RESUMEN
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.
Asunto(s)
Pollos , Virus de la Viruela de las Aves de Corral/genética , Infecciones por Herpesviridae/veterinaria , Herpesvirus Gallináceo 1 , Enfermedad de Newcastle/prevención & control , Vacunas Virales/genética , Animales , Anticuerpos Antivirales/biosíntesis , Anticuerpos Antivirales/sangre , Embrión de Pollo , Ensayo de Inmunoadsorción Enzimática/veterinaria , Virus de la Viruela de las Aves de Corral/inmunología , Proteína HN/genética , Proteína HN/metabolismo , Infecciones por Herpesviridae/prevención & control , Herpesvirus Gallináceo 1/genética , Herpesvirus Gallináceo 1/inmunología , Distribución Aleatoria , Vacunas Sintéticas/genética , Proteínas del Envoltorio Viral/genética , Proteínas del Envoltorio Viral/metabolismo , Proteínas Virales de Fusión/genética , Proteínas Virales de Fusión/metabolismoRESUMEN
A fowlpox virus expressing the chicken infectious bronchitis virus (IBV) S1 gene of the LX4 strain (rFPV-IBVS1) and a fowlpox virus co-expressing the S1 gene and the chicken type II interferon gene (rFPV-IBVS1-ChIFNgamma) were constructed. These viruses were assessed for their immunological efficacy on specific-pathogen-free (SPF) chickens challenged with a virulent IBV. Although the antibody levels in the rFPV-IBVS1-ChIFNgamma-vaccinated group were lower than those in the attenuated live IB vaccine H120 group and the rFPV-IBVS1 group, the rFPV-IBVS1-ChIFNgamma provided the strongest protection against an IBV LX4 virus challenge (15 out of 16 chickens immunized with rFPV-IBVS1-ChIFNgamma were protected), followed by the attenuated live IB vaccine (13/16 protected) and the rFPV-IBVS1 (12/16 protected). Compared to those of the rFPV-IBVS1 and the attenuated live IB vaccine groups, chickens in the rFPV-IBVS1-ChIFNgamma group eliminated virus more quickly and decreased the presence of viral antigen more significantly in renal tissue. Examination of affected tissues revealed abnormalities in the liver, spleen, kidney, lung and trachea of chickens vaccinated with the attenuated live IB vaccine and the rFPV-IBVS1 vaccine. In rFPV-IBVS1-ChIFNgamma-vaccinated chickens, pathological changes were also observed in those organs, but were milder and lasted shorter. The lesions in the mock control group were the most severe and lasted for at least 20 days. This study demonstrated that chicken type II interferon increased the immunoprotective efficacy of rFPV-IBVS1-ChIFNgamma and normal weight gain in vaccinated chickens although it inhibited serum antibody production.
Asunto(s)
Infecciones por Coronavirus/veterinaria , Virus de la Viruela de las Aves de Corral/inmunología , Glicoproteínas de Membrana/inmunología , Enfermedades de las Aves de Corral/prevención & control , Proteínas del Envoltorio Viral/inmunología , Vacunas Virales/inmunología , Animales , Anticuerpos Antivirales/sangre , Anticuerpos Antivirales/inmunología , Embrión de Pollo , Pollos/inmunología , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/prevención & control , Inmunidad Humoral , Virus de la Bronquitis Infecciosa/inmunología , Interferón gamma/inmunología , Enfermedades de las Aves de Corral/inmunología , Glicoproteína de la Espiga del Coronavirus , Vacunas Atenuadas/inmunología , Vacunas Sintéticas/inmunologíaRESUMEN
The Fusion (F) and Haemagglutinin-Neuraminidase (HN) genes of Newcastle disease virus (NDV) and the glycoprotein B (gB) gene of infectious laryngothracheitis virus (ILTV) as well as a LacZ reporter gene were all inserted into a nonessential gene of fowlpox virus (FPV) 017 strain by homologous recombination. The NDV and ILTV genes were each under the control of a fowlpox virus immediate early/late promoter (LP2EP2) while the LacZ reporter gene expression cassette was regulated by a P11 late promoter. A recombinant FPV harboring the F, HN and gB genes as well as the LacZ gene, designated as rFPV-F/HN/gB/LacZ, was obtained after ten cycles of blue plaque purification. The presence of the NDV and ILTV genes was confirmed by PCR. The expression of the recombinant proteins in rFPV-F/HN/gB/LacZ were characterized by Western blot (F and gB proteins) and indirect immunofluorescence test (F, HN and gB proteins). The results demonstrated that all four foreign proteins, which were encoded within a 10 kb gene fragment, could be expressed authentically and efficiently. Compared to the parental virus, rFPV-F/HN/gB/LacZ showed no obvious difference with respect to virus replication and cytopathogenic effects in chicken embryo fibroblasts (CEF) cell culture. Overall, our work suggests that FPV can be a useful live virus vector for the expression of multi- foreign genes against multiple avian pathogens.