Pseudorabies Virus Infection in Wild Boars in Japan

Abstract

ABSTRACT. In Japan, most pig populations are now free from pseudorabies virus (PRV) due to the recent success of an extensive eradication program. However, PRV infection persists in Japanese wild boars (Sus scrofa leucomystax), representing another potential reservoir for the virus in Japan. In this study, the seroprevalence of PRV in wild boars captured in three different prefectures was ascertained. A virus neutralization (VN) test showed that 6 of 173 serum samples (3%) were positive for VN antibody; glycoprotein E-ELISA revealed infection with the wild-type, but not the available vaccine strain, PRV. These results indicate that PRV has continued to spread among wild boars in Japan.KEY WORDS: Aujeszky's disease, pseudorabies virus, wild boar.J. Vet. Med. Sci. 73(11): 1535-1537, 2011 Pseudorabies virus (PRV), a member of the genus Varicellovirus in the subfamily Alphaherpesvirinae of the family Herpesviridae [9], is the causative agent of a contagious and epidemic disease, Aujeszky's disease, which affects swine at various production phases, causing high mortality in naive and newborn piglets and abortion in pregnant sows. This disease results in significant economic losses for the swine industry [3].In Japan, a PRV eradication program in domestic pigs has been successfully implemented; consequently, most domestic pig populations are now free from wild-type PRV and therefore are not vaccinated with a live attenuated vaccine. As this vaccine virus has a deletion in the glycoprotein E (gE) gene, vaccinated pigs can be serologically differentiated from those infected with wild-type PRV by the gE-ELISA. In 1997, a PRV epidemic in Nara Prefecture, Japan, resulted in the deaths of 24 hunting dogs due to PRV infection acquired after eating raw wild boar (Sus scrofa leucomystax) meat (Kouda, T. et al., In the 129th Annual Meeting of the Japanese Society of Veterinary Science, Tsukuba, 2000). This event suggested that wild boars may represent a potential source of PRV infection for other animals. However, there is currently little information about the present situation of PRV prevalence among wild boars in Japan. Here, we present the results of a seroepidemiological study of PRV in wild boars in Japan in order to clarify the seroprevalence of PRV in this population.A total of 173 serum samples were collected from wild boars in three different prefectures A, B and C, of Japan (Table 1). These three prefectures were located in the western part of Japan, were not next to each other and were free from PRV in their pig populations. Most animals were hunted with government permission during the winter season. Sera were inactivated by incubation at 56C for 30 min and then kept at -20C until use.Cloned porcine kidney (CPK) cells were kindly provided by the National Institute of Animal Health in Japan; these were cultured in Dulbecco's Modified Eagle's Medium (DMEM; GIBCO, NY, U.S.A.) supplemented with 10% fetal calf serum (FCS), 100 U/ml penicillin and 100 μg/ml streptomycin. Subsequently, the PRV Indiana strain was propag...

Monitoring of Pseudorabies in Wild Boar of Germany—A Spatiotemporal Analysis

“…These data indicate a large-scale but patchy distribution pattern with seroprevalences ranging from 0% to 72% depending on the region [7][8][9]. PRV-specific antibodies have also been detected in wild boar in coastal ranges of Northern Africa [10], northern Turkey [11], Japan [12,13] and the Korean peninsula [14]. In contrast, PRV infections appeared to be absent in wild swine of New Zealand, probably due to geographical isolation [15].…”

Influenza A virus infection in Japanese wild boars (<i>Sus scrofa leucomystax</i>)

“…Wild boars play an important role in the spread of viruses, including African swine fever virus [13], hepatitis E virus [16, 20], pseudorabies virus [9, 14] and Japanese encephalitis virus [12], to domestic animals and humans. However, there is currently no information about the IAV infection status in wild boars in Japan.…”

Isolation and characterization of a novel Rhabdovirus from a wild boar (Sus scrofa) in Japan

“…In Japan, wild boars represent a constant threat for introducing the viruses, such as Aujeszky's disease virus, into the commercial swine industry (Mahmoud et al, 2011). Therefore, wild boars may play a role in transmission WBRV1 into swine population in Japan and WBRV1 may have already infiltrated Japanese pig farms.…”

“…Numerous viruses have been detected in wild boar, including hepatitis E virus, Aujeszky's disease virus, porcine reproductive and respiratory syndrome virus, porcine parvovirus, classical swine fever virus, African swine fever virus, swine vesicular virus, swine influenza virus, and porcine circovirus type 2 (Meng et al, 2009;Montagnaro et al, 2010;Vengust et al, 2006;Vicente et al, 2002). In addition, we have recently isolated sapelovirus-like virus (wild boar sapelo virus-like virus 1; WBSV1) (Abe et al, 2011) and have detected antibodies to Aujeszky's disease virus, canine distemper virus, Japanese encephalitis virus, and hepatitis E virus in wild boars in Japan (Hara et al, 2014;Kameo et al, 2012;Mahmoud et al, 2011;Ohno et al, 2009). Human habitation of suburban areas and deforestation for agricultural purposes may increase the chance of wild boar contact with domestic animals and humans.…”