In vitro and in vivo infection of neural cells by a recombinant measles virus expressing enhanced green fluorescent protein

This study focused on the in vitro infection of mouse and human neuroblasto ma cells and the in vivo infection of the murine central nervous system wit h a recombinant measles virus. An undifferentiated mouse neuroblastoma cell line (TMN) was infected with the vaccine strain of measles virus (MveGFP), which expresses enhanced green fluorescent protein (EGFP), MVeGFP infected the cells, and cell-to-cell spread was studied by virtue of the resulting EGFP autofluorescence, using real-time confocal microscopy, Cells were diff erentiated to a neuronal phenotype, and extended processes, which interconn ected the cells, were observed. It was also possible to infect the differen tiated neuroblastoma cells (dTMN) with MVeGFP, Single autofluorescent EGFP- positive cells were selected at the earliest possible point in the infectio n, and the spread of EGFP autofluorescence was monitored. In this instance the virus used the interconnecting processes to spread from cell to cell. H uman neuroblastoma cells (SH-SY-5Y) were also infected with MVeGFP. The vir us infected these cells, and existing processes were used to initiate new f oci of infection at distinct regions of the monolayer, Transgenic animals e xpressing CD46, a measles virus receptor, and lacking interferon type 1 rec eptor gene were infected intracerebrally with MVeGFP. A productive infectio n ensued, and the mice exhibited clinical signs of infection, such as ataxi a and an awkward gait, identical to those previously observed for the paren tal virus (Edtag), Mice were sacrificed, and brain sections were examined f or EGFP autofluorescence by confocal scanning laser microscopy over a perio d of 6 h, EGFP was detected in discrete focal regions of the brain and in p rocesses, which extended deep into the parenchyma, Collectively, these resu lts indicate (i) that MVeGFP can be used to monitor virus replication sensi tively, in real time, in animal tissues, Cii) that infection of ependymal c ells and neuroblasts provides a route by which measles virus can enter the central nervous system in mouse models of encephalitis, and (iii) that upon infection, the virus spreads transneuronally.