Haptoglobin contributes to protect host from microbicidal reaction elicited by infection (Gabay & Kushner, 1999), and our results showed its production in response to antigen challenge as reported in previous bird studies assessing this inflammatory marker (van de Crommenacker et al., 2010; Martin et al., 2010; Millet et al., 2007). This evidence concerns the gene HP and infection.