A history of PHI among the patients further significantly affected the EBV-host relationship, which was not observed in non-vaccinated PHI patients [31]. Although we followed several of the vaccinated patients for 2–3 years, we cannot make any conclusion concerning the persistent effect of immunisation on EBV DNA load. All analysed patients were introduced on cART soon after ending the vaccine trials. The introduction Gamma-secretase inhibitor of cART affects the EBV host balance via the restoration of the CD4+ positive

cells. This is most likely a strong confounding factor on the effect of immunisation on the EBV DNA load. The immune stimulation caused by rgp160/alum may affect EBV in two ways. It may be either through influence on EBV replication resulting in MK-8776 manufacturer infection of more B cells, or EBV infected B lymphocytes may be

stimulated to proliferate through the activation of helper T-cells as a result of a Th2 enhancement by the vaccine. It has been shown that gp160 HIV-vaccination up-regulates immune activation T-cell markers, such as MHC class II and CD38 helper T-cells [32]. In an experimental prophylactic vaccination with gp120 in mice, the Th2-arm was activated [33]. The effects of therapeutic vaccination on T-cells might generate B-cell activation through non-specific immune stimulation in HIV infected individuals, as also shown for patients with autoimmune disease [15] and [32]. Our method detects B cell-associated EBV genome load. The method does not distinguish whether an expansion of EBV load in infected cells was caused by an increased copy-number or if it was caused by an increased number of infected cells. Using the same PCR method

in a study of blood from healthy donors, we have shown that the number of EBV genome copies vary between 1–5 copies per B cell in different B-cell subsets [34]. It is not known if this is also valid in HIV-1 infected patients. EBV-DNA PCR is a useful tool most for monitoring clinical course of lymphoproliferative disease and for identifying patients at risk for tumours [11] and [35]. Measurement of EBV genome levels is then usually performed in extra-cellular plasma as cell free virus DNA [35] and [36]. However, Stevens et al. [11] concluded that serum may not be an optimal clinical specimen for EBV DNA load-monitoring because it does not consider the presence of cell-associated virus, and uncontrolled cell lysis may give irreproducible results or overestimation of the DNA load. However, we could not detect any EBV-DNA in plasma from our patients, which might reflect their relatively intact immune status. EBV DNA is rarely if ever detected in plasma from healthy individuals [37]. Cell-free virus DNA is probably only detected when released from dying cells in EBV carrying tumours or when the EBV host balance is significantly disturbed. Free virus may also be derived due to the replication of virus in sites outside blood in hosts with relaxed control of EBV-latency.