Monoclonal antibodies against the nucleoprotein of mumps virus: their binding characteristics and cross-reactivity with other paramyxoviruses.

Twelve monoclonal antibodies (MoAbs) directed against the nucleoprotein (NP) of mumps virus were analysed for their binding characteristics. Competitive binding in enzyme-linked immunosorbent assay divided them into eight groups. Two of the MoAbs recognized exclusively 66 kD polypeptide of NP, two recognized 66 kD and 60 kD, and one recognized 66 kD (and 60 kD to a lesser extent) in Western blot assays under either denaturing or partially denaturing conditions. Under partially denaturing condition, another five MoAbs reacted faintly but the remaining two did not react at all. Under denaturing condition, on the other hand, these seven MoAbs showed little reactivity with any polypeptide. Furthermore, denaturation resulted in formation of other polypeptides 55 kD, 50 kD, and 43 kD which all were detected by MoAbs reacting with 66 kD and/or 60 kD. Previously demonstrated antigenic cross-reactivity among the NPs of mumps virus and those of human parainfluenza viruses type 2 and type 4 in radioimmunoprecipitation assay using polyclonal antisera was confirmed by an anti-NP MoAb which showed little reactivity in denaturing Western blot assay.