Saponin-adjuvanted vaccine protects chickens against velogenic Newcastle disease virus

Abstract

Despite extensive vaccination campaigns, Newcastle disease virus (NDV) remains endemic in many countries worldwide, and factors that contribute to this failure include mismatched vaccines, partial immunization, and poor husbandry practices. In order to overcome the problem of genetic divergence between circulating field strains and vaccine strains, we saponin-adjuvanted an Egyptian field strain and assessed its safety and immunogenicity in chickens. Immunization of chickens with the vaccine followed by challenge with a velogenic reference strain revealed the potential of the saponin-adjuvanted vaccine to induce a strong immune response that resulted in complete protection of chickens. Importantly, in vaccinated chickens, virus shedding was abolished, providing an added advantage over the currently available commercial live-attenuated and inactivated vaccines, which are unable to prevent shedding. A histopathological investigation demonstrated that the vaccinated chickens had less-severe lesions than challenged unvaccinated and mock-vaccinated chickens. We propose using this formulation as an alternative and improved NDV vaccine platform that can be exploited to control disease not only in Egypt but also in other disease-endemic countries.

WITHDRAWN: Evaluation of immunity and protection in chicken administered a developed vaccine against predominant Middle Eastern strains of genotypes VI and VII of velogenic Newcastle Disease Virus

“…The significant higher performance of the vaccinated-challenged broilers (TRTs 1, 2, and 3), in comparison to unvaccinated-challenged ones (TRTS 4, 5, and 6) ( Table 5) is most likely due to the significant difference in the vaccine-acquired humoral and CMI, an obtained data that is in agreement with previous documentations [29,30,31,32,33]. The similar high production parameters of lower mortality percent, lower feed conversion, and high live body weight in birds of TRT 7 and those of the negative controls reflect the safety of the developed killed vaccine on production [34], pending avoidance of stress, by careful handling of the birds during the subcutaneous administration of the vaccine.…”

Enhancement of the Immune Iesponse of Chickens Vaccinated With Adjuvanted Live Newcastle Disease Virus Vaccine

“…The results of the lymphocyte proliferation assay in our study revealed gradual increases in optical density in all vaccinated groups and reached the highest stimulation of lymphocyte proliferation at 14 th DPV and these results were nearly similar to El-Dabae et al, (26) who prepared Regarding the challenge test, full protection against sub-genotype VIId NDV challenge was achieved in vaccinated groups 2, 3, 4 and 6, while in vaccinated groups 1 and 5, 90% protection was achieved. A high percent of protection could be explained by previous studies that reported that the efficiency of live ND vaccines depends on the viral titer of the vaccinal dose where a dose of 10 4 -10 5 EID 50 is able to protect the birds against mortality and achieves 100% protection but could not prevent virus replication (29)(30)(31).…”

Avian Paramyxovirus Type 1 in Egypt: Epidemiology, Evolutionary Perspective, and Vaccine Approach

“…Other regions, including the fusion peptide ; heptad repeats a, b, and c (HRa 143-185, HRb 268-299, and HRc 471-500); transmembrane (TM) domain (501-522); and cytoplasmic (CT) tail (523-553) were subjected to aa analysis, where several mutations were reported, which might affect the folding and fusion activities of the protein as described in the fusion peptide (87,88) or the HRa, b, and c (89). The HRa is also supposed to include a potential antigenic epitope (90,(149)(150)(151)(152)(153)(154)(155)(156)(157)(158)(159)(160)(161)(162)(163); however, the Egyptian NDV isolates had only few reports of aa substitutions in this epitope (V168I and D170N). The TM domain affects the structural confirmation of the F protein, F-HN protein interaction, and fusion activity (91).…”

“…In Egypt, many NDV commercial traditional/classical genotype II vaccines are used in the Egyptian poultry field such as (i) live seed virus vaccine strains of LaSota, Hitchner, VG/GA, clone 30, PHYLMV, and others or (ii) inactivated (killed) virus vaccines, mainly the LaSota one (153). Recently, several recombinant and novel inactivated (Genotype VII; GVII) vaccines were introduced gradually to cope with the continuous evolution and spread of velogenic NDV-GVII (154,155). ND is endemic in Egypt, and there is an enormous pressure from the field circulation of diverse genotypes II, VI, and VII; massive poultry production; and direct and/or indirect contact with free-living and migratory birds, which generally represent a significant challenge to poultry holders.…”

“…Regarding the use of one killed vaccine S/C in chickens containing GVII strains, the results revealed 100% protection against clinical signs and mortality post-challenge with a similar genotype (162,164,168), which was accompanied with reduced viral shedding to <2.2 till the 10th day post virus challenge. Other findings included the stoppage at the fifth day (165) or the complete absence of virus shedding (154). Nevertheless, Sedeik et al ( 169) used an inactivated NDV genotype VII vaccine to immunize the birds against a challenged virus from the same genotype, where they showed protection of only 53.3% with presence of clinical signs and virus shedding.…”