages for LPS-induced apoptosis. However, several lines of evidence suggested that virus-infected M phi produce IFN-independent factors priming for apoptosis. For example, a soluble IFN type I receptor abrogated the antiviral activity, but not the ability of supernatants to prime uninfected M phi for LPS-induced apoptosis. It is suggested that the production of factors priming uninfected cells for apoptosis plays a part in virus-induced pathogenesis, e.g. in cattle afflicted with mucosal disease, or with infectious bovine rhinotracheitis, or in viral diseases inducing a marked lymphopenia. Copyright 2000 S. Karger AG, Basel.