Characterization of three different transgenic mouse lines that carry human poliovirus receptor gene--influence of the transgene expression on pathogenesis.

Three transgenic mouse lines, ICR-PVRTg1, ICR-PVRTg5, and ICR-PVRTg21, which are susceptible to poliovirus, have been established by introducing the human gene for poliovirus receptor (PVR) into the genome of mouse strain ICR. Genetic characterizations of the PVR gene were carried out on these mouse lines to define the approximate copy number, insertion site, and expression of the transgene in the central nervous system (CNS). The transgene was integrated in the chromosome 4, 12, and 13 of ICR-PVRTg1, ICR-PVRTg5 and ICR-PVRTg21 mice, respectively, and was stably transmitted to progeny mice. ICR-PVRTg1 appeared to have the most abundant copy numbers of the transgene and showed the highest level of PVR mRNA and membrane associated PVR protein in the CNS among the three mouse lines. Those in ICR-PVRTg21 and ICR-PVRTg5 were at intermediate and lowest levels, respectively. In the CNS, PVR mRNA was detected at high levels only in neurons of the spinal cord and brain stem where poliovirus can replicate, suggesting that the PVR mRNA expression confers cell specificity to poliovirus in the CNS. ICR-PVRTg1 and ICR-PVRTg5 showed the highest and the lowest sensitivity to poliovirus, respectively, whereas ICR-PVRTg21 was in-between. These results may suggest that poliovirus sensitivity of the mice is attributed to relative levels of PVR expression.