The virus remains localized to the epithelium of the upper respiratory tract and elicits a poor immune response. No doubt local IgA is important, but this has not yet been formally proved. Immunity to the homologous strain lasts for a few years at most, hence there is a high rate of reinfection. There is no cross-immunity between the HCV-229E and HCV-OC43 serotypes. Moreover, it is likely that new strains are continually arising by antigenic drift (mutation) and shift (recombination).
Although it is reasonable to assume that virus particles morphologically resembling coronaviruses and/or toroviruses which have repeatedly been visualized by electron microscopy in feces of patients with gastroenteritis replicate in the gut, it has yet to be demonstrated unequivocally that they cause disease in the human enteric tract.
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