Detection of eastern equine encephalomyelitis virus RNA in formalin-fixed, paraffin-embedded tissues using DNA in situ hybridization

Eastern equine encephalomyelitis (EEE) virus was detected in infected formalin-fixed horse and emu tissues and in infected chicken embryo fibroblasts. Results of in situ hybridization using a digoxigenin-labeled 40-base DNA probe complementary to a conserved region of the EEE virus RNA compared favorably with results of both virus isolation and serum neutralization tests. This technique may be useful for diagnosis of EEE virus infection in various animal species, especially when fresh tissues are not available for analysis, and also will provide a means for studying the involvement of alphaviruses in pathogenesis studies.