PATHOGENESIS AND CONTROL OF EMERGING REOVIRAL ARTHRITIS IN TURKEYS

Turkey arthritis reoviruses (TARVs) have been recognized in the US since 2011 to cause disease in market age turkeys. Novel strains continue to rise from frequent reassortment of TARVs with other field strains and rapid spontaneous mutations attributed to viral RNA-dependent RNA polymerase errors. Significant economic losses are incurred due to poor weight gain, increased feed conversion ratios, mortality as a result of culling or aortic rupture, and condemnations at the processing plants. Control measures currently being employed by some commercial farms are not effective mainly because the disease is not well understood. Attempts to understand TARV pathogenesis are complicated by the high prevalence of apparently "nonpathogenic" reoviruses in the intestines of commercial turkeys. The high prevalence of reoviruses in commercial settings throughout production cycles has also made it difficult to determine the age at which turkeys are susceptible to TARVs. Further, our field and experimental observations in commercial and specific-pathogen free (SPF) turkeys suggest that gut microbiota plays a role in initiation and establishment of TARV infection and subsequent induction of arthritis.Turkey reoviral arthritis needs to be comprehensively defined to lay the groundwork for development of effective control measures. The goal of the proposed work is to understand how viral, host, and microbial factors contribute toward the onset, development, and severity of reovirus-associated arthritis in turkeys. This goal will be accomplished through the following objectives: Objective 1. Define turkey reoviral arthritis in context of age-based host responses. We will evaluate the effect of age on tissue tropism of the virus, level of virus replication, and the onset and severity of the disease. We will also investigate how natural infection-induced and passively acquired maternal immune responses affect the onset and development of reoviral arthritis. Objective 2. Determine how microbiome modulation affects disease outbreak and severity. Turkey-specific microbiome modulator (probiotic) will be applied in a multi-omics approach to investigate how the disease is influenced by the interaction between microbiome, TARV, and the host.