Background: The mechanisms that determine the duration of fecal shedding of norovirus in humans have not been described in detail.
Objectives: We investigated serum inflammatory mediator levels in relation to the duration of viral shedding in norovirus infection.
Study design: A prospective cohort study of patients hospitalized with acute norovirus genogroup II infection. Rectal swab samples were obtained at inclusion and day 7, 14, 21 and 28. Serum levels of 42 inflammatory mediators were determined with a Luminex-based cytokine assay. Sera from 20 healthy blood donors served as controls.
Results: Altogether, 28 patients (54% women, median age 83 years, median duration of symptoms 3 days) were included. Twelve subjects cleared the virus within 14 days and 16 were norovirus-RNA positive for >21 days, constituting the two study groups ("rapid" vs. "slow" clearance). Individuals with norovirus infection had higher levels of IL-18, CXCL9, CXCL10, soluble IL-2 receptor and macrophage migration inhibitory factor (MIF), compared to controls (p<0.05), with the highest median concentrations in the slow clearance group. In contrast, CCL5 levels were lower in the slow compared to the rapid clearance group (median 54 vs. 134 ng/mL, p<0.05), and lower in norovirus-infected patients than in controls.
Conclusion: Low levels of CCL5 were associated with longer duration of viral shedding, suggesting that CCL5 may influence the clearance of norovirus.
Keywords: CCL5; Cytokines; Norovirus; Viral load; Viral shedding.
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