Development and characterization of murine monoclonal antibodies to first and second Ljungan virus genotypes

Ljungan virus (LV) is a rodent pathogen that causes diabetes and myocarditis in its natural host. In addition, LV has been associated with human disease during pregnancy and of neonates, respectively. A panel of 22 monoclonal antibodies (mAbs) against first and second LV genotypes were produced by immunization of BALB/c mice with whole virus. Thirteen mAbs were class IgG antibodies and nine were class IgM antibodies; all of them contained kappa light chains. All mAbs were reactive with LV by capture enzyme-linked immunosorbent assay and indirect immunofluorescence assay. In addition, five mAbs showed a positive staining in immunohistochemistry. No mAb bound to denatured capsid proteins detected by western immunoblotting. In contrast, the target capsid protein(s) of 20 mAbs were identified by immune precipitation, revealing the conformational nature of epitopes required for mAb binding. None of the mAbs reacted with third and fourth LV genotypes. mAbs characterized should provide useful tools for the development of diagnostic assays and the investigation of LV first and second genotype properties and its pathogenesis.