Neonatal mice inoculated with lymphocytic choriomeningitis virus (LCMV) have non-lytic persistent neuronal infection and disturbed behavior. We now show that LCMV replicates in neurons containing the neurotransmitter somatostatin without morphologic evidence of injury and that persistent neuronal LCMV infection in mice is attended by a decrease in brain levels of somatostatin mRNA. Brain levels of mRNA for another neurotransmitter peptide, cholecystokinin, are not decreased. These data are the first to localize a virus to a specific neurotransmitter-containing cell during in vivo infection and suggest that persistent viral infections could cause neurologic or psychiatric diseases through selective effects on brain levels of neurotransmitter mRNAs.