Formalin-fixed tissue was
embedded in paraffin and sectioned sagittally.
Immunohistochemical analysis
was performed by the avidin-biotin-immunoperoxidase technique (Vector Laboratories,
Burlingame, Calif.) using 3,3-diaminobenzidine as substrate and a
1:20 dilution of a monoclonal antibody (MAb) directed against the nucleocapsid
protein (N) of MHV-JHM (MAb clone 1-16-1, kindly provided by Julian Leibowitz,
Texas A & M University). Control slides from mice either uninfected or
inoculated with rLm-gp33 but not with virus were incubated in parallel. All slides
were read in a blinded manner