Sindbis virus will be employed as a model insect-vectored virus in studies investigating the interaction of these agents with the invertebrate hosts. The development of sindbis virus in tissue-cultured mosquito cell will be studies in an attempt to learn how this virus is able to establish state of infection in these cells without the gross cytopathic effect and cell death that occurs in cultured vertebrate cells. The morphological, genetic and biochemical/ molecular biological events occurring in the vertebrate cells will be determined and compared to analogous processes in cultured vertebrate cells. Particular attention will be given to the structure and function of a non-interferon antiviral compound produced specifically by the infected mosquito cell which inhibits the growth of the infecting virus. Arthropod-vectored, virus-induced diseases of man and domestic animals are in resurgence in the United States. Tissue-cultured arthropod cells are under consideration as a substitute for the production of vaccines. The information obtained from this study will provide important in understanding the virus, insect, cell relationship and establishment of non-toxic infection leading to transovarial transmission of insect viruses in nature and the disease process in man.