PCV2 AND PCV3 GENOTYPING IN WILD BOARS FROM SERBIA

Porcine circoviruses 2 and 3 (PCV2 and PCV3) are known agents of diseases in domestic pigs and wild boars. PCV2 is an economically important pathogen causing porcine circovirus-associated diseases (PCVAD), while the recently discovered PCV3 is associated with similar disorders. Wild boars can serve as a PCV reservoir for domestic pigs, which is a particular risk for pig farms with low biosecurity. Reports of these infections in Serbia are sporadic, and this study was intended as a follow-up to an earlier study. Our aim was to assess the prevalence and genetic characteristics of PCVs circulating in wild boars in a region in north-eastern Serbia with extensive hunting areas. In our study of 103 samples, 17.48% tested positive for PCV2 and 15.53% for PCV3. The low co-infection rates in 2.94% of the PCR-positive samples, suggests these viruses circulate independently. PCV2 prevalence was lower than in our previous study (40.32% out of 124 samples), but the genetic stability of circulating strains was detected with a clear genotype shift towards PCV2d-2. Moreover, this is the first report of PCV3 occurrence in wild boar in Serbia, and the detected strains were grouped into two genotypes: PCV3-1 and PCV3-3c. The PCV3-1 sequences were clustered with German strains, indicating the prevalence of this genotype in Europe. However, no further geographical correlation could be established, as the PCV3-3c representative was separated within the cluster containing Chinese and Indian strains. Furthermore, there was no correlation between PCV positivity and pathological findings in the sampled animals indicating subclinical infection. Genotipizacija PCV2 in PCV3 pri divjih prašičih iz Srbije Izvleček: Prašičja cirkovirusa 2 in 3 (PCV2 in PCV3) sta znana povzročitelja bolezni pri domačih in divjih prašičih. PCV2 je gospodarsko pomemben patogen, ki povzroča bolezni, povezane s prašičjimi cirkovirusi (PCVAD), medtem ko je nedavno odkriti PCV3 povezan s podobnimi boleznimi. Divji prašiči so lahko rezervoar PCV za domače prašiče, kar predstavlja tveganje zlasti za prašičerejske farme z nizko stopnjo biološke varnosti. Poročila o teh okužbah v Srbiji so sporadična, ta študija pa je bila zasnovana kot nadaljevanje predhodne študije. Naš cilj je bil oceniti razširjenost in genetske značilnosti PCV, ki krožijo med divjimi prašiči v regiji severovzhodne Srbije z obsežnimi lovišči. Testirali smo 103 vzorce, od katerih je bilo 17,48 % pozitivnih na PCV2 in 15,53 % na PCV3. Nizka stopnja sočasne okužbe pri 2,94 % vzorcev, pozitivnih na PCR, kaže, da ti virusi krožijo neodvisno. Prevalenca PCV2 je bila nižja kot v naši prejšnji študiji (40,32 % od 124 vzorcev), vendar je bila ugotovljena genetska stabilnost krožečih sevov z jasnim premikom genotipa v smeri PCV2d-2. To je tudi prvo poročilo o pojavu PCV3 pri divjih prašičih v Srbiji, odkriti sevi pa so bili razvrščeni v dva genotipa: PCV3-1 in PCV3-3c. Sekvence PCV3-1 so bile povezane z nemškimi sevi, kar kaže na razširjenost tega genotipa v Evropi. Vendar nadaljnje geografske povezave ni bilo mogoče ugotoviti, saj je bil predstavnik PCV3-3c ločen v skupini kitajskih in indijskih sevov. Poleg tega ni bilo povezave med pozitivnostjo PCV in patološkimi ugotovitvami pri vzorčenih živalih, kar kaže na subklinično okužbo. Ključne besede: PCV2; PCV3; genotipizacija; PCR; divji prašiči