Isolation and Identification of a Highly Divergent Kaeng Khoi Virus from Bat Flies ( Eucampsipoda sundaica ) in China

摘要

Background: Kaeng Khoi virus (KKV), which belongs to the genus Orthobunyavirus , family Perbunyaviridae , was originally isolated from the brain tissue of bats and may cause infection in humans. In this study, the KKV strain WDBC1403 was isolated from bat flies ( Eucampsipoda sundaica ), ectoparasites of the bat Rousettus leschenaultia , collected from Yunnan Province of China at the Sino-Burmese border. Methods and Results: The bat fly specimens were ground and inoculated in culture cells. The WDBC1403 strain was shown to induce cytopathic effects in Vero, baby hamster kidney (BHK-21), and Tb1Lu cells, but not in C6/36 cells; however, viral gene amplification was detected in the supernatants of C6/36 cells. Using electron microscopy, the virus was determined to be spherical, enveloped, and 80–90 nm in diameter; it was also shown to form plaques in BHK-21 cells and the titer reached 1 × 10~(6.57) plaque-forming units/mL 24 h after infection. The phylogenetic analysis showed that WDBC1403 is a KKV strain, but is independent of the original KKV strain (PSC-19). Viral genome analysis revealed that the nucleotide and amino acid sequence identities of the S, M, and L segments of WDBC1403 with PSC-19 were 88.2% and 96.1%, 76.7% and 85.0%, and 78.3% and 88.9%, respectively. Two amino acids were removed at the end of the open reading frame of the M segment, and 47 nucleotides were removed in the 3′-untranslated region of the M segment of the WDBC1403 strain compared with the PSC-19 strain. Conclusions: The WDBC1403 strain is a highly divergent KKV strain, suggesting that there are a variety of KKV strains that exhibit molecular differences. Moreover, because of the large variations in nucleotide and amino acid sequence in the M segment, which encodes an important membrane protein, further research on antigenicity and pathogenicity in humans and animals is needed.