Viral vectored vaccines are desirable alternatives for conventional infectious bronchitis virus (IBV) vaccines. We have recently shown that a recombinant Newcastle disease virus (rNDV) strain LaSota expressing the spike (S) protein of IBV strain Mass-41 (rLaSota/IBV-S) was a promising vaccine candidate for IBV. Here we evaluated a novel chimeric rNDV/avian paramyxovirus serotype 2 (rNDV/APMV-2) as a vaccine vector against IBV. The rNDV/APMV-2 vector was chosen because it is much safer than the rNDV strain LaSota vector, particularly for young chicks and chicken embryos. In order to determine the effectiveness of this vector, a recombinant rNDV/APMV-2 expressing the S protein of IBV strain Mass-41 (rNDV/APMV-2/IBV-S) was constructed. The protective efficacy of this vector vaccine was compared to that of the rNDV vector vaccine. In one study, groups of one-day-old specific-pathogenic-free (SPF) chickens were immunized with rLaSota/IBV-S and rNDV/APMV-2/IBV-S and challenged four weeks later with the homologous highly virulent IBV strain Mass-41. In another study, groups of broiler chickens were single (at day one or three weeks of age) or prime-boost (prime at day one and boost at three weeks of age) immunized with rLaSota/IBV-S and/or rNDV-APMV-2/IBV-S. At weeks six of age, chickens were challenged with a highly virulent IBV strain Mass-41. Our challenge study showed that novel rNDV/APMV-2/IBV-S provided similar protection as rLaSota/IBV-S in SPF chickens. However, compared to prime-boost immunization of chickens with chimeric rNDV/APMV-2, rLaSota/IBV-S and/or a live IBV vaccine, single immunization of chickens with rLaSota/IBV-S, or live IBV vaccine provided better protection against IBV. In conclusion, we have developed the novel rNDV/APMV-2 vector expressing S protein of IBV that can be a safer vaccine against IB in chickens. Our results also suggest a single immunization with a LaSota vectored IBV vaccine candidate provides better protection than prime-boost immunization regimens.
【저자키워드】 Infectious Bronchitis Virus, avian paramyxovirus vaccine vector, vaccine vector replication, poultry vaccines, 【초록키워드】 Efficacy, Vaccine, Vaccines, immunization, Protein, Effectiveness, vaccine candidate, age, group, homologous, newcastle disease virus, boost, Protective, chimeric, serotype, vectored vaccine, regimens, virulent, embryos, IBV, immunized, shown, evaluated, provided, provide, determine, the S protein, expressing, chick, SPF, expressing S protein, 【제목키워드】 novel, chicken, Comparative,