Vaccination experiments were carried out in Ethiopia to study the efficacy of the NDV-I 2 vaccine against challenge with an Ethiopian velogenic strain of NDV. In experiment A, which comprised 300 broiler chicks, the efficacy of the ocular/drinking water application of the HB1/La Sota vaccine was compared with the ocular/drinking water and the feed application of the NDV-I 2 vaccine on untreated barley and sorghum. The NDV-I 2 vaccine applied by eye-drop or drinking-water protected the chickens against challenge as efficiently as combined HB1/La Sota vaccination but untreated barley and sorghum were unsuitable vaccine carriers. The vaccine virus could not be recovered and chickens neither seroconverted nor were they protected. In experiment B, 120 broiler chicks were divided into 6 treatment groups. One group each received NDV-I 2 vaccine mixed with untreated barley or sorghum which was applied immediately, or 14 h after mixing and standing at ambient temperature. The fifth group was vaccinated intraocularly and via the drinking water with the NDV-I 2 vaccine. The sixth group remained untreated. Experiment B confirmed the results of experiment A. In experiment C, 100 chicks were divided into 5 groups of 20 chickens each. One group each received the NDV-I 2 vaccine on parboiled barley or sorghum as vaccine carriers 0 and 6 h after mixing. The last group remained untreated. Parboiled barley given 0 or 6 h and parboiled sorghum given 0 h after mixing with the vaccine led to seroconversion and protection of the chickens. Parboiled sorghum given 6 h after mixing with the vaccine did not. It is concluded that the thermostable NDV-I 2 vaccine may be a suitable vaccine for oral application under Ethiopian conditions.

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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.

SUMMARYDifferentiation of herpesvirus isolates has been performed mostly on the basis of biological properties and serology. In this study, 15 herpesvirus isolates from different species of birds were compared by restriction endonuclease analysis of genomic DNA. All herpesviruses were isolated in Europe or are used as vaccine viruses there. The isolates could be differentiated into seven groups based on restriction patterns. The largest group contains isolates from passeriform and psittacine birds and could further be subdivided into four subgroups. Two other groups are represented by herpesvirus isolates of quail and crane, and by isolates of pigeon and owl. Duck plague virus, herpesvirus of turkey, infectious laryngotracheitis virus and a herpesvirus isolate from tragopan all exhibited distinct restriction patterns. In general, our results parallel earlier cross-neutralization studies and yield additional, more detailed information on the relationship between different herpesvirus isolates of birds.

The objective of this work was the evaluation under our conditions of two commercial ELISA kits for the detection of antibodies to avian infectious laryngotracheitis (ILT) virus, one from Australia (Trop-ELISA, TropBio) and one from the USA (ProFLOK-ELISA, KPL), and to compare their performance with the conventional serum neutralization test (SNT) in chick embryo liver cells. Repeatability varied considerably, particularly when using the Trop-ELISA. Therefore, if individual results are important, at least two parallel measurements per serum sample are recommended. In 89.3% of the sera tested by SNT, results of two parallel measurements did not vary by more than one 2-fold dilution step. There was good linear correlation between both ELISAs and the SNT, the correlation coef® cient for the Trop-ELISA being r 5 0.758 and for the ProFLOK-ELISA r 5 0.867. The negative/positive cut-off was rede® ned to suit our conditions. Sera with a SN titre of $ 1:4 were considered positive. Sera with # 15% absorption in the ProFLOK-ELISA were considered clearly negative. For the Trop-ELISA, extinctions of $ 0.477 were considered positive, # 0.168 clearly negative. Values in between were regarded as doubtful for young chickens and as possibly due to non-speci® c reactions in older chickens. The sensitivity and speci® city of the ELISAs relative to the SNT were 87 and 77% for the Trop-ELISA, and 95 and 60%, respectively, for the ProFLOK-ELISA. However, the results indicate that the sensitivity of the ELISA is higher than that of the SNT, because most sera showed similar deviations from SNT results with both ELISAs. Generally, both ELISAs were a suitable alternative to the SNT under our conditions, as long as only negative/positive results are required.