Avian paramyxovirus serotype 1 isolates from the spinal cord of parrots display a very low virulence.
The spinal cord of 32 psittacines suffering from proventricular dilatation disease (PDD) was investigated. In six cases, a virus was isolated which upon electron microscopic examination revealed morphological details typical of members of the Paramyxoviridae. All isolates were subsequently characterized as avian paramyxovirus serotype 1 (APMV-1) by type-specific polyclonal antisera. According to their reactivity with APMV-1 specific monoclonal antibodies, the six isolates shared epitopes within the haemagglutinin-neuraminidase spike protein, distinct from pigeon-type paramyxoviruses and the LaSota vaccine strain. This grouping was further corroborated by properties of the haemagglutinin: all isolates showed a very thermosensitive haemagglutination activity and were rapid eluters. Virulence of the APMV-1 isolates in 1-day-old specific pathogen free (spf) chicken was very low, with intracerebral pathogenicity indices between 0 and 0.1. In embryonated spf chicken eggs, psittacine isolates replicated to high titres (10(8.6)-10(10.7) EID50/ml). However, they exhibited a reduced lethality over an observation time of 7 days (10(6.1)-10(8.3) ELD50/ml). In a haemagglutination inhibition test with parrot sera from birds with no history of APMV-1 vaccination, sera reacted preferentially with two isolates compared with APMV-1 vaccine strains LaSota and B1. The other four isolates exhibited a differentiated reaction pattern with the parrot sera, indicating an antigenic inhomogeneity. This is the first report of isolating very low virulent APMV-1 from neuronal tissue of parrots and implications for a possible role in slow progressing disease will be discussed.
Grund
C H
CH
Institut für Geflügelkrankheiten, Ludwig-Maximilians-Universität München, Oberschleissheim, Germany. christian.grund@avian.vet-med.uni-muenchen.de
Werner
O
O
Gelderblom
H R
HR
Grimm
F
F
Kösters
J
J
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002645:Chickens / Q000821:virology; D005260:Female; D005858:Germany / Q000453:epidemiology; D006386:Hemagglutination Tests / Q000662:veterinary; D008297:Male; D009521:Newcastle Disease / Q000453:epidemiology* / Q000821:virology*; D009522:Newcastle disease virus / Q000276:immunology* / Q000302:isolation & purification / Q000472:pathogenicity* / Q000648:ultrastructure; D010063:Ovum / Q000821:virology; D011563:Psittaciformes / Q000821:virology*; D012703:Serotyping; D013047:Specific Pathogen-Free Organisms; D013116:Spinal Cord / Q000821:virology; D037521:Virulence Factors
D000911:Antibodies, Monoclonal; D037521:Virulence Factors