Large and small plaque-forming viruses were isolated from the Onderstepoort strain of canine distemper virus (CDV). Small plaque virus, which was released more slowly from infected cells than large plaque virus, readily established persistent infections in Vero cells, whereas large plaque virus required undilute passage to do so. All persistently infected cultures eventually released small plaque virus. No difference was found in the size of polypeptides induced by either plaque-purified viruses or virus released from persistent cultures. Both dilute and undilute passage, large plaque virus produced an acute neurological illness in weanling hamsters, whereas small plaque virus failed to produce any clinical signs of disease for 3 months after inoculation. After this period 50% of the animals infected with small plaque virus showed a general deterioration in their condition and lesions were observed in the brain which resembled those found in cases of large plaque virus infection. Serum-neutralizing antibody titres to CDV rapidly increased after infection with small plaque virus, whereas animals infected with large plaque virus had low or undetectable levels. All hamsters infected with small plaque virus and a small number which survived large plaque virus infection had elevated titres of antibody over a test period of 15 months.
CampbellJ. J.,
CosbyS. L.,
ScottJ. K.,
RimaB. K.,
MartinS. J.,
AppelM.1980; A comparison of measles and canine distemper virus polypeptides. Journal of General Virology 48:149–159
ConferA. W.,
KahnD. E.,
KaestnerA.,
KrakowkaS.1975; Biological properties of a canine distemper virus isolate associated with demyelinating encephalomyelitis. Infection and Immunity 11:835–844
HallW. W.,
MartinS. J.,
GouldE. A.1974; Defective interfering particles produced during the replication of measles virus. Medical Microbiology and Immunology 160:155–164
LincolnS. D.,
GorhamJ. R.,
OttR. L.,
HegrehergG. A.1971; Etiologic studies of old dog encephalitis. I.Demonstration of canine distemper viral antigen in the brain of two cases. Veterinary Pathology 8:1–8
ReculardP.,
GuillonJ. C.1972; Etude experimentale de quelques souches du virus de la maladie de Carre du chien. Identification et definition des souches varientes. Annates de L’Institut Pasteur 123:477–487
RimaB. K.,
DavidsonW. B.,
MartinS. J.1977; The role of defective interfering particles in persistent infection of Vero cells by measles virus. Journal of General Virology 35:89–97