Antibodies protect mice against challenge with tick-borne encephalitis virus (TBEV)-infected macrophages

TBEV is a flavivirus highly pathogenic for humans. By transfer of antibodies directed to the TBEV surface glycoprotein E into mice, immune protection against subsequent inoculation with free TBEV particles could be achieved. After natural TBEV infection via the skin, however, cells of the monocyte/ macrophage lineage were recently demonstrated to represent an important source of local virus replication before viraemia occurs. Whether antibodies can protect against virus challenge when contracted in the form of infected cells, however, is still unclear. In the current study, TBEV antibodies protected mice against challenge with either free virus or TBEV-infected macrophages equally well. This observation may be of more general significance.