An Ulster 2C strain‐derived Newcastle disease vaccine: Vaccinal reaction in comparison with other lentogenic Newcastle disease vaccines

Abstract

Vaccinal reaction and seroresponse induced by an Ulster 2C strain derived Newcastle disease (ND) vaccine (ND) (PoulvacR NDW Broiler) were compared with those due to three other lentogenic ND vaccines (NDP, LZ58 and Clone 30) used in broilers in the Netherlands. Comparisons were made in SPF-WL hens and commercial broilers with maternally derived antibodies, using a fully standardized model. The criteria used were body weight gain and mortality rate following vaccine aerosol exposure and susceptibility to experimentally induced Colibacillosis. The NDW vaccine was the mildest, followed by Clone 30-, LZ58- and NDP vaccine. Although the seroresponse of SPF-WL hens exposed to NDW vaccine was significantly less than that induced by the other vaccines, the response was still substantial. Seroresponse to NDP-, LZ58- and Clone 30 vaccine did not differ significantly mutually. In broilers, serores-ponses to NDW- and Clone 30-vaccine were similar.

Progression of lesions in the respiratory tract of broilers after single infection with Escherichia coli compared to superinfection with E. coli after infection with infectious bronchitis virus

“…The E. coli strain 506 (O78; K80) was isolated from a commercial broiler (Van Eck and Goren, 1991). The E. coli culture was prepared as described by Matthijs et al (2003) and was used at a concentration of 10 7.6 CFU/ml.…”

“…At each time point, colibacillosis lesions were scored macroscopically. Lesion scoring was performed as described by Van Eck and Goren (1991) in the left and right thoracic airsac, pericardium and liver. Lesion scores ranged from 0 to 3 per organ, leading to a maximum score of 12 per bird (Van Eck and Goren, 1991).…”

Spray drying of an attenuated live Newcastle disease vaccine virus intended for respiratory mass vaccination of poultry

“…These particles are well suited for primary respiratory vaccination of poultry where deposition in the lower airways should be avoided to prevent post-vaccination reactions in the more vulnerable lungs [3][4][5]. To obtain this, vaccination of 1-day-old chickens should be performed with particles larger than 20 m, as determined in a previous study [37].…”

“…Knowing that a dose of approximately 10 3 EID 50 of a Clone 30 vaccine should be inhaled by a chicken to induce a good immune response [4], it can be calculated that each chicken should inhale approximately 10 g of the here developed powder vaccines.…”

“…A first problem is the broad droplet size distribution generated by the nebulizers currently used for liquid spray and aerosol vaccination: the presence of small, inhalable droplets in a coarse spray for primary vaccination often results in post-vaccination reactions [3][4][5] and a large fraction of non-inhalable droplets generated by fine aerosol nebulizers (e.g., 10-1000 m [6]) reduces the efficiency of secondary vaccinations. Furthermore, the efficiency of vaccines administered by spray or aerosol might be jeopardized due to the use of tap water for reconstitution (often containing virucidal agents, such as chlorines) [7], by large shear forces which are applied to the liquid in order to transform it into droplets [8] and most importantly, due to inactivation of the vaccine virus by evaporation of droplets after generation [3,5,9].…”