Third, two biomarkers in the sera of patients with poor listeriosis prognosis were distinguished: (i) low IL-17A/IL-6 ratios that reflected a shift in the immune balance toward Th2 anti-inflammatory responses and (ii) low production of anti-GAPDH1–22 antibodies that suggested reduced CD4+ T cell–B cell responses. This evidence concerns the gene IL6 and listeriosis.