A sertéscircovírusok kórtani jelentősége és genetikai jellemzői

Abstract

ÖSSZEFOGLALÁS A szerzők szakirodalmi adatok és saját eredményeik alapján összefoglalják a sertés-circovírusokkal kapcsolatos legfontosabb ismereteket. Míg a PCV1 általánosan apatogénnek tekinthető, a PCV2 jelentős gazdasági károkat okozó, endémiásan keringő vírus a sertésállományokban, amelyet az általa okozott szisztémás, sorvadásos megbetegedés kapcsán azonosítottak. A PCV3 járványtani jelentősége még vitatott, de feltehetőleg szaporodásbiológia zavarokat és szisztémás megbetegedést okozhat. A PCV4-et nemrégiben súlyos légzőszervi megbetegedéses és hasmenéses esetek vizsgálata során írták le. A hazai sertésállományok jelentős részében a PCV2 és PCV3 jellemzően szubklinikai formában kering és a genetikai elemzés alapján a PCV2d és PCV3a genotípus a legelterjedtebb. SUMMARY Based on literature data and their own results, the authors summarize the most important knowledge on porcine circoviruses (PCVs). PCVs belong to the Circovi- rus genus in the Circoviridae family. Circoviruses are among the smallest known viruses, characterized by a circular single-stranded DNA genome. To date, four types of PCVs have been identified. While PCV1 is generally considered non-pathogenic, PCV2 is a globally endemic virus, causing significant economic losses. PCV2 systemic disease (PCV2-SD), formerly called as postweaning multisystemic wasting syndrome (PMWS) was first identified in Canada in the early-mid 90s. PCV2-SD is clinically characterized by respiratory distress, wasting, diarrhea, jaundice and enlarged subcutaneous lymph nodes usually occur in the early phases of the infection. In Hungary, PCV2-SD (PMWS) was first reported in 1999. PCV2 was found to display an extremely high substitution rate, which led to the emergence of eight different genotypes (PCV2a–h) so far. However, most of the currently available vaccines are based on the PCV2a genotype. In 2016, a third circovirus species, PCV3 was identified in the United States in tissues of pigs suffering from PDNS, reproductive failure, myocarditis or multisystemic inflammation. Its exact pathological role is still under debate, but the virus is presumed to cause reproductive disorders in sows and systemic disease in weaned pigs and fatteners. Recently, Chinese researchers identified a new circovirus species, named PCV4, during the examination of severe respiratory disease and diarrhea cases. In Hungary, PCV2 and PCV3 typically circulate in pig populations subclinically, without causing severe clinical symptoms, and genetic analyses have shown that the most widespread genotypes are PCV2d and PCV3a.