One of the mechanisms of defense against viral infection is induction of apoptosis in infected cells. To escape this line of protection, genomes of many viruses encode for proteins that inhibit apoptosis. Murid herpesvirus 4 gene M11 encodes for homologue of cellular Bcl-2 proteins that inhibits apoptosis and autophagy in infected cell. To study a role of M11 in regulation of apoptosis we have established a yeast model system in which the action of M11 together with proapoptotic proteins Bax, Bak and Bid can be studied. When expressed in yeast, M11 did not inhibit autophagic pathway, so only effects of expression of M11 on activity of coexpressed proapoptotic proteins could be observed. In this experimental setting M11 potently inhibited both proapoptotic multidomain proteins Bax and Bak. The antiapoptotic activity of M11 was suppressed by coexpression of proapoptotic BH3-only protein tBid, indicating that M11 inhibits apoptosis likely by the same mechanism as cellular antiapoptotic proteins Bcl-2 or Bcl-XL. (C) 2011 Elsevier Inc. All rights reserved.