Efficacy of Vaccination against Infection with Velogenic Newcastle Disease Virus Genotypes VI and VII 1.1 Strains in Japanese Quails

Evaluation of the Newcastle disease virus genotype VII-mismatched vaccines in SPF chickens: A challenge efficacy study

Newcastle disease virus (NDV) strains, while falling under a single serotype, are classified into distinct genotypes. Genotype VII virulent NDVs pose a significant threat to poultry due to their association with high mortality rates and economic losses. This study aimed to evaluate the efficacy of three commercial live vaccines based on genotype II against genotype VII virulent NDV (vNDV) in specific pathogen-free (SPF) chickens. Forty one-day-old chickens were randomly divided into four groups (n = 10) and inoculated with one dose of each ND pneumotropic vaccine-B1, Clone.12IR, and La Sota-or received phosphate-buffered saline (PBS) as a control at eight days of age via eye drop. At 28 days of age (20th post-vaccination days), chickens were intramuscularly challenged with genotype VII virulent NDV (≥ 105 LD50). Serum samples were collected at 28 days of age (challenge day), 7 and 14 post-challenge days to measure NDV antibodies via the hemagglutination inhibition (HI) test. Cloacal and oropharyngeal swabs were taken on the 3rd, 5th, 7th, and 10th post-challenge days to evaluate virus shedding. Vaccinated groups exhibited significantly higher antibody titers and greater protection levels compared to the control group (P≤ 0.001). While HI antibody titer was not different at 28 and 35 days of age between vaccinated chickens, the Clone.12IR groups showed higher HI antibody titer compared to B1 at day 42 of age (9.43 vs. 7.42; P≤ 0.002). La Sota and Clone.12IR vaccines demonstrated superior protection against mortality compared to the B1 vaccine (90 %, 80% vs. 60 %, respectively) with 6.0 and 2.67 odds ratio of survivability. All three mismatched vaccines effectively curbed the shedding of virulent genotype VII NDV, with 0 % to 11 % positive cloacal samples up to the 3rd post-challenge day. These findings demonstrate that in the experimental setting, the administration of mismatched ND vaccines, particularly La Sota and Clone.12IR, confer protection against genotype VII virulent NDV and control viral shedding, which can help to develop effective vaccination strategies to mitigate the impact of vNDV outbreaks in the poultry farms.

Superior Efficacy of Apathogenic Genotype I (V4) over Lentogenic Genotype II (LaSota) Live Vaccines against Newcastle Disease Virus Genotype VII.1.1 in Pathogen-Associated Molecular Pattern-H9N2 Vaccinated Broiler Chickens

A comparison of the efficacy of apathogenic genotype I (V4) and lentogenic genotype II (LaSota) strains of live Newcastle disease virus (NDV) vaccines was performed following vaccination with pathogen-associated molecular pattern (PAMP) H9N2 avian influenza vaccine and challenge with velogenic NDV genotype VII.1.1 (vNDV-VII.1.1). Eight groups (Gs) of day-old chicks were used (n = 25). Groups 1-4 received a single dose of PAMP-H9N2 subcutaneously, while Gs (1, 5) and (2, 6) received eye drops of V4 and LaSota, respectively, as two doses. All Gs, except for 4 and 8, were intramuscularly challenged with vNDV-VII.1.1 at 28 days of age. No signs were detected in Gs 1, 5, 4, and 8. The mortality rates were 0% in Gs 1, 4, 5, and 8; 40% in G2; 46.66% in G6; and 100% in Gs 3 and 7. Lesions were recorded as minimal in Gs 1 and 5, but mild to moderate in Gs 2 and 6. The lowest significant viral shedding was detected in Gs 1, 2, and 5. In conclusion, two successive vaccinations of broilers with a live V4 NDV vaccine provided higher protection against vNDV-VII.1.1 challenge than LaSota. PAMP-H9N2 with live NDV vaccines induced more protection than the live vaccine alone.

Immunological evaluation of inactivated Newcastle disease vaccine depending on adjuvant composition

Newcastle disease is a global problem that is being recorded in most countries and also a serious obstacle to exchange of genetic material of poultry in various countries of the world. Control of the Newcastle disease comprises correct injection of efficacious vaccines so as to decrease or eliminate the clinical disease. Our goal was to perform comparative studies of the vaccines against Newcastle disease of water in oil type, the adjuvant being mineral oil mixed with emulsifiers (Span-80 and Tween-80) and ready-to-use adjuvant system (Montanide ISA 70), and study the impact of composition of adjuvant constituent on physical-chemical and immunogenic properties of inactivated vaccines. To reproduce virus-containing material and carried out titration of the viruses, we used chicken embryos free of pathogenic microflora. Aqueous phase for the preparation of emulsion-based vaccines of water in oil type consisted of antigen to Newcastle disease of La-Sota strain, manufactured by Biotestlab Ltd, and phosphate-saline buffer. To evaluate the effectiveness of the vaccine and induce immune response, we used 1-day old pathogen-free chickens, which were obtained from chicken embryos free of pathogenic microflora. As the positive control in the experiment, we used commercial vaccine. One-day chickens were divided into 3 groups (I, II, III) comprising 12 individuals each and one group (IV) consisting of 8 individuals as the control group with individual numeration. Chickens in groups I, II and III were divided into two subgroups (n = 8 and n = 4) to determine immunogenic efficiency and safety of the vaccine. Immunization was carried out through single subcutaneous injections in the region of the neck. To study immunogenic efficiency, the chickens were immunized with the dose of 0.1 mL (1 dose), and 0.2 mL (2 doses) to determine safety. After the immunization of 1-day old pathogen-free chickens with 0.1 mL dose, the obtained level of antibodies in the serum of vaccinated chickens on days 14, 21, 28, 35 and 42 after the vaccination indicated the ability of provoking the immune response to Newcastle disease at high level and safety of the vaccination for chickens. All the recipes of the examined series of the vaccines and the commercial vaccine produced appropriate level of viscosity according to the criterion equaling ≤ 200 mm2/s at Р <0.05, promoting fluidity of the vaccine and providing easier passage through the needle during the application. Both of the studied vaccines may be used in poultry farming for prophylaxis of Newcastle disease among chickens.