Presence Of Pseudorabies Virus Research Articles

Characterisation of pseudorabies virus in domestic pigs and wild boars in Croatia.

Serological data imply that pseudorabies (Aujeszky's disease) is present in domestic pigs and wild boars in Croatia. Therefore, this study included testing of brain tissue samples collected from 200 domestic pigs and 105 wild boars originating from seventeen districts of Croatia. The presence of pseudorabies virus (PrV) DNA was confirmed in samples originating from six domestic pigs (3%) and one wild boar (0.95%). Positive samples were sequenced and analysed on the basis of a gC genome fragment. PrV strains have shown to be genetically identical and they are strongly related to some representative strains in the relatively heterogeneous Clade A. The results clearly show that PrV is still circulating among the domestic pig population in Croatia. Furthermore, the presence of pseudorabies virus in wild boars underlines the importance of this species as a PrV reservoir. Continued surveillance is necessary to track the viral spread in order to achieve final eradication of the disease.

Molecular characterization of Belgian pseudorabies virus isolates from domestic swine and wild boar

Aujeszky's disease is an economically important disease in domestic swine caused by suid herpesvirus 1, also called pseudorabies virus (PRV). In several European countries, including Belgium, the virus has successfully been eradicated from the domestic swine population. The presence of PRV in the wild boar population however poses a risk for possible reintroduction of the virus into the domestic pig population. It is therefore important to assess the genetic relatedness between circulating strains and possible epidemiological links. In this study, nine historical Belgian domestic swine isolates that circulated before 1990 and five recent wild boar isolates obtained since 2006 from Belgium and the Grand Duchy of Luxembourg were genetically characterized by restriction fragment length polymorphism (RFLP) analysis and phylogenetic analysis. While all wild boar isolates were characterized as type I RFLP genotypes, the RFLP patterns of the domestic swine isolates suggest that a shift from genotype I to genotype II might have occurred in the 1980s in the domestic population. By phylogenetic analysis, Belgian wild boar isolates belonging to both clade A and B were observed, while all domestic swine isolates clustered within clade A. The joint phylogenetic analysis of both wild boar and domestic swine strains showed that some isolates with identical sequences were present within both populations, raising the question whether these strains represent an increased risk for reintroduction of the virus into the domestic population.

PATHOGEN EXPOSURE IN FERAL SWINE POPULATIONS GEOGRAPHICALLY ASSOCIATED WITH HIGH DENSITIES OF TRANSITIONAL SWINE PREMISES AND COMMERCIAL SWINE PRODUCTION

Surveys for evidence of exposure to pseudorabies virus (PRV), Brucella suis, swine influenza virus (SIV; human-like H1N1, reassortant type H1N1, H1N2-like H1N1 and H3N2), porcine circovirus 2 (PCV 2), and porcine respiratory and reproductive syndrome virus (PRRSV) in feral swine (Sus scrofa) were conducted in areas where feral swine were geographically associated with high densities of transitional swine premises in South Carolina and high densities of commercial swine production in North Carolina. In South Carolina, 10/50 (20.0%), 7/50 (14.0%), and 29/49 (59.2%) feral swine tested antibody positive for PRV, B. suis, and PCV-2, respectively. Antibodies to PRRSV (0/49) and SIV (0/49) were not detected. In North Carolina, antibodies to PRV and B. suis were not detected in serum samples from 120 feral swine; however, antibodies to PRRSV (1/120 [0.8%]), PCV-2 (86/120 [71.7%]; these included 80 positives plus six suspects), and SIV (108/119 [90.7%]) were present. The presence of PRV and B. suis in South Carolina may have been due to the introduction of infected feral swine into the area or to a previous association of feral swine with infected transitional swine. Their absence in the North Carolina populations may have been due to the absence of these disease agents in the feral swine originally introduced into the area and the lack of a potential for contact with infected commercial swine. Feral swine associated with commercial swine in North Carolina may have been exposed to SIV subtypes circulating in commercial swine via airborne spread of SIV from commercial swine facilities. Feral swine seropositive for PCV-2 were prevalent in both states, which may indicate efficient transmission from commercial swine and transitional swine, or that PCV-2 is widespread in feral swine. The low prevalence of animals with antibodies against PRRSV may indicate a less-than-efficient means of transmission from commercial to feral swine. Additional epidemiologic studies are needed to understand the risks and mechanisms of transmission of disease agents among commercial, transitional, and feral swine, and the role of feral swine as reservoirs of these disease agents.

Propagation of the pseudorabies virus particles to the amygdaloid complex after inoculation into rat's insular cortex

Amygdaloid complex (AC) is a heterogeneous group of subcortical nuclei and cortical structures which has a crucial role in the limbic system functions, and which is interconnected with many brain regions. The projections from the AC to the posterior insular cortex, were studied in 5 male adult rats by retrograde marking of neurons with pseudorabies virus (PRV). After inoculation of PRV into the insular cortex, rats were sacrificed after 51, 57 or 72 hours. The serial sections of AC were examined by using immunohistochemistry, with an antibody against PRV. The goal of this study was to identify the nuclei of rat AC with the presence of PRV, to estimate the density of PRV, and also to note the speed of PRV propagation from the posterior insular cortex to AC. Clear distribution of PRV particles in amygdaloid nucleus was observed in the rat brain after 72 hours while in earlier sacrificed animals (51 and 57 hours) there was no positive reaction. The high density of PRV-immunoreactive neurons was in the ipsilateral lateral and basolateral nucleus, as well as in the amygdalohippocampal area. The lower density was in the ipsilateral basomedial, central, medial, posterior cortical nucleus, and nuclei of lateral olfactory tracts, as well as in the contralateral basomedial nucleus. In conclusion, by PRV retrograde tracing was found that the main projections of AC to posterior insular cortex originate from lateral and basolateral nucleus which are known as important regions of sensory convergence of AC, and from the amygdalohyppocampal area, as well.

PSEUDORABIES VIRUS IN EUROPEAN WILD BOAR FROM CENTRAL ITALY

Tissue and blood samples were collected from 152 wild boars (Sus scrofa) from the Maremma area (Grosseto district, Central Italy) between November 2002 and January 2003. The presence of pseudorabies virus (PRV) antibodies, antigen, and DNA were confirmed by an enzyme-linked immunosorbent assay (ELISA), immunohistochemistry, and polymerase chain reaction (PCR), respectively. Of 152 animals, 62 (41%) were positive for viral antigen in tonsillar tissue. Of the 80 serum samples that were suitable for testing, 41 (51%) were positive for PRV antibodies. Positive immunohistochemistry results were confirmed by PCR. A significantly higher prevalence of PRV antigen and seroprevalence was detected in older animals. No differences were detected between males and females or for animals coming from different areas sampled. Results confirm that PRV is endemic in this wild boar population with a high prevalence of infection. The results of immunohistochemistry investigations demonstrated that a large number of wild boars harbor PRV in tonsillar tissues and should be considered as an important reservoir of PRV.

Mapping the rat somatosensory pathway from the anterior cruciate ligament nerve endings to the cerebrum

The anterior cruciate ligament (ACL) serves as the primary restraint to anterior tibial translation. In addition to this biomechanical function, the ACL appears to have a function in neuromuscular control. This hypothesis was formulated after the discovery of mechanoreceptors within the ACL. The full somatosensory pathway from the ACL to the cerebrum has yet to be elucidated. In order to map this sensory pathway, we conducted a viral trans-synaptic tracing experiment using the neurotropic pseudorabies virus (PRV). The pseudorabies virus was injected into the ACL of rats and allowed to replicate and spread trans-synaptically for 6-7 days. The brain and spinal cord of each sacrificed rat was then removed and processed immunohistochemically to detect the presence of PRV. PRV-immunoreactive neurons were found to be localized in several different regions from the spinal cord to the cerebrum. Four nuclei in the reticular formation of the brain stem demonstrated strong positive labeling: the mesencephalic reticular nucleus, magnocellular reticular nucleus, paragigantocellular reticular nucleus, and gigantocellular reticular nucleus. This finding suggests that the nerve endings of the rat ACL project into the cerebrum and that the reticular formation may play an important role in the afferent pathway of those nerve endings.

Detection of pseudorabies virus genomic sequences in apparently uninfected ‘single reactor’ pigs

With a pseudorabies virus (PrV) gB ELISA, performed on 480,000 pigs on 8,900 Swedish farms, approximately 1,300 cases were observed with only one single animal reacting positively. These animals were termed ‘single reactors’ (SR). In order to find explanations for this peculiar phenomenon, the presence of PrV was investigated in organs of immunosuppressed and non-immunosuppressed SR animals. The virus was not detected by immunohistochemistry, virus isolation or co-cultivation. An in situ DNA hybridization test detected PrV gC gene sequences in the olfactory bulb of one sow. A nested polymerase chain reaction (PCR) assay revealed gB, gE and gD gene sequences of PrV in the tissues of trigeminal ganglia, olfactory bulb, tonsils and brain. The nucleotide sequences of the amplicons revealed 98 to 100% homology with the corresponding sequences of PrV. The large latency transcript (LLT) was not detected in the organs of the SR pigs. Transmission of the SR phenomenon to animals in contact or to the next generation was not observed. Considering the present observations and the facts that (i) PrV vaccination is not applied in Sweden; (ii) the SR animals occur not only in the South, but also in Northern Scandinavia, which has no history of PrV infection and (iii) viral reactivation was not observed under natural conditions or after experimental immunosuppression, it is concluded that the SR phenomenon should hardly be considered as a typical PrV latency. The present findings show that certain herpesviral genomic sequences exist in apparently uninfected individuals.