Presence of Linda and Bungowannah pestiviruses in domestic pigs and wild boar . 82

In addition to APPV, another novel pestivirus provisionally termed Linda virus was recently discovered and suggested to be associated with CT in new born piglets (Lamp et al., 2017).

However, Linda virus or related pestiviruses such as Bungowannah virus was never reported from any other location and the epidemiology of these viruses were unknown. Therefore, we investigated the presence of these pestiviruses in domestic pigs and wild boar (Cagatay et al., 2018). The results of our studies demonstrated that pestivirus genomes closely related to Linda virus or Bungowannah virus were absent in the tested domestic pigs from Europe and Asia (Poland, Serbia, Italy, Switzerland, Taiwan) and wild boar from Germany (Cagatay et al., 2018). In agreement with our results, a recent study reported the absence of Linda virus genomes in domestic pig samples obtained between 1986 and 2018 from Switzerland

(Kaufmann et al., 2019). Absence of these viruses in domestic and wild pigs together with the previously reported broad cell culture tropism of Bungowannah virus (Kirkland et al., 2015) suggest a spillover infection of porcine hosts originating from another species. The original host of these pestiviruses remains unknown. In contrast to high genome detection rates of APPV, infections with Linda virus and Bungowannah virus seem to occur very rarely in pig populations. However, there are no tools available for serodiagnosis of Linda and Bungowannah pestiviruses so far. Development of broadly reactive serological assays for detection of antibodies reacting with these two unique pestiviruses, as well as related viruses is of particular interest. The availability of such assays may facilitate the identification of natural hosts of Bungowannah and Linda pestiviruses and will improve our knowledge about the epidemiology of these viruses.

5.3 Wild boar serves as a wild animal reservoir for APPV

Wild boar represents an important wild animal reservoir for porcine pestiviruses such as CSFV (Moennig, 2015). Identification of the wild animal reservoir is a crucial milestone to understand the epidemiology of APPV and implement tailored control strategies. Thus, we investigated the relevance of wild boar as a wild animal reservoir for APPV (Cagatay et al., 2018). Results of our studies showed that APPV is highly abundant in the investigated wild boar population in Lower Saxony (19% genome, 52% antibody detection rates) (Cagatay et al., 2018). Additionally, presence of APPV-specific antibodies in samples from Serbia indicates that APPV is likely to be abundant in other parts of Europe as well (Cagatay et al., 2018). Due to the difficulty of observing the new born piglets, there are no information available regarding the appearance of CT in wild boar. Experimental infections of wild boar should be performed in order to illuminate the ability of APPV to induce CT in wild boar.

Nevertheless, high genome and antibody detection rates suggest that wild boar may serve as a wild animal reservoir for APPV (Cagatay et al., 2018). In contrast to our findings, an

investigated wild boar population from Spain was reported to be almost free of APPV infections (Colom-Cadena et al., 2018). The only APPV genome positive sample showed 100% sequence identity to an APPV that was previously identified from domestic pigs.

However, seroprevalence of APPV has not been investigated and remains unknown for the investigated wild boar population in Spain (Colom-Cadena et al., 2018).

Genetic characterization of APPVs from wildlife provides useful information on the evolution of pestiviruses. APPV variants identified in German wild boar are genetically distinct to the APPVs from domestic pigs, even to those originated from the same region (Cagatay et al., 2018). It was speculated that APPV variants from wild boar might represent the native APPV genotype from the area (Cagatay et al., 2018). Additionally, APPV sequences from wild boar show remarkably close relationships, when compared to the high genetic diversity of APPVs in domestic pigs from the same country of origin (Cagatay et al., 2018). Behavior of wild boar may explain this conservation. Since this species typically do not stray long distances, interactions with other sounders remain limited. In the future, follow up studies from the same area and other regions should be conducted in order to analyze the dynamics and evolution of APPV infections in the wild boar population.

Interestingly, an APPV variant in wild boar from the city of Wolfsburg was identified to be more closely related to the APPVs from domestic pigs (Cagatay et al., 2018). Similar to our findings, a partial APPV sequence obtained from a wild boar near the city of Barcelona was reported to be identical to the APPV sequence identified in domestic pigs from approximately a decade ago (Colom-Cadena et al., 2018). These findings indicate an APPV transmission between domestic pigs and wild boar. Endemics in wild animal reservoir represent a constant threat to domestic pigs in the effected country and neighboring areas. In order to control and eradicate CSFV in the EU, oral immunization of wild boar together with special hunting strategies was applied (Moennig, 2015). If control and prevention of APPV is desired,

infection status of the wild boar populations in surrounding areas must be investigated.

Possible direct or indirect contact between domestic pigs and wild boar must be identified and eliminated. If wild boar populations are ensured to remain small and isolated, infections can be self-limiting as it was observed in CSF infections (Moennig, 2015).