Epidemiological Investigation and Genetic Analysis of Duck Circovirus in Korea from 2013 to 2022

Figure 1. Geographic distribution of DuCV samples tested in South Korea between 2013 and 2022. The number of samples collected varies across different regions, which is reflected by the varying colors. The relationship between sample density and color is indicated by the scale bar.

Figure 2. The relationship between the age distribution of DuCV samples and positive infection rates. The blue bars represent the number of samples tested at each age, while the red line represents the positive rate corresponding to each age group.

Figure 3. Phylogenetic analysis of complete DuCV genome sequences. The phylogenetic tree was constructed using the neighbor-joining method and the maximum composite likelihood model in MEGA 7.0 (1000 bootstrap replicates), based on the complete genome sequences of Korean DuCV strains and reference sequences submitted to NCBI GenBank from various countries. Different genotypes are denoted by colored backgrounds, and the outer ring indicates the countries from which the strains were isolated, as shown in the legend. Different shape markers preceding the sequences in the tree represent DuCV strains isolated in South Korea during different periods: green triangles indicate 24 Korean DuCV strains previously reported in 2011–2012, and red stars indicate 24 Korean DuCV strains identified in this study from 2013 to 2022.

Figure 4. Characteristic amino acid site mutations in the ORF1 (Rep protein) and ORF2 (Cap protein) sequences among different DuCV genotypes or subtypes.

Figure 5. Recombination analysis of representative events involving Korean DuCV-1b subtype isolates based on complete genome sequences. (A) Event 2: Korean DuCV-1b subtype D15-MR-122 (PP056147) and Chinese DuCV-2c subtype GX1104 (JX241046) as the putative parental strains of Chinese DuCV-1d subtype AHAU25 (MT646347). (B) Event 13: Korean DuCV-1b subtype D15-MR-122 (PP056147) and Chinese DuCV-1b subtype PX08 (KC460533) as the putative parental strains of Korean DuCV-1b subtype D14-JW-036 (PP056142). All analyses were implemented with a window size of 200 bp and a step size of 20 bp using the Kimura 2-parameter model. The X-axis indicates the location of the query sequence, and the Y-axis shows the percentage similarity between the parental sequences and the query sequence.