Long-term stability studies on protection against Newcastle disease by commercial live vaccine used in Brazil

The thermostability (TS) and efficacy offered by live vaccines against Newcastle disease strains B 1, La Sota, VG-GA and Ulster, produced or imported by four Brazilian laboratories, were evaluated during their validity period. Kinetic profiles were obtained from samples conserved in refrigerators during 0, 4, 8, 12, 16, 20 and 24 months after their manufacturing. The statistical analysis of the vaccine titre effect obtained by the fresh air (FA) method showed that the vaccine profiles were parallel and coincident, presenting a significant descending trend. The vaccine titres and efficiency proofs at the end of the validity period were above the level of legislation requirements and showed an average loss in titre of 0.40 and 0.66 log(10), within the first and second validity years, respectively. The titre obtained by TS, within the month after manufacturing, had no significant difference from the titre obtained by FA within 24 months after manufacturing, being their pairs of observations positively correlated (r = 0,49, p = 0.0003), showing that the TS method, which anticipates the vaccines' performance at the end of the validity period, can substitute the FA method 24 months after manufacturing. (C) 2009 The International Association for Biologicals. Published by Elsevier Ltd. All rights reserved.

The haematological profile of female bronze turkeys (Meleagris gallopavo) vaccinated with various commercial strains of Newcastle disease

The effects of vaccination on avian blood parameters are poorly understood. The present study was designed to evaluate whether different strains (Ulster 2C, B1, live LaSota and inactivated LaSota) of Newcastle disease vaccines had an effect on the haematological profile of female turkeys. Seventy-five female turkeys were allocated to treatment groups according to vaccination strain. All the birds, except those in the control group, were vaccinated at 32 weeks of age and revaccinated at 40 and 48 weeks of age. Blood samples were obtained for haematological analyses and serum samples for the haemagglutination inhibition test. Haemoglobin concentration was significantly lower (p < 0.05) in vaccinated female turkeys than in the control birds 28 days after vaccination. Monocytes were significantly higher (p < 0.05) in 44-week-old female turkeys vaccinated with inactivated LaSota strain compared with the other groups. Turkeys vaccinated with the B1 strain showed significantly higher (p < 0.05) total white blood cell counts compared with the other groups vaccinated with various commercial strains of the Newcastle disease virus. In conclusion, female turkeys showed significant differences in haemoglobin concentrations, monocytes and white blood cell counts when vaccinated against Newcastle disease.

Locally produced mucosal IgG in chickens immunized with conventional vaccines for Newcastle disease virus

Newcastle disease virus (NDV) is the causative agent of an economically important disease, which affects all species of birds worldwide. Current vaccination programs for NDV include the use of either low-virulent live-virus vaccines or inactivated vaccines to induce protective immunity while producing minimal adverse effects in birds. In order to further characterize the immune response elicited by live virus and inactivated NDV conventional vaccines in chickens, we evaluated the presence of specific antibodies in different secretions and in tissue culture supernatants of immunized birds. To this end, we analyzed all the samples by ELISA, using an indirect assay set up in the laboratory. Specific anti-NDV IgG antibodies were detected in tracheal and cloacal swabs and tracheal and intestinal washes of immunized animals. We also found specific anti-NDV IgG antibodies in tracheal and intestinal tissue culture supernatants, indicating that the IgG found in swabs and washes was not transudated from serum or, at least, was not all transudated from serum. Knowledge about the mechanisms involved in the immune response of chickens to different NDV vaccines should increase our understanding of the mucosal response against the virus and, eventually, provide new useful information for the development and evaluation of synthetic vaccines.

Newcastle disease virus vaccine strains: Immunogenicity is not influenced by ICPI

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Serum protein profiles of juvenile ring-necked pheasants vaccinated or not against newcastle disease

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determination of organ tropism of Newcastle disease virus (strain I-2) by virus isolation and reverse transcription-polymerase chain reaction

The vaccines 1-2 and V4 are avirulent strains of Newcastle disease virus. Organ tropism of strain V4 has been determined and the virus has a predilection for the digestive tract. Tropism of strain 1-2 has not yet been determined. The objective of this study was to determine the distribution of strain 1-2 in various body organs and fluids following vaccination in comparison with V4. Four-week-old chickens were vaccinated by eye drop separately with these two avirulent strains. Virus isolation and the reverse transcription-polymerase chain reaction technique were employed to detect 1-2 and V4 viruses in various tissues and body fluids for 7 days following vaccination. Tissues from the respiratory tract showed earlier positive signals than tissues from other organs for chickens vaccinated with strain 1-2. Conversely, tissues from mainly digestive tract produced earlier positive signals than from respiratory tract and other organs from chickens vaccinated with strain V4. In early infection, strain 1-2 had preferential predilection for the respiratory tract and strain V4 for the digestive tract. Later after vaccination, other organs showed positive results from chickens vaccinated with both 1-2 and V4 strains. The differences in organ tropism observed in this study suggest that 1-2 may perform better than V4 as a live vaccine strain.

Newcastle disease virus in penguins from King George Island on the Antarctic region

Here we report the isolation of Newcastle disease virus (NDV) from cloacal swabs obtained from penguins in the South Atlantic Antarctic region (62 degrees 08S, 58 degrees 25W). Samples of 100 penguins from King George Island were tested by real-time PCR, of which 2 (2%) were positive for NDV. The positive samples were isolated in embryonated chicken eggs and their matrix and fusion proteins genes were partially sequenced. This was complemented by the serological study performed on the blood of the same specimens, which resulted in a 33.3% rate of positivity. (C) 2010 Elsevier B.V. All rights reserved.

Protection levels of vaccinated pigeons (Columba livia) against a highly pathogenic newcastle disease virus strain

The purposes of this study were to model a vaccination regimen for Newcastle disease virus (NDV) in pigeons, and to evaluate the susceptibility and behavior of vaccinated birds against a highly pathogenic NDV Brazilian strain. Antibody response was assessed by means of hemagglutination inhibition test (HI), and viral genome excretion by means of RT-PCR. Vaccinal strains (La Sota and Ulster) induced high antibody titers without any adverse effects, both in inoculated and in sentinel birds. A viral strain pathogenic for chickens did not produce clinical signs of the disease in experimentally infected pigeons. Only 4 out of 10 vaccinated pigeons shed NDV genome, and just for two days. Results confirmed the high infectivity of the vaccinal strains used, as all nonvaccinated pigeons showed antibody titers as high as those of vaccinated birds.