A recombinant fowlpox virus (rFPV) coexpressing the Newcastle disease virus (NDV) fusion and hemagglutinin-neuraminidase genes and infectious laryngothracheitis virus (ILTV) glycoprotein B gene was constructed. This virus was then evaluated for its ability to protect specific-pathogen-free (SPF) chickens against clinical symptoms and death after challenge by virulent NDV and ILTV. SPF chickens were grouped and vaccinated with the rFPV and commercial NDV (La Sota) and ILTV attenuated live vaccine (Nobilis ILT), respectively. After challenge with NDV 10 days postvaccination, 70% of chickens vaccinated with rFPV were protected from death, whereas 100% of the commercial NDV-vaccinated chickens were protected from death. In contrast, 100% of the unvaccinated chickens died after challenge. After challenge with ILTV, both the rFPV and commercial ILTV-vaccinated chickens were completely protected from death and 70% of chickens were protected from respiratory signs. In comparison, 100% of the unvaccinated chickens developed severe respiratory disease and 10% of chickens died. The protective efficacy was also measured by the antibody responses and isolation of challenge viruses. Results showed that this rFPV could be a potential vaccine for preventing NDV and ILTV by a single immunization.

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Avibacterium paragallinarum is the causative agent of infectious coryza. Here we report the draft genome sequence of reference strain 221 of A. paragallinarum serovar A. The genome is composed of 135 contigs for 2,685,568 bp with a 41% G+C content.

A blocking enzyme-linked immunosorbent assay (B-ELISA) kit for the diagnosis of infectious coryza was developed in this study. The kit was based on a recently described blocking ELISA that uses monoclonal antibodies to achieve specificity for antibodies to either Haemophilus paragallinaru m serovar A or serovar C. The results showed that the B-ELISA kit detected 96 and 90%, respectively, of chickens vaccinated or challenged with H. paragallinaru m serovar A. When used on chickens vaccinated or challenged with H. paragallinaru m serovar C, the kit detected 77 and 40%, respectively, as positive. The majority of sera from vaccinated chickens were still positive on the serovars A and C ELISAs 4 months after vaccination. Based on pen trial data, the serovar A B-ELISA kit had a sensitivity of 95% and a specificity of 100%. The serovar C B-ELISA kit had a sensitivity of 73% and a specificity of 100%. A range of field sera was examined with the kit, generating results that correlated with the known vaccination/disease history of the flocks examined. As freeze drying the monoclonal antibodies and the conjugate had some effect on optimal working concentration, the kit used liquid solutions of these two reagents. The kit could be stored for 7 days at 37°C, 10 months at 4°C and more than 1 year at -20°C. Our results suggest that the kit would be a useful aid in the diagnosis of infectious coryza in China and other countries where H. paragallinaru m serovars A and C are the predominant or sole serovars.

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