Maternal and developmental immune challenges alter behavior and learning ability of offspring.

Stimulation of the offspring immune response during development is known to influence growth and behavioral phenotype. However, the potential for maternal antibodies to block the behavioral effects of immune activation during the neonatal period has not been assessed. We challenged female zebra finches (Taeniopygia guttata) prior to egg laying and then challenged offspring during the nestling and juvenile periods with one of two antigens (keyhole limpet hemocyanin (KLH) or lipopolysaccharide (LPS)). We then tested the effects of maternal and neonatal immune challenges on offspring growth rates and neophobia and learning ability of offspring during adulthood. Neonatal immune challenge depressed growth rates. Neophobia of adult offspring was influenced by a combination of maternal treatment, offspring treatment, and offspring sex. Males challenged with LPS during the nestling and juvenile periods had reduced learning performance in a novel foraging task; however, female learning was not impacted. Offspring challenged with the same antigen as mothers exhibited similar growth suppression and behavioral changes as offspring challenged with a novel antigen. Thus, developmental immune challenges have long-term effects on the growth and behavioral phenotype of offspring. We found limited evidence that matching of maternal and offspring challenges reduces the effects of immune challenge in the altricial zebra finch. This may be a result of rapid catabolism of maternal antibodies in altricial birds. Our results emphasize the need to address sex differences in the long-term effects of developmental immune challenge and suggest that neonatal immune activation may be one proximate mechanism underlying differences in adult behavior.