An important disease-ameliorating contribution of CCR5 has been documented in settings of trypanosomiasis [28], toxoplasmosis [29], influenza [30], [31], parainfluenza [32], West Nile encephalitis [7], tick-borne encephalitis [10], genital herpes [33], and chlamydia infection [34], while no significant effect of CCR5 deficiency on the outcome of other microbial infections could be found [35]–[39]. Here, CCR5 is linked to influenza.