FIG 2.

The olfactory bulb is the primary site of HCoV OC43 neuroinvasion. (A) Fifteen-day-old mice were inoculated with HCoV OC43 by the intracerebral (I.C.), intranasal (I.N.), or intralingual (I.L.) route. At 5 days postinoculation, the brains were harvested and the M RNA copy number was assessed by quantitative RT-PCR. Each circle represents a probed brain for a single mouse. The percentages of brains containing M RNA are shown underneath. (B) In addition to the brain, blood and livers were also collected from the same mice inoculated intranasally and probed for M RNA. (C) Mice inoculated intranasally were sacrificed after 1 to 5 days and probed for M RNA. (D) Zinc sulfate (ZnSO₄) instillation 3 days before intranasal virus inoculation significantly abrogated neuroinvasion. Results are from two independent experiments. *, P < 0.05; **, P < 0.01.