Response to experimental vaccination against newcastle disease in domestic ducks (Anas platyrhynchos): Clinical and immunological parameters

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Immunological and clinical parameters of newcastle disease vaccination in bronze Turkeys (Meleagris gallopavo)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Clinical and immunological aspects of newcastle disease vaccination in budgerigars (Melopsittacus undulatus)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relevance of Chinese goose (Anser cygnoides) in experimental epidemiology of Newcastle disease

This study aimed to characterize the true epidemiological role played by the Chinese goose (Anser cygnoides) as a potential source of infection by the Newcastle disease virus (NDV). For this, Specific-Pathogen-Free chicks (SPF) were used and were housed with Chinese geese that had been inoculated with a pathogenic strain (velogenic viscerotropic, strain São João do Meriti) of NDV (DIE50=108.15/0.1 mL) pathogenic to chickens, by the ocular-nasal route. Each group was composed of 6 SPF Leghorn chicks and 3 geese. At 6 days (Group I) and 14 days (Group II) after inoculation of the Chinese geese with NDV, SPF chicks were put into direct contact with each goose group. Cloacal swabs were collected from both species (Chinese geese and SPF chicks) 6, 10 and 20 days after challenge to genome viral excretion by Reverse Transcription Polymerase Chain Reaction (RT-PCR). Chinese geese did not demonstrate any clinical signs of Newcastle disease (ND). They were refractory to the clinical disease with the NDV. However, NDV genome was detected 20 days after challenge. Therefore, NDV carrier status was demonstrated by Chinese geese. Moreover, 100% of SPF chicks housed with the infected Chinese geese had died by 6 (Group I) and 14 days (Group II) after challenge. Thus, the transmission of the pathogenic virus from the Chinese geese to cohabiting SPF chicks was evident within 20 days of the experimental infection. This reveals the epidemiological importance of Chinese geese as a potential transmitter of NDV infection to other commercial birds that could be raised in close proximity.

Relevance of lovebirds (Agapornis roseicollis Selby, 1836) in experimental epidemiology of Newcastle disease

Studies were made to clarify the role that was played by the lovebirds (Agapornis roseicollis) in the epidemiological plan, under the perspective of its being a potential source of infection of Newcastle Disease Virus (NDV). The study used Specific-Pathogen-Free chicks (SPF) that were housed with lovebirds inoculated with a pathogenic strain (velogenic viscerotropic) of NDV pathogenic to chickens, by the ocular-nasal via. Each group was composed of six SPF chicks and four lovebirds. After five days of the inoculation of the lovebirds with NDV, SPF chicks were put together with each group of lovebirds. Cloacae swabs were collected after 9, 14 and 21 days post-challenge in both species (lovebirds and SPF chicks) for genome viral excretion by Reverse Transcription Polymerase Chain Reaction (RT-PCR). Lovebirds did not demonstrate any clinical signs of NDV. They were refractory to the clinical disease with the NDV. However, NDV genome was detected 9 and 21 days after challenge. This study shows that lovebirds can be carriers NDV. Moreover, 100% of SPF chicks allocated with the infected lovebirds demonstrated clinical signs and lesions suggestive of NDV. In these birds, NDV genome was detected 9, 14 and 21 days after challenge. Thus, the transmission of the pathogenic virus from the lovebirds to SPF chicks that were housed together was evident until 21 days of the experimental infection. This study reveals the importance of lovebirds from the epidemiological point of view as potential source of infection of the NDV to other avian species that could be raised near this species. © Asian Network for Scientific Information, 2012.

Investigation of the state of virus carrier of newcastle disease in budgerigars (melopsittacus undulatus)

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

Humoral antibody immune response of newcastle disease vaccination in lovebirds (Agapornis roseicollis)

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

A liquid-phase-blocking concanavalin A enzyme-linked immunosorbent assay for the detection of antibodies against Newcastle disease virus in serum of free-ranging pigeons

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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.

Proceedings of the conference on Newcastle disease.

Mode of access: Internet.

Sequence variation in the Newcastle disease virus genome

Full-length genome sequences of five virulent and five avirulent strains of Newcastle disease virus isolated between 1998 and 2002 in Victoria and New South Wales, Australia were determined. Comparisons between these strains revealed that coding sequence variability in the haemagglutinin-neuraminidase (HN), matrix (M) and phosphoprotein (P) gene sequences appeared to be more variable than in the fusion (F), nucleocapsid (N) and RNA dependent-RNA replicase (L) genes. Sequence analysis of a number of other isolates made during the recent virulent NDV outbreaks, also identified the presence of a number of variants with altered F gene cleavage sites, which resulted in altered biological properties of those viruses. Quasispecies analysis of a number of field isolates indicated the presence of virulent virus in one particular isolate. Gene sequence analysis of the progenitor virus isolated in 1998 showed very little sequence variation when compared to that of a progenitor-like virus isolated in 2001 demonstrating that in the field. viral genome sequence variation appears to be biologically restricted to that of a consensus sequence. (c) 2005 Elsevier B.V. All rights reserved.

Deduced amino acid sequences surrounding the fusion glycoprotein cleavage site and of the carboxyl-terminus of haemagglutinin-neuraminidase protein of the avirulent thermostable vaccine strain I-2 of Newcastle disease virus

A single-tube RT-PCR technique generated a 387 bp or 300 bp cDNA amplicon covering the F-0 cleavage site or the carboxyl (C)-terminus of the HN gene, respectively, of Newcastle disease virus (NDV) strain 1-2. Sequence analysis was used to deduce the amino acid sequences of the cleavage site of F protein and the C-terminus of HN protein, which were then compared with sequences for other NDV strains. The cleavage site of NDV strain 1-2 had a sequence Motif of (112)RKQGRLIG(119), consistent with an avirulent phenotype. Nucleotide sequencing and deduction of amino acids at the C-terminus of HN revealed that strain 1-2 had a 7-amino-acid extension (VEILKDGVREARSSR). This differs from the virulent viruses that caused outbreaks of Newcastle disease in Australia in the 1930s and 1990s, which have HN extensions of 0 and 9 amino acids, respectively. Amino acid sequence analyses of the F and HN genes of strain 1-2 confirmed its avirulent nature and its Australian origin.

Development of a rapid biological assay for determination of potency of Newcastle disease vaccine (strain I-2)

A rapid biological assay based on incubation time has been developed for determination of the potency of Newcastle disease virus strain I-2 vaccine. It is based on the observation that the interval between inoculation and the first detection of haemagglutinin (HA) depends on the titre of the vaccine inoculated. Chicken embryonated eggs were inoculated with different titres (10(9), 10(6) and 10(3) EID50/0.1 ml) of vaccine and incubated for 24 h. At hourly intervals, 5 eggs from each vaccine titre were tested for the presence of HA. The results showed that the HA activity was detected from 5, 11 and 15 h after inoculation with vaccine doses of 10(9), 10(6) and 10(3) EID50, respectively. On the basis of these results it is suggested that if there is no HA detected from 5 to 11 h after inoculation of eggs with the vaccine virus, the vaccine should not be used to vaccinate chickens as it might have an infectivity titre of less than 10(6) EID50/0.1 ml, which is equivalent to the recommended single chicken dose. It is concluded that measuring the time between inoculation of the vaccine virus and the onset of HA activity might provide an estimate of the titre of the vaccine within 24 h.

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.