Significance of determining intrauterine infections with classical swine plague virus within programme of curbing and eradicating this disease

Abstract

Intrauterine infection of the fetus occurs if a pregnant non-vaccinated sow is infected with the virus of classical swine plague (CSF). The infection of the fetus results in the occurrence of viremia and the distribution of the virus in fetal tissue is similar to the distribution which is established in post-natal infected swine. The objective of these investigations was to determine intrauterine (transplacental) infection in the event of the appearance of CSF in different periods of pregnancy in non-vaccinated and vaccinated sows. The examined material were organs and tissue of fetuses within two examined cases of CSF in non-immune pregnant sows. In the third examined case of CSF, the material comprised the blood of piglets before suckling the colostrum, animals originating from vaccinated sows, at a farm in which CSF had been diagnosed. Samples of tissue and blood of the piglets were examined for the presence of antigens and specific antibodies against the CSF virus using the immunoenzyme technique (ELISA). Even though the investigations were performed on a small number of samples, the obtained results raise the question of the possibility of the occurrence of intrauterine infection with a CSF field virus in sows vaccinated with the C-strain of CSF. The syndrome of a carrier sow and persistent infections are the chief problem factors that need to be considered within the programme of curbing and eradicating classical swine plague.

Ukoliko se suprasna nevakcinisana krmača inficira virusom klasične kuge svinja (KKS) dolazi do nastanka intrauterine infekcije fetusa. Posledica infekcije fetusa je pojava viremije. Distribucija virusa u njihovim tkivima je slična onoj koja se ustanovljava kod postnatalno inficiranih svinja. Cilj ispitivanja je bio ustanovljavanje intrauterine (transplacentarne) infekcije u slučaju pojave KKS u različitim periodima suprasnosti kod nevakcinisanih i vakcinisanih krmača. U okviru dva slučaja KKS kod neimunih suprasnih krmača materijal za ispitivanja je obuhvatao organe i tkiva fetusa. U trećem ispitivanom slučaju KKS, materijal je obuhvatao krv prasadi pre sisanja kolostruma, koja su bila poreklom od vakcinisanih krmača, na farmi gde je dijagnostikovana KKS. Uzorci tkiva i krvi prasadi su ispitivani na prisustvo antigena i specifičnih antitela protiv virusa KKS imunoenzimskom (ELISA) tehnikom. Iako su ispitivanja obavljena na malom broju uzoraka, dobijeni rezultati nameću pitanje mogućnosti nastanka intrauterine infekcije terenskim virusom KKS kod krmača vakcinisanih K-sojem virusa KKS. Sindrom krmače kliconoše i perzistentne infekcije su glavni otežavajući faktori koje je potrebno dodatno sagledavati u okviru programa suzbijanja i eradikacije KKS.