Pseudorabies, or Aujeszky’s disease, is a is a notifiable worldwide infection of of domestic and feral swine that swine that causes economic losses for the swine for the swine industry. In In domestic pigs, the virus is pigs, the virus is responsible for for nervous and/or respiratory symptoms; in in pregnant sows, it is one of the major sows, it is one of the major causes of stillbirth, mummification, embryonic death, and and infertility (SMEDI). It is known that PRV It is known that PRV infection in wild boar is in wild boar is associated with low with low pathogenicity and and attenuated or or absent symptomatology, but but limited information is is available about the about the ability of the virus to of the virus to infect the the foetuses of of infected wild boar wild boar pregnant sows. Due to sows. Due to scarce information about the about the reproductive consequences, we we investigate the the possible intrauterine vertical transmission of the virus in wild boar of the virus in wild boar pregnant sow sow living in a in a highly infected area. A area. A number of 54 of 54 hunted wild boar were wild boar were sampled during 2018–2019, and and blood, genital and nasal and nasal swabs, placenta, and and fetuses were were collected for for serological and and molecular investigations. A A seroprevalence of 74% of 74% (40/54) was was detected, while 1/24 while 1/24 pregnant sow and 1/24 sow and 1/24 pooled foetuses tested positive by PCR (gene gB). This is the first by PCR (gene gB). This is the first evidence of viral of viral detection in in foetuses from from seropositive pregnant wild boar. This wild boar. This finding suggests the the possible pathogenetic role of PRV on role of PRV on pregnancy in wild boar and the in wild boar and the existence of an of an additional transmission route.
Pseudorabies (PR) or Aujeszky’s disease is a notifiable worldwide infection of domestic and feral and wild swine that was first described in the early twentieth century [1][2]. The disease is characterised by neurological and reproductive porcine disorders causing economic losses for the swine industry.
The causative agent is Suid herpesvirus 1 (SuHV-1), also known as pseudorabies virus (PRV), or Aujeszky’s disease virus (ADV), a member of the family Herpesviridae, subfamily Alphaherpesvirinae, genus Varicellovirus [2].
PRV can infect many species, but despite its wide host range, which includes nearly all mammals, the natural hosts for PRV are members of the Suidae family, in particular domestic pigs and wild boar. In these animals, the virus is able to establish a lifelong latent infection in neuronal and non-neuronal cells, so swine and wild boar survive the infection and behave like a reservoir of PRV [3][4].
In pigs, PRV transmission mainly occurs by an oro-nasal route due to the high density of swine in farms, which allows for nose-to-nose contact and disease shedding. The venereal transmission has been suggested as the main route in feral swine and wild boar [2][5][6]. Higher viral seroprevalence in females, along with the presence of viral DNA in nasal secretions, suggests that PRV is mainly transmitted oro-nasally within female groups throughout the year, whereas venereal transmission is limited to the mating season [3][6][7]. Secondary routes of transmission are through contact with fomites or by ingestion of contaminated carcasses of other infected animals, such as feral swine, wild boar, rodents, or carnivores [2][8][9].
Due to great economic impact on the swine industry, most of the European countries have implemented eradication programs with the purpose of eradicating PRV and guaranteeing free trade within Europe[10].
Since the 1980s, PR has spread globally due to the changes in swine management with the rise of intensive farming and to the appearance of highly virulent strains of PRV[2][11]. Therefore, infection, prevention, and control plans including large-scale vaccination with gE-deleted vaccines have been put in place in farmed pigs. To date, the disease has been eradicated within the domestic pig population in several European nations such as Denmark, Finland, Austria, France, Germany, Hungary, Switzerland, Sweden, Slovakia [2]. Canada, New Zealand, and the United States have been declared as “Aujeszky’s Disease-free” [12][13].
Due to scarce information about the reproductive consequences of PRV infection, we investigate the implications of the virus in wild boar pregnant sow living in a highly infected PRV area.
The article has been published on 10.3390/ani10020366