Human coronavirus OC43 infection induces chronic encephalitis leading to disabilities in BALB/C mice

The notion that an infectious respiratory pathogen can damage the central nervous system (CNS) and lead to neurological disease was tested using a human respiratory coronavirus, the OC43 strain of human coronavirus (HCoV-OC43). First, primary cell cultures were used to determine the susceptibility of each type of neural cells to virus infection. Neurons were the target cells, undergoing degeneration during infection, in part due to apoptosis. Second, neuropathogenicity was investigated in susceptible mice. Intracerebral inoculation of HCoV-OC43 into BALB/c mice led to an acute encephalitis with neuronal cell death by necrosis and apoptosis. Infectious virus was apparently cleared from surviving animals, whereas viral RNA persisted for several months. Some of the animals surviving to acute encephalitis presented an abnormal limb clasping reflex and a decrease in motor activity starting several months post-infection. These results suggest that viral persistence could be associated with an increased neuronal degeneration leading to neuropathology and motor deficits in susceptible individuals.