Nonspecific Mouse Hepatitis Virus Positivity of Genetically Engineered Mice Determined by ELISA

초록

Mouse hepatitis virus (MHV) is a major pathogen in laboratory mice that usually leads to fatal diseases, such as hepatitis,multiple sclerosis, encephalitis, and respiratory disease. MHV has a high infection rate, and it needs to be detected assoon as possible to prevent its spread to other facilities. However, MHV detection by enzyme-linked immunosorbentassay (ELISA) often gives false positives; thus, it is very important that the results are confirmed as true positives in theearly infection stage or distinguished as false positives with more accurate, reliable methods. Under microbiologicalscreening, MHV ELISA-positive mice were found in four GFP-tagging transgenic mice. To verify the detection of theMHV antigen directly, reverse transcription polymerase chain reaction (RT-PCR) was performed, and the mice weredetermined to be MHV negative. Additional serum antibody-based screening was conducted with three different ELISAkits, and multiplexed fluorometric immunoassay (MFIA) was performed to confirm their accuracy/sensitivity. In brief,the ELISA kit for A59 nucleocapsid protein (MHV-A59N) revealed MHV ELISA positivity, while other ELISA kits(MHV-S lysate and MHV-JHM lysate) demonstrated MHV negativity. In MFIA, only the test for the recombinant A59nucleocapsid antigen was MHV positive, which was consistent with the ELISA results. These results suggest that theELISA kit with the recombinant A59 nucleocapsid antigen might induce non-specific MHV ELISA positivity and thatconfirmation is therefore essential.

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