FIG 4 .
Construction of NS4b-expressing recombinant MHV. (A) Diagrammatic representation of MHVMut genome (expressing catalytically inactive NS2H126R). The letters designate genes encoding structural proteins, and the numbers designate ORFs encoding nonstructural proteins. ORFs 1a and 1b together comprise 20 kb and are not to scale. (B) Wild-type or catalytic mutant NS4b genes are lined up with the MHV ORF4a or ORF4b insertion site to construct chimeric viruses. Nuclear localization signals (NLSs) and phosphodiesterase (PDE) domains are indicated.