Detection of Herpesviruses in Wild Bird Casualties in Slovenia

Abstract

The complete host range of avian herpesviruses in wild birds is unknown, and information about nucleotide sequences is available only in limited cases. The aim of this study was to detect the presence of herpesviruses in wild birds and to gain more information about their phylogenetic relationship. Oropharyngeal and cloacal swabs from 447 wild birds from 15 different orders presented as wildlife casualties were examined for herpesvirus presence with PCR targeting a fragment of the DNA polymerase gene. Herpesviruses were detected in oropharyngeal and/or cloacal swabs in 34 (7.5%) birds belonging to 11 species from six different avian orders: Accipitriformes, Charadriiformes, Columbiformes, Falconiformes, Passeriformes, and Strigiformes. The results of phylogenetic analysis showed that various herpesviruses sequences are present in the wild bird population. Some herpesviruses are host species–specific, whereas in some cases very similar sequences were detected through different avian orders, which confirms findings that herpesviruses are not always restricted to bird species. It seems that herpesvirus transmission could occur by predation from avian prey, and even by superpredation—for example, large owls, such as the Eurasian eagle owl (Bubo bubo) or Ural owl (Strix uralensis), preying on smaller raptors. This can lead to greater infection exposure and is in line with the fact that raptors were the most infected species group. Nevertheless, the individual or simultaneous detection of herpesviruses in oropharyngeal and cloacal swabs shows that both swab samples should be used for herpesvirus detection in wild birds.

Infection due to Buteo buteo herpesvirus in a common buzzard (Buteo buteo insularum)

“…CoHV-1 (previously pigeon herpesvirus, falcon Herpesvirus, and stringid herpesvirus) was first described from domestic pigeon ( Columba livia ) lofts in the United States in 1945 ( 29 ) and has subsequently been documented in pigeons around the world ( 6 , 8 , 14 ). CoHV-1 causes a multisystemic disease with high mortality ( 4 , 7 ) when introduced into a naïve or immunosuppressed population of pigeons.…”

“…Experimental infections indicate that the virus can cross between different avian species, including non-raptorial ( 33 ). Natural infections of raptors with CoHV-1 have been observed in North America, Eurasia, and Australia ( 8 , 9 , 11 , 14 ). In contrast to the natural infection of CoHV-1 in columbiformes, which usually causes low mortality because of transmission of maternal immunity, the infection of CoHV-1 in raptors usually causes mortality rates approaching 100% ( 8 , 33 ).…”

“…According to our phylogenetic tree, the closest related viruses to Buteo buteo HV would be a herpesvirus (AY571851) detected in an Indian vulture ( 36 ), and another herpesvirus (MW533128) identified in a golden eagle ( 14 ), both within the same order and family (order Accipitriformes; family Accipitridae) as the common buzzard. The phylogenetic tree also shows that Buteo buteo HV is genetically closely related to other HVs detected in the order Strigiformes, family Strigidae, but more differentiated from other avian herpesviruses such as CoHV-1, Gallid HV-1, and PsHV-1.…”

“…Experimental infections indicate that the virus can cross between different avian species, including non-raptorial (33). Natural infections of raptors with CoHV-1 have been observed in North America, Eurasia, and Australia (8,9,11,14).…”

“…Herpesvirus (HV) infections have been diagnosed in wild birds from America, Europe, the Middle East, Asia, and Australia affecting different avian host species of several different orders, including raptors, columbids, Galliformes, Anseriformes, and psittacines (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14).…”