Detection of mammalian orthoreovirus type-3 (Reo-3) infections in mice based on serotype-specific hemagglutination protein sigma-1.

BACKGROUND: Reovirus type-3 infections cause severe pathologies in young mice and thus influence animal experiments in many ways. Therefore, the Federation of Laboratory Animal Science Associations (FELASA) recommends an annual screening in laboratory mice as part of a thorough health monitoring program. Based on the high protein sequence homology among the different reovirus serotypes, immunofluorescence antibody assay and other indirect methods relying on the whole virus are presumably cross-reactive to antibodies triggered by mammalian orthoreovirus infections independent of the serotype. METHODS: The serotype-specific protein σ-1 was expressed in Escherichia coli with an N-terminal Strep-tag and a C-terminal His-tag. The purified Strep-rσ-1-His-construct was used to develop an indirect ELISA by testing defined positive and negative sera obtained by experimental infection of mice as well as field sera. RESULTS: The Strep-rσ-1-His-ELISA provided high sensitivity and specificity during validation. Notably, a high selectivity was also observed for sera positively tested for other relevant FELASA-listed pathogens. Screening of field samples indicated that a commercial reovirus type-3-based ELISA might be cross-reactive to other murine reovirus serotypes and thus produces false-positive results. CONCLUSIONS: The prevalence of reovirus type-3 might be overestimated in German animal facilities and most likely in other countries as well. The occurrence of other reovirus serotypes, however, raises the question if murine health monitoring programs should be extended to these pathogens.

Highly sensitive ELISA for the serological detection of murine rotavirus EDIM based on its major immunogen VP6.

Precise health monitoring of laboratory animals is a critical factor for surveillance and accuracy of animal experiments. Rotavirus epizootic diarrhea of infant mice (EDIM) leads to infections in mice that can influence animal studies, e.g., by altering the intestinal physiology. Thus, the aim of this study was establishing a highly sensitive and specific ELISA for the serological detection of EDIM infections in rodents. First, virus proteins were separated by SDS-PAGE and immunogenic proteins were visualized by immunoblotting and identified after in-gel digestion by tandem mass spectrometry. Subsequently, the major immunogen VP6 (virus protein 6) was expressed in Escherichia coli in high yields, purified by affinity chromatography, and used to establish an indirect ELISA. The diagnostic sensitivity and specificity were both above 99 % and the selectivity better than 98.7 % for animals infected by other pathogens listed by the Federation of Laboratory Animal Science Associations. Importantly, the Strep-rVP6-His-ELISA was more sensitive than a commercial virus-based ELISA and is a time- and cost-efficient complement to EDIM-specific immune-fluorescence assays. In conclusion, the assay can improve health monitoring by reducing the risk of missed EDIM infections in animal housing facilities, thereby improving animal welfare, reliability of animal studies, and protection of precious mice breeds.