FIG 1.

MERS-CoV NS4a and NS4b recombinant mutants. (A) MERS-CoV genome RNA with open reading frames shown. (B) NS4a and NS4b proteins expressed by wild-type and mutant MERS-CoVs. The catalytic His residues of the PDE are shown, and the vertical black bar indicates the NLS of NS4b; the red lettering indicates amino acid substitutions of the catalytic His residue and within the NLS. (C) Expression of viral proteins from recombinant MERS-CoV viruses. A549^DPP4 cells were infected at an MOI of 10 with WT MERS-CoV, MERS-ΔNS4a, MERS-ΔNS4ab, MERS-NS4b^H182R, or MERS-NS4b^NLSmut or mock infected. Cell lysates were prepared at 24 and 48 h postinfection, analyzed by SDS-PAGE, and probed by Western blotting with rabbit antiserum against NS4a and NS4b or mouse monoclonal antibodies against MERS nucleocapsid protein (N) and GAPDH. The Western blot data are from one representative of three independent infections.