Immune evasion by human herpesviruses and its effect on vaccine development.

Abstract

In our lifetime we will encounter at least one if not several human herpesviruses. These viruses elicit a strong immune response upon primary infection. However, this immune response is unable to clear the virus due to its immune evasive properties. Instead, it drives the virus into a latent state. In healthy individuals these viruses are considered fairly harmless, whereas in immunocompromised individuals they are associated with the onset of serious diseases. These complications and the discomfort which can be associated with infection are strong motivators for vaccine development. By reviewing the clinically most relevant herpesviruses a general pattern emerged concerning the problems encountered during vaccine development. For instance, some human herpesviruses are able to avoid immune detection even when a good memory response is present. Therefore, vaccine development for these viruses appears to be nearly impossible. Additionally, individuals encounter some herpesviruses before their first birthday which complicates vaccination against a primary infection. Aside from vaccinating against primary infections, another strategy would be to vaccinate against complications associated with reactivation or immune deficiency. This field is even more challenging, it seems unlikely one can boost a deficient immune system. In this thesis an overview of the immune response, the immune evasion properties and the status of vaccine development is provided for the clinically most relevant human herpesviruses.