Pseudorabies virus can be classified into five genotypes using partial sequences of UL44

Abstract

Suid herpesvirus 1 (SuHV-1) is the causative agent of pseudorabies (PR), a disease of great importance due to the huge losses it causes in the swine industry. The aim of this study was to determine a method for genotyping SuHV-1 based on partial sequences of the gene coding for glycoprotein C (gC) and to elucidate the possible reasons for the variability of this region. A total of 109 gCsequences collected from GenBank were divided into five major groups after reconstruction of a phylogenetic tree by Bayesian inference. The analysis showed that a portion of gC (approximately 671 bp) is under selective pressure at various points that coincide with regions of protein disorder. It was also possible to divide SuHV-1 into five genotypes that evolved under different selective pressures. These genotypes are not specific to countries or continents, perhaps due to multiple introduction events related to the importation of swine.

Keywords: bioinformatics; glycoprotein; pseudorabies.

Figure 1

Phylogenetic treereconstructed using Bayesian inference. The results showthe distributionof the samplesinto five major groups supported by high probability values. The clusters were not distributed by geographical areas. However, such groupings show consistent results, and the discrepancies in the locations of the samples can be taken as evidence of different introductions of SuHV-1 into a country or region.

Figure 2

Alignment of gC sequences provides evidence of hotspots in the protein, using the standard strain Shope as a reference. The sequences represent the amino acid variation in each cluster. The figure only shows the amino acid substitutions that separate the SuHV-1 isolates in the five groups shown in this work.

Figure 3

Results from the Selecton software for the N-terminal region of gC. The color scale indicates locations subject to positive, neutral or purifying selective pressure. The N-glycosylation sites are marked in solid lines, and the HBD sare indicated by dashed lines. These sites are highly conserved, with amino acids substitutions found only in group E. The hot spot located between residues 175 and 185 shows the highest degree of positive pressure.