Obtention of porcine aminopeptidase-n transgenic mice and analysis of their susceptibility to transmissible gastroenteritis virus.

To obtain a laboratory animal model for transmissible gastroenteritis virus (TGEV) infection, transgenic mice (Tg) were produced by introducing two porcine aminopeptidase-n (APN) cDNA-derived constructs into the mouse genome. In the first construct, the APN cDNA was fused in 5' with the 1 kb upstream region of the APN gene and in 3' with the SV40 small intron and polyadenylation site. In the second construct, the 5' end of the APN cDNA was replaced by the corresponding domain of the APN gene comprising the three first introns, an additional intron (the rabbit beta-like globine intron 2) was inserted at the 3' extremity of the construct and the resulting DNA stretch was placed under the control of the rat intestinal fatty acid-binding protein (I-FABP) gene promoter. Transgenes were obtained with these two constructs, and RNA expression was evidenced by RT-PCR with the second construct in a transgene lineage. Using two different immunoassays, expression of the porcine APN protein was not detected in the transgenic intestines of animals of the RT-PCR positive lineage. Northern blot analyses did not revealed TGEV replication in infected adult mice. Additional assays will be carried out on young animals to detect potential TGEV susceptibility.