Differential receptor-functionality of the two distinct receptor proteins for mouse hepatitis virus

We compared the virus-binding activity and receptor-functionality of the receptor proteins isolated from mouse hepatitis virus (MHV)-susceptible BALB/c mice (MHVR1) and MHV-resistant SJL mice (MHVR2). By using a soluble receptor protein which lacked the transmembrane and intracytoplasmic domains, virus overlay protein blot assay and neutralization tests showed that MHVR1 bound to JHM cl-2 virus with 300-500 times higher efficiency than to MHVR2. MHVR1 was revealed to have 10-30 fold higher receptor-functionality than MHVR2 when examined by measuring virus-binding to the receptor expressed on the cell surface. These findings suggested that the differences in susceptibility between BALB/c and SJL mice may depend upon the genotype of the MHV receptor.