It has been proposed that C9 activation during pregnancy leads to a pro-inflammatory, pro-coagulant, and tissue damaging environment surrounding the fetus. For example, high levels of anaphylatoxins, such as C5a, induce the release of potent antiangiogenic factors, which sequester growth factors that are essential for normal placental development and healthy pregnancy. However, these studies seem at odds with a number of reports that C9 is activated during pregnancy. Such disparities may reflect the difficulties inherent in performing longitudinal studies in DL-Carnitine hydrochloride pregnant women. Further, to our knowledge, no analysis of functional C9 activity against pathogens has been performed using samples from pregnant women. Thus, the question of how C9 functions against pathogens such as influenza virus during pregnancy remains unresolved. Human studies pose significant obstacles to addressing this experimental question because of differences in anti-influenza virus antibody levels among subjects, which confounds the analysis of the role of C9 in neutralization. Thus, we sought to identify an influenza-naı ¨ve pregnancy model system that closely mimics the pregnancy physiology of women. Mice are the most common animal model used in pregnancy studies because Amantadine hydrochloride they are relatively inexpensive, are reared in an easily controlled environment, and their short gestation period enables rapid experiments and large sample sizes. However, murine reproductive physiology differs greatly from that of humans. The African green monkey is a strikingly suitable model for studies of reproductive physiology, with many characteristics in common with humans. For example, AGMs have cycle types, hormone levels, and pregnancy physiology very similar to those of humans. Additionally, while AGM fetal development occurs in a similar fashion as humans, the 5.5-month AGM gestation period is slightly compressed and more accessible than that of humans. For this study, the Wake Forest University Primate Center Vervet Research Colony served as a source for groups of pregnant and control female AGMs. Access to the VRC enabled us to perform longitudinal sampling during and after pregnancy. Here, we demonstrate the utility of this novel AGM model system by determining how C9 levels and the capacity for C9mediated virus neutralization change during pregnancy.