These changes could be reflective of patterns observed in other studies demonstrating that mosquitoes infected with blood-borne pathogens actively modify ROS metabolism in midgut cells to control levels of hydrogen peroxide (H2O2), which in turn is an important modulator of downstream innate immune responses (e.g., Toll pathway), antimicrobial peptide production, and pathogen infection (Molina-Cruz et al., 2008; Herrera-Ortiz et al., 2011; Oliveira et al., 2011, 2012). This evidence concerns the gene TLR4 and infection.