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Molecular Phylogeny of Suid Herpesvirus 1
Phylogenetic analysis using only partial sequences of the
us8 gene in DNAsp identified a total of 31 haplotypes; 23 of
these haplotypes were formed exclusively by sequences from
China. Only 11 polymorphic sites were observed in Western
haplotypes (i.e., 5 singleton variable sites and 6 parsimony
informative sites). In contrast, 53 polymorphic sites were
observed in Eastern haplotypes (i.e., 38 singleton variable
sites and 15 parsimony informative sites)
Phylogenetic analysis of partial ul44
sequences demonstrated that SuHV-1 has a slow rate of
genetic evolution and can be divided into five groups that
are designated as A, B, C, D, and E [10]. Genetic groups A
and C are formed by strains isolated from outbreaks of PR
related to feral pigs. Groups B and D are formed by strains
isolated from outbreaks related to domestic pigs. Group E is
the most genetically diverse group and includes strains from
Eastern regions, primarily China.
In some cases, SuHV-1
strains exhibit the same genetic profile for up to twenty years
in the same region [6, 8].
Cluster 2 exhibited a characteristic genetic diversity. The
high variability observed in the us6, us8, and ul44 genes is
not consistent with the evolution of SuHV-1 described in
other studies [6–8]. Goldberg et al. [5] reported that SuHV-
1 isolates from outbreaks of PR that occurred in the USA in
the state of Illinois in 1989 exhibited greater variability than
isolates from other regions of the world. Nevertheless, the
variability of these isolates was appreciably smaller than the
genetic distance observed in Cluster 2 in this work.
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Genotyping of the Pseudorabies Virus by Multiplex PCR Followed by Restriction Enzyme Analysis
The BamHI-RFLP is able to discriminate the SuHV-1 into four genotypes. Genotypes I and II are distributed worldwide, and genotypes III and IV, originally described in Denmark and Thailand, respectively, were no longer reported [3]. Currently, genotype I is prevalent in populations of wild boars in Europe [8].
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Phylogenetic analysis, genome evolution and the rate of gene gain in the Herpesviridae
We used complete sequence data from 30 complete Herpesviridae genomes to investigate phylogenetic relationships and patterns of
genome evolution. The approach was to identify orthologous gene clusters among taxa and to generate a genomic matrix of gene content.
We identiWed 17 genes with homologs in all 30 taxa and concatenated a subset of 10 of these genes for phylogenetic inference. We also
constructed phylogenetic trees on the basis of gene content data. The amino acid and gene content phylogenies were largely concordant,
but the amino acid data had much higher internal support. We mapped gene gain events onto the phylogenetic tree by assuming that
genes were gained only once during the evolution of herpesviruses. Thirty genes were inferred to be present in the ancestor of all herpesvirus,
a number smaller than previously hypothesized. Few genes of recent origin within herpesviruses could be identiWed as originating
from transfer between virus and vertebrate hosts. Inferred rates of gene gain were heterogeneous, with both taxonomic and temporal
biases. Nonetheless, the average rate of gene gain was »3.5£ 10¡7
genes gained per year, which is an order of magnitude higher than the
nucleotide mutation rate for these large DNA viruses
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Epidemiology of Aujeszky's disease
Principal Features of the Epidemiology of Aujeszky’s Disease – Suid herpesvirus 1 Infection – in Swine and Cattle.
The development of the disease situation in pigs in Denmark has clearly illustrated that SuHV1 has the ability to change in the degree of pathogenicity over time. Changes occurred in two steps. In the early 1960's respiratory strains developed, which were spread rapidly between herds due to animal contacts, mainly by trade, and later in the 1970's strains developed, which had an even higher degree of pathogenicity for both cattle and swine. These new strains were found to be syncytial in contrast to earlier isolates from traditional outbreaks. And that the new respiratory or syncytial strains had not been introduced from abroad was confirmed with absolute certainty by restriction fragment pattern analyses of virus DNA.
That syncytial virus strains were more virulent than non-syncytial strains was later substantiated by results from examination of isolates from England and Northern Ireland.
The special manifestation of Aujeszky's disease in cattle showing pruritus on the hindquarters was regularly associated with use of a boar from a boar centre for natural service of a sow shortly before appearance of the clinical disease. In most cases examined, virus was found in the vagina of the affected bovine animals, although in low titres, and in three outbreaks – the only cases investigated early enough to be successful - virus was demonstrated in the vagina of a sow. It was found that animal sodomy (zoophilia/bestiality) seemed to play a role in the transmission of the genital infection from swine to cattle, and this conclusion is further substantiated by comprehensive supplementary information given in this review article. From the fact that genital infection in cattle is closely correlated with contemporary genital infection in swine on the same premises and from the many reports over the years on infection in cattle showing pruritus on the hindquarters, it can additionally be concluded that the SuHV1 infection in a great part of the 20th century was maintained as a porcine genital infection in many European countries.
 Willy Wanker, Danish pig farmer.
Name changed. File photo.
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