In contrast to most gammaherpesviruses, Bovine herpesvirus 4 (BoHV-4) has a broad range of host species both in vitro and in vivo. Several in vitro studies demonstrated that some human cell lines are sensitive or even permissive to BoHV-4. These observations led to the hypothesis that cross-species transmission of BoHV-4 could lead to human infections. In the present study, we investigate the sensitivity of BoHV-4 to neutralization by naïve human sera in order to determine if humans exhibit innate anti-viral activities against this virus. Our results demonstrate that human sera from naïve individuals, in contrast to the sera of naïve subjects from various animal species, neutralize BoHV-4 efficiently. A series of complementary experiments were performed to unravel the mechanism(s) of this neutralization. The data obtained in this study demonstrates that human serum neutralizes BoHV-4 in a complement dependent manner activated by natural antibodies raised against the Galalpha1-3Galbeta1-4GlcNAc-R epitope expressed by bovine cells.