2007 Annual Report 1a.Objectives (from AD-416) 1. Determine the ontogeny of innate immune activity by alveolar macrophages/dendritic cells. 2. Determine the severity of respiratory syncytial virus (RSV) infection and the extent of alterations in alveolar macrophage/dendritic cell innate immune responses in pre-term and full-term lambs. 1b.Approach (from AD-416) 1. The extent of alveolar macrophage/dendritic cell expression of toll-like receptors and cytokines will be determined in pre-term and full-term lambs using real-time polymerase chain reaction (PCR) assays. 2. The extent to which RSV alters the expression of toll-like receptors and cytokine gene expression will be determined by real-time PCR assays. 3.Progress Report This report serves to document research conducted under a reimbursable agreement between ARS, Iowa State University, and the PHS National Institutes of Health. Additional details of research can be found in the report for the parent project 3625-32000-091-00D, Controlling Losses from Respiratory Disease in Cattle, Sheep and Goats. We determined that bovine respiratory syncytial virus (BRSV) can productively infect neonatal ovine lung dendritic cells (DCs) and alveolar macrophages. Next, we determined whether there was a modulation of proinflammatory or immunomodulatory cytokines during the early stages of BRSV infection (day 3 or day 5 PI). A real-time PCR assay for the nonstructural protein 2 (NS2) gene was used for determining that BRSV can replicate in lung DCs and alveolar macrophages. Finally, real-time PCR assays were developed for ovine cytokines. The data indicate that BRSV induces immunomodulatory cytokine production (IL-4 and IL-10) which would result in a failure to clear BRSV and leave the host susceptible to secondary bacterial infections. Data from the studies of lung dendritic cells was published in Viral Immunology (1). A second manuscript is to be submitted detailing the results of experiements with alveolar macrophages. Review Publications Fach, S.J., Meyerholz, D.K., Gallup, J.M., Ackermann, M.R., Lehmkuhl, H.D., Sacco, R.E. 2007. Neonatal Ovine Pulmonary Dendritic Cells Support BRSV Replication with Enhanced IL-4 and IL-10 Gene Transcripts. Viral Immunology. 20(1):119-130.