The bovine rotavirus VP2 protein is the major component of the core and forms the most internal layer surrounding the dsRNA genome. We have constructed recombinant baculoviruses expressing truncated VP2 proteins. The nucleic acid binding activity of these truncated proteins was tested by North-Western blotting experiments with single-stranded and double-stranded probes. The nucleic acid binding domain in VP2 was localized between amino acids 1 to 132. Recombinant proteins bound single-stranded and double-stranded nucleic acids, but showed less affinity for double-stranded RNA and DNA. Interactions of VP2 with the genome were investigated in viral single-shelled particles by u.v.-cross-linking. In these experiments, only VP2 protein bound the genomic RNA in purified single-shelled particles.