2011 Annual Report 1a.Objectives (from AD-416) The objective of this collaborative agreement is to gain a better understanding of specific immune response to Foot-and-Mouth Disease Virus (FMDV) infection and vaccination and to identify the genetic basis of animals with high and low responder phenotypes. The objectives are: 1. to describe the early steps of the specific immune response against FMDV infection, 2. to describe the immune response elicited by inactivated FMDV vaccination, and 3. to determine the heritability of the response to FMDV vaccination in cattle populations. 1b.Approach (from AD-416) 1. The early steps of specific immune response against FMDV infection will be done through infection by aerosol inoculation delivery route and subsequent virus detection of respiratory tissues through immunostaining and real-time RT-PCR will be done. Replication sites will be correlated to anti-FMDV antibody-producing cells and studied. 2. The immune response elicited by inactivated FMDV vaccination will be studied. Cells responsible for antibody production will be determined through ELISpot assay and analyzed for protective response elicted by inactivated FMDV vaccines. These cells will genotyped with the aim of correlating host genotype with host resistance/recovery after experimental infection or induction of protection post vaccination. Results obtained from in vivo experiments will then be compared to in vitro responses. 3. The heritability of response to FMDV vaccination will be conducted studies of vaccinated bovine populations in Argentina with known pedigree. Estimates of heritability will be calculated to assess host genetic influence to FMDV vaccination response. These estimates will be used to assess merit of further efforts to identify bovine strains purported to demonstrate enhanced levels of innate resistance to FMDV. This will determine if selection for host resistance is possible and if significant gentetic differentiation is possible to identify. 3.Progress Report Significant information was generated regarding the beginning of the FMDV-specific local immune responses in naïve cattle. This includes organ and tissues involved, magnitude and isotypes of the antibodies induced and the temporal evolution of all these parameters. A manuscript describing this work is currently under preparation. In addition, a set of 334 paired samples from primo vaccinated calves were analyzed, resulting in the identification of groups of calves descending from the same sire with significantly better humoral responses to the primo vaccination. This project was monitored through email and telephone exchange and site visits to INTA.