Can genotype mismatch really affect the level of protection conferred by Newcastle disease vaccines against heterologous virulent strains?. Issue 27 (22nd June 2018)

• Record Type: Journal Article
• Authors: Liu, Haijin; de Almeida, Renata Servan; Gil, Patricia; Majó, Natàlia; Nofrarías, Miquel; Briand, François-Xavier; Jestin, Véronique; Albina, Emmanuel
• Is Part Of: Vaccine. Volume 36:Issue 27(2018)
• Page Start: 3917
• Page End: 3925
• Publication Date: 2018-06-22
• Subjects: Newcastle disease -- Vaccine -- Genotype mismatch -- Viral shedding -- Protection; Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2018.05.074
• Languages: English
• ISSNs: 0264-410X

Abstract

Highlights: Commercial ND vaccine could not prevent chicks from viral shedding of genotype XI NDV. Genotype II and XI ND vaccines were generated by reverse genetics. Both vaccines protected chickens from ND caused by genotype II, VII and XI NDV. Both vaccines totally stopped viral shedding from different NDV genotypes. Genotype mismatch alone is not the reason for ND outbreaks in immunized chickens. Abstract: Newcastle disease (ND), caused by virulent class II avian paramyxovirus 1 (Newcastle disease virus, NDV), occurs sporadically in poultry despite their having been immunized with commercial vaccines. These vaccines were all derived from NDV strains isolated around 70 years ago. Since then, class II NDV strains have evolved into 18 genotypes. Whether the vaccination failure results from genotype mismatches between the currently used vaccine strains and field-circulating velogenic strains or from an impaired immune response in the vaccination remains unclear. To test the first hypothesis, we performed a heterologous genotype II vaccine/genotype XI challenge in one-day old specific pathogen free (SPF) chicks and reproduced viral shedding. We then produced two attenuated strains of genotype II and XI by reverse genetics and used them to immunize two-week old SPF chickens that were subsequently challenged with velogenic strains of genotypes II, VII and XI. We found that both vaccines could induce antibodies with hemagglutination inhibition titers higher than 6.5 log2 . Vaccination also completely prevented disease, viral shedding in swabs, and blocked viral replication in tissues from different genotypes in contrast to unvaccinated chickens that died shortly after challenge. Taken together, our results support the hypothesis that, in immunocompetent poultry, genotype mismatch is not the main reason for vaccination failure.