Excessive levels of IL-13, and the functionally related IL-4, are associated with increased allergic responses (Th2 inflammation and asthma) and resistance to parasites; the inclusion of inhibitory receptors of these Th2 molecules in vaccines has augmented immunity to infections such as HIV (Wijesundara et al., 2013; Ranasinghe et al., 2014; Bao and Reinhardt, 2015). This evidence concerns the gene IL4 and infection.