3.2 Amplification, sequencing and genome characterization of PiCV genomes
A total of Sixty-seven full genomes were successfully amplified, sequenced and assembled in this study were deposited in GenBank under Accession numbers: MW181925 to MW181991 (Table 2). The assembled circular whole genome sequences were detected as eleven multiple sizes and was ranging from 2030 to 2045 nt in sizes with their cap gene ranging from 813 to 828 nt in length and rep gene of 948 or 954 nt as shown in Table 2 and S1. Among these variable genome length, the most common genome sizes were encompassing 2037 (n=21), and 2042 (n=13) nucleotides, respectively (Table 2). The sequence comparison of the complete PiCV genomes revealed nucleotide homologies of 84.2%–100% among the 67 identified PiCV strains. The complete genome sequences of the 67 identified PiCV strains exhibited sequence similarities with Chinese PiCV reference strains (83.0%–97.8% nucleotide identity) and the PiCV reference strains from the other countries (82.0%–98.3% nucleotide identity) (Table 3). In particular, four unique nucleotide substitution (CG-GCGA) was found in the intergenic region between therep and cap stop codons of two strains (SX1/SN/2017/MW181932 and YB4/SN/2018/MW181981) compared with the 67 PiCV strains obtained in this study and the other reference PiCV strains available from the NCBI GenBank, respectively.