Infection with an H2 recombinant herpes simplex virus vector results in expression of MHC class I antigens on the surfaces of human neuroblastoma cells in vitro and mouse sensory neurons in vivo

The majority of neurons in herpes simplex virus (HSV)-infected murine sensory ganglia are transiently induced to express MHC-I antigens at the cell surface, whereas only a minority are themselves productively infected. The aim of the current work was to determine whether MHC-I antigens can be expressed on the surfaces of infected neurons in addition to their uninfected neighbours. To address this aim a recombinant HSV type 1 strain, S-130, was used to deliver a mouse H2Kd gene, under control of the HCMV IE-1 promoter/enhancer, into human neuroblastoma cells in vitro and mouse primary sensory neurons in vivo. S-130 expressed H2Kd antigens on the surfaces of IMR-32 cells, a human neuroblastoma cell line that expresses very low levels of MHC-I constitutively. In K562 cells, which do not express MHC-I constitutively, H2Kd and β2-microglobulin (β2m) were shown to be co-expressed at the cell surface following S-130 infection. This observation was taken as evidence that class I heavy chain (αC) molecules encoded by the expression cassette in the HSV genome were transported to the cell surface as stable complexes with β2m. Significantly, after introduction of S-130 into flank skin, H2Kd antigens were detected on the surfaces of primary sensory neurons in ganglia innervating the inoculation site. Our data show that HSV-infected murine primary sensory neurons and human neuroblastoma cells are capable of expressing cell-surface MHC-I molecules encoded by a transgene. From this, we infer that up-regulation of αC expression is, in principle, sufficient to overcome potential impediments to neuronal cell surface expression of MHC-I complexes.