Perspectives on the Evolution of Porcine Parvovirus

Abstract

Porcine parvovirus (PPV) is one of the main causes of porcine reproductive failure. It is important for swine industries to understand the recent trends in PPV evolution. Previous data show that PPV has two genetic lineages originating in Germany. In this study, two more genetic lineages were defined, one of which was distinctly Asian. Additionally, amino acid substitutions in European strains and Asian strains showed distinct differences in several regions of the VP2 gene. The VP1 gene of the recent PPV isolate (T142_South Korea) was identical to that of Kresse strain isolated in the USA in 1985, indicating that modern PPV strains now resemble the original strains (Kresse and NADL-2). In this study, we compared strains isolated in the 20th century to recent isolates and confirmed the trend that modern strains are becoming more similar to previous strains.

Keywords: South Korea; evolution; phylogenetic analysis; porcine parvovirus.

Figure 1

Phylogenic trees created with the non-structure protein gene (NS1), viral protein gene (VP1), and major structural protein (VP2) sequences. The scale axis indicates the distance in years and posterior probabilities are indicated according to the color of the branches. The phylogeny was estimated using the Bayesian continuous-time Markov chain (CTMC) method with Beast version 1.8.2. The phylogenic tree was visualized and edited using FigTree version 1.4.2, in the following order: 1: NS1, 2: NS1, VP1, VP2, 3: VP1, 4: VP2.

Figure 1

Phylogenic trees created with the non-structure protein gene (NS1), viral protein gene (VP1), and major structural protein (VP2) sequences. The scale axis indicates the distance in years and posterior probabilities are indicated according to the color of the branches. The phylogeny was estimated using the Bayesian continuous-time Markov chain (CTMC) method with Beast version 1.8.2. The phylogenic tree was visualized and edited using FigTree version 1.4.2, in the following order: 1: NS1, 2: NS1, VP1, VP2, 3: VP1, 4: VP2.

Figure 1

Phylogenic trees created with the non-structure protein gene (NS1), viral protein gene (VP1), and major structural protein (VP2) sequences. The scale axis indicates the distance in years and posterior probabilities are indicated according to the color of the branches. The phylogeny was estimated using the Bayesian continuous-time Markov chain (CTMC) method with Beast version 1.8.2. The phylogenic tree was visualized and edited using FigTree version 1.4.2, in the following order: 1: NS1, 2: NS1, VP1, VP2, 3: VP1, 4: VP2.

Figure 2

Bayesian time-scaled phylogeny of porcine parvovirus (PPV) (NS1, VP1, and VP2 genes) with inferred geographical location states. The branches of the maximum clade credibility tree were colored according to the most probable location state of their descendent nodes. The color codes are defined in the insert legend.

Figure 3

Maximum clade credibility tree for the complete VP1 gene of PPV using spatial diffusion of the time-scaled genealogy modeled as a standard continuous-time Markov chain (CTMC) process over discrete sampling locations, using Beast Version 1.8.2. Scaled phylogeny of PPV inferred the geographical location states. The branches of the maximum clade credibility tree are colored according to the most probable location state of their descendent nodes. The color codes are defined in the insert legend. The phylogenetic tree was visualized and edited using FigTree version 1.4.2.

Figure 4

Indirect immunofluorescence of assay of PK-15 cells infected with PPV. (a) Infected cells fluoresced green, and (b) control cells stained in the same manner (200× magnification).

Figure 5

Cartoon structure of NADL-2, Kresse, Challenge, Germany Vaccine Tornau, South Korea 2003 (accession number: AY390557.1), and T142_South Korea strains drawn chronologically with Mol soft Mol Browser 3.8–5 according to the original publication from the National Center for Biotechnology Information (NCBI) Structure database [17]; accession number: 1K3V.