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SUMMARYPigeon immunoglobulin classes IgG and IgA were purified and specific isotype antisera were produced in rabbits. The antisera were used to develop a quantitative assay for both immunoglobulins.Serum IgG concentrations in relation to age showed a similar pattern in pigeons to that in chickens. The same applies to the transfer of maternal immunoglobulins via egg. Besides this transfer mechanism, an additional transfer of immunoglobulins exists in the pigeon via feeding of crop milk. Crop milk contains considerable amounts of IgA (1.45 mg/ml) and significantly less IgG (0.34 mg/ml). During day 1 intestinal absorption of IgA is possible to a very low extent. Most of the IgA, as well as IgG, remains in the intestine to provide local immunity.

A total of 103 Escherichia coli isolates from psittaciform birds were examined for the presence of genes coding for shigatoxin 1 (Stx1), shigatoxin 2 (Stx2) and for intimin (eae), using the polymerase chain reaction (PCR). Sixty-eight E. coli strains were isolated from necropsy cases and faecal samples, the other 35 were from 205 cloacal swabs from Psittaciformes with various conditions. All isolates were tested for enterohaemorrhagic E. coli-haemolysin (HlyEHEC), some also for Stx production, but there was no geno-typic or phenotypic evidence of Stx in any of them. Seven isolates, six from birds with diarrhoea, harboured the eae gene, three of them belonging to the O110:H6 serotype, one each to serotypes O153:H10, O131:H 2 , O63:H6 and Osp:H6. These seven eae-positive strains were negative for shigatoxin and HlyEHEC, and the hlyEHEC gene was not detectable by PCR. However, a PCR amplifying the enteropathogenic E. coli (EPEC)-speci® c bundle-forming pili structural gene bfpA detected four bfpA positive strains (three of serotype O110:H6, one O131:H 2 ) among the seven eae positive strains, which classi® es them as EPEC. Our ® ndings suggest that shigatoxin-producing E. coli are uncommon, but that EPEC should be considered as potential pathogens in psittaciform birds, which may be a source of human EPEC infections.

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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.