Host entry by gamma-herpesviruses-lessons from animal viruses?

The oncogenicity of gamma-herpesviruses (gammaHVs) motivates efforts to control them and their persistence makes early events key targets for intervention. Human gammaHVs are often assumed to enter naive hosts orally and infect B cells directly. However, neither assumption is supported by direct evidence, and vaccination with the Epstein-Barr virus (EBV) gp350, to block virion binding to B cells, failed to reduce infection rates. Thus, there is a need to re-evaluate assumptions about gammaHV host entry. Given the difficulty of analysing early human infections, potentially much can be learned from animal models. Genomic comparisons argue that gammaHVs colonized mammals long before humans speciation, and so that human gammaHVs are unlikely to differ dramatically in behaviour from those of other mammals. Murid Herpesvirus-4 (MuHV-4), which like EBV and the Kaposi's Sarcoma-associated Herpesvirus (KSHV) persists in memory B cells, enters new hosts via olfactory neurons and exploits myeloid cells to spread. Integrating these data with existing knowledge of human and veterinary gammaHVs suggests a new model of host entry, with potentially important implications for infection control.