Long-term effects of an early simulated viral infection on behavior and immunity in zebra finches (Taeniopygia guttata)

Early-life experiences can permanently shape physiology and behavior through developmental programming of neuroimmune and endocrine systems. This dissertation investigates how early-life immune challenge (ELIC) with the viral mimetic polyinosinic:polycytidylic acid (poly I:C) influences immune ontogeny, growth, cognition, and social behavior in zebra finches (Taeniopygia guttata). Across four integrative chapters, I examined the mechanistic and behavioral consequences of transient immune activation during a critical developmental window. In Chapter 1, I demonstrate that saline-injection alters antibody profiles, revealing that even brief injection stress can program lasting changes in immune phenotype. Chapter 2 shows that ELIC induces acute sickness behaviors—such as reduced begging and altered activity—and long-term reductions in mass, reflecting energetic trade-offs between immunity and growth. In Chapter 3, I report that early immune challenge impairs learning proficiency and increases sex-dependent cognitive differences, with males more strongly affected than females. Finally, Chapter 4 reveals that developmental immune activation reshapes adult social behavior and stress reactivity: poly I:C-challenged birds exhibit reduced aggression and anxiety-like behaviors, indicating a shift toward more passive coping strategies. Together, these findings demonstrate that early immune activation can reorganize neuroimmune–endocrine circuits to produce integrated, lifelong changes in physiology and behavior. This work highlights immunity as a central driver of behavioral plasticity, linking developmental perturbation to individual variation in fitness and disease ecology.