Department of Veterinary Tropical Distes, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
Abstracts of the papers presented at the International Conference of Indian Virological Society on “Emerging and Re-emerging viral Diseases of the Tropics and Subtropics” at Indian Agricultural Research Institute, New Delhi, India, December 11–14, 2007.
Comparative studies of canine distemper virus (CDV) strains from Africa with that of other established lineages have been hampered for a long time because of lack of field strains from Africa for in vitro experiments. Since the isolation of the Onderstepoort vaccine strain in the 1930s, there has not been any reports of CDV isolations in Southern Africa, thus the need to isolate field CDV from clinical specimens and provide a pool of local strains for characterization. Clinical specimens consisting of whole blood, spleen, brain and cerebrospinal fluid from dogs with clinical signs suggestive of distemper were collected from Veterinary clinics and laboratories in South Africa. The animals displayed the catarrhal, systemic, and nervous forms of the disease. 125 specimens from 98 dogs were inoculated into Vero cells expressing canine signalling lymphocyte activation molecule with a tag (Vero.DogSLAMtag). Cytopathic effect (CPE) in form of syncytia formation was observed in 28 specimens within 24 hours of inoculation and CDV was confirmed by immunofluorescence and electronmicroscopy. We have generated a pool of local isolates of wild-type CDV for further molecular characterisation and showed that virus isolation remains a useful adjunct for diagnostic virology testing. Enlarging the collection of CDVs from Africa and CDV-specific sequences obtained globally from a growing number of host species would provide the basis for understanding the molecular epidemiology of CDV and the improvement of current CDV vaccines. We conclude that CDV isolation from whole blood using Vero.DogSLAMtag represents a specific and sensitive method for the antemortem diagnosis of distemper in dogs; it is also a relatively cheap way to confirm CDV in living animals in addition to yielding viruses for studies on the emergence, evolution, maintenance of CDV and the efficacy of vaccines against changing viruses. This report for the first time isolation of wild-type CDV from Africa using Vero.DogSLAMtag.
