Immunodominant epitopes on the NS1 protein of MVE and KUN viruses serve as targets for a blocking ELISA to detect virus-specific antibodies in sentinel animal serum.

Two mosquito-borne flaviviruses, Murray Valley encephalitis (MVE) and Kunjin (KUN), are the aetiological agents of Australian encephalitis. MVE causes a severe and potentially fatal form of the disease while KUN is responsible for only a few relatively mild cases. Therefore it is important that serological tests used in flavivirus surveillance differentiate between infections with these two viruses. However, this has been hampered in the past by the close antigenic relationships between flaviviruses in traditional serological assays. An epitope blocking ELISA using MVE-specific and KUN-specific monoclonal antibodies (mAb) reacting to the non-structural protein NS1 of these viruses and a flavivirus group-specific mAb reacting to the envelope (E) protein was assessed for testing sentinel animals for seroconversion to specific flavivirus infections. Using these assays we were able to detect serum antibodies to a variety of flavivirus in laboratory infected rabbits, and naturally infected chickens and in the case of primary infections, differentiate those caused by KUN or MVE. These assays are now used routinely in our laboratory for testing chicken sera from sentinel flocks in the Kimberley and Pilbara regions of north Western Australia.

Glycosylation and antigenic variation among Kunjin virus isolates.

Previous studies have found Kunjin (KUN) virus isolates from within Australia to be genetically homogenous and that the envelope protein of the type strain (MRM61C) was unglycosylated and lacked a potential glycosylation site. We investigated the extent of antigenic variation between KUN virus isolates from Australia and Sarawak using an immunoperoxidase assay and a panel of six monoclonal antibodies. The glycosylation status of the E protein of each virus was also determined by N glycosidase F (PNGase F) digestion and limited sequence analysis. The results showed that KUN viruses isolated within Australia oscillated between three antigenic types defined by two epitopes whose expression was influenced by passage history and host cell type. In contrast an isolate from Sarawak formed a stable antigenic type that was not influenced by passage history and was distinct from all Australian isolates. PNGase F digestions of KUN isolates indicated that 19 of the 33 viruses possessed a glycosylated E protein. Nucleotide sequence of the 5' third of the E gene of selected KUN isolates revealed that a single base change in PNGase F sensitive strains changed the tripeptide N-Y-F (amino acids 154-156 of the published sequence) to the potential glycosylation site N-Y-S. Further analysis revealed that passage history also had a significant influence on glycosylation.

The treatment of acute necrotizing ulcerative gingivitis.

The destruction of the interdental papillae and formation of permanent gingival craters are common sequelae of acute necrotizing ulcerative gingivitis. These craters can be disfiguring, especially in the anterior gingiva, and can act as a nidus for recurrent episodes. Traditional therapy has emphasized a surgical approach for elimination of these defects, often increasing the esthetic problems. The purpose of this paper is to review the treatment modalities of acute necrotizing ulcerative gingivitis and illustrate an alternative treatment approach of periodic scaling, root planing, and antimicrobial rinses with 0.12% chlorhexidine. With this therapeutic regimen, the disease process can be reversed and damaged papillae may regenerate.