Herpesvirus Infection in a Breeding Population of Two Coexisting Strix Owls

Abstract

Birds are a frequent host of a large variety of herpesviruses, and infections in them may go unnoticed or may result in fatal disease. In wild breeding populations of owls, there is very limited information about the presence, impact, and potential transmission of herpesvirus. The herpesvirus partial DNA polymerase gene was detected using polymerase chain reaction in oropharyngeal swabs of 16 out of 170 owls examined that were captured in or near nest boxes. Herpesvirus was detected in Ural owls (Strix uralensis), in both adults and young, but not in tawny owls (Strix aluco). In yellow-necked mice (Apodemus flavicollis), as the main prey of tawny owls and Ural owls in the area, herpesvirus was detected in the organs of 2 out of 40 mice captured at the same locations as the owls. Phylogenetic analysis showed that the herpesvirus sequences detected in the Ural owls differed from the herpesvirus sequences detected in the yellow-necked mice. The results indicate that herpesvirus infection exists in the breeding wild Ural owl population. However, herpesvirus-infected owls did not show any clinical or productivity deviances and, based on a phylogenetic comparison of detected herpesvirus sequences and sequences obtained from Genbank database, it seems that mice and other rodents are not the source of owl infections. The most probable transmission pathway is intraspecific, especially from adults to their chicks, but the origin of herpesvirus in owls remains to be investigated.

Detection of Herpesviruses in Wild Bird Casualties in Slovenia

“…Within Accipitriformes, herpesvirus sequences detected in five common buzzards were identical and were clustered together with the herpesvirus sequence detected in a golden eagle in our study and with the vulture herpesvirus detected in an Indian vulture (Gyps indicus). Even though raptors, Accipitriformes and Strigiformes, were the most infected group of species, even in this group we found herpesvirusresistant species despite the higher number of individuals being examined-for example, sparrowhawks (Accipiter nisus) and especially tawny owls (Strix aluco)-which also agrees with previous studies (13,15,45).…”

“…These results align with the fact that domestic pigeons are considered a natural reservoir of CoHV-1 and are a potential source of infection for any susceptible native species that might coexist with them or consume them (51). However, in tawny owls no CoHV-1 was detected in this or previous studies (13,15) even though they occasionally prey on domestic pigeons (52); this may be related to their polymorphism (13) or coevolved lower susceptibility to herpesvirus, but this requires further study.…”

“…However, detection and phylogenetic analysis of other herpesvirus sequences detected in three long-eared owls and one Ural owl in this study showed that these herpesvirus sequences have a distant relationship with known CoHV-1 and other alphaherpesvirus partial DNA polymerase sequences. These findings confirm the presence of different herpesvirus in owls (13), in which virus transmission between conspecifics was found to be more likely than transmissions from small mammals consumed as prey (15). However, interspecific disease transmission can take place at least occasionally due to intraguild superpredation; for example, when the Ural owl preys upon the long-eared owl (42).…”

“…The natural host range of avian herpesviruses is highly restricted, and most herpesviruses are thought to have evolved in association with a single host species (23). Although previous studies have detected different partial DNA polymerase sequences in owls and their prey (14,15), some studies describe the detection of identical partial DNA polymerase sequences in different bird species, also suggesting the possible transmission of herpesvirus between species; for example, in domestic pigeons and raptors (10)(11)(12)(13). Some studies also show that some species of large gulls could predate on other bird species, including feral pigeons (46)(47)(48).…”

“…Numerous field studies and detection of CoHV-1 in raptors suggest that consumption of infected prey species, in particular pigeons, is most likely the source of herpesvirus infections in hawks, eagles, and owls (9)(10)(11). Furthermore, CoHV-1 was also detected in other nonraptorial birds (12), and recent studies have shown that many additional herpesviruses, which differ from CoHV-1, have been identified in various live-free living birds such as owls and songbirds (13)(14)(15). In birds of prey, the disease caused by CoHV-1 is known as herpesvirus hepatitis or inclusion body disease, and in some cases it is described as fatal, with mortality approaching 100% (11).…”