Epstein Barr virus (EBV) and Cytomegalovirus (CMV) are both widely spread herpesviruses that infect immune cells and establish latency (in B cells and in cells of the monocytic lineage respectively) in the host after primary infection and they are considered as a part of our “virobiome”. The time-point for infection is associated with socio-economic conditions, and sero-conversion occurs comparably late in Westernized countries. Although herpesvirus latency influences the immune system also in the asymptomatic host, the mechanisms behind this are still not very clear. As herpesviruses and man have co-evolved for a long time, several of these virus-induced effects on our immune system could be beneficial or at least confer an immunological imprint that we consider as “normal”. This is relevant to consider today, with the knowledge that the time-point for sero-conversion is more and more delayed, in particular in Westernized countries - is there for example an immunological advantage of an early EBV infection? For EBV, an infection during infancy is usually asymptomatic, but a later infection in adolescence or adulthood is frequently associated with mononucleosis. These age-related differences in symptoms has been ascribed the differences in immune maturation between infants and adults, but is still poorly understood.

We recently described that an early EBV-infection (before 2 years of age) is associated with a protection against early and persistent IgE-sensitization, while a later infection is associated with an increased risk (Saghafian-Hedengren et al 2010). The mechanisms behind this possible protection are however also still unknown. Still, both EBV and CMV latency is associated with significant impact on immune parameters in children. We have that early infection (<2years) with EBV and CMV correlates with both adaptive (T cells) and innate (NK cells) function at two years of age (Nilsson et al 2009, Saghafian-Hedengren et al 2009).

We continue to investigate how EBV and CMV influence different B-, NK-, and T- cell compartments in children in terms of basic characteristics and functional features in a large prospective allergy cohort. Further we perform in vitro infections of immune cells from children to explore the role of age at infection, but also co-infection and allergy, for the immune response to the infection.

 

References

Saghafian-Hedengren, S., Sverremark-Ekström, E., Lilja, G., Linde, A., & Nilsson, C. (2010). Early life EBV-infection protects against persistent IgE-sensitization. J Allergy Clin Immunol. 125:433-38

Nilsson, C., Larsson, A.K., Montgomery, S.M., Sverremark-Ekström, E., Linde, A., Lilja, G., & Troye Blomberg, M. (2009). EBV and CMV are differentially associated with numbers of cytokine-producing cells and early atopy. Clin Exp Allergy. 39:509-17

Saghafian-Hedengren, S., Sundström, S., Sohlberg, E., Nilsson, C., Troye-Blomberg, M., Berg, L., & Sverremark-Ekström, E. (2009). Herpes virus seropositivity in childhood associates with decreased monocyte-induced NK-cell IFN-γ production. J Immunol. 182:2511-17