Browsing by Author "Nauwynck, H. J."

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Antigenic differences among porcine circovirus type 2 strains, as demonstrated by the use of monoclonal antibodies
(Journal of General Virology, 2008) Lefebvre, D. J.; Costers, S.; Doorsselaere, J. V.; Misinzo, G.; Delputte, P. L.; Nauwynck, H. J.
This study examined whether antigenic differences among porcine circovirus type 2 (PCV-2) strains could be detected using monoclonal antibodies (mAbs). A subtractive immunization protocol was used for the genotype 2 post-weaning multisystemic wasting syndrome (PMWS)-associated PCV-2 strain Stoon-1010. Sixteen stable hybridomas that produced mAbs with an immunoperoxidase monolayer assay (IPMA) titre of 1000 or more to Stoon-1010 were obtained. Staining of recombinant PCV-2 virus-like particles demonstrated that all mAbs were directed against the PCV-2 capsid protein. Cross-reactivity of mAbs was tested by IPMA and neutralization assay for genotype 1 strains 48285, 1206, VC2002 and 1147, and genotype 2 strains 1121 and 1103. Eleven mAbs (9C3, 16G12, 21C12, 38C1, 43E10, 55B1, 63H3, 70A7, 94H8, 103H7 and 114C8) recognized all strains in the IPMA and demonstrated neutralization of Stoon-1010, 48285, 1206 and 1103, but not VC2002, 1147 and 1121. mAbs 31D5, 48B5, 59C6 and 108E8 did not react with genotype 1 strains or had a reduced affinity compared with genotype 2 strains in the IPMA and neutralization assay. mAb 13H4 reacted in the IPMA with PMWS-associated strains Stoon-1010, 48285, 1206 and VC2002, and the porcine dermatitis and nephropathy syndrome-associated strain 1147, but not with reproductive failure-associated strains 1121 and 1103. mAb 13H4 did not neutralize any of the tested strains. It was concluded that, despite the high amino acid identity of the capsid protein (¢91 %), antigenic differences at the capsid protein level are present among PCV-2 strains with a different genetic and clinical background.
Increased yield of porcine circovirus-2 by a combined treatment of PK-15 cells with interferon-gamma and inhibitors of endosomallysosomal system acidification
(2007-12-17) Misinzo, G.; Delputte, P. L.; Lefebvre, D. J.; Nauwynck, H. J.
Treatment of porcine kidney (PK-15) cells with either interferon-gamma (IFN-g) or endosomallysosomal system acidification inhibitors increases replication of porcine circovirus type 2 (PCV2). In the present study, the effect of a combination of these treatments on the number of infected cells and virus yield was tested. The number of PCV2 (Stoon-1010)-infected PK-15 cells increased in cells treated with ammonium chloride (445 39% increase), IFN-g (446 8%), ammonium chlorideþ IFN-g (1721 283%), chloroquine diphosphate (1037 121%), chloroquine diphosphateþIFN-g (2199 255%), monensin (950 178%) and monensinþIFN-g (1948 60%). Combined IFNg and endosomal-lysosomal system acidification inhibitors increased PCV2 yield by up to 50 times compared to untreated PK-15. This augmented virus replication in PK-15 cells may be helpful in the production of PCV2 vaccines.