Abstract: 【Objective】 The presence of several common honey bee viruses in colonies located in Beijing were investigated in the past years. The Chronic bee paralysis virus (CBPV) was found that its occurrence in diseased colonies was significantly higher than in healthy ones. CBPV was supposed to be investigated in diseased colonies. Since the data on CBPV are little, the objective of this study is to investigate the occurrence and variation of CBPV from China so as to provide a theoretical basis for the prevention of CBPV disease. 【Method】 A total of 136 samples from diseased colonies in Sichuan, Anhui, Zhejiang, Henan, Shandong, Shanxi, Heilongjiang and Beijing in 2014-2015 were collected and detected for CBPV by RT-PCR. Ten heads of bees were randomly collected from each sample. Total RNA was extracted using the TRIZOL method. RNA quality was qualitatively and quantitatively determined by electrophoresis and NanodropND-2000. The first chain of cDNA was synthesized using total RNA as template. The specific fragments of CBPV were amplified using cDNA as template. All amplified bands were performed by agarose gel electrophoresis. Parts of the positive PCR products were sequenced and analyzed. The occurrence of CBPV from each sample was confirmed by comparing the amplified bands with the positive ones. To analyze the phylogeny of Chinese CBPV isolates, RdRP genes of all CBPV positive samples were amplified using cDNA as template, then sequenced and analyzed. The gene sequences were submitted to GenBank for accession numbers. RdRP genes obtained from this study were analyzed and compared with those available on GenBank. All reference sequences and the sequences from this study were aligned using the software of CLUSTAL W. The phylogenetic tree of CBPV was conducted using the neighbor-joining method of MEGA 6.0. 【Result】 RNA integrity from honey bee heads of all samples was relatively preserved. The RNA yield was (980.5±37.1)ng·mL^-1 and A₂₆₀/A₂₈₀ was 1.92-2.24. A total of 120 samples out of 136 were positive for CBPV and the positive rate was 88.2%. A target band was amplified from each positive sample. The nucleotide sequences of positive PCR products shared ＞99% sequence identity with target sequences. RdRP sequence analysis revealed that in total 8 CBPV isolates were obtained in this study, and the nucleotide sequences shared ＞97% sequence identity with those from other countries. Accession numbers for Chinese isolates of CBPV were KT374042-KT374049. There are 5 branches for the worldwide CBPV isolates including two European clades (European clade 1 and European clade 2), two Chinese-Japanese clades (Chinese-Japanese clade 1 and Chinese-Japanese clade 2), and one US clade. All 8 CBPV isolates in this study belongs to the same branch, and had been grouped with 4 Japanese isolates and 6 previous Jiangsu isolates into two mixed Chinese-Japanese clades. 【Conclusion】 CBPV is probably widely spreaded in diseased Apis mellifera colonies in China, and the genetic relationship of prevalent CBPV isolates in China exist no obvious geographical characteristics, seem to be closely related to Japan strains. Intensive CBPV surveillance should be urgently carried out, and put more attention to its function of early warning.

Key words: Apis mellifera ligustica, Chronic bee paralysis virus (CBPV), RT-PCR diagnosis, phylogenetic tree