Molecular Phylogeny of Suid Herpesvirus 1

Pseudorabies is a disease that significantly impacts the swine industry. This disease is caused by Suid Herpesvirus 1 (SuHV-1), which is a double-stranded DNA virus that belongs to the Herpesviridae family and the Alphaherpesvirinae subfamily and exhibits a slow rate of genetic evolution. The aim of this study was to use both full and partial sequences of SuHV-1 genes available in GenBank to examine the evolution and divergence of viruses isolated in different parts of the world. Partial and complete sequences of SuHV-1 genes were obtained either from GenBank (i.e., us6, us7, us8, us9, ul14, ul49.5, and ul44) or from genetic sequencing of Brazilian SuHV-1 samples. The results of this study corroborate previous phylogenetic studies of SuHV-1 that demonstrated different evolutionary profiles of isolates from different parts of the globe, with a rapid genetic dispersion of Chinese isolates. All of the phylogenetic trees generated in this study demonstrated a large genetic distance between SuHV-1 isolates from the Western and Eastern regions of the world. 1. Introduction Pseudorabies (PR) is a disease that significantly impacts the swine industry. This disease is caused by Suid Herpesvirus 1 (SuHV-1), which is a double-stranded DNA virus that belongs to the Herpesviridae family and the Alphaherpesvirinae subfamily and exhibits a slow genetic evolution. The primary hosts of SuHV-1 are domestic or wild pigs (Sus scrofa). This disease also affects cows, dogs, and cats, but, in these species, the disease is fatal in nearly 100% of cases [1]. Although PR has been eradicated in domestic swine in many countries, such as the United States, Germany, and England, this disease still occurs in wild boars and other feral swine in these countries [2]. SuHV-1 has only one serotype and can be genetically typed using methods including whole genome enzymatic restriction with BamHI, which demonstrates the presence of four genomic types [3, 4]. However, most recent publications also use partial sequences of the ul44 gene to evaluate the genetic variation of SuHV-1 isolates [5–8]. This gene encodes glycoprotein C (gC), which is a protein that is considered to be a potent inducer of the immune response and the principal component of adhesion to host cell receptors [9]. Phylogenetic analysis of partial sequences of ul44 separates SuHV-1 into five genotypes, with specific clades that include sequences derived from viruses isolated from domestic pigs or wild boars [10]. The us8 gene has also been used for phylogenetic analysis of SuHV-1 [6, 11, 12]. This gene is more conserved than