Untersuchungen der genetischen Varianz aktueller Isolate des porzinen Parvovirus

Studies on the genetic variability of recent isolates of porcine parvovirus The aim of this study was to review the antigenetic variability of porcine parvovirus and to examine the role of porcine parvovirus in reproductive failure. Organ specimens of 500 fetuses and stillborn piglets from a total of 172 farms were analysed. Total DNA was isolated from the explants and quantitative as well as qualitative PCR was subsequently carried out. In 82 samples (15,8%) out of 28 farms (16,3%), PPV was diagnosed. In this study, we were able to show that rectal swabs are suitable substrates from which to detect porcine parvovirus in sows using a PCR analysis. In 12 out of 19 rectal swabs PPV genome was amplified. In one PPV-positive sample the sow was infected a minimum of 45 days before the rectal swab was collected. An attempt was made to cultivate porcine parvovirus out of 22 PPV-positive organ specimens of different origin. However, only 5 isolates could be cultivated and the production of progeny virus was very low in two of these isolates. Although multiple passages were performed, the virus yield did not increase. As the viral capsid is the target of host protective immunity against PPV, the complete gene of the structural protein of 7 field isolates was amplified and sequenced. The obtained sequences were aligned with the porcine parvovirus-strains NADL-2, Kresse, one challenge-virus of the year 1986 and with the vaccine strain of IDT. The sequence homology among the isolates sequenced is very high (on the level of nucleotide acids minimum 98,7%, on the level of amino acids minimum 97,7). Phylogenetic analysis revealed that there is only a distant relationship between NADL-2, Kresse and the challenge-virus on the hand and the field isolates on the other hand. A comparison of the aligned PPV-sequences from field isolates with the published sequence of two primers recommended for diagnostic PCR revealed single nucleotide differences. Therefore, it appears possible that the primer sequences published may not be suitable for a diagnostic PPV-PCR in the field. Taken as a whole, these data suggest that the porcine parvovirus may have altered antigenetically. Furthermore, the obtained sequences from field isolates of PPV now permit the examination of the antigenetic consequence of this evolution to develop effective vaccines against the PPV strains now present in the field.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Ludwig-Maximilians-Universität

Year

2003

Author dc:creator

• Zimmermann, Pia

Repository record source_url

https://edoc.ub.uni-muenchen.de/1198/

OAI identifier oai:identifier

oai:edoc.ub.uni-muenchen.de:1198