Species selective interaction of Alphaherpesvirinae with the "unspecific" immune system of the host.

During evolution Herpesviridae have developed glycoproteins, which interact with essential components of the immune system. Besides immunoglobulin-binding proteins (= Fc-receptors), expressed by several members of the herpesfamily, the interaction with the complement system plays a role in the pathogenicity of herpes simplex virus. Here we report that the ability to interact with the third complement component (C3), the central mediator of complement activation, was also found among several animal alphaherpesviruses. This interaction appeared to be species-selective as the viral proteins preferentially bound to the C3 originated from the respective host. That could provide a possible explanation for the evolution of a variety of herpesviruses as the species tropism observed among Herpesviridae may be influenced by specific adaptation of protective virus-proteins to the immune system of the different hosts. The data have critical implications for the studies of virus host interactions in heterologous systems and support a role for the C3-binding proteins in pathogenesis. Since the C3-binding proteins are conserved among different herpesviruses they could serve as suitable subunit-vaccine candidates.