Avian reovirus (ARV) is a disease agent that causes economic losses in the poultry industry. The available vaccines do not confer full protection. One possible reason is the existence in the field of many virulent serotypes with no cross protection. Several ARV strains have been isolated in Israel in the last few years. In this study, we investigated the diversity of the sigma C protein of ARV because this is the most variable protein in the virus and it induces the production of neutralizing antibodies. Sigma C from two virulent isolates was sequenced, cloned, and expressed. The protein sequence differed from the attenuated vaccine strain (strain 1133) but was similar to a U.S. virulent strain (strain 1733). Those differences led to a change in the antigenic index of the protein, mainly at three sites. Sera of infected birds in a field trial and of birds in a controlled experiment vaccinated with the recombinant sigma C protein showed high titers in enzyme-linked immunosorbent assay to the recombinant protein and lower titers to the attenuated vaccine strain. This means that sigma C can be used as a diagnostic tool for the detection of antibodies relevant for protection and in the future as a subunit vaccine. The results of this study highlight the need to reconsider vaccinations against ARV in terms of the strains to be used and of the method of identifying protective antibodies transferred to progeny.

The impact of chicken infectious anemia virus (CIAV) infection on commercial chicken flocks in Israel was examined by analyzing flocks with or without typical CIAV signs, signs of other diseases, or apparently healthy flocks. In 23 flocks (broilers and layers) of ages up to 8 wk, typical signs of CIAV infection (stunting, gangrenous dermatitis, and secondary bacterial infections) were recorded. When permitted by flock owners, in several cases among these 23 flocks the morbidity, mortality, and performance parameters were recorded; the presence of CIAV was detected by polymerase chain reaction (PCR); and the antibody status of parents and broilers was measured. In addition, total mortality, number of birds sold, total kilograms of meat sold, density (kg/m2), mean age at slaughter, daily growth rate in grams, total kilogram of food consumed, food conversion rate, and the European Index were calculated. We also surveyed flocks affected by other diseases, such as tumors, respiratory diseases, or coccidiosis, and flocks with no apparent clinical signs. The latter flocks were negative by CIAV-PCR, indicating that typical CIAV clinical signs are associated with one-step PCR-CIAV amplification. However, a small amount of CIAV might still be present in these flocks, acting to induce the subclinical effects of CIAV infection. These data indicate a link between the presence of virus sequences and typical CIAV signs and strengthen the concept that CIAV infection has a negative economic impact on the chicken industry.

A novel infectious bronchitis variant, designated as IS/885/00, associated with nephritis, was isolated from outbreaks in 23 broiler farms in Israel. The virus was first identified by reverse tran scriptase-polymerase chain reaction and showed a distinct restriction fragment length polymorphism pattern from previously described Israeli isolates. Sequence analysis of the S1 gene and the deduced amino acid sequence revealed 97.2% protein similarity to genotype IS/720/99 and 71.6% similarity to the vaccine strain HI 20, the only strain permitted for use in this country. A database search in GenBank revealed a closely related isolate from Egypt, Egypt/Beni-Seug/01, with 96.6% similarity. Other published nephropatbogenic infectious bronchitis virus strains/isolates shared less than 77% similarity with IS/885/00. A vaccine protection test ill specific-pathogen-free chicks indicated 91% protection to the trachea and only 25% protection to the kidneys in vaccinated birds challenged with IS/885/00.

The incidence of Campylobacter jejuni/coli was examined in five flocks of broilers monitored from hatch to slaughter, in feed and water and in litter samples. A total of 1440 samples from 720 broilers was examined. Campylobacter spp. were not isolated from broiler chicks at 1 day of age and were only isolated from one broiler chick in one flock at 1 week of age. In three flocks Campylobacter spp. were isolated from all chicks sampled at 4 weeks of age. In the fourth flock all chicks sampled were negative until 8 weeks of age when all were positive. The fifth flock remained negative throughout the 8 weeks of its life. Campylobacter spp. were not found in 20 samples of food and water. Of 20 litter samples they were found in only two. Eleven broiler flocks were examined only at slaughter. Twenty-four caecal samples were examined from each flock. In three flocks no Campylobacter spp. were isolated, in one flock one broiler chick was positive and in seven flocks from 58% to 100% of sampled broilers were positive. A total of 146 isolates was typed; 123 were C. jejuni and 23 C. coli, these belonged to 46 serotypes. In some flocks several serotypes were identified, some of them were not found again on further examinations of the same flocks during the growing period.