Isolation and pathogenicity of a novel recombinant pseudorabies virus from the attenuated vaccine and classical strains

Figures

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  Figure 1. Isolation and identification of PRV HN2201 strain. (A) The cytopathic effects (CPEs) and indirect immunofluorescent results (IFA) of HN2201 in Vero cells at 48 h post infection. (B) Growth curve of HN2201 in Vero cells at an MOI of 0.01. (C) Detection of the PRV gE, gG, and TK genes by PCR, the ddH2O and PRV strain JS-2020 (OR271601) were used as negative and positive control, respectively.

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  Figure 2. Nucleotide sequence and phylogenetic analysis of gE, gG, and TK genes. Nucleotide sequence alignment of the gE (A) and TK (B) genes of HN2201, Ea and HB-98 strain. The nucleotide deletions were marked with the red box. (C–E) Phylogenetic trees based on the gG (C), partial gE (D) and TK (E) nucleotide sequences were generated using MEGA7 software with the ML method. (F) Proposed model of genomic recombination of HN2201 strain. HB-98-vaccinated pigs were infected with classical PRV strain. HN2201 was produced through acquiring the gG gene during the replication of different PRV strains.

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  Figure 3. Amino acid and phylogenetic analysis of gB, gC, and gD genes. Amino acid alignment of the gB (A), gC (B) and gD (C) genes of HN2201 and referenced strains. The characteristic amino acid deletions of Chinese genotype II PRV strains were marked with the red box comparing to the Bartha strain. The characteristic amino acids specific to the earlier Chinese classical strains (Ea and Fa) were marked with green star. The amino acid mutations of HN2201 were marked with red circle comparing to the Ea strain. (D–F) Phylogenetic trees based on the gB (D), partial gC (E) and gD (F) nucleotide sequences were generated using MEGA 7.0 software with the ML method.

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  Figure 4. Pathogenicity of HN2201 in piglets. Nine-week-old health piglets were infected with 2 mL of HN2201 (106 TCID50/mL). The daily temperature (A), scores of clinical signs (B), average daily weight gain (C), and survival percent (D) were recorded and analyzed, respectively. (E) Histopathological examination (HE) and immunohistochemistry staining (IHC) results of HN2201 infected or mock piglet. Original magnification 200 × .