We have generated doubly transgenic (DT) mice that independently express cDNA genes for the nucleocapsid protein (NP) and the surface glycoproteins (GP) of lymphocytic choriomeningitis virus (LCMV). By RT-PCR, transcription of both transgenes was detected at low levels in brain and kidney but was not observed in the thymus. Additionally, transcription of the GP transgene was observed in the spleen. Following challenge with exogenous LCMV, an anti-NP CTL response was induced in LCMV-infected DT mice, suggesting that nonresponsiveness to NP had not been established. In contrast, LCMV-infected DT mice were nonresponsive to GP and failed to mount any CTL response against GP, either at Day 7 or Day 30 postinfection or following expansion of splenocyte populations in vitro. A significant number (33%) of adult DT mice survived intracerebral infection with LCMV, suggesting that virus-induced immunopathology in the central nervous system can be diminished by combined expression of the transgenes whereas no protective effect was conferred on singly transgenic mice, expressing NP or GP alone. The DT mice therefore create a novel host genetic background for comparative studies of the anti- LCMV immune responses relative to parental C57BI/6 mice.
Bibliographical noteFunding Information:
We thank Ms Jenny Price for skillful technical assistance for the microinjection and reimplantation procedures, Dr. Michael Nerenberg for conceptual and practical advice during the establishment of the transgenic mouse lines, Dr. Eric Butz and Dr. Steve Jameson for advice with T-cell functional assays, Dr. J. Carlos Manivel for expert interpreta- tion of histology slides, and Dr. Michael B. A. Oldstone and Dr. Matthias von Herrath for critical reviews of this manuscript. These experiments were initiated in Dr. Michael B. A. Oldstone’s laboratory at The Scripps Research Institute and his interest and insight are gratefully acknowledged. Support was provided in part by Public Health Service Grants NS12428 and AG04342 (M.B.A.O. and P.J.S.) and AI25224 (P.J.S.) and by the University of Minnesota Graduate School Grant-in-Aid Program (P.J.S.). J.C.Z. received partial support as a predoctoral fellow from Public Health Service Training Grant CA09138.