Detection of Venezuelan Equine Encephalitis Virus From Brain Samples of Equines With Encephalitis

Alphavirus species are globally distributed zoonoses, primarily transmitted by arthropods. In Costa Rica, Venezuelan equine encephalitis virus (VEEV) and Eastern equine encephalitis virus (EEEV) are endemic. The objective of this study is to detect these viruses in brain samples from equines displaying nervous signs. For this purpose, four published universal RT-PCR methods were compared. The most sensitive and specific RT-PCR method was used to test a total of 70 brain samples, including 40 from bovines and 30 from equines, all exhibiting nervous signs. In the positive cases, eight different brain regions were extracted and tested using this RT-PCR. Positive cases were confirmed through sequencing. Among the four universal RT-PCR assays, Torii RT-PCR demonstrated the highest sensitivity and specificity for diagnosing VEEV and EEEV. Not all assessed brain regions showed DNA amplification. None of the bovine brains was positive and out of the 30 equine brain samples, only four tested positive, and sequencing confirmed two of these samples as VEEV subtype IE. Torii RT-PCR successfully detected VEEV in pools of the hip-pocampus, spinal cord, and basal nuclei, making these brain regions suitable for diagnosing this virus. None of the samples were positive for EEEV.