First identification and isolation of Varicellovirus Equidalpha1 in aborted fetal lung tissues of donkeys

Abstract

Abstract Background: Varicellovirus equidalpha1 (formerly Equid alphaherpesvirus 1, EqAHV-1) is commonly linked to horse abortion. Currently, there are no reported cases of abortion resulting from EqAHV-1 infection in donkeys. Case presentation: This was the first survey-based study of Chinese donkeys, which identified EqAHV-1 in three aborted fetal lung tissues of donkeys via PCR technique. This survey was conducted in Chabuchar County, north Xinjiang, China, 2020. A donkey EqAHV-1 strain (Chabuchar/2020) was successfully isolated in MDBK cells. Moreover, the ORF33 sequence of the donkey-origin EqAHV-1 Chabuchar/2020 showed a high level of similarity, both in nucleotide (nt) (99.7 to 100%) and amino acid (99.5 to 100%) sequences, with horse EqAHV-1 strains. The discovery of EqAHV-1 Chabuchar/2020 revealed a remarkably consistent region, leading to its classification within cluster 1 of horse EqAHV-1 strains. Further, analysis of the expected ORF30 nt sequence revealed that donkey EqAHV-1 strains contained guanine (G) at the 2254 position of nt, leading to the presence of aspartic acid (D) at the 752 positions of the viral DNA polymerase. Therefore, these strains were classified as horse neuropathogenic strains. Lastly, a phylogenic network model was constructed via partial ORF68 nt sequences. This model disclosed that newly identified donkey EqAHV-1, and China's EqAHV-1, which was found in aborted Yili horses, comprised a novel independent VIII group. Conclusion: This study showed the first detection and isolation of EqAHV-1 as an etiological agent of abortions in donkeys. Further analysis of the ORF33, ORF30, and ORF68 sequences indicated that the donkey EqAHV-1 contained the neuropathogenic genotype in the VIII group. It is important to pay attention to EqAHV-1 infection in the donkey population, even though the virus has only been identified in donkey abortions in China.