Recently, it has become obvious that not only CD8 T-cells, but also CD4 T-helper cells are required for the induction of an effective, long-lasting cellular immune response. In view of the clinical importance of cytomegalovirus (CMV) and human immunodeficiency virus (HIV) infection, we developed 2 strategies to simultaneously reactivate viral antigen-specific memory CD4 and CD8 T-cells of CMV-seropositive and HIV-seropositive subjects using mRNA-electroporated autologous CD40-activated B cells. In the setting of HIV, we provide evidence that CD40-activated B cells can be cultured from HAART-naive HIV-1 seropositive patients. These cells not only express and secrete the HIV p24 antigen after electroporation with codon-optimized HIV-1 gag mRNA, but can also be used to in vitro reactivate Gag antigen-specific interferon-gamma-producing CD4 and CD8 autologous T-cells. For the CMV-specific approach, we applied mRNA coding for the pp65 protein coupled to the lysosomal-associated membrane protein-1 to transfect CD40-activated B cells to induce CMV antigen-specific CD4 and CD8 T-cells. More detailed analysis of the activated interferon-gamma-producing CMV pp65 tetramer positive CD8 T-cells revealed an effector memory phenotype with the capacity to produce interleukin-2. Our findings clearly show that the concomitant activation of both CD4 and CD8 (memory) T-cells using mRNA-electroporated CD40-B cells is feasible in CMV and HIV-1-seropositive persons, which indicates the potential value of this approach for application in cellular immunotherapy of infectious diseases.

Tuberculosis (TB) infection is relatively frequent among travellers to high incidence-countries, especially in long-term travellers and those involved in health work. It is important to diagnose recent infection, both for the affected individual and to prevent further transmission. Based on published literature, we assess the value of interferon-γ release assays (IGRAs) as a complement to or replacement of the tuberculin skin test (TST) for the diagnosis of latent TB infection in the setting of a travel clinic. A comparison of available IGRAs with the TST in terms of operating characteristics and practical considerations is presented. We conclude that IGRAs offer some practical advantages that may benefit certain well-defined patient groups of a travel clinic, but that current evidence is incomplete. We identify research questions to better define the role of IGRAs in these populations.

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