RESUMO
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.
Assuntos
Galinhas , Vírus da Varíola das Aves Domésticas/genética , Infecções por Herpesviridae/veterinária , Herpesvirus Galináceo 1 , Doença de Newcastle/prevenção & controle , Vacinas Virais/genética , Animais , Anticorpos Antivirais/biossíntese , Anticorpos Antivirais/sangue , Embrião de Galinha , Ensaio de Imunoadsorção Enzimática/veterinária , Vírus da Varíola das Aves Domésticas/imunologia , Proteína HN/genética , Proteína HN/metabolismo , Infecções por Herpesviridae/prevenção & controle , Herpesvirus Galináceo 1/genética , Herpesvirus Galináceo 1/imunologia , Distribuição Aleatória , Vacinas Sintéticas/genética , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/metabolismo , Proteínas Virais de Fusão/genética , Proteínas Virais de Fusão/metabolismoRESUMO
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.
