Genomic Sequencing and Comparison of Sacbrood Viruses from <i>Apis cerana</i> and <i>Apis mellifera</i> in Taiwan

• Main Authors: Ju-Chun Chang, Zih-Ting Chang, Chong-Yu Ko, Yue-Wen Chen, Yu-Shin Nai
• Format: Article
• Language: English
• Published: MDPI AG 2021-12-01
• Series: Pathogens
• Subjects: sacbrood virus; sacbrood disease; <i>Apis cerana</i>; <i>Apis mellifera</i>
• Online Access: https://www.mdpi.com/2076-0817/10/1/14

Sacbrood virus (SBV) was the first identified bee virus and shown to cause serious epizootic infections in the population of <i>Apis cerana</i> in Taiwan in 2015. Herein, the whole genome sequences of SBVs in <i>A. cerana</i> and <i>A. mellifera</i> were decoded and designated AcSBV-TW and AmSBV-TW, respectively. The whole genomes of AcSBV-TW and AmSBV-TW were 8776 and 8885 bp, respectively, and shared 90% identity. Each viral genome encoded a polyprotein, which consisted of 2841 aa in AcSBV-TW and 2859 aa in AmSBV-TW, and these sequences shared 95% identity. Compared to 54 other SBVs, the structural protein and protease regions showed high variation, while the helicase was the most highly conserved region among SBVs. Moreover, a 17-amino-acid deletion was found in viral protein 1 (VP1) region of AcSBV-TW compared to AmSBV-TW. The phylogenetic analysis based on the polyprotein sequences and partial VP1 region indicated that AcSBV-TW was grouped into the SBV clade with the AC-genotype (17-aa deletion) and was closely related to AmSBV-SDLY and CSBV-FZ, while AmSBV-TW was grouped into the AM-genotype clade but branched independently from other AmSBVs, indicating that the divergent genomic characteristics of AmSBV-TW might be a consequence of geographic distance driving evolution, and AcSBV-TW was closely related to CSBV-FZ, which originated from China. This 17-amino-acid deletion could be found in either AcSBV or AmSBV in Taiwan, indicating cross-infection between the two viruses. Our data revealed geographic and host specificities between SBVs. The amino acid difference in the VP1 region might serve as a molecular marker for describing SBV cross-infection.