Targonski PV, Jacobson RM, Poland GA. 2007. reduced rate of recurrence of effector CD4 T cells in aged animals. Aged animals also mobilized inflammatory cytokines to higher levels in the BAL fluid. Finally, we compared changes in gene manifestation using microarray analysis of BAL fluid samples. Our analyses exposed that the largest difference in sponsor response between aged and young adult animals was recognized at day time 4 postinfection, having a significantly higher Tolfenpyrad induction of genes associated with inflammation and the innate immune response in aged animals. Overall, our data suggest that, in the absence of preexisting antibodies, CA04 illness in aged macaques is definitely associated with changes in innate and adaptive immune responses that were shown to correlate with increased disease severity in additional respiratory disease models. INTRODUCTION Influenza computer virus infections pose a significant health problem and remain among the best causes of morbidity and mortality in the elderly (19). This is in part due to the lower rate of seroconversion and poor immunogenicity of the seasonal influenza vaccines observed in the elderly (6, 28, 30). The threat of influenza computer virus illness is definitely amplified by antigenic drift (mutations in the genes encoding hemagglutinin [HA] and neuraminidase [NA]) as well as the potential to create fresh genomic reassortants (especially during interspecies transmission), which leads to the intro of fresh viral strains that the population is largely na?ve toward (23). In April 2009, a new reassortant swine-origin H1N1 influenza computer virus emerged, and by June 2009, the World Health Organization declared this computer virus to be the cause of the 1st influenza pandemic of the 21st century. In contrast to Tolfenpyrad seasonal influenza computer virus, in which 90% of Tolfenpyrad reported deaths are associated with advanced age, the pandemic H1N1 computer virus caused more severe morbidity and mortality in children and young adults, with 87% of deaths involving individuals between the age groups of 5 and 59 years and 70% of the reported hospitalizations in individuals 50 years of age. (4a, 12). Several hypotheses were put forth to explain the reduced severity of the disease in the elderly. The most common hypothesis was that older individuals were safeguarded due to the presence of preexisting cross-reactive antibodies acquired by exposure to circulating H1N1 strains during the 1950s (9, 34). However, only 30% of individuals who were given birth to before 1950 experienced cross-neutralizing antibodies, and only 50% of individuals who received the 1976 vaccine generated cross-neutralizing antibodies (9). These observations suggest that additional factors may have contributed to the safety of older individuals. Another mechanism put forth to explain the increased severity of the disease in more youthful adults is the deposition of pulmonary immune complexes produced by weakly cross-reactive nonneutralizing antibodies generated by exposure to seasonal influenza Tolfenpyrad computer virus (21). Although these immune Tolfenpyrad complexes correlated with severe lung injury, whether they are a result or the cause remains to be determined. Thus, it is possible that additional factors contributed to this reversal in age-related susceptibility. To characterize the effect of age FGFR3 within the sponsor response to 2009 H1N1 pandemic influenza computer virus illness in the absence of preexisting immunity, we compared viral lots and sponsor response between na?ve young adult and aged rhesus macaques infected with 2009 H1N1 virus strain CA04. Although influenza computer virus studies are usually carried out in rodents or ferrets, the close genetic and physiological homology of nonhuman primates to humans makes them a strong model to investigate influenza computer virus pathogenesis. Indeed, studies in cynomolgus macaques (of the National Institutes of Health (22a), the Office of Animal Welfare, and the United States Division of Agriculture. All animal work was authorized by the Oregon National Primate Research Center (ONPRC) Institutional Animal Care and Use Committee, which is definitely accredited from the American Association for Accreditation of Laboratory Animal Care (PHS/OLAW Animal Welfare Assurance A3304-01). All methods were carried out.