Molecular detection and genetic characterization of porcine circovirus 4 (PCV4) in Thailand during 2019–2020

Figures

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  Figure 1. Geographic distribution of PCV4-tested swine farms (n = 145) in Thailand. The black flag indicates the Ratchaburi province where the positive samples were collected for complete genome sequencing. The locations of the 3 districts found PCV4-positive farms are indicated in the black pin.

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  Figure 2. Phylogenetic tree based on the complete genome sequences of 3 Thai PCV4 strains and other reference strains. The Thai PCV4 sequences obtained in this study were marked with solid black circles. The colored background represented the country of origin of the PCV4 viruses. The phylogenetic tree was constructed using the neighboring-joining method with a p-distance model and bootstrapping at 1000 replicates.

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  Figure 3. Comparison of Cap amino acid sequences of PCV4 isolates in this study. Dots are used to denote the residues that are consistent with HNU-AHG1 (MK986820). The red boxes indicate the amino acid at positions 27 and 212, previously proposed for differentiation of PCV4a and PCV4b. Mutations at residues position 80 of Thai PCV4 strains are shown with the green box.

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  Figure 4. Gross and microscopic lesions and in situ hybridization (ISH) using PCV4-specific probe targeting Cap gene of PCV4. Grossly, lung failed to collapse with dark red to purple consolidation and diffuse fibrinous attachment in the pleura (A). Lung: PCV4-positive cells were characterized by pink to brilliant red in the cytoplasm of bronchial epithelial cells (arrows) (B). Tracheobronchial lymph node: positive signals were observed in lymphocytes and histiocyte-like cells in the lymphoid follicle (arrows) (C). No hybridization signals were seen in the internal negative control of lung and tracheobronchial lymph node (D,E).